Table 3.
Results of intervention studies.
| References | Offspring Kidney-Related Outcomes Reported | Conclusion, Limitations & Recommendations | ||
|---|---|---|---|---|
| Measures | Significant difference between Groups | Results | ||
| Intervention Studies (n = 3) | ||||
| Stewart et al. 2010 [26] | BP (mmHg) | No significant difference between vitamin A or β-Carotene groups and placebo group (in crude model or after adjustment for child’s age or gender) | Adjusted difference (Mean (S.D.)) Systolic BP Vitamin A: −0.19 (−0.94, 0.56) β-Carotene: −0.21 (−1.00, 0.58) Diastolic BP Vitamin A: −0.03 (−0.90, 0.83) β-Carotene: −0.19 (−1.07, 0.70) |
Limitations 1. High percentage of missing data for some biochemical measures reduced power to detect differences between groups. 2. The prevalence of hypertension and micro-albuminuria was only 5%, reflecting a low disease risk and power to detect risk factors. 3. Observations only applicable to rural population Strengths 1. Presents data from a large cohort of more than 13,000 children 2. More than half of all women consumed >80% of their intended supplements 3. A high rate of follow-up was achieved, with no differential losses and a high degree of comparability across groups. 4. Study design minimized the risk of confounders Conclusion No evidence of an overall effect of maternal supplementation with vitamin A or β-Carotene on BP or risk of microalbuminuria. |
| Risk of hypertension | No overall difference between supplement groups | Adjusted OR (95%) Vitamin A: 1.14 (0.72, 1.79) β-Carotene: 0.81 (0.46, 1.44) |
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| Risk of microalbuminuria (≥30 microalbumin/creatinine mg/g) | No overall difference between supplement groups | Adjusted OR (95%) Vitamin A: (0.40, 3.71) β-Carotene: 0.68 (0.20, 2.30) |
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| Stewart et al. 2009 [25] | BP (mmHg) | No difference between intervention groups and control for both systolic and diastolic BP | - |
Limitations High numbers of missing data, decreased the sample size and power to find significant differences among treatment groups. Strengths This study provides unique data for the effects of micronutrient supplementation during pregnancy on risk factors for chronic disease from a RCT with high compliance and a high rate of follow-up. Conclusion 1. No impact of antenatal MMS on BP. 2. 36% reduction in the risk of microalbuminuria when all supplementation groups containing folic acid were compared with the control, suggesting a protective role of folic acid on kidney function. |
| Risk of microalbuminuria (≥3.4 albumin/creatinine mg/mmol) | Significant reduction among mothers in the folic acid and folic acid + iron + zinc groups compared with the control | OR (95% CI) Folic acid:0.56 (0.33, 0.93) Folic acid + iron: 0.77 (0.49, 1.22) Folic acid + iron + zinc: 0.53 (0.32, 0.89) Multiple micronutrient: 0.70 (0.44, 1.11) |
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| Hawkesworth et al. 2013 [24] | Diastolic BP (mmHg) | Lower in early food than late food (p = 0.01) | Mean difference of 0.74 (95% CI: 0.18, 1.30) |
Limitations 1. Women only randomly assigned to encouragement to food supplementation rather than provided with food supplementation itself. 2. The study lacked control arms and a MMS arm that also contained iron. 3. Age of offspring may be too young to see differences in renal or cardiovascular outcomes. Strengths Large sample size, good retention of participants Conclusion Overall there was limited evidence for long-lasting impacts of pregnancy supplementation on offspring blood pressure or markers of kidney function. |
| Higher in MMS compared with iron and folate (p = 0.03) | Mean difference of 0.65 (95% CI: 0.06, 1.24) | |||
| No difference between high and low iron intervention | - | |||
| Systolic BP (mmHg) | No effect of food or nutritional supplementation | - | ||
| Kidney Volume (cm3/m2) | No effect of food or nutritional supplementation | - | ||
| eGFR from plasma Cystatin C (ml/(min × 1.73 m2) | No difference between early or late food | - | ||
| Higher in offspring whose mothers received 60mg of iron during pregnancy vs. 30mg (p = 0.04) | Mean difference of 4.98 (95% CI: 0.30, 9.67) |
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MMS: Multiple Micronutrient Supplementation; BP: Blood Pressure; eGFR: estimated glomerular filtration rate; CKD: Chronic kidney disease; RCT: Randomized controlled trial.