 The concept of vitamins was first described by none other than Dr. Funk. In his landmark paper in 1912, the concept that there were complex compounds that our body couldn't make from scratch and so had to get from our diet. By the mid-20th century, all of the vitamins had been discovered and isolated, but it wasn't until the 60s 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% fat-free diet on himself for six months, ironically, he felt better. His high blood pressure went away, he felt more energetic, his migraines disappeared. This one-man experiment fortified the medical profession's doubt that essential fatty acids had any relevance to human nutrition, until TPN was developed in the 1960s. Total parenteral nutrition, meaning feeding someone exclusively through an IV, initially developed for babies born without working intestines. But the first preparations were fat-free, because we didn't think humans needed fat. And so they rapidly induced severe 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 they were giving it to after an abdominal gunshot wound, we don't just need fat, but specific fats like omega-3s. And so when they switched to soybean oil, instead she was restored to normal. The fact that 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. A spoonful of orange juice worth of vitamin C would be enough to avoid scurvy the overt vitamin C deficiency disease, but no one considers that enough vitamin C for optimal health. What would optimal omega-3 status look like? Well, doubt has been cast on the role in heart health, which appears to be based on a faulty premise in the first place, and so taking extra omega-3s for our heart might not make any sense, but what about for our baby's brain? Extra DHA may not help pregnant or breastfeeding fish eaters, but those who want to avoid the contaminants in fish can take supplements of pollutant-free algae oil to get the best of both worlds for their babies. But what about adults? No apparent psychological or neurological benefit of DHA supplementation for the general public, but what about in those who don't eat fish? Take the famous alpha-omega trial. Thousands of people randomized for over three years to get either long-chain omega-3s from fish, short-chain omega-3s from plants or placebo, and they found no significant benefits for any kind of omega-3 supplementation on global cognitive decline, but most were eating fish, already getting preformed DHA in their diet, and so general population studies like this that found no benefit can't fully inform us about the role of DHA in brain health any more than giving half of these people oranges, finding no difference in scurvy rates, zero in both groups, and concluding that 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 among like 18 to 45 year olds, but they all only lasted a few months at most, whereas the 2013 study lasted six months. So if all the studies either showed 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, four showed nothing, one showed a benefit, one showed a harm. So if it was just about boosting brain function in the short term, I'd err on the side of caution and spend my money elsewhere. But what about preserving brain function over the long run?