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It’s no surprise that fruits and vegetables play a dominant role in brain-healthy patterns of eating, just as they do in healthy diets for your body as a whole. But it may be that eating fruits and vegetables helps protect your brain beyond general health benefits. Specific types of produce may confer particular brain benefits, as well.
As found in studies of the MIND diet, research on the brain benefits of specific foods has focused in particular on berries. Although blueberries have attracted the most scientific attention, other berries including strawberries, raspberries, blackberries, bilberries, huckleberries, and cranberries, as well as grapes and currants, contain similar pigment compounds called anthocyanins. These give berries their distinctive red, purple, and blue colors. Anthocyanins can cross the blood-brain barrier to become localized in areas of the brain related to learning and memory. In the brain, anthocyanins decrease vulnerability to the oxidative stress that occurs with aging, reduce inflammation, and may increase neuronal signaling.
An analysis of data on berry consumption among some 16,000 women over age 70 participating in the Nurses’ Health Study suggests how berries might affect aging brains. The women were tested for memory and other cognitive functions every two years and completed dietary questionnaires every four years. Researchers found that those who consumed two or more half-cup servings of strawberries or blueberries per week experienced slower mental decline—equivalent over time to up to 2½ years of delayed aging.
In other research, some data from Alzheimer’s patients indicate that blueberries could forestall the brain damage that is a hallmark of the disease.
Berries in the Lab
Tufts laboratory research further bolsters evidence for the potential brain benefits of berries. In one study, Barbara Shukitt-Hale, PhD, and her colleagues tested blueberry and strawberry powders added to the diets of 42 aged lab rats. Compared to rats fed only their normal diet, those consuming diets supplemented with berries had enhanced motor performance and improved cognition, specifically working memory. The berries also boosted production of neurons in the hippocampus and of insulin-like growth factor 1 (ILGF 1), which has been associated with learning and memory.
Interestingly, the different polyphenol compounds in the berries also produced some different results. Rats getting blueberry powder performed better on psychomotor coordination, for example, while those in the strawberry group did better in tests of general balance and coordination.
Previous studies conducted at Tufts found that the addition of blueberries to the diet improved short-term memory, navigational skills, balance, coordination, and reaction time. Compounds in blueberries seem to jump-start the brain in ways that get aging neurons to communicate again.
Adding the Benefits of Berries to Your Diet
Don’t be put off by seasonal spikes in the prices of fresh berries at the supermarket. Berries retain their healthy qualities when dried or frozen and can be enjoyed year- round. Consider starting your day with a smoothie that contains a few handfuls of fresh berries (using frozen berries reduces the amount of ice you need to add to your blender).
While whole fruits (even pureed in a blender) are a healthier choice than juices, which sacrifice most of the fruits’ fiber con-tent, the anthocyanins in berries and grapes seem to survive juicing. Randomized, controlled trials have produced promising evidence for the effects of cranberry, blueberry, and grape juice on cognitive performance in older adults.
One study, for example, tested the effects of Concord grape juice versus a placebo beverage in elderly volunteers already suffering mild cognitive impairment. After 16 weeks, those who drank grape juice scored better on tests of memory than those in the placebo group. Measurement of brain activity revealed greater activation in the grape-juice group, suggesting increased blood flow in areas of the brain associated with learning and memory.
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