One serving a day: how wild blueberries affect the condition of blood vessels

A scientific review has shown that wild blueberries most consistently affect the condition of blood vessels, surpassing their effect on blood sugar, cholesterol, and other cardiometabolic indicators. This discovery links the berry to heart benefits, reduced metabolic risks, and a possible impact on cognitive health in old age. This was reported by writes Earth.com.

Researchers at Florida State University, summarizing data from long-term clinical studies, recorded repeated improvements in vascular reactivity across different groups. The effect manifested both within a few hours and accumulated with regular consumption. This makes blood vessels a key area for further research into how improved blood circulation can affect metabolism, gut health, and brain function.

Blood vessels have a thin inner layer, the endothelium, which regulates their relaxation. Wild blueberries contain polyphenols that support the nitric oxide signaling system and reduce oxidative stress, promoting vascular flexibility and responsiveness.

According to the head of the study, Dr. Sarah Johnson, these berries are distinguished by their high content of polyphenols and nutrients, and their effects are not limited to a single mechanism. At the same time, several possible pathways of action make it difficult to establish clear cause-and-effect relationships, so additional research is needed.

The data also shows that only 5–10% of polyphenols from blueberries are absorbed before reaching the large intestine. The remaining substances are processed by the gut microbiome, converting them into metabolites, which can account for up to 40% of the active compounds associated with health benefits. This process partly explains why blood markers after consuming the same amount of berries can differ among individuals.

Evidence for this link comes from a small controlled study that tracked microbiome changes during daily consumption of wild blueberries. Adult participants consumed approximately 30 grams of freeze-dried blueberry powder daily for six weeks. Analysis of stool samples showed an increase in bacteria of the genus Bifidobacterium, which are associated with fiber digestion.

Because the researchers controlled for antibiotic intake, they were able to link these bacterial changes specifically to diet. However, the study was small, and larger trials are needed to determine whether these microbiome changes lead to real improvements in cardiac and metabolic health.

A short study also showed that daily consumption of wild blueberry juice for a week increased nitric oxide levels, which promotes blood vessel relaxation. Systolic pressure decreased moderately, but the result was not statistically significant. This highlights the need for longer trials comparing juice and whole berries using uniform blood pressure measurement protocols.

Reviews of research indicate that the benefits of blueberries most often arise from regular consumption of typical portions, close to one cup per day, regardless of the form – frozen berries, yogurt, or oatmeal. At the same time, the processing method can affect the rate of absorption, as the breakdown of plant cell walls releases sugars and polyphenols earlier. While there are no direct comparisons of different forms, powders and juices should be considered as separate products, not as complete substitutes for whole berries.