Table III.
Observational studies on the effect of both glycemic index/glycemic load and dairy on acne
| Source; country | Study design; no. of participants | Participant characteristics | Measures | Outcome summary | Strengths | Limitations | Quality of evidence |
|---|---|---|---|---|---|---|---|
| Ismail et al,34 2012; Malaysia | Case-control study; 44 patients with acne, 44 controls | 18-30 y olds from a dermatology clinic (with acne) and a university campus (control). | Interview on the frequency of milk consumption and 3-d food diary. Dermatologist-evaluated acne severity (comprehensive acne severity scale). | High glycemic load (175 ± 35 in patients with acne vs 122 ± 28 in controls), milk (OR 3.99 [1.39-11.43]), and ice cream (OR 4.47 [1.77-11.266]) consumption associated with acne. | Appropriate sample size. Well-defined case selection and exposure classification. | Unrepresentative control selection (university student). | 6 |
| Burris et al,35 2014; New York City | Cross-sectional study; 248 | 18-25 y olds from “public locations” in New York. | Questionnaire on dietary intake. Self-reported acne severity. | Higher GI (51.8 ± 3 vs 48.9 ± 4.6) and daily milk servings (0.7 ± 0.7 vs 0.3 ± 0.5) associated with acne severity. | None. | Low sample size. Potential recruitment bias. Potential biases in exposure (limited) and outcome classification (self-report). | 4 |
| Wolkenstein et al,36 2015; France | Cross-sectional study; 1375 patients with acne, 891 control patients | 15-24 y olds from a national French database who self-reported acne status. | Questionnaire on dietary habits and acne severity. | Daily consumption of chocolate and sweets associated with acne (OR 2.38 [1.31-4.31]). Dairy and sugary drink consumption not associated. | Appropriate sample size. Generalized exposure classification. | Potential recruitment bias. Potential bias in outcome classification (self-report). | 7 |
| LaRosa et al,37 2016; United States | Case-control study; 120 patients with moderate facial acne, 105 controls | 14-19 y olds from dermatology and pediatric clinics. | Structured telephone interviews assessing 24-h dietary recall. Dermatologist-evaluated facial acne (global acne assessment scale). | Increased servings of low-fat/skim milk (0.61 vs 0.41) in moderate acne cases compared with those in acne-free controls. Glycemic load not associated. | Appropriate case and control selection. Well-defined exposure and outcome classification. | Low sample size. | 6 |
| Çerman et al,38 2016; Turkey | Case-control study; 50 patients with acne, 36 controls | Participants (mean age: 18.8 y) recruited from a dermatology outpatient clinic. | Self-reported dietary intake over 1 wk. GL and GI calculated using a dietary analysis software. Dermatologist-assessed acne severity. | GI (47.24 ± 6.6 for patients with acne and 44.52 ± 6.58 for controls) and GL increased in patients with acne. Milk consumption not associated. | Well-defined exposure and outcome classification. | Low sample size. Low effect size. Unrepresentative control selection (hospital volunteer). | 5 |
| Okoro et al,39 2016; Nigeria | Cross-sectional study; 464 | Secondary school students (mean age: 13.6 y) recruited from 4 sites. | Interview on dietary habits and questionnaire on food frequency. Dermatologists evaluated the presence of acne. | Daily milk consumption (72.6% cases vs 62.0% controls) and cake (77.8% cases vs 62.3% controls) associated with acne. | Well-defined exposure and outcome classification. | Low sample size. | 8 |
| Suppiah et al,40 2018; Malaysia | Case-control study; 57 patients with acne, 57 control patients | 14 y or older recruited from a single hospital clinic. | Questionnaires on dietary habits. Dermatologist-assessed acne (comprehensive acne severity scale). | Milk (OR 2.19 [1.04-4.65]) and chocolate (OR 2.4 [1.08-5.33]) consumption associated with acne. | Appropriate sample size. Appropriate case and control selection. Well-defined outcome classification. | Limited exposure classification (Y/N format). | 5 |
| Aalemi et al,41 2019; Afghanistan | Case-control study; 279 patients with acne, 279 controls | 10-24 y olds from a single dermatology clinic. | Questionnaire on food consumption. Dermatologist-evaluated facial acne (global acne assessment scale). | Whole milk (OR 2.36 [1.39-4.01]) and low-fat milk consumption (OR 1.95 [1.10-3.45]) associated with acne severity. Chocolate associated with acne. | Appropriate sample size. Appropriate case and control selection. Well-defined outcome and exposure classification. | None. | 8 |
| Karadağ et al,42 2019; Turkey | Case-control study; 3826 patients with acne, 759 controls | 12-31 y olds from 26 different clinics. Control subjects had no record of past or present acne. | Questionnaire on eating frequency and habits. Dermatologist-evaluated acne severity (global acne assessment scale) | Chocolate associated with acne (OR 1.48 [1.24-1.76]). Milk and cheese not associated (OR 1.13 [0.94-1.36]). | Appropriate sample size. Multiple institutions. Appropriate case and control selection. Well-defined exposure and outcome classification. | None. | 9 |
| Akpinar Kara and Ozdemir,43 2020; Turkey | Case-control study; 53 patients with acne, 53 controls | 13-44 y olds from dermatology, nutrition, and dietetics clinics at a single hospital. | Interview on the frequency and quantity of food consumed over 3 d. Dermatologist-evaluated facial acne (global acne assessment scale). | Cheese associated with acne (P < .05). No association found with other dairy products. Increased carbohydrates correlated with acne severity (correlation coefficient 0.36; P < .01). | Appropriate case and control selection. Well-defined exposure and outcome classification. | Low sample size. | 7 |
| Dreno et al,44 2020; France, Germany, Italy, Brazil, Canada, and Russia | Cross-sectional study; 2826 participants with acne and 3853 control patients. | 15-39 y olds recruited from the internet. | Questionnaire on personal nutritional habits and the presence of clinically confirmed acne. | Dairy (OR 1.21 [1.1-1.35]), whey protein (OR 3.94 [3.29-4.71]), and high-GI food consumption associated with acne. | Appropriate sample size. Appropriate case and control selection. | Potential recruitment bias. Limited exposure classification (Y/N). Potential bias in outcome classification (self-report). | 6 |
| Penso et al,45 2020; France | Cross-sectional study; 24,452 | Participants (mean age: 57 y); 75% women and 25% men) from the French NutriNet-Santé study. | Questionnaire on food intake at baseline and every 6 mo. Self-reported acne presence and severity. | Fatty and sugary products (aOR 1.54 [1.09-2.16]), sugary beverages (aOR 1.18; [1.01-1.38]), and milk products (aOR 1.12; [1.00-1.25]) associated with acne. | Appropriate sample size. Longitudinal exposure classification. | Potential recruitment bias. Potential biases in outcome classification (self-report). Significant demographic differences in comparison groups. | 5 |
| Anaba et al,46 2021; Nigeria | Case-control study; 56 cases, 56 controls | ≥25-y-old women recruited from an outpatient clinic. | Questionnaire on dietary frequency and intake. Dermatologist-evaluated acne presence and severity (comprehensive acne severity scale). | Milk consumption, cakes, sweets, and starchy foods not associated with acne presence, severity, or frequency. | Appropriate case and control selection. Well-defined exposure and outcome classification. | Low sample size. Generalizability. | 4 |
aOR, Adjusted odds ratio; GI, glycemic index; GL, glycemic load; OR, odds ratio.