Do DHA Supplements Improve Brain Function?

The concept of vitamins was first described by none other than Dr. Funk. In his landmark paper in 1912, he discussed the notion that there were complex compounds our body couldn’t make from scratch, so we had to get them from our diet. By the mid-20th century, all the vitamins had been discovered and isolated, but it wasn’t until the 1960s that we realized that certain fats were essential, too.

In 1929, the necessity for fat was definitively settled… “in the diet (of the rat),” but when one of the researchers tried a 99 percent fat-free diet on himself for six months, ironically, he felt better. His high blood pressure went away, he felt more energetic, and his migraines disappeared. This one-man experiment “fortif[ied] the medical profession’s doubt that essential fatty acids had any relevance to humans,” until TPN—Total Parenteral Nutrition, meaning feeding someone exclusively through an IV—was developed in the 1960s. TPN was initially developed for babies born without working intestines. Because we didn’t think humans needed fat, “the first preparations were fat free, and they rapidly induced severe EFA [essential fatty acid] deficiencies, ultimately convincing the medical community” that some fats are indeed essential. They started out using safflower oil, but, as they discovered in a young girl given the oil after an abdominal gunshot wound, we don’t just need fat—we need specific fats like omega-3s. So, when they switched from safflower oil to soybean oil, she was restored to normal.

The fact it took so long and under such extreme circumstances to demonstrate the essential nature of omega-3s illustrates how hard it is to develop overt omega-3 deficiency. Of course, the amount required to avoid deficiency is not necessarily the optimal amount for health. The vitamin C in a spoonful of orange juice would be enough to avoid scurvy (the overt vitamin C deficiency disease), but no one considers that enough vitamin C for optimal health.

As I discuss in my video Should We Take DHA Supplements to Boost Brain Function?, what would optimal omega-3 status look like? Well, doubt has been cast on its role in heart health (see Is Fish Oil Just Snake Oil?), which appears to have been based on a faulty premise in the first place (see Omega-3s and the Eskimo Fish Tale), so taking extra omega-3s for our heart might not make any sense (see Should We Take EPA and DHA Omega-3 for Our Heart?). But what about for our baby’s brain (see Should Pregnant and Breastfeeding Women Take DHA?)? Extra DHA may not help pregnant or breast-feeding fish-eaters, but those who want to avoid the contaminants in fishes can take supplements of pollutant-free algae oil to get the best of both worlds for their babies (see Should Vegan Women Supplement with DHA During Pregnancy?). What about adults? There doesn’t appear to be any apparent psychological (see Fish Consumption and Suicide) or neurological (see Is Fish “Brain Food” for Older Adults?) benefit of DHA supplementation for the general public, but what about in those who don’t eat fish?

The famous Alpha Omega Trial randomized thousands of people over three years to get either long-chain omega-3s from fish, short-chain omega-3s from plants, or placebo. The result? The study found no significant benefits for any kind of omega-3 supplementation on global cognitive decline. However, most of the subjects were eating fish, thereby already getting pre-formed DHA in their diets. General population studies like this, that find no benefit, can’t fully inform us about the role of DHA in brain health. It would be akin to giving half these people oranges, finding no difference in scurvy rates (zero in both groups), and concluding vitamin C plays no role in scurvy.

In 2013, for the first time, DHA supplementation was found to improve memory and reaction time among young adults who rarely ate fish. Previous randomized, controlled trials failed to find such a benefit among18- to 45-year-olds, but they only lasted a few months at most, whereas the 2013 study lasted for six months. If all the studies showed either no effect or a positive effect, one might give it a try. But in one of those shorter trials, DHA supplementation didn’t just fail to show benefit—it appeared to make things worse. After 50 days, those who consumed the DHA had worse memory than those taking the placebo. So, out of the six randomized controlled trials for DHA supplementation, four showed nothing, one showed a benefit, and one showed a harm. If it were just about boosting brain function in the short term, I’d err on the side of caution and spend my money elsewhere.


What about the long term though? See Should Vegans Take DHA to Preserve Brain Function?.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

 

Should We Increase Our Protein Intake After Age 65?

A study that purported to show that diets high in meat, eggs, and dairy could be as harmful to health as smoking supposedly suggested that “[p]eople under 65 who eat a lot of meat, eggs, and dairy are four times as likely to die from cancer or diabetes.” But if you look at the actual study, you’ll see that’s simply not true: Those eating a lot of animal protein didn’t have four times more risk of dying from diabetes—they had 73 times the risk. Even those in the moderate protein group, who got 10 to 19 percent of calories from protein, had about 23 times the risk of dying of diabetes compared to those consuming the recommended amount of protein, which comes out to be about 6 to 10 percent of calories from protein, around 50 grams a day.

So, the so-called low protein intake is actually the recommended protein intake, associated with a major reduction in cancer and overall mortality in middle age, under age 65, but not necessarily in older populations. When it comes to diabetes deaths, lower overall protein intake is associated with a longer life at all ages. However, for cancer, it seems to flip around age 65. I discuss this in my video Increasing Protein Intake After Age 65.

“These results suggest that low protein intake during middle age followed by moderate to high protein consumption in old adults may optimize healthspan and longevity.” Some have suggested that the standard daily allowance for protein, which is 0.8 grams of daily protein for every healthy kilogram of body weight, may be fine for most, but perhaps older people require more. The study upon which the recommended daily allowance (RDA) was based indicated that, though there was a suggestion that the “elderly may have a somewhat higher requirement, there is not enough evidence to make different recommendations.” The definitive study was published in 2008 and found no difference in protein requirements between young and old. The same RDA should be adequate for the elderly. However, adequate intake is not necessarily optimal intake. The protein requirement “studies have not addressed the possibility that protein intake well above the RDA could prove beneficial,” or so suggests a member of the Whey Protein Advisory Panel for the National Dairy Council and a consultant for the National Cattlemen’s Beef Association.

A study followed sedentary individuals over the age of 65 for 12 years and found they lose about one percent of their muscle mass every year. If you force people to lie in bed for days at a time, anyone would lose muscle mass, but older adults on bedrest may lose muscle mass six times faster than young people also on bedrest. So, it’s use it or lose it for everyone, but the elderly appear to lose muscle mass faster, so they better use it. The good news is that in contrast to the 12-year U.S. study, a similar study in Japan found that the “[a]ge-related decreases in muscle mass were trivial.” Why the difference? It turns out that in the Japanese study, “the participants were informed about the results of their muscle strength, [so] they often tried to improve it by training before the next examination.” This was especially true among the men , who got so competitive their muscle mass increased with age, which shows that the loss of muscle mass with age is not inevitable—you just have to put in some effort. And, research reveals that adding protein doesn’t seem to help. Indeed, adding more egg whites to the diet didn’t influence the muscle responses to resistance training, and that was based on studies funded by the American Egg Board itself. Even the National Dairy Council couldn’t spin it: Evidently, strength “training-induced improvements in body composition, muscle strength and size, and physical functioning are not enhanced when older people…increase their protein intake by either increasing the ingestion of higher-protein foods or consuming protein-enriched nutritional supplements.”

Is there anything we can do diet-wise to protect our aging muscles? Eat vegetables. Consuming recommended levels of vegetables was associated with basically cutting in half the odds of low muscle mass. Why? “[T]he alkalizing effects of vegetables may neutralize the mild metabolic acidosis” that occurs with age, when that little extra acid in our body facilitates the breakdown of muscle. I’ve discussed before how “[m]uscle wasting appears to be an adaptive response to acidosis.” (See my video Testing Your Diet with Pee and Purple Cabbage for more on this.) We appear to get a chronic low-grade acidosis with advancing age because our kidney function starts to decline and because we may be eating an acid-promoting diet, which means a diet high in fish, pork, chicken, and cheese, and low in fruits and vegetables. Beans and other legumes are the only major sources of protein that are alkaline instead of acid-forming. And indeed, a more plant-based diet—that is, a more alkaline diet—was found to be positively associated with muscle mass in women aged 18 to 79.

So, if we are going to increase our protein consumption after age 65, it would preferably be plant-based proteins to protect us from frailty. No matter how old we are, a diet that emphasizes plant-based nutrition “is likely to maximize health benefits in all age groups.”


What was that about a study that purported to show that diets high in meat, eggs, and dairy could be as harmful to health as smoking? See my video Animal Protein Compared to Cigarette Smoking.

Protein is so misunderstood. For more on the optimal amount of protein, see Do Vegetarians Get Enough Protein? and The Great Protein Fiasco.

Interested in learning more about the optimal source of protein? See:

What about the rumors that plant protein is incomplete? See The Protein Combining Myth.

For information on buffering the acid in our blood, see Testing Your Diet with Pee and Purple Cabbage.

And, for more on acid/base balance, see:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Meat Can Cause Stress Hormone Levels to Rise and Testosterone levels to Drop

A critique of the scientific validity of the dietary advice in Men’s Health magazine discovered nuggets claiming meat can give men “a testosterone boost,” but we’ve known for a quarter century that a meal with that much fat can drop testosterone levels by nearly one-third within hours. In fact, a significant drop of both free and bound testosterone in the bloodstream occurs within just one hour of it going in one’s mouth, whereas a low-fat meal of mostly carbs has no such effect. Based on in vitro studies on the effects of fat on testicle cells in a petri dish, researchers suspect fat in the blood may actually suppress testosterone production in real time. If you feed people lots of eggs and meat, including fish and poultry, and then switch them to a diet with bread, fruit, vegetables, and sugar—but about the same amount of fat—all their testosterone levels go up. Even more importantly, however, all their levels of cortisol, a stress hormone produced by our adrenal glands, go down.

Having low stress hormone levels is good, because high cortisol levels may “strongly predict cardiovascular death” in men and women both with and without pre-existing cardiovascular disease. In fact, this may help explain “death from a broken heart,” the heightened heart attack and stroke risk in the immediate weeks following the loss of a spouse. Higher cortisol levels days, months, or even years after losing someone you love may increase cardiac risk and reduce immune function. And, the rise in stress hormone levels from the loss of a spouse, a bump of about 50 points, is less than the bump you get by eating high-meat diet.

Cortisol may also help explain why those who are depressed tend to put on abdominal fat. The reason obesity around the middle is associated with elevated cortisol secretion may be that abdominal fat kind of sucks it up, so the accumulation of fat around our internal organs may be an adaptation by which our body deals with excess stress.

These spikes in stress hormone levels every time we eat a lot of meat may not just affect our health, but that of our children, which I discuss in my video Maternal Diet May Affect Stress Responses in Children. “Substantial evidence now suggests that maternal diets of high protein density have adverse effects on the fetus.” For example, back in the 1960s, an experiment was performed on pregnant women in Motherwell, Scotland, in which they were told to eat a high-meat diet in hopes of preventing preeclampsia, a disease of pregnancy. It didn’t work. In fact, the lowest preeclampsia rates I’ve ever seen were among women eating strictly plant-based diets—only 1 case out of 775 pregnancies. Preeclampsia normally strikes about 5 percent of pregnancies, so there should have been dozens of cases, suggesting a plant-based diet could alleviate most, if not all, of the signs and symptoms of this potentially serious condition. So what did happen when pregnant women went from eating about one daily portion of meat to about two portions a day? Mothers who ate more meat and fewer vegetables during pregnancy gave birth to children who grew up to have higher blood pressures.

“One explanation proposed for the adverse effects of high-meat/fish consumption is that this may increase maternal cortisol concentrations, which, in turn, affect the developing fetus,” resetting his or her stress hormone thermostat to a higher level. But, we don’t know until we put it to the test. And indeed, researchers found higher blood cortisol levels “in both the sons and daughters of women who had reported higher meat/fish” consumption, about a 5 percent increase for every meat serving per day. Such diets may present a metabolic stress to the mother and kind of reprogram the adrenal axis of their children, leading to lifelong hypercortisolemia, elevated levels of stress hormones in the blood. This may help explain why every daily portion of meat during late pregnancy may lead to a 1 percent greater fat mass in their children by the time they reach adolescence. So, this could increase the risk of their children becoming obese later in life and thus has “important implications for public health and in terms of prevention of obesity.”

What if they’re already born? We may be able to bring down children’s stress hormone levels with similar dietary changes, but this is just baseline stress hormone levels. Do children of mothers who eat more meat during pregnancy also have exaggerated responses to life stressors? Researchers put them through a stressful challenge—public speaking and mental arithmetic—and then measured their cortisol responses. If their mom ate less than two servings of meat/fish a day while she was carrying them, they got little shots of stress hormones from their adrenal glands. Those whose moms ate more really got stressed out, and those whose moms ate the most—17 or more servings a week, which is more than 2 servings each day—appeared to be really quaking in their boots. In a way, you are what your mother ate.


Want more craziness from Men’s Health magazine? Check out my video Changing a Man’s Diet After a Prostate Cancer Diagnosis.

Here are some other popular videos about eating healthfully during pregnancy:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: