Blueberries are a fruit that contain many compounds that may be beneficial for health including anthocyanins. Anthocyanins are a type of flavanol that give blueberries their dark blue color and are reported to have antioxidant and anti-inflammatory properties. Although there is mixed evidence on whether short-term blueberry supplementation can improve cognition, some evidence suggests that adding blueberries to the diet may be beneficial for brain health. Some sources of blueberries may contain pesticides, but blueberry consumption is generally safe. Less is known about blueberry supplement products.
There is conflicting evidence whether short-term consumption of blueberries or blueberry supplements will improve cognition, though as part of a diet blueberry consumption long-term may be associated with a reduced risk of cognitive decline. Our search identified:
Two systematic reviews suggested that blueberry supplementation may improve cognition or brain function in elderly individuals and patients with mild cognitive impairment [1; 2]. However, a review of the individual studies suggests that although blueberry supplementation may improve certain aspects of cognition, most cognitive tests do not show a benefit. For instance, one study reported that freeze-dried blueberry powder over six months in 37 elderly individuals improved executive function but had no effect on memory, attention, or reaction time [3]. Another study suggested that six-month treatment with a blueberry extract in 122 elderly individuals improved memory on two out of five cognitive tests at three months, but there was no improvement in cognition on any tests at six months [4]. Similar results were reported in studies of patients with subjective cognitive impairment or mild cognitive impairment with mixed results in treated patients [5; 6].
These mixed results could be due to several factors. Most of the studies were small (usually including less than 40 individuals), and most of them were short (the longest being six months). One observational study of 16,010 women suggested that high blueberry intake may be associated with less cognitive decline over four years [7]. This suggests that, although we do not have sufficient data on short-term blueberry supplementation, blueberries may be a good part of a healthy diet for brain health. However, more research is needed whether long-term consumption of blueberries can reduce the risk of Alzheimer’s disease.
No clinical trials for blueberry supplements or blueberry consumption have been conducted in Alzheimer’s patients. Preclinical studies, however, suggest that blueberries may be beneficial. Blueberry supplementation was reported to improve cognition, reduce neuronal death, improve the connections between brain cells, increase antioxidant activity in the brain, and reduce inflammation, although it did not reduce Alzheimer’s-specific biomarkers (i.e., amyloid and tau) [8; 9; 10; 11; 12]. No studies in humans have confirmed these preclinical findings.
Blueberry consumption is generally safe. There is some concern that non-organic blueberries may contain more pesticides than organic blueberries [13]; however, the USDA does not suggest that blueberries contain excessive levels of pesticides [14]. Less is known about blueberry supplements bought in vitamin stores. There is no peer-reviewed research on the safety of blueberry supplements or blueberry consumption.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
Most clinical trials have used freeze dried blueberry supplements (22-45 g per day) that are the equivalent of 1-2 cups of blueberries per day and were provided by blueberry trade associations. An observational study suggested that more than one serving of blueberries per week (half a cup) was associated with less cognitive decline than no blueberry consumption. Less information is known about blueberry supplements bought in vitamin stores.
Full scientific report (PDF) on Cognitive Vitality Reports