By Dr. Mercola
Fish is often described as "brain food," and that is largely because it contains omega-3 fats. Docosahexaenoic acid, or DHA, an omega-3 fat, is an essential structural component of your brain.
Approximately 60 percent of your brain is composed of fats — 25 percent of which is DHA. DHA is found in high levels in your neurons – the cells of your central nervous system, where it provides structural support.
Low DHA levels have been linked to memory loss and Alzheimer's disease, and since your body cannot produce omega-3 on its own, you must get it from your daily diet. DHA-rich foods include fish, liver, and brain, so it's easy to know why (in the US, at least) fish is the preferred dietary source.
Eating Baked Fish May Improve Your Memory
A new study has added further support for adding more fish to your diet, although there are some important caveats to consider. The study found people who consumed baked (or broiled) fish at least once a week had more grey matter in their brain.
Specifically, compared to those who didn't consume fish on a regular basis, regular fish eaters had 14 percent greater grey-matter volume in the area responsible for cognition and more than 4 percent greater volume in the area responsible for memory.1
The DHA molecule has unique structural properties that provide optimal conditions for a wide range of cell membrane functions, and grey matter is a particularly membrane-rich tissue.
Eating fried fish did not lead to this benefit, which isn't surprising since carefully choosing your cooking methods, and your cooking oils, can make or break your meal from a nutritional standpoint.
Past research has also found that while eating baked and broiled fish improves heart health, eating fried fish increases heart failure risk.2 This is likely due to the trans fats and oxidized aldehydes in fried fish, which are not only linked to heart damage but also to brain damage (including brain shrinkage linked to Alzheimer's disease).
While both broiled and baked fish were linked to better brain function, I would suggest sticking with baking (particularly at lower temperatures). I don't generally recommend broiling, since high-temperature cooking (grilling, broiling, barbecuing, and frying) can lead to the formation of cancer-causing substances like heterocyclic amines (HCAs) in your food.
One surprising element to the study was that there was no association found between blood levels of omega-3s and brain benefits, which suggests there may have been other brain-boosting lifestyle factors at play in the frequent fish eaters.
Perhaps their diets were healthier in other respects as well. Still, the research speaks for itself when it comes to the health benefits of omega-3 fats, including for your brain.
Your Brain May Degenerate Without Enough Omega-3 Fats
The introduction of high-quality, easily digested nutrients from seafood into the human diet coincided with the rapid expansion of grey matter in the cerebral cortex -- a defining characteristic of the modern human brain.
Research is showing that degenerative conditions can not only be prevented but also potentially reversed with omega-3 fats. For example, in one study, 485 elderly volunteers suffering from memory deficits saw significant improvement after taking 900 milligrams (mg) of DHA per day for 24 weeks, compared with controls.3
Another study found significant improvement in verbal fluency scores after taking 800 mg of DHA per day for four months compared with placebo.4 Furthermore, memory and rate of learning were significantly improved when DHA was combined with 12 mg of lutein per day.
Interestingly, research suggests that the unsaturated fatty acid composition of normal brain tissue is age-specific, which could imply that the older you get, the greater your need for animal-based omega-3 fat to prevent mental decline and brain degeneration.
Still, omega-3s are also incredibly important for brain health during development, both in utero and during childhood. One study of 8- to 10-year-old boys looked at how DHA supplementation might affect functional cortical activity, and the results were quite impressive.
The data indicated that there were significant increases in the activation of the dorsolateral prefrontal cortex part of the brain in the groups receiving supplemental DHA. This is an area of your brain that is associated with working memory.
They also noticed changes in other parts of the brain, including the occipital cortex (the visual processing center) and the cerebellar cortex (which plays a role in motor control).5 Of course, the overall health benefits of omega-3 fats go far beyond brain health.
Omega-3 deficiency is believed to be a significant underlying factor of up to 96,000 premature deaths each year! Yes, this deficiency was recently revealed as the sixth biggest killer of Americans, so taking this recommendation to heart could prove to be lifesaving.
Omega-3 Fats Might Help Your Brain Heal and 'Preserve' Your Brain in Old Age
It appears there is virtually no area of brain health left untouched by omega-3s. After a traumatic injury, the brain inflammation that occurs can continue for long periods of time unless, as leading omega-3 expert Dr. Barry Sears stated, "there's a second response that turns it off." Fish oil, it appears, can help do just that, when given in sufficiently high doses.
You can read about one remarkable case of omega-3 fats for healing brain injury here. Another study, published in the journal Neurology, reported that "older women with the highest levels of omega-3 fats… had better preservation of their brain as they aged than those with the lowest levels, which might mean they would maintain better brain function for an extra year or two."6
The researchers assessed the omega-3 fat levels in the red blood cells (RBCs) of more than 1,100 women then, eight years later, their brain volumes were measured using an MRI scan.
The women whose omega-3 levels were the highest—7.5 percent—at the outset of the study had 0.7 percent larger brain volume. Their hippocampus, which plays an important role in memory formation, was also 2.7 percent larger.
The researchers summarized their findings stating that "we did not find an association between RBC DHA + EPA levels and age-associated cognitive decline in a cohort of older, dementia-free women." However, their findings do suggest that omega-3 can be helpful in slowing down age-related brain atrophy. The study's lead author also indicated that previous studies have shown eating non-fried oily fish twice a week and taking fish oil supplements can raise your mean red blood cell level of EPA and DHA to 7.5 percent—the same level as the women with the highest omega-3 levels had in his study.
Is Fish a Good Source of Omega-3 Fat?
It can be. Interestingly enough, and fortunately for us, the types of fish that tend to suffer the least amount of toxic contamination also happen to be some of the best sources of fat and antioxidants. So, by choosing wisely, the benefits of a diet high in fish can still outweigh the risks of contamination. Most major waterways in the world are contaminated with mercury, heavy metals, and chemicals like dioxins, PCBs, and other agricultural chemicals that wind up in the environment. There are a couple of exceptions to this rule, one being wild-caught Alaskan salmon. I eat about three ounces of Wild Alaskan salmon every other day or so.
The risk of authentic wild-caught Alaskan sockeye salmon accumulating high amounts of mercury and other toxins is reduced because of its short life cycle, which is only about three years. Additionally, bioaccumulation of toxins is also reduced by the fact that it doesn't feed on other, already contaminated, fish. You will want to avoid farm-raised salmon (and other types of farm-raised fish), which are notorious for being heavily contaminated (and disastrous for the environment).
Not only that, but farmed salmon may contain only about half of the omega-3 of wild salmon. Other fish with short life cycles also tend to be better alternatives in terms of fat content, so it's a win-win situation – lower contamination risk and higher nutritional value. A general guideline is that the closer to the bottom of the food chain the fish is, the less contamination it will have accumulated. This includes:
Sardines, in particular, are one of the most concentrated sources of omega-3 fats, with one serving containing more than 50 percent of your recommended daily value.7 They also contain a wealth of other nutrients, from vitamin B12 and selenium to protein, calcium, and choline, making them one of the best dietary sources of animal-based omega-3s. If you eat fish frequently and want to take precautions, you can also do what I do: whenever I eat fish, I eat it with chlorella tablets. The chlorella is a potent mercury binder and if taken with fish will help bind the mercury before your body can absorb it, so it can be safely excreted in your stool.
Fish Oil Versus Krill Oil: What's the Difference?
You're probably aware that if you don't eat a lot of fish, you can supplement your diet with omega-3 fats with fish oil. Less widely known is that you can also get your omega-3s from krill oil, and it may, in fact, be preferable to do so. A helpful form of plant-based omega-3 can also be found in flaxseed, chia, hemp, and a few other foods, but the most beneficial form of omega-3 (animal-based) -- containing two fatty acids, DHA and EPA, which are essential to fighting and preventing both physical and mental disease -- can only be found in fish and krill.
Why might you be better off with krill? The omega-3 in krill is attached to phospholipids that increase its absorption, which means you need less of it, and it won't cause belching or burping like many other fish oil products. Additionally, it contains almost 50 times more astaxanthin, a potent antioxidant, than fish oil. This prevents the highly perishable omega-3 fats from oxidizing before you are able to integrate them into your cellular tissue. In laboratory tests, krill oil remained undamaged after being exposed to a steady flow of oxygen for 190 hours. Compare that to fish oil, which went rancid after just one hour. That makes krill oil nearly 200 times more resistant to oxidative damage compared to fish oil!
When purchasing krill oil, you'll want to read the label and check the amount of astaxanthin it contains. The more the better, but anything above 0.2 mg per gram of krill oil will protect it from rancidity. To learn more about the benefits of krill oil versus fish oil, please see my interview with Dr. Rudi Moerck, a drug industry insider and an expert on omega-3 fats. If you don't eat fish regularly, a krill oil supplement is one of the few supplements I recommend to virtually everybody. If you prefer to get your omega-3s from your diet, then be sure you're eating sardines, anchovies, herring, and/or wild-caught salmon on a regular basis.