Capsinoids, Red Pepper, May Lower Glucose in People Over 40 Years of Age

Crushed red pepper flakes in a glass shaker at Pizza Hut in Hyderabad,India
People often seek nonprescription drug options for chronic diseases. Capsaicin, found in foods like red peppers, is of particular interest to both patients and physicians. Researchers studied whether these had a beneficial effect on glucose, insulin, or glycated hemoglobin levels.

A systematic review and meta-analysis found inconsistent evidence of the benefits of glycemic control from supplementation with capsinoids. These findings were published in The International Journal of Clinical Practice.

Researchers from Tehran University of Medical Sciences in Iran searched publication databases through May of 2020 for studies of capsinoids in the setting of glycemic control. A total of 8 studies comprising 530 participants were included in this analysis. The studies were of parallel (n=7) or crossover designs (n=1) and were published between 2003 and 2018.

Patients were aged between 20 and 57.5 years, populations were healthy (n=3), overweight or obese (n=2), overweight (n=1), had low high-density lipoprotein cholesterol (n=1), or had gestational diabetes mellitus (n=1). Studies were conducted in the United States (n=2), Korea (n=2), China (n=2), Japan (n=1), and the Netherlands (n=1).

The studies of capsaicin (n=4), red pepper (n=2), capsinoid (n=1), and paprika xanthophylls (n=1) used a daily dose from 2 to 135 mg for 3-13 weeks with the endponts of changes to glucose (n=8), insulin (n=4), glycated hemoglobin (HbA1C; n=3), and homeostatic model assessment for insulin resistance (HOMA-IR; n=3).

For glucose, no overall effect was reported (weighted mean difference [WMD], -0.27; 95% CI, -1.9 to 1.37 mg/dL; P =.75; I2, 59.6%, P=011).

Stratified by study features, significant group differences were reported among studies which used a red pepper intervention (WMD, -2.28; 95% CI, -2.89 to -1.68 mg/dL; P <.001; I2, 0.0%), ³12-week exposure (WMD, -1.89; 95% CI, -2.46 to -1.32 mg/dL; P <.001; I2, 72.0%), sample size >50 (WMD, -1.86; 95% CI, -2.42 to -1.28 mg/dL; P <.001; I2, 69.9%), participants >40 years of age (WMD, -2.15; 95% CI, -2.74 to -1.56 mg/dL; P <.001; I2, 0.0%), and both genders (WMD, -1.89; 95% CI, -2.46 to -1.32 mg/dL; P <.001; I2, 66.5%).

In the pooled analysis, no effect was reported for insulin (WMD, -0.9; 95% CI, -1.76 to 1.57 mU/mL; P =.913; I2, 77.2%), HbA1C (WMD, 0.01%; 95% CI, -0.04% to 0.05%; P =.712; I2, 32.8%), or HOMA-IR (WMD, 0.52; 95% CI, -0.29 to 1.32; P =.208; I2, 91.5%).

A single study reported a significant effect from red pepper supplementation on insulin (WMD, -1.60; 95% CI, -2.16 to -1.04; P <.001) and HOMA-IR (WMD, -0.30; 95% CI, -0.44 to -0.16; P <.001).

This analysis was limited by the heterogeneous study populations and active interventions.

The study authors concluded that there was no clear benefit on glycemic control from supplementation with capsinoids, however, “capsinoids and red pepper significantly reduce glucose in people older than 40 years.”  


Amini MR, Talebyan A, Payandeh N, Sheikhhossein F, Mohtashaminia F, Gholami F. The effects of capsinoids and fermented red pepper paste supplementation on glycaemic control: a systematic review and meta-analysis of randomised controlled trials. Int J Clin Pract. Published online September 6, 2021. doi:10.1111/ijcp.14803