4. Feeding Your Brain

While the most important nutritional protection you can give your brain involves eating an overall healthy dietary pattern, it’s also true that certain specific foods and food groups seem to be especially important for brain health (see Box 4-1, “Brain Food”). Fortunately, these brain-healthy choices are also good for your cardiovascular system and overall health. So, as you feed your brain, you’ll also be taking care of the rest of your body.

The Positives of Fruits and Vegetables

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 (see Box 4-2, “How Much Produce Is Enough?”). But, it may be that eating fruits and vegetables helps protect your brain beyond general health benefits.

Berries for Your Brain

As we saw with the MIND diet in chapter 2, research on the brain benefits of specific foods has focused in particular on berries. Pigment compounds called anthocyanins that give berries their distinctive red, purple, and blue colors can cross the blood-brain barrier to become localized in areas of the brain related to learning and memory. Anthocyanins are found in fruits such as blueberries, strawberries, raspberries, blackberries, bilberries, huckleberries, and cranberries, as well as grapes and currants. In the brain, anthocyanins decrease vulnerability to the oxidative stress that occurs with aging, reduce inflammation, and may increase neuronal signaling.

Recent research in animals at Tufts further bolsters evidence for the potential brain benefits of berries. 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 chow, 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. 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 animal 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.

Berries Beyond the Lab

Evidence for a similar benefit in humans comes from an analysis of data on berry consumption among some 16,000 women over age 70 participating in the Nurses’ Health Study. 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 two and a half years of delayed aging.

In other research, some data in Alzheimer’s patients indicate that blueberries could forestall the brain damage that is a hallmark of the disease.

Berries, such as blueberries, 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 blueberries (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 content, 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, who were 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 using functional magnetic resonance imaging revealed greater activation in key parts of the brain among the grape-juice group, suggesting increased blood flow in areas of the brain associated with learning and memory.

Phytochemicals Feed Your Brain

The anthocyanins in berries and the compounds called polyphenols found in apple, grape, and citrus fruits and juices (particularly those that have been mechanically squeezed with the peels) are examples of natural plant compounds called phytochemicals (or phytonutrients). Diane L. McKay, PhD, an assistant professor at the Tufts’ Friedman School and a scientist in its Human Nutrition Research Center on Aging Antioxidants Laboratory, explains, “These are not classic nutrients like vitamins. These are compounds present in plants that have biological activity that confers health benefits, such as improving markers of disease risk. All phytochemicals have antioxidant activity, but that is not necessarily their mode of action in the body

There is growing evidence that fruits and vegetables containing phytochemicals can counteract age-related declines in cognitive functioning. Among the most-studied phytochemicals are the large group of polyphenols, which include catechins (found, for example, in tea) and flavanols (found in chocolate).

For a Youthful Brain, Eat Your Veggies

Eating more vegetables also has been associated with cognitive protection. One study at Rush University found that two servings a day of vegetables prevented the equivalent of five years of mental aging. Participants who ate at least 2.8 servings of vegetables a day over a span of six years slowed their rate of cognitive decline as measured by standardized tests by about 40 percent compared to those who consumed less than one serving a day. Researchers speculated that the high vitamin E content of vegetables might be key to this apparent benefit, noting that vegetables are typically consumed with some fats, which increases the absorption of vitamin E and other fat-soluble antioxidant nutrients.

Another study, involving nearly 2,000 older, dementia-free Japanese-Americans, provides support for the idea that vegetable juice as well as whole vegetables may help fend off Alzheimer’s disease. In the nine-year study, participants who drank at least three glasses of fruit or vegetable juice per week were 76 percent less likely to develop Alzheimer’s compared with those who averaged less than one glass per week. Even those who drank only one or two servings weekly had some protection compared with those who consumed less juice.

Nuts Not Just an Indulgence

Once thought of as an indulgence, nuts are increasingly being recognized as a contributor to an overall healthy diet. Consuming nuts can help improve cholesterol levels and protect your heart and arteries, which is also good for your brain. Some studies also have looked specifically at possible cognitive benefits from nuts (see Box 4-3, “Almonds Counter Post-Lunch Brain Dip”).

In the Spanish PREDIMED study, adding extra nuts to the Mediterranean diet seemed to boost protection for aging brains. Those consuming a Mediterranean diet plus an ounce of mixed nuts daily scored better in tests of memory than participants assigned to a control group.

In a study done at Tufts, the phytochemicals and healthy fats in walnuts seemed to improve brain function in laboratory rats. For eight weeks, the animals were randomly assigned to eat a diet containing zero percent, two percent, six percent, or nine percent walnuts. Then, they were given age-sensitive tests of balance, coordination, and spatial memory. Rats that consumed the two percent and six percent walnut-enriched diets showed improved motor and cognitive function. The six-percent-walnut diet would equate to a human eating one ounce of nuts per day. Intake of larger amounts of walnuts did not provide additional benefits.

Nut Nutrition

Like other plant foods, nuts—including not only tree nuts but also peanuts (technically legumes)—are rich sources of phytochemicals. These little nutritional powerhouses are also excellent sources of vitamin E and magnesium. Individuals consuming nuts have higher intakes of folate, beta-carotene, vitamin K, lutein plus zeaxanthin, phosphorus, copper, selenium, potassium, and zinc than those who do not consume nuts.

Though nuts vary in their mix of vitamins, minerals, and heart-healthy fats, the type of nut you choose to consume probably doesn’t matter much. You might do best by simply eating a variety of nuts, consumed as a substitute for less-healthy snacks.

Benefits of Chocolate

The ancient Olmec, Mayan, and Aztec peoples were onto something about the benefits of chocolate when they began consuming it, mostly in the form of cocoa beverages, some 3,500 years ago. Today science is finding that phytochemical compounds called flavanols found in dark chocolate (the darker, the better) and cocoa have cardiovascular benefits. But in news that cheered chocoholics everywhere, those same compounds also may be good for your brain. Most recently, scientists published the first prospective cohort study to show an inverse association between regular long-term chocolate consumption and cognitive decline in humans (see Box 4-4, “Chocolate Slows Cognitive Decline for Some”).

Also making headlines and garnering cheers from chocolate lovers was the 2016 Maine-Syracuse Longitudinal Study. Involving 968 participants ranging from 23 to 98 years old, the study linked frequent chocolate consumption to benefits for neurocognition and behavior. Habitual chocolate intake was related to cognitive performance, measured with an extensive battery of neuropsychological tests. More frequent chocolate consumption was significantly associated with better performance on overall composite scores and the Mini-Mental State Examination. Chocolate eaters also did better on specific tests of visual-spatial memory and organization, working memory, scanning and tracking, and abstract reasoning.

Making Your Brain Work Better

Dark chocolate might also have benefits for specific mental functions, even in the short term, according to a study published in 2015. The eight-week study of 90 cognitively healthy older volunteers randomly assigned to three different levels of cocoa flavanols found improvements in verbal fluency and tests of visual attention and task switching, with greater benefits associated with higher amounts. Both the high- and intermediate-flavanol beverages were associated with significantly greater improvements in scores, compared to the low-flavanol drink.

In another study, a chocolate drink high in flavanols enabled participants to complete memory-related tasks with less effort. The randomized trial compared three strengths of flavanol-laden beverages on 63 volunteers, ages 40 to 65, over a 30-day period. No difference was seen in tests of mental accuracy and reaction time. But, while performing the memory-related tasks, during which their brain activity was monitored with CT scans, participants in the middle and top groups of flavanol supplementation required less brain activity to accomplish the tasks than those in the lowest group. According to a study of people in Luxemburg, chocolate also may improve insulin resistance, which could in turn help protect the heart and brain.

Cocoa Effective Against Impairment

Other findings suggest that cocoa may have greater benefits for people who have already suffered cognitive impairments than those who are cognitively healthy, although others report preventive benefits. In one Italian clinical trial, for example, older adults with mild cognitive impairment improved their scores on some mental tests when they consumed cocoa flavanols. Importantly, researchers noted, the improvements in cognitive function were seen over a relatively short period of time, just eight weeks.

Another study tested the effects of cocoa consumption in 60 volunteers, average age 73, who had hypertension and/or diabetes. Although none had dementia, 17 suffered from a condition called impaired neurovascular coupling (NVC), a measure of blood flow in the brain as it relates to nerve cells (neurons). Researchers initially tested two levels of flavanols in cocoa, consumed twice a day for 30 days. Participants were encouraged to alter their diets to compensate for the extra calories in the cocoa. No significant differences were seen between the two types of cocoa, so the results from both groups were merged. Participants free of impaired NVC showed no significant benefits from cocoa consumption. But the small group of volunteers with impaired NVC saw dramatic changes after just a month of cocoa intake: Neurovascular coupling improved by more than double, and scores on standard cognitive tests jumped 30 percent.

Chocolate Choices

Cocoa flavanols also are associated with improvements in blood pressure, blood glucose, and insulin resistance. So it isn’t clear whether the benefits in cognition seen in such studies are a direct consequence of cocoa flavanols or a secondary effect of these general improvements in health.

If you do decide to up your chocolate intake in hopes of brain benefits, keep in mind that chocolate has plenty of calories and often comes with lots of added sugar and saturated fats. Finding chocolate choices high in flavanols can be a challenge, adds Jeffrey Blumberg, PhD, director of Tufts’ HNRCA Antioxidants Research Laboratory: “The FDA does not require food producers to list the content of flavonoids, such as those that give dark chocolate its health benefits, in the Nutrition Facts panel or elsewhere on the label. Moreover, because of lawsuits, some products that used to cite their ‘flavonoid’ or ‘flavanol’ or ‘natural antioxidant’ content (e.g., on chocolate and tea) no longer do so. Because there is no reference standard (RDA or DV) for flavonoids, per FDA guidelines no product can claim to be a good or rich source of them.”

Benefits of Coffee

Another product once thought to be an indulgence to limit or avoid that’s now been shown to have health benefits is coffee. The 2015 Dietary Guidelines Advisory Committee concluded that coffee is safe to drink at typical levels of consumption, and suggested it could actually have health benefits. For example, a large Korean study reported that people drinking three to five cups of coffee daily were 41 percent less likely to show signs of coronary artery calcium than non-coffee drinkers. This calcification is an early indicator of the artery-clogging plaques that characterize atherosclerosis. The study, published in Heart, may help explain one mechanism by which coffee benefits the cardiovascular system. Previous studies, the researchers noted, have linked coffee consumption to improved insulin sensitivity and reduced oxidation of LDL cholesterol (oxidation makes these particles more dangerous). Findings on coffee and coronary artery calcium, however, have been mixed, possibly because prior studies had a lag time of seven to eight years between measures of coffee intake and subsequent calcification.

Some studies as well as popular lore, however, had raised the possibility that coffee might raise the risk of atrial fibrillation (“afib”)—heart “flutters” that can be serious. But a Chinese study put that notion to the test by combining the findings from a half-dozen prior observational studies totaling nearly 230,000 participants. Publishing their analysis in the Canadian Journal of Cardiology, the researchers reported that participants grouped as high caffeine consumers—more than 500 milligrams daily, or about six cups of American coffee—were actually less likely (16 percent) to develop afib. With each additional regular daily intake of 300 milligrams of caffeine, afib risk declined 6 percent.

Coffee contains a wealth of phytochemicals with possible cardiovascular benefits. In turn, these are probably also important to brain health.

Caffeine Effects

Coffee is also a leading source of caffeine, and other benefits from coffee consumption, perhaps not surprisingly, are associated with its caffeine content. Researchers have tested mice given water spiked with caffeine—the human equivalent of about five cups of coffee a day—versus mice given plain water to drink. The mice had been specially bred to develop an Alzheimer’s-like disease. After several months, the mice that received only water had difficulty navigating in mazes, while the caffeinated mice easily found their way out of the mazes.

Studies in humans have found that caffeine consumption in midlife may help to protect against cognitive decline later in life. Recent results from the Baltimore Longitudinal Study of Aging showed that caffeine intake was associated with better baseline global cognition among participants age 70 and older.

Another study concluded that older women who drank at least three cups of coffee daily were 18 percent less likely to develop problems with verbal recall and 33 percent less prone to memory problems than those who drank less coffee. Similar results were seen for tea, leading researchers to identify caffeine as the source of the benefit. Other evidence suggests caffeine intake may be tied to a lower risk of dementia (see box 4-5 “For Older Women, More Caffeine May Mean Less Dementia Risk”).

Coffee could also help ward off depression. A Harvard study reported that women consuming two or three cups of regular coffee per day were 15% less likely to develop depression over a follow-up period of 10 years than those drinking one cup a day or less. Those drinking four cups a day were at 20% lower risk.

Don’t Add Calories to Your Coffee

If you’re drinking coffee in part for its brain benefits, make sure you’re not canceling out those positives by dosing your cup with extra calories. You may not give much thought to adding a splash of cream and a spoonful of sugar to your coffee or tea, but these add-ins can add up in calories. A study published in Public Health aimed to figure out just how much. Scientists analyzed data gathered in the National Health and Nutrition Examination Survey (NHANES) from 13,185 coffee drinkers and 6,215 tea consumers over about a decade.

Based on self-reports of what people drank over a 24-hour period, it was calculated that drinking coffee with caloric add-ins was, on average, associated with a daily increase of 69 calories compared to drinking it black. Drinking tea with add-ins resulted in an average daily increase of 43 calories compared to plain tea. With both beverages, sugar contributed the most to calories from add-ins and amounted to an average of 2 to 2½ teaspoons daily. Dairy add-ins increased saturated fat intake.

“Consider gradually reducing, then eventually omitting, sugar and sugary syrups in these drinks, and replace cream with low-fat or skim milk,” says Ruopeng An, PhD, the lead author of the study at the University of Illinois at Urbana-Champaign.

Benefits of Tea

Similarly, tea might benefit the brain in many different ways. Jeffrey Blumberg, PhD, senior scientist at Tufts’ HNRCA Antioxidants Research Laboratory, says, “As investigators continue to study the multiple effects that tea has on human health, more research supports tea’s potential in helping reduce the incidence of major diseases. In some respect, it is good to think of tea as a plant food.”

Studies support cognitive benefits from most types of tea, but especially green tea. All tea comes from the leaves of the Camellia sinensis bush. Green tea is unfermented and minimally processed, the leaves simply withered and steamed. Black tea is fermented and oxidized. Oolong tea is partly oxidized, between green and black tea. White tea is made from partly opened buds and young leaves, which are steamed and dried. (Herbal “tea” is not actually made from tea leaves, but may have health benefits nonetheless—see below.)

One small clinical trial reported that green tea improves the connectivity between parts of the brain involved in tasks of “working memory.” Swiss researchers tested the effects of a beverage containing 27.5 grams of green-tea extract (equivalent to about two cups of brewed green tea) against a placebo. Healthy young male volunteers were then faced with a battery of working-memory tasks, while their brains were monitored using magnetic resonance imaging. Men who had been given the beverage containing green-tea extract showed increased connectivity between the brain’s right superior parietal lobe and the frontal cortex. This effect on connectivity within the brain coincided with improvements in actual cognitive performance on working-memory exercises.

In another study of people with mild memory impairment, daily supplements of green tea extract plus L-theanine (an amino acid unique to tea) over four months improved memory and mental alertness compared to a placebo.

Polyphenols in Tea

Like other plants, tea is a rich source of phytochemicals, including compounds called phytochemicals. One reason green tea might be especially good for your brain is that it contains a polyphenol compound called EGCG (epigallocatechin-3-gallate). Researchers at the University of Michigan have reported that EGCG prevents the formation of potentially dangerous amyloid aggregates associated with the development of Alzheimer’s disease. A green-tea extract also broke down existing aggregates in proteins that contained metals—copper, iron, and zinc—associated with the disease.

British scientists have tested the effect of green tea extracts on “balls” of amyloid proteins created in the lab. The extracts caused the shape of the balls to distort in such a way that they could no longer bind to nerve cells and disrupt their functioning.

Tea and Blood Pressure

Another way drinking tea might benefit your brain is by keeping a lid on high blood pressure, which is the number-one risk factor for strokes and vascular dementia. One Australian study reported that drinking three cups daily of regular black tea was associated with a small but significant drop in blood pressure. Researchers divided 95 study participants, ages 35 to 75, into two groups: One group drank three cups of black tea daily, while a control group drank a placebo beverage containing the same amount of caffeine but no actual tea. At the study’s start, participants had systolic blood pressure readings ranging from 115 to 150 mmHg (normal to stage-one hypertension). After six months, those in the tea-drinking group saw an average drop in systolic pressure (the top number) of two to three points and about a two-point drop in diastolic pressure, compared to the control group.

Although those improvements are small, researchers said they had important potential public-health benefits: “At a population level, the observed differences in blood pressure would be associated with a 10 percent reduction in the prevalence of hypertension and a 7 percent to 10 percent reduction in the risk of heart disease and stroke.”

Hibiscus vs. Hypertension

Herbal teas may have their own blood-pressure benefits. Hibiscus is one of the most common ingredients in herbal teas; it gives the beverages a fruity, tart taste and red color. This fruit of a flowering plant is rich in antioxidants including anthocyanins, flavones, flavonols, and phenolic acids. Research led by Diane L. McKay, PhD, of Tufts’ HNRCA Antioxidants Research Laboratory, has shown that a few cups a day of herbal-tea-containing hibiscus can help to lower high blood pressure in pre-hypertensive and mildly hypertensive adults as effectively as some medications do.

In one study, Dr. McKay and colleagues recruited 65 pre- or mildly hypertensive volunteers, ages 30 to 70. About half of the participants drank three cups of hibiscus tea per day for six weeks, while a control group received a placebo beverage containing artificial hibiscus flavoring and color. Those who drank the hibiscus tea saw a 7.2-point drop in their systolic blood pressure, significantly more than the placebo group. Those results are comparable to that delivered by standard blood-pressure medications. Participants with the highest blood pressure at the study’s start showed the most significant reductions.

Wine and Resveratrol Research

Another “plant food” consumed as a beverage that is being studied for brain benefits is wine (along with grape juice). One focus of such research is a compound called resveratrol, found in red wine and grape juice, a type of polyphenol produced as part of a plant’s defense system against disease. Resveratrol is also found in dark chocolate.

German researchers tested supplements of 200 milligrams of resveratrol daily for six months versus a placebo in 46 cognitively healthy people, ages 50 to 80. At the end of the study, participants randomly assigned to the resveratrol supplements scored better on memory tests and showed greater functional connectivity in their brains.

Action Against Alzheimer’s

Scientists have shown that the polyphenols in red wine block the formation of proteins that contribute to the development of the toxic plaques found in the brains of individuals with Alzheimer’s disease. These red-wine compounds also reduce the toxicity of existing plaques. Natural chemicals found in red wine as well as in green tea can interrupt the process by which Alzheimer’s proteins latch onto brain cells.

Keep in mind, however, that research on resveratrol is in the very early stages, and it may be that benefits are associated only with amounts impossible to consume except from supplements. That is the case, for example, of recent research on resveratrol and changes in the brain associated with Alzheimer’s disease. Resveratrol stabilized the levels of beta-amyloid protein in patients given two grams daily—the equivalent of the amount in 1,000 bottles of wine. The year-long study recruited 119 people with diagnoses of probable Alzheimer’s. As the disease progresses, beta-amyloid levels ordinarily drop as the proteins are converted into toxic plaques in the brain. But in patients randomly assigned to resveratrol, that decline slowed—possibly, scientists suggested, because resveratrol stimulates enzymes that slow metabolism and cellular aging. Researchers cautioned that further investigation is needed to determine whether resveratrol has a beneficial effect, and that the results don’t mean people should begin taking supplements.

Like all alcoholic beverages, moreover, wine should be consumed only in moderation—no more than two glasses a day for men and one for women.

Don’t Forget Water

While drinking cocoa, coffee, tea, and wine may have brain benefits, the most important beverage for your brain is plain old water—and you might not be getting enough. Older people may be less sensitive to thirst, so it’s especially important for them to stay hydrated.

Dehydration has negative effects on your mood and cognitive performance, including memory, attention, and motor skills. Research on hydration and brain function—especially on positive effects of drinking more fluids—is limited and contradictory, however. The safest bet is to make sure you drink plenty of fluids (coffee and tea count, too) that don’t add calories, and to pay attention to your body’s thirst signals.

Another reason to prefer water for hydration is that some concerns have been raised about negative effects of the sweeteners used in diet sodas. While it’s too soon to say you should swear off these beverages, water is always a smart choice (see Box 4-6, “Should You Avoid Diet Soda?”).

Seafood and Cognition

Seafood, especially the fatty varieties high in fish oil (heart-healthy omega-3s), seems to have brain benefits. Even if you’ve never been a big seafood eater, it’s not too late to reduce your risk of cognitive impairment and dementia by eating more fish. In fact, a recent study reports that this dietary change may be more beneficial later in life. Chinese researchers reported that age significantly modify the association between fish consumption and cognitive change: Among adults ages 65 and older, those who ate one or more weekly serving of fish saw a slower rate of cognitive decline compared to those consuming less fish. The difference was equivalent to what would be expected from 1.6 years of difference in age. Fish consumption was also associated with a slower decline in composite and verbal memory scores. No associations were observed, however, among those ages 55 to 64.

People at higher risk of developing Alzheimer’s because of genetic factors might also benefit more from eating more fish. Carriers of the APOE4 genetic factor for Alzheimer’s disease might be able to reduce their risk simply by eating more fish, according to data from the Rush Memory and Aging Project. Higher seafood intake was also associated with greater brain levels of mercury, found in some fish varieties, but this was not linked to neuropathology. An accompanying editorial noted that the results suggest that seafood “can be consumed without substantial concern of mercury contamination diminishing its possible cognitive benefit in older adults” (see Box 4-7, “Fish Benefits Outweigh Mercury Concerns”).

The Role of Omega-3s

Fatty acids play an important role in brain health, so it makes sense that seafood rich in the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenioc acid (DHA) could be good for your brain. DHA is the most prominent fatty acid in the brain, especially in the neurons of the cerebral cortex—the brain’s grey matter responsible for memory, language, and thinking.

The importance of omega-3s in general and DHA in particular to seafood’s cognitive effects was demonstrated in a Tufts study several years ago. It involved nearly 900 elderly men and women initially free of dementia, who were screened for cognitive decline every two years. Following up an average nine years later, the researchers documented 99 cases of dementia, including 71 with Alzheimer’s disease.

Among the 488 participants who also completed a dietary questionnaire, those with the highest blood DHA levels reported that they ate an average of nearly three fish servings a week. Participants with lower DHA levels ate substantially less fish. Those with higher blood levels of DHA, as well as those eating the most fish, had a dramatically lower risk of dementia and Alzheimer’s disease. Subjects with the highest DHA levels had a 47 percent reduced risk of dementia and a 39 percent lower risk of Alzheimer’s.

Though a form of omega-3 called alpha-linolenic acid (ALA) found in plants can be converted in your body to the more complex types found in fish, this conversion is not very efficient. The best way to obtain EPA and DHA is to consume fish, especially fatty varieties such as salmon, sardines, and mackerel (see Box 4-8, “Shopping for Seafood”).

Are fish-oil pills, which also contain EPA and DHA, as beneficial as eating fish? We’ll weigh the evidence in the next chapter. But nothing beats eating more fish—in part because of what you don’t eat when fish is the entrée: Dining on salmon instead of a ribeye steak gives you healthy fat instead of saturated fat.

Gray Matter and Fish

People who eat more fish also literally have more grey matter than non-fish eaters. In a study using MRI scans, people eating broiled or baked fish, but not fried fish, on a weekly basis had greater volumes of gray matter in the brain’s hippocampus and frontal and temporal lobes. In subsequent cognitive testing, only 3.2 percent of those with the highest fish intake and greatest preservation of gray matter developed mild cognitive impairment or dementia. That was a sharp contrast to the 30.8 percent of non-fish eaters who’d suffered such cognitive decline. Average scores for working memory were significantly better among weekly fish eaters, too.

Researchers concluded, “Consuming baked or broiled fish promotes stronger neurons in the brain’s grey matter by making them larger and healthier. This simple lifestyle choice increases the brain’s resistance to Alzheimer’s disease and lowers risk for the disorder.”

Fish Smarts

That’s not the only study to find that baked and broiled (or grilled) fish are more beneficial than fried fish. This is likely due to the extra calories and saturated or trans fat added to fried fish in the breading and frying process. The type of fish commonly used for frying may also be a factor: Cod and other whitefish varieties are much lower in omega-3 content than other types of fish.

Shellfish generally falls short on omega-3s, too. Although shrimp, for example, is a lean source of high-quality protein, it is low in total fat and thus also low in omega-3 fatty acids. The omega-3 content of crab is somewhat higher, similar to that of canned light tuna, although it varies widely by species.

The recommendations to eat more seafood remain a work in progress, much like other links between specific types of food and cognition. No single food or group of foods is a “magic bullet” against Alzheimer’s and dementia, but the right food choices, as part of an overall healthy dietary pattern, can nonetheless help improve your odds.

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