Strategic interventions in clinical randomized trials for metabolic dysfunction-associated steatotic liver disease (MASLD) and obesity in the pediatric population: a systematic review with meta-analysis and bibliometric analysis

Abstract

Background

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as non-alcoholic fatty liver disease (NAFLD), is a prevalent hepatic condition linked to metabolic alterations. It gradually causes liver damage and potentially progresses to cirrhosis. Despite its significance, research, especially in the pediatric population, is limited, leading to contradictory findings in diagnosis and treatment. This meta-analysis aims to synthesize existing literature on therapeutic interventions for MASLD in children and adolescents.

Methods

A comprehensive search of randomized controlled clinical trials yielded 634 entries from PubMed, Scopus, and Web of Science up to 2023. Interventions included medications, behavioral modifications, dietary changes, probiotics, supplements, surgical procedures, or combinations. The analysis focused on studies with treatment duration of at least 3 months, employing a random-effects REML meta-analysis model. Treatment effects on anthropometric measurements and biochemical components were examined and adjusted for heterogeneity factors analysis. A bibliometric analysis for insights into research contributors was performed.

Results

The systematic review incorporated 31 clinical trials, with 24 meeting criteria for meta-analysis. These comprised 3 medication studies, 20 with supplements, 4 focusing on lifestyle, and 4 centered on diets. Significant overall treatment effects were observed for ALT, AST, BMI, and HOMA-IR mainly by supplements and lifestyle. Meta-regression identified age, BMI changes, and treatment duration as factors modifying ALT concentrations. Bibliometric analysis involving 31 linked studies highlighted contributions from 13 countries, with the USA, Spain, and Chile being the most influential.

Conclusions

We conclude that supplementation and lifestyle changes can effectively impact ALT and AST levels, which can help address liver issues in obese children. However, the evaluation of risk bias, the high heterogeneity, and the bibliometric analysis emphasize the need for more high-quality studies and broader inclusion of diverse child populations to provide better therapeutic recommendations.

Trial registration

PROSPERO, CRD42023393952. Registered on January 25, 2023.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12916-024-03744-x.

Background

The metabolic dysfunction-associated steatotic liver disease (MASLD), formerly named non-alcoholic fatty liver disease (NAFLD), is a prevalent hepatic condition associated with metabolic disruptions leading to gradual liver tissue damage (steatosis and steatohepatitis) and eventual progression to cirrhosis or subsequent hepatocellular carcinoma [1]. In the pediatric population, MASLD is one of the leading causes of chronic liver disease, and its global prevalence has been estimated between 7 and 35%, depending on the diagnosis method, setting population, and geographical region [2]. The prevalence is higher in children and adolescents with obesity (about 34.2%) [2] and is expected to increase alongside the global obesity pandemic. The causes of MASLD include hormonal, genetic, or lifestyle-associated factors, alongside cardiometabolic risk factors (excess of adipose tissue, high lipid profile levels, insulin resistance, or glucose intolerance).

Additionally, studies have identified genetic mutations affecting hepatic fat metabolism that increase the risk of MASLD (i.e., PNPLA3 1148 m and TM6SF2 E167K) [3]. Despite its clinical consequences, pediatric MASLD is commonly underdiagnosed due to the lack of accurate, validated, and accessible diagnostic tools in clinical settings.

No effective treatments are currently available for MASLD in adult and pediatric populations [4]. The focus of management revolves around lifestyle modifications (diet and exercise), food supplements (e.g., vitamin E, probiotics, omega-3 fatty acids), and bariatric surgery [5]. Dietary improvements and increased physical activity are primary treatments for pediatric MASLD due to its strong association with excess weight gain and obesity. Lifestyle intervention studies vary significantly in design, duration, inclusion criteria, outcomes, and approaches, and interpreting results is challenging [6].

Aims

Considering the clinical relevance of MASLD in the pediatric population and the scarce evidence about effective interventions for this condition, the primary objective of this study was to identify and synthesize studies of therapeutic interventions for MASLD in children and to perform a meta-analysis to calculate the effect of different therapeutic strategies targeted to improve biochemical, anthropometric, and histological parameters related to MASLD and its progression stages. This study includes the most significant number of analyzed studies and synthesizes the latest evidence to offer a robust and nuanced understanding of the efficacy and safety of various interventions.

Additionally, a bibliometric analysis [7, 8] was conducted to analyze the research landscape, identify gaps, and elucidate the impact and network of researchers within this field. This exploration aimed to identify evolving themes and treatments, offering insights into future trajectories for research.

Methods

This systematic review followed the PRISMA (Preferred Reporting Items for Systemic Reviews and Meta-Analyses) guidelines for systematic reviews and meta-analyses [9]. The protocol for this study was registered in PROSPERO on January 25, 2023, and assigned the registry number CRD42023393952 [10].

The research question was developed using the PICO (patients, intervention, comparison, outcomes) framework as follows:

Participants/population

We included randomized controlled clinical trials (RCTs) involving pediatric patients of all ages and both sexes diagnosed with metabolic-associated fatty liver disease (MAFLD), non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), fatty liver, and liver steatosis. Analysis for sex comparison was not possible as most papers did not analyze these contrasts.

Intervention

Only studies that addressed treatments to improve MASDL in children and adolescents were included. Therapeutic interventions included alternative medicine, pharmacological approaches, nutritional interventions, behavioral interventions, and surgical procedures.

Comparisons

The systematic review included RCTs comparing treatments or strategies, including but not limited to placebo, medication, behavioral modifications, dietary changes, probiotics, supplements, and surgical procedures. To mitigate the placebo effect, studies with a minimum treatment duration of 3 months were eligible for inclusion in the meta-analyses.

Outcomes

Data extraction focused on assessing the size of treatment effects on various parameters, including hepatic enzymes (alanine aminotransferase (ALT), aspartate transaminase (AST), gamma-glutamyl transferase (GGT), anthropometric measurements (BMI, body fat percentage, waist circumference), biochemical components (HDL-cholesterol (HDL-C), triglycerides (TG), glucose, LDL-Cholesterol (LDL-C)), and other cardiometabolic risk factors (insulin resistance measurements, total cholesterol (TC), uric acid).

Search strategies

The search strategies employed Ovid MEDLINE, Cochrane CENTRAL, and Web of Science databases to retrieve literature published up to 2023, explicitly targeting randomized controlled clinical trials. The search terms utilized subject headings and keywords related to NAFLD, NASH, fatty liver, and liver steatosis. Pediatric population descriptors were adapted from LeClercq et al. [11]. The Cochrane Highly Sensitive Search Strategy was incorporated to identify randomized trials in MEDLINE, Ovid Format (2008 revision). No restrictions regarding date, language, or filters were applied to the search. The search strategy initially developed for Ovid MEDLINE was subsequently adapted for use in Cochrane CENTRAL and Web of Science. The Supplementary Literature Research Strategy (Additional File 13: Supplementary file 13) provides detailed information on the used literature search.

To expand our literature search, we proactively contacted authors from obesity and diabetes meetings with abstracts, aiming to include any additional studies and gray literature in our analysis.

Eligibility criteria for outcomes of MASLD

The systematic review considered RCTs that evaluated the effect of therapeutic interventions in the pediatric population (18 years or younger) diagnosed with MASLD, NAFLD, NASH, fatty liver, and liver steatosis diagnosed by biochemical, image tools, or liver biopsy. The range of interventions encompassed pharmaceutical, behavioral, surgical, nutritional, and alternative approaches. Our criteria did not impose limitations based on language, sex, or blinding status. Exclusions comprised retrospective and observational studies, commentaries, expert opinions, editorials, and other non-original studies. Studies in children with diabetes diagnoses were excluded. For the meta-analysis, interventions with less than 12 weeks of treatment were excluded, while those falling below this threshold were included in the qualitative systematic review.

Studies selection

Study entrees were initially retrieved from three databases: Ovid Medline (n = 448), Cochrane CENTRAL (n = 429), and Web of Science (n = 596).

Data extraction process

Post-search, all identified citations were compiled and imported into EndNote 20 (Clarivate Analytics), with duplicates removed. A pilot title/abstract screening involving 1,106 citations was executed using Rayyan [12], ensuring a minimum 75% agreement between reviewers before the formal review commenced. Subsequently, abstracts and titles were screened independently by 27 reviewers against the inclusion criteria using Rayyan, and at least two independent reviewers screened each paper.

A data extraction adapted from the Cochrane Collaboration was used for data collection. Detailed information was extracted, such as type of intervention, age of participants, treatment duration, year of study development, country of residence, eligibility criteria, sample size, definition of intervention and control groups, treatment blinding, and effect sizes (Cohen’s d). Discrepancies were resolved through re-analysis by groups of four investigators. The authors were contacted for additional information when necessary. The main outcomes focused on ALT, AST, GGT, TG, LDL-C, HDL, TC, glucose, HOMA-IR, BMI reduction, waist circumference, body fat percentage, and biochemical metabolism parameters considered as associated outcomes.

Quality and risk of bias assessment

The planned quality assessment involved the Jadad scale [13] and the risk of bias using the description of randomization, blinding withdrawals, and dropouts in the studies.

Both the study scanning and selection, along with data extraction using the Cochrane tool and quality assessment via the Jadad scale, were carried out in a paired manner by investigators to minimize bias. For the systematic review, studies with a Jadad score greater or equal to 3 were included, while those with a score > 3 were included for the meta-analysis.

We evaluated the risk of bias (RoB) that reflects the methodological quality of the included studies using the criteria published by Higgins et al. [14] that include the following domains assessed: (1) random sequence generation, (2) allocation concealment, (3) blinding participants and personnel (performance bias), (4) blinding of outcome assessment (detection bias), (5) incomplete outcome data (attrition bias), (6) selective reporting (reporting bias), and (7) other bias. The evaluation was done by groups of three researchers to obtain agreement with the scores and was reviewed by another independent team.

This assessment helps to determine the reliability and validity of the included studies in a systematic review or meta-analysis, ensuring that the conclusions drawn are based on robust and credible evidence with graphics generated for easy interpretation of the results (Fig. 2).

Fig. 2.

Risk of bias assessment. Low risk of bias (green) indicates that the study has a low likelihood of bias affecting the results. Unclear risk of bias (yellow) indicates insufficient information to determine the risk of bias. A high risk of bias (red) indicates that there is a high likelihood that bias could have influenced the study’s results. The right column shows treatment’s groups. Using multiple combinations of interventions increases the complexity and does not allow blindness implementation

Statistical analysis

Sample size, means, and standard deviations were extracted from the included studies’ data for the statistical analysis. Cohen’s d size of effects with 95% confidence intervals (95% CI) was computed to summarize contrasts between intervention types and overall interventions. All models were analyzed using restricted maximum likelihood (REML) random effects models due to the high variation between the effect sizes.

Heterogeneity was assessed using tau² and I² statistics. The tau² measures the between-study variance in a random-effects meta-analysis to quantify the variability in effect sizes attributable to heterogeneity rather than chance. The tau² specifies the value of the between-study variance parameter or the random effects in meta-regression. Meanwhile, the I² statistic describes the proportion of total variation in study estimates due to heterogeneity rather than chance [15].

In order to address bias in the randomization process such as significant differences in basal weight between treatments in some studies, we adjusted the meta-analysis using mean baseline values [16] and effect sizes, assessed with Hedges’ g [17], to correct for small sample sizes. We have displayed unadjusted and adjusted results in forest plots for ALT, AST, BMI, and HOMA-IR. These results indicate similar point effect estimates with small standard errors. In addition, we performed meta-regressions to examine potential sources of heterogeneity, considering mean age, mean BMI, gross domestic product (GDP) by country, sex distribution, and study duration as contributing variables.

The Egger test was conducted on the slopes in the weighted regression of the effect size to evaluate the presence of publication bias.

Sensitivity analysis

The sensitivity analysis was performed with a one-study-removed to evaluate the stability and reliability of the meta-analysis results. This strategy helped to detect any single study that significantly altered the pooled effect size (Additional File 14: Supplementary file 14).

Statistical analyses were performed with Stata 18.0 (StataCorp, College Station TX).

Bibliometric analysis

A bibliometric analysis of the papers in this systematic review was conducted to identify research networks investigating therapeutic interventions for MASLD in children and trends and co-occurrence of themes in the literature. The bibliometric analysis was performed with the VOSviewer release 1.6.19 [18].

The analysis sought to identify relationships between investigators, so researchers with at least two published studies were included. The methodology incorporated performance measurement (research impact), network analysis, and scientific mapping to conduct a systematic evaluation of citation patterns, publication trends, and author collaborations [19–21].

Results

A total of 1473 studies were initially retrieved from three databases: Ovid Medline (n = 448), Cochrane CENTRAL (n = 429), and Web of Science (n = 596). After removing duplicates and applying eligibility criteria, 1386 studies were excluded, leading to the final inclusion of 87 studies. Figure 1 presents a PRISMA flow diagram detailing the study retrieval and screening process.

Fig. 1.

PRISMA 2009 flow diagram for study selection

These 87 studies underwent data extraction using the Cochrane tool and were subsequently assessed for quality using the Jadad scale. Following a thorough third-round screening based on inclusion criteria, 31 studies were ultimately selected for the systematic review, with 24 chosen for the subsequent meta-analysis (Fig. 1).

Characteristics of included studies

In the systematic review, 31 controlled clinical trials involving overweight and obese children subjected to various weight-loss interventions were considered. The distribution of interventions was as follows: pharmaceutical (3 studies), supplements (21 studies), lifestyle modifications (2 studies), diet (6 studies), supplement plus lifestyle (2 studies), and diet plus supplement (1 study). An aggregate analysis of the studies is described in Table 1. Three studies evaluated at least two different types of interventions [22–24].

Table 1.

Characteristics of the analyzed interventions (n = 31). Mean age was adjusted by study's group sample size. *For the cross-over design, the mean age was not provided

Type of intervention	N (31)	Control group mean age	Intervention group mean age	References
A. Medication	3	12.6	13.1	[6, 22, 23]
B. Supplementation	20
B1. Only supplements	17	12.0	11.7	[25–41]
B2. Supplements + Lifestyle	2	12.8	12.3	[24, 42]
B3. Supplements + Diet	1	4 to 14 years*		[43]
C. Lifestyle	2	14.3	15.0	[44, 45]
D. Diet	6	13.6	13.7	[46–51]

The age differences among strategies for intervention show minor variability. The average age for medications was 12.6 years for the control group and 13.1 years for the intervention group. In contrast, dietary-only interventions exhibited comparable ages between groups (13.6 for controls and 13.7 for interventions). Supplement-only studies included younger individuals, with mean ages of around 12.0 years for the control group and 11.7 years for the intervention group. Lifestyle interventions predominantly involved older children, with mean ages of 14.3 for the control group and 15.0 for the intervention group. These age trends could suggest intervention strategies tailored for different age groups or developmental stages.

Participant countries

The geographical distribution of participant cities revealed Italy with the highest frequency of studies (n = 11), followed by the USA (n = 7) and Iran (n = 5). Other contributing countries included Turkey, Brazil, Egypt, China, Hong Kong, India, South Korea, Poland, Spain, Sri Lanka, and Thailand.

Risk of bias and quality assessment

For the studies included in the meta-analysis, the median total Jadad score was 5 (IQR: 4–5). According to the evaluation, 95.8% (n = 23) of the studies reported an adequate blinding method, and 91.6% (n = 22) used an adequate randomized method.

Regarding the risk of bias, we found that most of the included studies had a low overall risk of bias, as shown in Fig. 2. Because of the nature of the intervention, the studies with diet were not blinded to participants or health personnel.

Synthesis of results

This systematic review and meta-analysis included data from 2066 participants across randomized controlled studies targeting children with MASLD. The median of participant children per study was 60 (Q1 = 44, Q3 = 75). The predominant interventions frequently employed, either individually or in combination, were supplements, diet, lifestyle modifications, and medications (Table 1). The characteristics of the included studies are described in Table 2.

Table 2.

Descriptive analysis of the systematic review

Author, year, country	Participants (inclusion criteria)	Sample size	Intervention implemented (INT)/versus placebo (PLB) or control (CTL)	Type of intervention	Treatment duration (months)	Objective	Significant differences between groups and variables
1) Nobili V, [25] 2006, Italy	1. Children (aged 3–18 years) 2. Persistently elevated serum aminotransferase levels 3. Diffusely echogenic liver in imaging studies suggestive of fatty liver 4.No use of drugs known to induce steatosis	Total: 90 INT: 45 PLB: 45	INT: vitamin E (600 IU/day) and vitamin C (500 mg/day) + diet PLB: nutritional counseling + placebo	Supplement	12	To compare the effect of a nutritional programed alone or combined with alpha-tocopherol and ascorbic acid on alanine aminotransferase (ALT) levels, and insulin resistance (IR) in biopsy-proven NAFLD children	Yes: Among subjects who lost excessive weight, ALT and body weight percentage changes were significantly related. HOMA-IR and ALT significantly decreased in both groups No: The addition of antioxidant vitamins E and C to a healthier diet and daily regular physical activity seems to have no significant effect on reducing circulating ALT levels, liver brightness, and IR in NAFLD children
2) Nobili V, [26] 2008, Italy	1. Persistently elevated serum aminotransferase levels 2. Diffusely echogenic liver on imaging studies suggestive of fatty liver 2. Biopsy consistent with the diagnosis of NAFLD	Total: 53 INT: 25 PLB: 28	INT: vitamin E (600 IU/day) and vitamin C (500 mg/day) + lifestyle intervention PLB: capsules of placebo + lifestyle intervention	Supplement	24	To determine the efficacy of lifestyle intervention with or without antioxidant therapy in pediatric NAFLD	Yes: Lifestyle intervention with diet and increased physical activity induces weight loss and significantly improves liver histology and laboratory abnormalities in pediatric NAFLD No: Alpha-tocopherol plus ascorbic acid does not seem to increase the efficacy of lifestyle intervention alone
3) Wang CL, [42] 2008, China	1. Children 10–17 years 2. BMI > 95th percentile for age and sex 3. NASH (ultrasound) 4. ALT > 1.5 times over the upper normal limit	Total: 76 INT1: 19 INT2: 19 CTL: 38	INT 1: lifestyle intervention (summer camp) INT 2: vitamin E (100 mg/day) CTL: without any intervention	1. Lifestyle 2. Supplement	1	To investigate the short-term effect of a lifestyle intervention on liver biochemistry and fasting insulin levels and compare it with that of vitamin E therapy in obese children with NAFLD	Yes: Both a short-term lifestyle and vitamin E therapy were effective in NAFLD. Compared with vitamin E, lifestyle intervention is more effective (triglyceride, cholesterol, and insulin resistance)
4) Akcam M, [22] 2011, Turkey	1. Children 9–17 years 2. Liver steatosis and obesity	Total: 67 INT1: 22 INT2: 22 CTL: 23	INT1: metformin (850 mg/day) INT2: Vit E (400 IU/day) CTL: diet, exercise, and behavioral therapy	1. Medication 2. Supplement	6	To evaluate the therapeutic effect of vitamin E and metformin in a population of obese adolescents with NAFLD	Yes: Metformin treatment is more effective than dietary advice and vitamin E treatment in reducing insulin resistance and ameliorating metabolic parameters such as fasting insulin and lipid levels in obese adolescents with NAFLD
5) Lavine J, [23] 2011, United States	1. Patients aged 8 to 17 years with NAFLD (defined by liver biopsy demonstrating > or equal 5% fat content) 2. Persistently elevated levels of ALT were eligible	Total: 173 INT1: 58 INT2: 57 PLB: 58	INT1: vitamin E (400 mg/day) INT2: metformin (500 mg/day) PLB: identical placebo	1. Supplement 2. Medication	24	To evaluate whether reduction in ALT defined as 50% or less of the baseline level or 40 U/L or less at visits every 12 weeks from 48 to 96 weeks of treatment. Improvements in histological features of NAFLD and resolution of NASH were secondary outcome measures	Yes: The mean change in hepatocellular ballooning scores at 96 weeks was significant with vitamin E and metformin compared to placebo No: Neither vitamin E nor metformin was superior to placebo in attaining the primary outcome of sustained reduction in ALT level in patients with pediatric NAFLD
6) Nobili V, [27] 2011 Roma	1. Persistently elevated serum alanine transaminase (ALT ≥ 40 U/l) 2. Diffusely hyperechogenic liver at ultrasonography 3. Liver biopsy consistent with NAFLD	Total: 60 INT1: 20 INT2: 20 CTL: 20	INT1: DHA (250 mg/day) INT2: DHA (500 mg/day) CTL: linoleic acid (290 mg/day) supplied with germ oil	Supplement	6	To investigate whether dietary supplementation with docosahexaenoic acid (DHA) decreases liver fat content in children with non-alcoholic fatty liver disease (NAFLD)	Yes: DHA supplementation for 6 months reduced liver fat content and increased insulin sensitivity in children with NAFLD. However, 250 mg/day of DHA was as effective as 500 mg/day in obtaining these outcomes No: There was no effect on alanine transaminase and body mass index
7) Nobili V, [28] 2013, Italy	1) Age < 18 years 2) Persistently elevated serum alanine transaminase (ALT 40 U/L) 3) Diffusely hyperechogenic liver at ultrasonography 4) Liver biopsy consistent with NAFLD	Total: 60 INT1: 20 INT2: 20 PLB: 20	INT1: DHA (250 mg/day) INT2: DHA (500 mg/day) CTL: linoleic acid (290 mg/day) supplied with germ oil	Supplement	24	This study aimed to determine whether dietary supplementation with docosahexaenoic acid (DHA) can decrease liver fat content in children with NAFLD	Yes: DHA supplementation improved liver steatosis in children with NAFLD. Doses of 250 mg/day and 500 mg/day of DHA appear equally effective in reducing liver fat content Triglycerides were lower in the DHA groups than in the placebo group at any time, and ALT was lower in these groups from month 12 onwards. HOMA was lower in the DHA 250 mg group vs. placebo at months 6 and 12
8) Ghergherehchi R, [29] 2012, Iran	1. Children with BMI higher than 97th percentile for age and sex 2. ALT, AST levels at least 1.5 times more than the upper limit of normality (5–40 IU/L) 3. Signs of hepatic steatosis in ultrasonography	Total: 33 INT: 17 PLB: 16	INT: vitamin E (400 mg/day) + lifestyle PLB: placebo + lifestyle	Supplement	6	The purpose of this study was to investigate the effects of administering vitamin E for six months on the serum levels of hepatic enzymes and liver lipid content	Yes: In 6 months of therapy, there was a significant change in body mass index, serum aminotransferases, triglycerides, total cholesterol, and low-density lipoprotein-cholesterol levels in both groups No. ALT decreased to normal levels in 8 of 17 patients (47.05%) in the lifestyle and vitamin E group and 7 of 16 patients (43.75%) in the lifestyle and placebo group. Similarly, the improvement in the grade of steatosis on ultrasonography after intervention was the same in both groups
9) Jin Rl, [51] 2014, USA	1) Self-identification as Hispanic 2) Ages 11–18 years; BMI ≥ 85th percentile for age and gender 3) Average self-reported consumption of at least 3 servings of sweet beverages (equivalent to 24 fl oz) per day	Total: 21 INT: 12 CLT: 9	INT: 3 servings (8 fl oz bottles) of study-provided beverages daily (33 g of glucose per serving) CLT: 3 servings (8 fl oz bottles) of study-provided beverages each day (33 g of fructose per serving)	Diet	1	To evaluate whether hepatic steatosis and associated cardiovascular risk factors would be improved after 4 weeks of substitution of usual high fructose-containing beverages with study-provided glucose-only beverages	No: there was no significant change in hepatic fat or body weight in either group Yes: In the glucose beverage group there was significantly improved adipose insulin sensitivity, high sensitivity C-reactive protein (hs-CRP), and low-density lipoprotein (LDL) oxidation
10) Alisi A, [30] 2014, Italy	1.BMI > 85th percentile 2. Biopsy-proven NAFLD	Total: 44 INT: 22 PLB: 22	INT: VSL#3 (sachets) + lifestyle intervention PLB: placebo sachets + lifestyle intervention	Supplement	4	To assess the effect of VSL#3 supplementation on fatty liver	Yes: Supplementation with VSL#3 significantly improves fatty liver and BMI in children with NAFLD No: No between-group differences were detected in triglycerides, HOMA and ALT
11) Janczyk W, [31] 2015, Poland	1. Age > 5 < 19 years 2. Overweight or obesity 3. ALT activity ≥ 1.3 times the upper limit of normal 4. Presence of hyperechogenic liver on ultrasound or 5. Liver histology consistent with NAFLD/nonalcoholic steatohepatitis	Total: 64 INT: 30 PLB: 34	INT: omega-3 fatty acids, DHA and EPA (450–1300 mg/day) PLB: omega-6 sunflower oil	Supplement	6	To evaluate the efficacy and safety of omega-3 fatty acid supplementation in children with nonalcoholic fatty liver disease (NAFLD)	Yes: Patients in the omega-3 group had lower levels of aspartate aminotransferase and gamma-glutamyl transpeptidase, and significantly higher levels of adiponectin No: Omega-3 fatty acid supplementation did not increase the number of patients with decreased ALT levels, and it did not affect liver steatosis on ultrasound
12) Miccheli A, [32] 2015, Italy	1. BMI > 85th percentile 2. Biopsy-proven NAFLD	Total: 44 INT: 22 PLB:22	INT: VSL#3 (1 sachet/day if the subject’s age was < 10 years, 2 sachets/day in children aged ≥ 10 years) PLB: placebo (1 sachet/day if the subject’s age was < 10 years, 2 sachets/day in children aged ≥ 10 years)	Supplement	4	To identify urinary metabolic profiles, characterizing the effect of VSL#3 treatment on obese NAFLD children undergoing a lifestyle intervention	Yes: Supplementation with VSL#3 significantly improved fatty liver and BMI and provided differentially expressed urinary metabolites ('biomarkers') in children with NAFLD, as compared with the placebo group
13) Pacifico L, [33] 2015, Italy	1. Age < 18 years 2. BMI > 85th percentile according to age- and gender 3. Persistently elevated ALT levels 4. NAFLD diagnosis by MRI and liver biopsy consistent with NAFLD	Total: 51 INT. 25 PLB: 26	INT: DHA (250 mg/day) PLB: linoleic acid (290 mg/day)	Supplement	6	To analyze whether 6-month treatment with DHA improves hepatic fat. Secondary: Waist circumference, ALT, triglycerides, insulin, hepatic fat fraction, visceral adipose tissue, epicardial fat	Yes: DHA supplementation decreases liver and visceral fat and ameliorates metabolic abnormalities (ALT, triglycerides, BMI, insulin sensitivity) in children with NAFLD No: There were no significant between-group changes for LV function
14) Della Corte C, [34] 2016, Italy	1. Age 4–16 years 2. Liver biopsy result consistent with a diagnosis of NAFLD/NASH 3. Decreased serum vitamin D levels (< 20 ng/ml) 4. ALT levels < 10 upper limit of normal 5. No laboratory and/or clinical signs of liver decompensation	Total: 41 INT:18 PLB:23	INT: DHA (500 mg/day) + vitamin D (800 IU/day) PLB: identical capsules (placebo)	Supplement	12	To test the effect of daily DHA (500 mg) plus vitamin D (800 IU) treatment, in obese children with biopsy-proven NAFLD and vitamin D deficiency, in a randomized, double-blind placebo-controlled trial	Yes: DHA plus vitamin D treatment reduced the NAFLD Activity Score (NAS), in the treatment group (5.4 v1.92; p < 0.001 for baseline versus end of study). The triglycerides (174.5 vs. 102.15 mg/dl), ALT (40.25 vs. 24.5 UI/l) and HOMA-IR (4.59 vs. 3.42) were all decreased with treatment No: There was no change in fibrosis score
15) Famouri F, [35] 2017, Iran	Children 5–16 years with NAFLD	Total: 40 INT:20 PLB: 20	INT: silymarin tablets (5 mg/kg/d, divided 3 doses with meal) + lifestyle PLB: lifestyle	Supplement	3	To investigate about this herbal drug on recovery of liver function tests and sonographic changes	Yes: Silymarin can improve fatty infiltration of liver and liver function in children and adolescents. ALT, AST, and TG were improved significantly No: LDL and HDL did not change during intervention in case group
16) Famouri F, [36] 2017, Iran	1. Children 10–18 years 2. BMI ≥ 85th percentile 3. Sonographic findings of NAFLD	Total: 64 INT: 32 PLB: 32	INT: Prokid -Lactobacillus and Bifidobacterium (1 capsule/day) CTL: placebo capsule	Supplement	3	To evaluate the effects of some probiotics on sonographic and biochemical NAFLD	Yes: Supplementation with probiotic can be effective in improving pediatric NAFL. ALT, AST, cholesterol, HDL, TG, and waist circumference decreased After the trial, compared with the placebo group, the frequency of normal liver ultrasonography was significantly higher, and the frequency of high-grade fatty liver was significantly lower than the placebo group (p < 0.05)
17) De Lira CT, [44] 2017, Brazil	1. Age 13–18 years with good general health 2. BMI > 95th percentile according to the Centers for Disease Control (CDC) 3. Tanner stage 3 to 4	Total: 84 INT1: 26 INT2: 25 CTL: 33	INT1: high-intensity training (HIT) + nutritional, psychological and clinical counseling. INT2: low-intensity training (LIT) + nutritional, psychological and clinical counseling CTL: adolescents with lower intrinsic motivation	Lifestyle	3	To evaluate the effects of low versus high-intensity aerobic training on biomarkers related to NAFLD in adolescents with obesity	Yes: A significant improvement in lipid profile, ALT, AST, BMI, and fat mass was observed, irrespective of the intensity of aerobic training
18) Schwimmer JB, [50] 2018, USA	1. Adolescent boys aged 11 to 16 years 2. Clinical-pathological diagnosis of NAFLD and current evidence of active disease	Total: 40 INT: 20 CTL: 20	INT: low sugar diet CTL: usual diet	Diet	2	To test the hypothesis that free sugar restriction would reduce hepatic fat content in children with NAFLD	Yes: Significant improvement in hepatic steatosis. ALT and total cholesterol levels improved No: There were no changes in glucose, insulin, and insulin resistance
19) Chan DFY [45], 2018, Hong Kong	1. Post-pubertal adolescents aged 14-–8 years 2. Primary obesity (BMI ≥ Pc 95th of a local reference)	Total: 52 INT: 26 [20] CTL: 26 [22]	INT phase I (INT PI): dietitian-led lifestyle modification intervention (D-MLP) Maintenancephase II (INT MPII): bimonthly visits for dietary advice (P-CON) CTL: usual clinical routine pediatric consultations	Lifestyle	16	To evaluate the efficacy of a dietitian-led lifestyle modification programed (D-LMP) to reduce NAFLD in obese adolescents	Yes: A dietitian-led lifestyle modification intervention reduced intra-hepatic triglyceride content (IHTC), BMI z-score and body fat in obese Chinese adolescents with NAFLD
20) Nobili V, [37] 2019, Italy	1. Children 4–16 years with liver steatosis (with biopsy) 2. ALT levels < 10 upper limit of normal 3. Without signs of liver decompensation	Total: 70 INT: 35 PLB: 35	INT: hydroxytyrosol (HXT) (oral dose of 7.5 mg + 10 mg of vitamin E) PLB: capsules of placebo	Supplement	4	To test the potential efficacy, assessed by improvement of oxidative stress parameters and liver ultrasound, and tolerability of a mixture of vitamin E and HXT in children and adolescents with biopsy proven NAFLD	Yes: The treatment improved the main oxidative stress parameters (carbonylated proteins (PCOs), S-nitrosylated proteins (PSNOs) and advanced glycation end products (AGEs)), insulin resistance (TG, fasting insulin and HOMA-IR), and steatosis in children with NAFLD No: Anthropometric parameters remained almost unchanged in both groups (Placebo and Treatment arms)
21) Goyal P, [24] 2019, India	1. Child (5–18 years) with obesity using WHO standard reference and without alcohol intake	Total: 106 INT1:26 INT2:27 INT3:26 PLB:27	INT1: probiotics capsules VSL#3 + Lifestyle INT2: probiotics capsules VSL#3 INT3: lifestyle PLB: placebo capsules (corn flour)	Supplement  +  Lifestyle	4	To evaluate the potential of probiotic VSL#3 and Lifestyle modification in obese pediatrics with NAFLD	Yes: Probiotic VLS#3 and lifestyle intervention are effective for managing NAFLD in obese child but VSL#3 plus lifestyle intervention significantly the most pronounced therapy for reducing fatty liver grades and biochemical parameters (AST, ALT, GGT, LDL-c, HSCRP, cholesterol, TG, uric acid, FBG) and increase in HDL-c
22) Negri R, [43] 2020, Italy	1.Children 4–14 years 2. BMI > 85th percentile 2. Liver steatosis by US	Total: 52 (T1) INT 34; PLB 27 (T2) INT 26; PLB 26	Cross-over trial design INT: calorie-restricted regimen (CRC) + lycopene-enriched tomato juice supplementation together with basil and oregano extract in extra virgin olive oil PLB: calorie-restricted regimen	Diet + Supplement	4	To evaluate the effect of lycopene-enriched tomato juice on liver damage in obese children affected by NAFLD	Yes: The tomato-supplemented group had a more profound reduction in BMI, HOMA-IR, cholesterol, TG, liver size, and steatosis No: Leptin decreased in both groups
23) Akbulut U, [49] 2021, Turkey	1. Age 9–17 years 2. BMI z-score > 85th percentile 3. Diagnosis of NAFLD 4. ALT levels greater than twice the upper limit of the normal level (males > 50 U/L, females > 44 U/L) 5. Fatty liver disease detected at ultrasonography	Total: 45 INT: 23 CTL: 22	INT: Mediterranean diet (composition of 35–40% fat (with < 10% of energy constituting saturated fat),40–44% carbohydrate, and 20% protein) CTL: low-fat diet (composition of 55% of energy from carbohydrates, 20–25% from fat (with < 10% of energy consisting of saturated fat), and 20–25% from protein)	Diet	3	To determine the effects of a Mediterranean Diet or a low-fat diet on reducing hepatic steatosis and insulin resistance in children with NAFLD	Yes: Over 12 weeks, both Mediterranean and low-fat diets decreased hepatic steatosis and improved insulin sensitivity. The Mediterranean diet group experienced a more significant decrease in insulin resistance
24) Cohen CC, [48] 2021, USA	1. Adolescent boys aged 11 to 16 years 2. Clinical-pathological diagnosis of NAFLD	Total: 39 INT: 16 CTL: 13	INT: low sugar diet CTL: usual diet	Diet	2	To test the effect of longer-term dietary sugar restriction on hepatic de novo lipogenesis (DNL) in adolescent boys with NAFLD	Yes: Hepatic DNL, hepatic fat, and fasting insulin decreased in the treatment group versus the control group
25) Namakin K, [38] 2021, Iran	1. Children 12–18 years 2. Fatty liver (ultrasonography) 3. Vit D level < 30 ng/mL	Total: 101 INT: 51; PLB:50	INT: Vitamin D capsules, a 50000 U Perl once a week PLB: placebo with the same dosage, color, and package and for the same duration	Supplement	3	To determine the effect of vitamin D (Vit D) on ultrasonography and laboratory indices of NAFLD and some blood biochemical indicators in children	Yes. The mean changes in hemoglobin (Hb), uric acid, HDL-C, LDL-C, insulin, albumin, and ALT were significantly higher in the study group compared to controls (p < 0.05) No: The mean changes in AST, ALP, and CRP did not significantly differ between the two groups
26) Saneian H, [39] 2021, Iran	1. Children (5–15 years old) with NAFLD 2. Increases liver enzymes more than 40 unit/L	Total: 55 INT: 30 PLB: 25	INT: 50 mg/kg/day L-carnitine twice a day PLB: identical placebo per day	Supplement	3	To assess the effect of L-carnitine supplementation on NAFLD in children and adolescents	No: L-carnitine did not have significant effect on improving biochemical and sonographic markers of NAFLD in children and adolescents
27) Yurtdas G, [47] 2021, Turkey	1. Adolescents (11–18 years) 2. BMI ≥ 95th percentile 2. With NAFLD	Total: 44 INT: 22 CTL: 22	INT: Mediterranean diet CTL: low-fat diet	Diet	3	To compare the effects of MD versus a standard LFD on hepatic steatosis, liver enzymes, and inflammatory and oxidative stress markers in adolescents with NAFLD	Yes: At the end of the study, severity of hepatic steatosis, serum transaminase levels, and insulin resistance decreased significantly in both groups with no significant differences between groups The amount of decrease in AST levels in the MD group was greater than the LFD group (p < 0.05). In the MD group, serum total antioxidant capacity, paraoxanase-1, and glutathione peroxidase levels increased (p < 0.05); it did not change in the LFD group compared to baseline (p > 0.05). C-Reactive Protein (CRP) levels decreased only in the MD group (p = 0.008), interleukine-6 decreased only in the LFD group (p = 0.031)
28) Vos MB, [6] 2022, USA	1. Age 8–17 years 2) Histologic evidence of NAFLD with or without fibrosis and a NAFLD activity score (NAS) of ≥ 3 3) ALT ≥ 50 U/l	Total: 67 INT: 33 PLB: 34	INT: losartan capsules (100 mg/day) PLB: placebo capsules	Medication	6	To determine whether a 24‐week treatment with losartan improves biomarkers of liver inflammation in children with NAFLD	No: Losartan did not significantly reduce ALT, AST, GGT, lipids, glucose, insulin, and HOMA-IR in children with NAFLD compared to placebo
29) Schmidt K, [46] 2022, USA	1. Latino adolescents (11–18 years) 2. Obesity (BMI ≥ 95th percentile) 3. Elevated liver fat	Total: 76 INT: 42 CTL: 34	INT: restricting free sugar intake to < 10% of total calories CTL: packet of handouts with general diet advice	Diet	3	The aim of the study was to test the effects of a clinical intervention to reduce dietary sugar compared with standard dietary advice on liver fat change and secondary-endpoint changes in liver fibrosis, liver enzymes, and anthropometrics	No: In Latino youth with obesity, a dietitian-led sugar reduction intervention did not improve liver fat, liver fibrosis, liver enzymes and body composition compared with control
30) Rodrigo T, [40] 2022, Sri Lanka	1. Children 5–15 years 2. BMI > 2 standard deviation for age according to WHO 3. AST/ALT ratio < 1 4. Ultrasound evidence of hepatic steatosis, including grade I to III	Total: 84 INT: 43 PLB: 41	INT: probiotic capsule (One capsule for children < 12 years and 2 capsules for children > 12 years) + structured diet + physical activity PLB: a capsule without probiotic strains + structured diet + physical activity	Supplement	6	To evaluate the effects of probiotics on metabolic derangement in obese children with nonalcoholic fatty liver disease/nonalcoholic steatohepatitis (NAFLD/NASH)	No: The probiotics have no advantage over lifestyle modification for improving obesity-associated metabolic derangement in children
31) El Amrousy [41], 2022, Egypt	1.Obese children less than 18 years 2. Biopsy-proven NAFLD 3. Serum 25 (OH) D level less than 20 ng/ml	Total: 100 INT: 50 PLB: 50	INT: vitamin D (2000 IU/day) PLB: shape and packages of the placebo were the same as that of vitamin D	Supplement	6	To evaluate the role of vitamin D supplementation on the hepatic fat content and NAFLD progression in children	Yes: There was a significant improvement of the hepatic steatosis and lobular inflammation by liver biopsy in the treatment group after treatment. There was significant decrease of AST, ALT, TG, LDL, FBG, FBI, and HOMA- IR and significant increase of vitamin D levels and HDL in the treatment group compared to the placebo group (P < 0.05) No: There was no significant effect on the hepatocyte ballooning or hepatic fibrosis

Abbreviations : ALT Alanine Aminotransferase, BMI Body Mass Index, DHA Ω-3 Fatty Acid Docosahexaenoic Acid, GGT Gamma-Glutamyl Transferase, HDL High-Density Lipoprotein, INT intervention group, LDL Low-Density Lipoprotein, NAFLD Non-Alcoholic Fatty Liver Disease, PLB placebo group, TG triglycerides, VLDL Very Low-Density Lipoprotein, Vt1 Ventilatory Threshold, VitD Vitamin D, VitE Vitamin E

The studies were insufficient to synthesize sex distribution. No studies were found that evaluate the effect of traditional medicine or surgical treatments on MASLD parameters.

Twenty-four studies that met the inclusion criteria (Jadad score > 3) were included in the meta-analysis. However, one of these studies [27] did not provide the necessary data (means and standard deviations) for the analysis, so its data were not included in the final findings.

The following outcomes describe the significant size of effects. Overall point effects estimations > 0.20 (i.e., ALT, AST, BMI, and HOMA-IR) were adjusted by baseline values and for a small sample size with Hedges' g.

Liver enzymes (primary outcome)

Liver enzyme levels, ALT, and AST (unadjusted in Figs. 3A and 4A) demonstrated responsiveness to interventions. ALT levels were significantly reduced (Cohen's d = − 0.34), primarily influenced by diet, lifestyle, and supplements. AST levels exhibited a noteworthy overall reduction (Cohen's d = − 0.52), driven by lifestyle changes (Cohen's d = − 0.35) and substantial impact from supplements (Cohen's d = − 0.81), while medication showed a modest effect (Cohen's d = − 0.17). The adjustment with Hedge’s g had smaller 95% confidence intervals, as shown in Figs. 3B and 4B.

Fig. 3.

Forest plot of ALT levels using random effects model. Panel A shows the treatment’s overall effect was small to medium (Cohen-d − 0.34 95%CI − 0.65, − 0.03). Most studies showed the effect on improving the ALT concentration. Panel B shows the overall adjusted size of the effect remained the same with smaller 95% confidence intervals

Fig. 4.

Forest plot of AST levels using random effects model. Panel A shows medium effect on AST. Panel B shows less uncertainty with smaller confidence intervals

Cardiometabolic risk variables (associated outcomes)

In general, the analyses found notable effects on cardiometabolic risk variables. The BMI forest plot (Fig. 5A) shows significant modification through dietary interventions Cohen's d = − 0.53 and supplements, particularly vitamin E in combination with lifestyle changes and other strategies (Cohen's d = − 0.37). The overall effect across all treatments was − 0.27, indicating a trend toward significance despite considerable heterogeneity (I² = 89.8%). The adjustment with Hedge’s g had smaller 95% confidence intervals for BMI, as shown in Fig. 5B. Waist circumference (Additional file 1: Supplemental Fig. 1) was also positively impacted by dietary changes Cohen's d = − 0.51 and lifestyle modifications Cohen's d = − 0.25, with an overall modest effect of − 0.1 and moderate heterogeneity (I² = 28.6%). Other cardiometabolic risk factors were insulin resistance and lipid concentration.

Fig. 5.

Forest plot of BMI using random effects model. Panel A shows the overall effect on BMI was small (Cohen-d = − 0.27 (95%CI − 0.55, 0.01) p = 0.06. Michelli, et al. [32] has the highest size of effect, more than 3 standard deviations of difference. This big difference was attributed to differences in the opposite effects of placebo vs. active treatment. Panel B showed adjusted values diminishing the variation of Michelli study and increasing precision in the 95% confidence interval

Insulin resistance

Insulin resistance, assessed by HOMA-IR, showed an overall reduction in Cohen’s d = − 0.30, predominantly influenced by supplements Cohen’s d = − 0.64 (Fig. 6A, with adjustment in Fig. 6B).

Fig. 6.

Forest plot of HOMA-IR calculation using random effects model. Panel A shows treatments had small to medium effect on HOMA-IR levels. Panel B shows increased precision with adjusted size of effects with smaller 95% confidence intervals

No significant effects

No significant effects were observed for GGT, glucose, total cholesterol, LDL-c, and triglycerides (Additional files 2, 3, 4, 5, 6: Supplemental Figs. 2, 3, 4, 5, and 6), except for a modest reduction in glucose with supplements Cohen’s d = − 0.30 (95%CI: − 0.59, − 0.01). The combination of supplements and lifestyle exhibited a negligible effect, potentially attributed to heterogeneity.

Heterogeneity sources

A meta-regression analysis was conducted to detect possible explanations for heterogeneity. We included mean age, mean BMI, study duration, and GDP from each country. The main results are described in Table 3. The heterogeneity of studies was explained partially with small effects by age, BMI, GDP, and study duration. Meanwhile, the size of effect due to changes in BMI had medium effects on the concentration of ALT and AST (Additional files 7, 8: Supplemental Figs. 7 and 8). An interesting finding was the effect of age on HOMA-IR response; younger children showed better responses (Additional file 9: Supplemental Fig. 9).

Table 3.

Meta-regression coefficients

Variables (z-transf)	BMI	Age	GIP	Duration	Constant	d-Cohen BMI†	Egger p-value
BMI	-—-	0.181 (− 0.169, 0.531)	− 0.107 (− 0.487, 0.606)	0.246 (− 0.114, 0.606)	− 0.28 (− 0.59, 0.03)	-—-	0.003
ALT	0.014 (− 0.292, 0.319)	0.219 (− 0.101, 0.538)	− 0.325 (− 0.643, − 0.01)**	0.311 (0.024, − 0.598)**	− 0.31 (− 0.57, − 0.05)	0.698 (0.189, 1.206)***	0.018
AST	0.128 (− 0.324, 0.581)	0.28 (− 0.215, 0.775)	− 0.151 (− 0.70, 0.398)	0.28 (− 0.201, 0.761)	− 0.58 (− 0.97, − 0.18)	0.973 (0.617, 1.329)***	< 0.001
LDL-c	− 0.384 (− 0.704, − 0.063)**	− 0.018 (− 0.355, 0.318)	0.489 (0.103, 0.874)**	− 0.178 (− 0.573, 0.218)	− 0.31 (− 0.57, − 0.05)	− 0.456 (− 0.954, 0.042)*	0.018
GGT	− 0.517 (− 1.232, 0.199)	1.071 (− 0.057, 2.20)	− 0.31 (− 1.44, 0.82)	0.006 (− 0.677, 0.689)	− 0.101 (− 0.52, 0.31)	0.144 (− 0.481, 0.769)	0.676
Glucose	0.028 (− 0.496, 0.552)	0.211 (− 0.358, 0.779)	0.458 (− 0.013, 0.928)	− 0.505 (− 0.885, − 0.124)	0.05 (− 0.26, 0.36)	0.037 (− 0.434, 0.509)	0.084
HOMA-IR	− 0.285 (− 0.59, 0.02)*	0.576 (0.228, 0.924)**	0.254 (− 0.007, 0.515)	− 0.175 (− 0.394, 0.044)	− 0.174 (− 0.35, − 0.004)	0.449 (− 0.135, 1.035)	0.045
TC	0.065 (− 0.285, 0.415)	0.127 (− 0.235, 0.489)	0.232 (− 0.174, 0.639)	− 0.102 (− 0.481, 0.276)	− 0.16 (− 0.47, 0.15)	0.106 (− 0.215, 0.427)	0.476
TG	− 0.06 (− 0.348, 0.227)	− 0.028 (− 0.318, 0.262)	0.445 (0.087, 0.803)**	− 0.158 (− 0.446, 0.13)	− 0.20 (− 0.46, 0.06)	− 0.10 (− 0.528, 0.328)	0.223
WC	− 0.115 (− 0.470, 0.239)	− 0.054 (− 0.334, 0.227)	0.121 (− 0.237, 0.480)	0.18 (− 0.020, 0.379)	− 0.14 (− 0.30, 0.02)	0.472 (− 0.081, 1.025)*	0.003

Egger: small studies effect. ^†Meta regression of z-transformed variables on individual BMI’s Cohen-d size of effect

Abbreviations: GBMI body mass index, DP gross domestic product, TG Triglycerides, TC total cholesterol, LDL Low density lipoprotein, WC Waist circumference

*p-value < 0.1, **p < 0.05, ***p < 0.001

The Egger analysis showed that small sample sizes of the studies were significant contributors to bias. Most studies had small sample sizes with wide effects, contributing to heterogeneity (Additional file 10: Supplemental Fig. 10).

The sensitivity analysis showed that the overall effect size remained relatively stable across the different studies, indicating that no study unduly influenced meta-analysis results. The results of the sensitivity analysis are described in the (Additional file 14) Supplementary File 14 .

Bibliometric analysis

The bibliometric analysis was conducted using data from 29 publications in the systematic review (Additional file 11: Supplemental Fig. 11, panel A). These publications received 1834 citations, excluding instances where the authors cited their own work. On average, each publication received approximately 95.9 citations. The h-index, which tells us about the impact of the research, was 19. Table 4 shows the ten most highly cited publications from the network analysis of MASLD and obesity in children.

Table 4.

Top 10 highly cited publications on the network analysis of MASLD and obesity in pediatric population

Rank	Author names (year)	Institution	Country	Language	J Impact Factor (2022)	Total citations (by Dec 2023)	Reference (PMID)
1	Lavine, JE et al. (2011)	Columbia University	USA	English	120.7	761	[23] (21521847)
2	Nobili, V et al. (2008)	Bambino Gesu Children's Hosp & Res Inst	Italy	English	14	303	[26] (18537181)
3	Alisi, A et al. (2014)	Bambino Gesu Children's Hosp & Res Inst	Italy	English	7.6	302	[30] (24738701)
4	Nobili, V et al. (2011)	Bambino Gesu Children's Hosp & Res Inst	Italy	English	5.2	207	[27] (21233083)
5	Famouri, F et al. (2017)	Isfahan Univ Med Sci	Iran	English	2.9	154	[36] (28230607)
6	Nobili, V et al. (2006)	Bambino Gesu Children's Hosp & Res Inst	Italy	English	7.6	132	[25] (17206944)
7	Schwimmer, JB et al. (2019)	Emory University	USA	English	120.7	131	[50] (30667502)
8	Nobili, V et al. (2013)	Bambino Gesu Children's Hosp & Res Inst	Italy	English	3.9	109	[28] (23220074)
9	Wang, CL et al. (2008)	Zhejiang University	China	English	4.3	96	[42] (18330955)
10	Janczyk, W et al. (2015)	Children's Memorial Health Institute	Poland	English	5.1	89	[31] (25771388)

Co-authorship analysis

(Additional file 11) Supplemental Figure 11, panel A, shows the co-authorship map, displaying 246 authors, with 27 having at least two published papers. Few authors (n = 3) had the highest influence based on total link strength (12 documents, 1340 citations, 182 total link strength). The research group led by Lavine Joel E appears to be the oldest in publications in the field of MASLD and obesity in the pediatric population.

In terms of total link strength, Emory University had the most influence (5 documents, 553 citations, 13 total link strength), followed by the University of California, San Diego (4 documents, 902 citations, 13 total link strength) and Columbia University (2 documents, 767 citations, 9 total link strength) (Additional file 11) Supplemental Figure 11, Panel B).

The co-authorship map reflected nine countries, five of which met the threshold of having at least two papers published for co-authorship. (Additional file 11) Supplemental Figure 11, panel C shows the number of papers provided by country, with Italy having the highest influence (11 documents, 1329 citations, 2 total link strength) and the longest track record of producing publications in the field of MASLD and obesity in the pediatric population. The USA (9 documents, 1627 citations, 2 total link strength) and Iran (3 documents, 163 citations, 0 total link strength) followed.

Discussion

This meta-analysis evaluated the effectiveness of supplementation, diet, lifestyle, and medication interventions in improving biochemical and anthropometric parameters in children with MASLD. Our results showed a significant but small effect size on ALT and AST levels, primarily influenced by supplementation, diet, and lifestyle modifications. Diet and supplemental interventions resulted in a slight decrease in BMI.

ALT is commonly used as a screening test for MASLD in children, and when combined with a high AST level, it indicates more severe liver damage [52]. Therefore, the observed decrease in these enzyme levels could indicate an improvement in liver damage in children driven by supplement interventions, particularly with vitamin D and probiotics [32, 41]. Only two studies in this review demonstrated a decrease in liver steatosis, ALT, and AST after interventions with vitamin D [41] and probiotics [32]. A similar result was observed in one study reporting a decrease in ALT (but not in AST) with DHA [33]. The benefits of these supplements, alongside DHA, are discussed in the context of their mechanisms and potential in managing MASLD [53].

Vitamin D supplementation in MASLD improves insulin sensitivity by regulating insulin gene transcription and improving glucose intake by muscle and reduces hepatic and adipose tissue inflammation. Higher vitamin D levels are correlated with higher adiponectin levels, while vitamin D deficiency activates inflammation processes that increase liver inflammation. Additionally, vitamin D diminishes liver fibrosis; for instance, in vitro, vitamin D inhibits the proliferation of liver stellate cells [53]. Low levels of vitamin D have been observed in the pediatric population with MASLD [54].

Regarding probiotics, there are no precise mechanisms behind their positive effect on liver transaminases and steatosis. However, studies in both children and adults have observed benefits in liver parameters [54]. In terms of DHA supplementation, omega − 3 polyunsaturated fatty acids (PUFAs) regulate mechanisms related to fat accumulation in the liver, such as de novo lipogenesis, fatty acid oxidation, triglyceride catabolism, and have anti-inflammatory effects [55].

Considering that oxidative stress plays an important role in MASLD progression, the effect of vitamin E on MASLD parameters has been evaluated due to its antioxidant activity. Additionally, vitamin E regulates the expression of genes encoding for interleukin IL-1b, IL-2, and IL-4 (El Hadi H, PMID: 29,337,849). In adults, vitamin E has improved ALT and AST levels [56], contrasting with no beneficial effects in pediatric patients [22, 23].

The results indicated that vitamin D, DHA, and probiotics can improve liver enzyme levels in children with MASLD. However, there is not enough evidence to recommend their use in clinical settings for managing MASLD in children. The supplement doses and study sample sizes varied widely across the evaluated studies. Hence, future research should aim to evaluate the recommended dosage as part of MASLD treatment in children. Furthermore, it is essential to highlight that most studies evaluating supplement interventions also offered lifestyle recommendations to both intervention and control groups. As a result, the observed effects could be a response to the interaction between supplements and lifestyle modifications in children.

Diet and exercise (lifestyle modifications) are the first treatment options for MASLD in children to reduce risk factors associated with this condition [52]. Our results showed that the Mediterranean diet [47] and reduction of dietary sugar [46] interventions had a positive pooled effect on BMI, WC, ALT, AST, GGT, and HOMA-IR [46, 47]. However, the effect size was small, and both studies were at high risk of bias. Despite the randomization process, the BMI of participants in the intervention and control groups differed at baseline. This discrepancy affected the meta-analysis results, even after adjusting for BMI baseline. Therefore, these results should be carefully interpreted. Other studies have shown Mediterranean diet has efficacy in reducing BMI, body fat content, and abdominal obesity in children and adolescents [57]. Still, few studies have evaluated its effects on MASLD. Otherwise, lifestyle interventions had a significant pooled effect on decreasing hepatic enzymes and LDL-C but not in anthropometric variables.

There is no evidence to suggest a specific diet for managing pediatric MASLD. Current guidelines advise avoiding sugar-sweetened beverages, improving diet quality, increasing physical activity, and reducing screen time [52]. Our results suggest that a combination of lifestyle modifications and supplementation may be more effective than lifestyle modifications alone in improving MASLD in children. However, more RCTs are needed to determine the most effective doses of supplements, the best combinations of these, and lifestyle changes, depending on the pediatric population to be treated.

A limited number of studies have evaluated the effects of medications on children. The present meta-analysis did not show an overall improvement in any of the parameters being assessed of MASLD due to medication intervention with metformin and losartan. One of the included studies found that metformin improves hepatocellular ballooning [19], but its effect was like that of vitamin E supplementation. Although biochemical parameters did not show a significant reduction, vitamin E supplementation and metformin could have significant and measurable effects on MASLD. Further investigation is needed to determine whether treatment or supplementation provides a more significant benefit.

Due to the lack of evidence, there are no current recommendations for medication treatment in pediatric MASLD. A recent retrospective case series study [58] evaluated the effect of a GLP-1 receptor agonist on ALT concentrations in nine children with type 2 diabetes mellitus and elevated ALT levels. The study found a 69% reduction in ALT levels, suggesting a potential beneficial effect of this drug on MASLD management that should be addressed in RCTs. GLP-1 receptor agonists have shown improvement in steatosis and steatohepatitis in adults with type 2 diabetes [59]. Additionally, pioglitazone has shown promise in ameliorating steatosis and lobular inflammation in adults with NASH [60]. However, the use of pioglitazone in the pediatric population is not approved due to concerns regarding cardiovascular risks and bladder cancer [61]. Clinical trials are underway to test novel drugs like GLP-1 receptor agonists and PPAR-γ agonists such as lanifibranor [62]. However, none of these trials involve children.

Our research highlights a lack of high-quality evidence to form specific therapeutic recommendations for MASLD in children concerning supplementation, diet, lifestyle, and medication. We aimed to reduce bias by adjusting for baseline BMI, which improved precision, but heterogeneity remained high, and effect sizes were small. The stratified meta-analysis by intervention category to account for the age differences by intervention types allowed the assessment of effect sizes considering age-related variability. We utilized meta-regression for potential sources of heterogeneity, employing age as a moderator variable to assess its impact on intervention outcomes. The combination of stratified meta-analysis and meta-regression facilitated a detailed interpretation of the findings, enabling the assessment of the influence of age differences on the efficacy of the studied interventions.

The absence of RCTs might be due to ethical considerations when involving children [63]. Ethical guidelines require minimizing risks and ensuring that interventions are non-invasive and effective. Informed consent presents another challenge, involving evaluating children’s capacity to comprehend the study’s implications. Parental consent is typically necessary, but researchers must communicate study details in an age-appropriate manner and ensure voluntary participation [64].

The bibliometric analysis shows that there is an increasing focus on research related to MASLD and pediatric obesity. This indicates that there are collaborative relationships among a small number of researchers and organizations dedicated to developing treatments [65, 66]. Despite these collaborations, the analysis reveals a significant gap in research across various countries, limiting the understanding of cultural and environmental influences on MASLD development. Given the findings of our recent study [67] on the substantial impact of environmental disparities on adult stature and metabolic outcomes, future research should prioritize exploring these environmental and cultural factors in diverse populations.

Our study acknowledges several limitations, including the scarcity of researchers focusing on MASLD in the pediatric population and the lack of RCTs in certain regions, indicating a concentration of research efforts in a few geographical areas. We also detected publication bias, where studies with small sample sizes and positive results may disproportionately influence overall outcomes. It is essential to critically evaluate whether the influence of highly cited small-sample studies is justified or biased.

We recognize high heterogeneity among included studies. Meta-regressions identified baseline BMI as a significant source of heterogeneity, suggesting that differences in baseline weight substantially affect the effectiveness of therapeutic interventions on liver enzyme levels. To address this, we performed meta-regressions, which significantly reduced variations within studies, as indicated by lower tau² values. However, the high I² values showed that the relative percentage of variation due to heterogeneity remained considerable.

Our bibliometric analysis suggests future research should include underrepresented regions to provide a more comprehensive global perspective on MASLD, contributing to effective and tailored treatment strategies.

Conclusion

In conclusion, the effective management of MASLD in children requires a multifaceted approach. Lifestyle changes (diet and physical activity) continue to be the first option for treating MASLD. While diet, supplements, and lifestyle adjustments have shown significant effects, the clinical impact size was minimal when considering baseline BMI. Therefore, more high-quality studies are needed to offer therapeutic recommendations. Our findings call for increased research efforts to develop evidence-based therapeutic strategies, aiming to improve the natural course of MASLD progression and reduce the risk of advanced liver disease from an early age.

Abbreviations

ALT

Alanine aminotransferase

AST

Aspartate aminotransferase

BMI

Body mass index

DHA

Ω-3 Fatty acid docosahexaenoic acid

DP

Gross domestic product

GGT

Gamma-glutamyl transferase

HDL

High-density lipoprotein

HOMA-IR

Homeostatic model assessment for insulin resistance

INT

Intervention group

LDL

Low-density lipoprotein

MASLD

Metabolic dysfunction-associated steatotic liver disease

NAFLD

Non-alcoholic fatty liver disease

NASH

Non-alcoholic steatohepatitis

PLB

Placebo group

RCTs

Randomized clinical trials

REML

Random-effects meta-analysis

TC

Total cholesterol

TG

Triglycerides

VLDL

Very low-density lipoprotein

Vt1

Ventilatory threshold

VitD

Vitamin D

VitE

Vitamin E

WC

Waist circumference

Authors' contributions

All authors participated in this paper’s design, data analysis, and writing. All authors read and approved the final manuscript.

Data Availability

Additional File 12 contains the extracted data used in the meta-analysis. Additional File 13 describes and illustratesthe data search strategies.

Declarations

Ethics approval and consent to participate

This meta-analysis did not involve any direct interaction with human or animal subjects; it exclusively utilized publicly available data from previously published studies.

Consequently, there was no requirement for Institutional Review Board (IRB) approval. The protocol was registered in PROSPERO (CRD42023393952) to ensure methodological transparency and to adhere to best practices in systematic review research.

Competing interests

The authors declare that they have no competing interests. They do not work for private laboratories and have not received any payments.