Overview

Blueberries belong to the genus Vaccinium: highbush cultivated blueberries (V. corymbosum) dominate the commercial supply, lowbush “wild” blueberries (V. angustifolium, mostly from Maine and eastern Canada) are smaller and more intensely flavored, and European bilberry (V. myrtillus) is a related but distinct species. They are a genuinely low-calorie, fiber-containing fruit and one of the most-studied sources of dietary anthocyanins.

Active compounds and evidence

The characteristic blue-purple color comes from anthocyanins — primarily cyanidin-3-glucoside, delphinidin, and malvidin derivatives — which are water-soluble flavonoid pigments with strong antioxidant activity in vitro. Wild/lowbush blueberries generally contain a higher anthocyanin concentration per gram than cultivated highbush berries, though both are good dietary sources.

Cognitive function: Small human trials (including work from the USDA Human Nutrition Research Center on Aging) have found modest improvements in memory and task performance in older adults consuming blueberry supplementation over several weeks. The effect sizes are modest and study populations small; this is an active research area rather than settled science.
Cardiovascular markers: Randomized trials have reported small reductions in blood pressure and improvements in arterial stiffness with daily blueberry intake (around 1 cup or an equivalent powder dose) over 4–8 weeks, though results vary by study population and dose.
Glycemic index: Blueberries have a relatively low glycemic index (commonly cited around the low-to-mid 50s), and their fiber content slows glucose absorption compared with juice or sugar-added products.

Safety and contraindications

Blueberries are safe for the general population as a whole food. Considerations:

Blood thinners: No significant known interaction; unlike some high-vitamin-K greens, blueberries are not a concern for warfarin patients specifically, though patients on anticoagulants should discuss overall diet with their care team.
Portion for glycemic control: People managing blood glucose closely should count blueberries as a carbohydrate portion, favoring fresh or unsweetened frozen over dried (which concentrates sugar) or juice (which removes fiber).
Anthocyanins are heat- and light-sensitive: They degrade with prolonged cooking, so raw or lightly processed (fresh, frozen, or briefly cooked) forms retain the most.

Practical notes

Frozen blueberries, flash-frozen at peak ripeness, retain nutritional value comparable to fresh and are a practical year-round option. Fresh berries keep about 1–2 weeks refrigerated; washing just before eating (not before storage) reduces mold growth.

Sources

Clinically reviewed by Dr. Shilpa Thakur. Last reviewed 2026-07-20. Educational information, not medical advice; consult a qualified clinician or dietitian for individualized guidance.