Authors: Majid Fotuhi
How big was the effect? Interestingly, just being part of the study seemed to offer some benefit. Those in the placebo group improved their performance over the twenty-four weeks, most likely due to the benefits of taking part in a study. But when researchers adjusted their results to control for such an effect, the DHA group still performed better—as if their brains were three years younger than their actual ages.
It’s important to note that not all studies published have shown DHA to have late-life brain benefits. But if you look at the studies as a whole, as I did for a paper published in
Nature Clinical Practice Neurology
in 2009, it’s clear that most point toward protection against late-life Alzheimer’s disease.
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For that article, I put together a summary illustration that showed how DHA increases blood flow, reduces inflammation, and reduces the collection of proteins in the brain associated with Alzheimer’s disease.
Just a few years later, I saw my own diagram included as part of a presentation at a large international conference. The author, Veronica Witte, had recently completed research exploring whether DHA, combined with EPA, would have an impact on the size of the hippocampus—a study I had strongly considered doing myself. Her research showed noticeable growth in the size of the hippocampus in participants who had taken this omega-3 fatty acid combination.
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DHA: Your Daily Dose
While I always favor real food over supplementation, the truth when it comes to DHA is that it’s almost impossible to get as much as you need through diet alone. Therefore, I recommend eating two servings of fish per week (fatty fish like salmon, halibut, and tuna are the best sources of DHA) and supplementing with a daily dose of 1,000 milligrams of DHA (100 to 200 milligrams for children).
When buying a supplement, be sure to select a product that comes from a reputable manufacturer. Most products with DHA derived from fish also include EPA, which is a bonus for your heart health. However, if you are a vegetarian, you can also get your DHA from algal sources. Since fish obtain their DHA from algae, these supplements are just as good as DHA derived from fish (MIDAS used algal DHA), without concerns about environmental toxins or sustainability.
Products come in the form of pills, chews, gels, gummies, and liquids, so if you try one and don’t like it, keep trying. You’ll also find an increasing array of products on the market—from milk, to yogurt, to baby food, to crackers, bread, and snacks—that have DHA as an additive. These can be a good source of additional DHA.
Other omega-3s are found in plant sources like flaxseed oil, walnuts, and canola oil. You can consider these brain food, since they do improve heart health and thus likely boost oxygen to the brain. However, they don’t include DHA, so they should be an addition to your DHA supplement, not a replacement.
DHA is water soluble, so it’s generally safe to take, although it does thin blood, so anyone who also takes blood-thinning medication—such as Coumadin—should talk to his or her doctor before taking DHA.
Favorite Flavonoids
Flavonoids are compounds found primarily in plants and are a significant feature of the human diet. There are some four thousand flavonoids that have been identified, but not all have been studied for their brain benefits. Many of those that have been studied have been found to offer benefits for a number of different medical conditions. Some—such as blueberries and spinach—were discovered to have antioxidant and anti-inflammatory properties, and thus find their way onto many a brain-food list.
They’re there for good reason. Antioxidants do aid brain health, primarily by ridding the body of free-radical oxygen molecules, which it creates naturally in a process called oxidation. Oxidation occurs when our immune system sends germ-busting cells in to attack an intruder. The cells, called microglia, produce free radicals, which attach to the attacker and kill it. That’s all very helpful, and quite necessary, but free radicals can also attach to healthy cells and kill them—an unintended side effect that seems to be more common with aging. Antioxidants offset this effect, with the long-term benefit that fewer healthy cells are killed.
But some flavonoids are more than mere antioxidants; they also increase blood flow to the brain and have been shown to boost BDNF, growing the brain by promoting neurogenesis in the hippocampus. Flavonoids can also contribute to the formation of nitric oxide in the body, which relaxes blood vessels, thereby improving blood flow. Some flavonoids help in other ways, too, by activating the energy source—mitochondria—in our bodies’ cells, in much the same way exercise does. One—green tea—has even been shown to promote healthy brain activity.
I have studied many of the flavonoids, and of those that I have examined, the ones I have listed here have the strongest scientific data to support them. That’s not to say there aren’t others, but since there is little commercial value in an expensive clinical trial, such trials are hard to come by.
Here are some brain-friendly flavonoid-rich foods (presented in alphabetical order):
Apples
Apple skins are an excellent source of quercetin, an up-and-coming flavonoid with a wide range of benefits. Quercetin reduces plaque buildup in the arteries and may reduce the risk of hypertension. But it is most studied for its ability to reduce fatigue and increase endurance. A study in animals showed rats given quercetin voluntarily increased their exercise levels and had greater endurance.
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When researchers looked at slices of the animals’ muscles, they saw higher numbers of mitochondria, which you’ll recall is the energy source of cells.
The same team of researchers gave 500 milligrams of quercetin twice a day to participants in a human study.
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After seven days, the study subjects were able to exercise 13.2 percent longer than a control group. This was a small study and more research needs to be done, so for now my recommendation is to stick to natural sources rather than supplementation. You can add quercetin from other dietary sources, which include citrus fruits, berries, onions, parsley, sage, and tea.
Beets
A good source of nitrites, beets can help increase blood flow to the brain. I recommend eating them once a week, as I do in my own home.
Blueberries
Blueberries are well known for their antioxidant and anti-inflammatory properties. And there’s ample evidence that they are, indeed, good for the brain. In one study, published in 2012, researchers at the University of Reading in the United Kingdom fed rats a blueberry-rich diet for seven weeks. Compared to a control group of rats eating a regular diet, those who’d had blueberries added to their diet improved their spatial memories and were able to learn at a much faster rate. As expected, blueberry-fed rats also had higher levels of BDNF in their hippocampi.
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Other studies have shown that the blueberries increase BDNF in the hippocampus, which we know to be key to growing the brain.
Caffeine
There’s good news and bad news about caffeine. First, the good news: caffeine has been shown to increase BDNF in the hippocampus, at least in rats. In one study, researchers at the University at Albany, SUNY, put caffeine to the test by comparing four groups of rats: those eating a high-fat control diet, those eating a high-fat diet plus caffeine, those eating a regular diet with caffeine, and a control group eating a regular diet.
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They found that caffeine prevented not only weight gain but also the cognitive decline associated with a high-fat diet. Interestingly, caffeine also prevented or reversed a decrease of BDNF seen in the hippocampi of the rats fed a high-fat diet alone.
Now the bad news: too much caffeine comes with its own problems—notably, jitteriness, stomach discomfort, and high blood pressure. Not only that, a caffeine high can be followed by a distinct low, setting up an endless cycle of highs and lows as you drink coffee to recover, crash, then drink more coffee to recover. There isn’t clear science telling us the optimal dose, but based on anecdotal evidence and my own experience, I recommend one cup of coffee in the morning and one cup of herbal tea in the afternoon.
Cocoa
I don’t often get to tell my patients to splurge when it comes to food, but I do enjoy recommending cocoa for them. Flavonoid-rich cocoa is tied to a small reduction in blood pressure among people who take it, thanks most likely to its blood-flow improving properties.
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One product that includes cocoa is dark chocolate, which is delicious and brain boosting. (Look for products that have at least 70 percent cocoa.)
Cocoa’s blood-flow attributes likely have a brain-boosting effect, but cocoa may also boost BDNF, though more study needs to be done. Meanwhile, in August 2012 chocolate lovers got some news to savor from the
New England Journal of Medicine:
a study found that nations with high per-capita chocolate consumption produced more Nobel laureates than those with lower chocolate consumption.
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Curcumin
Curcumin, a bright yellow powder, is a natural product of the curry spice turmeric and has been shown to have a multitude of beneficial effects, including acting as an anti-inflammatory and increasing blood flow to the brain. In animal studies, curcumin has shown potential for reducing the aggregation of toxic amyloid proteins associated with Alzheimer’s disease.
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In one study, curcumin improved spatial learning and memory in rats with amyloid plaques in their brains.
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Several years ago, I was traveling in Japan as a visiting professor and had the pleasure of meeting with Dr. Masahito Yamada, a professor and the chairman of neurology at Kanazawa University Graduate School of Medical Science. Dr. Yamada has extensively studied curcumin. As I toured his lab, I was able to see some of this work in petri dishes containing clumps of amyloid plaques. In the dishes to which curcumin had been added, the plaques had dissolved.
Clearly curcumin is a powerful flavonoid with strong potential for brain health. Some people point to the much lower prevalence of Alzheimer’s disease in India, where curcumin is a mainstay of the diet. In India, the rate of Alzheimer’s disease is about a quarter the rate in the United States (although, of course, there could be other factors driving that difference).
Unfortunately, curcumin is not easily absorbed into the bloodstream. Researchers are on the hunt for better ways to facilitate absorption of curcumin. (One option is to combine it with piperine.) In the meantime, I recommend adding it to your meals as a spice. My wife, Bita, who takes great pains to ensure our family follows a brain-healthy diet, makes curcumin an addition to many a meal.
Pecans and Pistachios
These nuts can be good sources of choline, an essential nutrient that increases a memory-related neurotransmitter in the brain called acetylcholine. Pistachios also supply vitamin E and omega-3s, so I recommend adding both to your diet as snacks. Like other nuts, walnuts are also rich in antioxidants.
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Red Grapes
The skin of red grapes contains resveratrol, a polyphenol with antioxidant properties that has been shown to increase blood flow to the brain and to increase the production of BDNF in animals.
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Resveratrol protects against heart disease by reducing inflammation and platelet aggregation, which reduces the risk of heart attacks. It is believed to also protect against cancer and diabetes.
Peanuts and mulberries are other sources of resveratrol (and cocoa supplies it in lower doses). The big question is not whether resveratrol helps but how much is needed to experience a brain benefit. For now, I recommend simply adding resveratrol-rich flavonoids to your diet rather than taking a supplement. But there is such strong evidence for resveratrol that I am in the midst of conducting a clinical trial to document its role in improving memory. In that study, my team is comparing resveratrol with Fruitflow (a tomato extract), which seems to have properties similar to resveratrol.
Spinach
Like blueberries, spinach has been shown to be an antioxidant with brain benefits. In one study by researchers at the University of South Florida’s College of Medicine, rats fed a diet with spinach supplements for six weeks were able to learn faster than those fed a normal diet.
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Spinach is also high in protein, making it a good addition to a balanced diet. (Getting the bulk of your protein from red meat, by comparison, also increases your exposure to fats.) And spinach is a good source of vitamins A, C, K, E, and some B, folate, and calcium. I love spinach and add it to my diet any chance I get.
Tea
Black and green tea are excellent sources of L-theanine, an amino acid that has been shown to enhance the brain’s alpha waves
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as well as increase BDNF.
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One animal study showed that L-theanine can actually increase neurogenesis in the hippocampus.
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