The Best Berries for Brain Health

A meta-analysis of randomized controlled trials on berries for brain function reported significant improvements in memory, but most of the studies were on blueberries. What about other berries? In rats, raspberries can ameliorate some of the impaired learning and memory induced by a high-fat diet. Cherries can also boost rat cognition, yet when put to the test in people tart cherry juice failed to significantly improve outcomes compared to Kool-Aid-like controls after taking into account the sheer number of variables tested. Cranberry juice also flopped, and raspberries have only been clinically tested in a mixture with other berries.

Young adults were randomized to a smoothie containing about 2.5 ounces (70 g) each of whole strawberries, blueberries, blackberries, and raspberries, blended with around a half cup (120 ml) of water. The berries maintained and improved cognitive performance for six hours compared to a control drink matched for sugar and vitamin C content, but not flavor. Another multiberry study randomized older men and women to a strange smoothie with blueberries, strawberries, black currants, elderberries, lingonberries, and a tomato. After five weeks of daily smoothies, study subjects performed better on short-term memory tests and, as a bonus, their LDL cholesterol also dropped about 10 points.

When you test six fruits at a time you don’t know which are responsible, but there are human trials exclusively testing strawberries. A randomized, double-blind, placebo-controlled trial in older adults found that the equivalent of two cups (473 ml) of fresh strawberries a day could indeed improve some aspects of cognition compared to placebo. Blueberries versus strawberries for age-related deficit reversal have only been pitted head-to-head in rats (blueberries won).

In the original landmark study, “Blueberry Supplementation Improves Memory in Older Adults,” the researchers ended the paper suggesting that “consistent supplementation with blueberries may offer an approach to forestall or mitigate neurodegeneration.” To date, though, the longest interventional trial has only been 24 weeks. To see if short-term improvements in cognition translate into affecting the course of brain aging, we must look to observational trials that follow multitudes of people for years.

Harvard University researchers, using decades of dietary data from the Nurses’ Health Study, followed the cognitive function of more than 16,000 women for years. Higher, long-term consumption of berries was related to significantly slower rates of cognitive decline, even after careful consideration of confounding factors like socioeconomic status. That is, even after taking into account the fact that richer people tend to eat more berries. This study provided the first population-based evidence that greater intakes of blueberries and strawberries were highly associated with slower rates of cognitive decline, and not just by a little bit. The researchers found that women who consumed at least one serving of blueberries and two servings of strawberries each week had slower rates of cognitive decline—by as much as two and a half years—compared with those who didn’t eat berries. These results suggest that simply eating a handful of berries every day, one easy and delicious dietary tweak, may slow your brain’s aging by more than two years.

A more recent study that followed the cognition of hundreds of twins over a decade found that less than a quarter cup (60 ml) a day of blueberries worth of anthocyanins, or around a cup (240 ml) a day of strawberries, seemed to slow cognitive aging by four years. But what about preventing full-blown dementia? Only one study so far, the Rush Memory and Aging Project, addressed this. The only berry question they had on their food frequency questionnaire was on strawberry intake, but indeed, after following older men and women for years, those who reported eating strawberries at least once a week had a 24 percent decreased risk of developing Alzheimer’s dementia.