Diet and lifestyle impact the risk factors for insulin resistance and related disorders, such as metabolic syndrome and type 2 diabetes. The polyphenols in many plant foods support antioxidant status and promote a healthy inflammatory response. These compounds may also support healthy glucose metabolism and insulin sensitivity.

Studies have been conducted to investigate the consumption of chocolate to determine the impact and potential benefits of cocoa flavonoids on our health, including metabolic health. Cocoa flavonoids may promote normal glucose metabolism by several potential mechanisms, such as enhancing glucose uptake into cells by increasing glucose transporter type 4 (GLUT4) translocation, enhancing insulin secretion, modulating insulin signaling, enhancing insulin sensitivity in peripheral tissues, and increasing beta-cell survival. Additionally, cocoa flavonoids support antioxidant status and promote a healthy inflammatory response, potentially mitigating the roles that excess oxidative stress and chronic inflammation may play in insulin resistance and associated disorders.

One randomized, placebo-controlled, double-blind study with 84 participants examined the effects of flavonoid-rich chocolate on metabolic markers. The participants consumed 2 g of dark chocolate with 70% cocoa or 2 g of milk chocolate for 6 months. Compared with the milk chocolate, the dark chocolate had a higher content of polyphenols, especially flavonoids, gallic acid, and catechin. There was three times the proportion of flavonoids in the dark chocolate compared to the milk chocolate. Consuming dark chocolate for 6 months led to a significant decrease in fasting plasma glucose and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). The group consuming the dark chocolate also experienced improved blood pressure, total cholesterol levels, low-density lipoprotein cholesterol levels, triglycerides levels, and waist circumference. There was also significant prevention of DNA damage and an improvement of the nucleus integrity of the cell, likely due to flavonoids supporting antioxidant status in the body.

A systematic review and meta-analysis examined the effects of cocoa flavanols on cardiometabolic health, analyzing 19 randomized controlled trials with a total of 1,131 participants. These studies used cocoa flavanols ranging from 166 to 2,110 mg/day (from cocoa products, chocolate, or supplements) for a period of 2 to 52 weeks, respectively, according to the individual study. The analysis of the data found that consuming cocoa flavanol led to a significant improvement in insulin sensitivity, with a weighted mean difference of −2.33 μ/mL for fasting insulin, −0.93 HOMA-IR, and −0.83 mg/dL for C-reactive protein. There was also a significant improvement in triglycerides and high-density lipoprotein cholesterol levels. 

The flavonoid content of cocoa varies, dependent on cultivation, fermentation, and percentage of cocoa in the product. Studies using various types of chocolate have found a potential for regular consumption of flavonoid-rich dark chocolates with a high percentage of cocoa to support health, which includes helping to promote healthy blood glucose metabolism and metabolic health.*

By Kendra Whitmire, MS, CNS