A scientific review in *Critical Reviews in Food Science and Nutrition* concludes that the strongest and most consistent human evidence on wild blueberries points to improved blood vessel function, with additional findings described as promising for blood pressure, blood lipids, blood sugar regulation, gut microbiome changes and some measures of cognition.
A scientific review published in Critical Reviews in Food Science and Nutrition compiled results from 12 human clinical trials conducted over 24 years in four countries examining wild blueberries and cardiometabolic health.
The review grew out of an expert symposium organized by the Wild Blueberry Association of North America (WBANA) in Bar Harbor, Maine, bringing together 12 specialists across fields including nutrition, cardiovascular and cognitive health, and gut microbiology. The organizers said participants received travel reimbursement to attend the meeting, but no funding was provided for writing or developing the review.
Across the trials assessed, the most consistent finding was improved vascular function. The authors described evidence that wild blueberries may support endothelial function—how well blood vessels relax and respond to stimuli—with some studies reporting changes within hours of a single serving and others reporting benefits after regular intake over weeks or months.
The review also highlighted the gut microbiome as a possible contributor. The authors said wild blueberries provide fiber and polyphenols that largely reach the colon intact, where gut microbes convert them into metabolites that can enter the bloodstream. They noted that only about 5% to 10% of these compounds are metabolized or absorbed in the small intestine, and that microbial metabolites may account for up to 40% of active compounds measured in blood after eating polyphenol-rich foods. In one six-week clinical study cited in the review, adults who consumed 25 grams of freeze-dried wild blueberry powder daily saw increases in beneficial Bifidobacterium species.
For people with elevated cardiometabolic risk, the authors described findings on blood pressure, blood lipid markers (including total cholesterol, LDL cholesterol and triglycerides) and blood sugar control as encouraging, while emphasizing that larger, well-controlled clinical trials are still needed.
The review also summarized intervention studies in older adults suggesting wild blueberry intake may support aspects of cognitive performance, including thinking speed and memory. The authors linked these outcomes to broader cardiometabolic effects, such as circulation, and reported that improvements have been observed after both single servings and longer-term intake.
"What makes wild blueberries remarkable is that they contain numerous polyphenols and nutrients and don't appear to exert their health benefits through just one mechanism," said Sarah A. Johnson, an associate professor at Florida State University and lead author of the review. The authors outlined potential pathways that may be involved, including nitric oxide signaling that supports circulation, as well as mechanisms related to inflammation and oxidative stress, lipid and glucose metabolism, and interactions with the gut microbiome.
Wild blueberries—also known as lowbush blueberries—are grown in Maine and Eastern Canada, and the review said they contain around 30 distinct anthocyanin forms. It also noted that wild blueberries are often sold frozen, and that the serving amounts studied translate in practical terms to about one cup per day.
"Wild blueberries have been valued by people for thousands of years," said Dorothy Klimis-Zacas, a professor of clinical nutrition at the University of Maine and a co-lead author of the review.
The authors said individual results may vary based on baseline health, medications, background diet, metabolism and differences in the gut microbiome, and they called for future studies designed to identify which people benefit most, clarify optimal doses and food forms, and expand the biomarkers measured.
