Are blueberries the superfood we are looking for? Well, as we know, blueberries have been used as “food as medicine” for a very long time. Blueberries have a wide spectrum nutritional profile and have antioxidant and anti-inflammatory properties. The increased consumption of berries has been shown to improve cognitive function and reduce the risk of cardiovascular disease. There are concerns regarding the ability to greatly increase and maintain an individual’s daily fruit and vegetable consumption over a long-term period (particularly to the nutritional guidelines of 5 servings of vegetables and 2 servings of fruit per day). The role of dietary supplementation with bioactive components, such as those in blueberries, is a tasty and feasible dietary intervention to improve health.
In this study by Stull and colleagues, participants were randomised to consume either a smoothie containing 22.5 g blueberry bioactives (blueberry group, n = 15) or a smoothie of equal nutritional value without added blueberry bioactives (placebo group, n = 17) twice daily for 6 weeks. There was a total of 1462 mg of total phenolics, 668 mg of anthocyanins per day. The blueberry and placebo smoothies were identical in physical appearance and macronutrient content apart from the addition of the blueberry bioactives to the blueberry smoothie.
Daily dietary supplementation with whole blueberries improved insulin sensitivity in obese, nondiabetic, and insulin-resistant participants. The mean change in insulin sensitivity was improved significantly more in the blueberry group compared to the placebo group. The percent change in insulin sensitivity was greater in the blueberry group (22.2 ± 5.8%) compared to the placebo group (4.9 ± 4.5%) (P = 0.02). Insulin sensitivity was enhanced in the blueberry group at the end of the study.
Consumption of smoothies (in the case of this study with blueberries) may be an attractive and convenient dietary approach for adults and children who do not consume the recommended daily amounts of fruits and vegetables. However, the daily consumption of fruit and vegetables should always be promoted.
Stull AJ et al. Bioactives in Blueberries Improve Insulin Sensitivity in Obese, Insulin-Resistant Men and Women. J Nutr. 2010 Oct; 140(10): 1764-1768.