Effect of low-carbohydrate diet on adiponectin level in adults: a systematic review and dose-response meta-analysis of randomized controlled trials

Abstract

Background

To the best of our knowledge, no previous study has reported findings on the effects of low-carbohydrate diet (LCD) on adiponectin concentration.

Objective

The current systematic review and dose-response meta-analysis was carried out to systematically review the available controlled clinical trials about the effect of LCD on adiponectin level in adults.

Methods

Literature searches of PubMed/Medline, Scopus and Web of Sciences were conducted up to August 2019. Randomized controlled trials (RCTs) which assessed the effect of LCD on the adiponectin level were selected.

Results

Eleven studies, including 1047 participants (LCD = 534 and control = 513), were included in the meta-analysis. Proportion of carbohydrate from calorie was from 4 to 34%. Time of the follow-up varied between studies and ranged from 6 to 152 weeks. LCD intake mildly but significantly increased adiponectin (0.02 µg/ml, 95% CI: 0.01 to 0.03, P < 0.001). Dose-response analysis indicated a nonlinear association between the percentage of carbohydrate and change in adiponectin level from baseline (P = 0.04). After subgroup analysis based on the proportion of carbohydrate from calorie, there was a significant increase in adiponectin concentration in studies that prescribed <30% of calorie from carbohydrates (0.12 µg/ml, 95% CI: 0.07–0.18). In contrast, diets which consisted ≥30% of carbohydrates had no significant effect on adiponectin (0.50 µg/ml, 95% CI: −0.46 to 1.48). Also, meta-regression analysis revealed that age (β = 0.04, P = 0.15), baseline BMI (β= −0.15, P = 0.15), time of follow-up (β = 0.01, P = 0.17), percentage of carbohydrates (β = 0.004, P = 0.90), percentage of protein (β= −0.12, P = 0.08), percentage of fat (β = 0.20, P = 0.61) and baseline adiponectin (β = 0.001, P = 0.97) are not sources of heterogeneity.

Conclusion

This systematic review and meta-analysis demonstrated a mild but significant effect of LCD on adiponectin concentration compared to control groups.

Keywords:

• Meta-analysis
• low-carbohydrate diet
• adiponectin

Disclosure statement

F.S, M.G, A.SM and M.M declared no potential personal or financial conflicts of interest.

Author’s contribution

F.S and M.G contributed in conception, design, search, statistical analyses, data interpretation and manuscript drafting. A.SM contributed in design, search, data interpretation and manuscript drafting. M.M supervised the study. All authors approved the final manuscript for submission