The Effect of Coconut Water on Blood Glucose and Insulin in Humans Depends on their Metabolic Status

Coconut water, a popular health food in Asia, is gaining popularity in the US due to its low glycemic index and is being promoted as a good beverage alternative to sugary drinks for people preferring a low carbohydrate diet or who are on intermittent fasting regimens. Given its increased popularity and confusing information in the public domain, some suggesting no impact on blood glucose, we aimed to establish the effect systematically. We hypothesized that coconut water may mildly increase blood glucose and insulin in all subjects as it contains at least ~9 g of total carbohydrates. We conducted a clinical study in humans (n=11, ages 16 and above) wherein fasting blood glucose and insulin were measured at baseline and again at 40 min and 120 min after drinking 250 mL of either fresh or bottled coconut water. As hypothesized, coconut water increased blood glucose and insulin in the majority of subjects in 45 min, and returned to baseline by 2 h post consumption. The mean increase from baseline was 8.90 mg/dL for glucose and 9.53 uIU/mL for insulin. Further, there was a clear trend of higher increase in prediabetic subjects (n=5) compared to the normal subjects (n=5), with insulin increase being statistically significant. There was no difference in the response to fresh versus bottled coconut water. In conclusion, the effect of coconut water on blood glucose and insulin was mild, however, the magnitude may depend on a person's baseline metabolic status.