This is Your Brain on Fat

Likely the most misunderstood macronutrient, fats are an indispensable part of our diet and serve a number of critical bodily functions, including a major role in the health of our brains. Much like carbohydrates however, the types of fats, as well as the quantity we ingest matters. And when it comes to brain health, it's hard to argue against omega-3 fatty acids as the most beneficial fats we can consume.

Both omega-3 and omega-6 are "essential" fatty acids, meaning the body does not produce them on its own and we therefore must get them from our diet. Omega-6 fats tend to be fairly abundant in the western diet, as they occur in high concentrations in many commonly used vegetable and cooking oils like grapeseed, soybean, corn, sesame, and canola oils. Unfortunately, these oils tend to be highly industrially-processed and may overload our systems with pro-inflammatory omega-6 fats. Our bodies need an inflammatory response to heal injuries and illness, but chronically elevated inflammation has been linked to a host of lifestyle diseases like cancer, cardiovascular disease, and diabetes. 

Omega-3s on the other hand, are much less prevalent in many people's diets and many are deficient in these highly beneficial fatty acids. There are three primary types of omega-3s: ALA (alpha-linolenic acid), DHA (docosahexaenoic acid), and EPA (eicosapentaenoic acid). ALA is most common in our diets, coming from plant foods like walnuts, avocados, flaxseeds, chia seeds, and canola oil. EPA and DHA are much harder to come by in food sources, and are almost exclusively found in fatty fish like herring, mackerel, salmon, sardines, and anchovies. The body can convert some ALA into DHA and EPA, but the conversion rate is very poor (10% or less of ALA becomes DHA/EPA).

In terms of direct brain health benefits, DHA and EPA are where the money is. This means that if we are not consuming the recommended 8-12 oz of fatty fish per week (and few people are), we will become chronically deficient in these potent omega-3s. But what exactly do we mean when we say "potent"? What's the big deal if I'm not consuming fish all the time?

EPA and DHA are crucial for normal brain function throughout all stages of life, beginning in the womb. DHA is critical for the development of the fetal brain, and research has correlated pregnant women's consumption of fatty fish and fish oil with higher scores on tests of intelligence and brain function in early childhood. As we age, EPA and DHA play a major role in maintaining brain function via their role in the structure of brain cell membranes and communication between brain cells.

Among the senior population, low blood levels of DHA have been associated with decreased brain size, a sign of accelerated brain aging. Rates of Alzheimer's disease and dementia are climbing all over the world as populations age and people live longer, and these neurodegenerative disorders have become the fifth leading non-accidental cause of death in the United States. There is still no cure for Alzheimer's and dementia, so the emphasis has been placed on prevention. Sadly, once these diseases have set in, it is usually too late to see significant improvements or any chance of reversal.

In comes omega-3 fatty acids. While research on the effects of omega-3s on symptoms of Alzheimer's and dementia has yielded few positive results, there has been promising data on mitigating milder forms of age-related cognitive decline. Increased consumption of fatty fish in particular has led to improvements in memory, mood, and learning ability in those with mild memory loss or other symptoms of cognitive decline.

Outside of the aging population, research on omega-3s effect on mood and symptoms of depression has been gaining steam in its own right. These benefits appear to be linked primarily to EPA, which tends to have more of an anti-inflammatory effect vs. DHA, which serves more of the structural role in maintaining brain cell membranes. A meta-analysis published in 2019 in the journal Translational Psychiatry found that test subjects ingesting 1g or more of EPA a day experienced a significant drop in symptoms of depression, on par with that of antidepressant medications alone. So regular consumption of omega-3s may not only ward off a drop in brain function as we age, it may keep us feeling happier on the way there.

We're now deep into this discussion, and you may have noticed there has been little mention of omega-3 supplements. While fish oil or other omega-3 supplements are a great way to make up for a dietary deficiency, research on the effectiveness of supplemental omega-3s on preventing cognitive decline has been less conclusive than that of food sources. This is not to say that taking a fish oil supplement has no benefit, as the mood-related benefits don't appear to be exclusive to dietary sources and may be reaped via supplements as well. In addition, a supplemental form may support normal brain function throughout life.

Your best bet is probably a combination of both, and it doesn't always have to be salmon! Tuna, herring, mackerel, sardines, anchovies, halibut, and rainbow trout also pack in the omega-3s to keep that noggin of yours chugging along smoothly.