Wild Blueberries for Gut, Brain, and Cardiometabolic Health in Prediabetes

In the U.S., 35.3 million adults have type 2 diabetes mellitus (T2DM) and 96 million have prediabetes. Eight out of 10 people with T2DM die from cardiovascular disease. People with T2DM also have a 50% higher risk of developing dementia compared to healthy counterparts. Further, studies show that gut microbes play a major role in the development of T2DM. Prevention and treatment of T2DM focus on lifestyle changes including dietary modifications such as increased consumption of deep-colored fruits like berries. Blueberries are rich in fiber and phytochemicals and have several health benefits. We and others have shown that blueberry intake improves heart health in healthy men, hypertensive postmenopausal women, and men and women with metabolic syndrome. Yet, a comprehensive study in women with prediabetes that measures changes in cognitive performance and the underlying heart and gut health has not been conducted to date. Thus, the overall objective of this study is to investigate and bring forth evidence that wild blueberries improve gut, cardiometabolic, and cognitive function in women with prediabetes.

Therefore, this pilot six-week randomized, placebo-controlled parallel-arm clinical trial aims to investigate whether daily consumption of 22 g of freeze-dried wild blueberry powder improves gut, cardiometabolic, and cognitive function in women with prediabetes. Investigators hypothesize that daily consumption of wild blueberries will improve cardiometabolic parameters, gut dysbiosis, and cognitive impairments in our study population. To test these hypotheses, the following specific aims are proposed. To investigate whether daily consumption of 22 g of freeze-dried wild blueberry powder:

• Reduces levels of fasting blood glucose (FBG), insulin, and HOMA-IR (homeostatic model assessment of insulin resistance) and improves lipid profile in women with prediabetes.
• Reduces blood pressure and improves endothelial function in women with prediabetes.
• Improves cognitive function (verbal memory and executive functions [inhibition, working memory, cognitive flexibility]) in women with prediabetes.
• Favorably modulates gut microbiota composition in women with prediabetes.
• Improves serum markers of oxidative stress and inflammation in women with prediabetes.

Additionally, whether changes in the gut microbiota are associated with changes in cardiometabolic and cognitive function outcomes and whether changes in cardiometabolic outcomes are associated with changes in cognitive function parameters will be explored.

Inclusion criteria

• Women aged 20-65 years old
• Prediabetes (fasting blood glucose 100-125 mg/dL and/or HbA1c percentage between 5.7-6.4)
• Body Mass Index between 25-30 kg/m^2

Exclusion criteria

• Allergies to berries
• Use of insulin, antidiabetic, antibiotics, and anti-inflammatory drugs
• Active cancer, gastrointestinal, renal, thyroid, stage 1 & 2 hypertension and other cardiovascular diseases, neurological diseases, or severe head injury
• Smoking
• Consumes greater than 2 alcoholic beverages per day
• Consumes antioxidant, probiotic, and prebiotic supplements
• Pregnant or Lactating
• Actively participating in a weight loss program
• Currently taking berry supplements or recently participated in another study taking berry supplements