Americans are famous for consuming high-calorie diets that lack essential nutrients. One of these absent nutrients is Omega-3 fatty acid, aka fish oil. Our brains are built on a foundation of fatty acid molecules and if we consume too little of the critical ones the consequence is impaired thinking and emotional imbalance often resulting in mood disorders and psychosis. For almost four decades, we've heard about the potential benefits of taking Omega-3 supplements. However, there is still only limited evidence that consuming Omega-3 fatty acid supplements every day can actually delay the development or reduce the symptoms of depression or schizophrenia.
A recent publication in the prestigious journal
Nature Medicine investigated the consequences of a life-long
diet deficient in Omega-3 fatty acid. What these researchers discovered is that a poor diet may lead to various mood and
cognitive disorders because they disrupt the normal function of our brain's endogenous
marijuana neurotransmitter system. The neurobiological links between diet,
depression, higher cognitive function and marijuana are becoming better understood. This is what we understand thus far:
In wealthy countries such as the US, inexpensive high-calorie high fat foods make up a substantial portion of our diet and predispose us to malnutrition and obesity. Recent studies indicate that when we are obese our large fat cells infuse cannabinoids (the endogenous variety) into our blood; this process is thought to be responsible for the uncontrollable binge eating (think "the munchies") often reported by obese people who are otherwise successful at controlling their eating habits. Not only that, these endogenous cannabinoids enhance our appreciation of sweet tasting foods.
A recent study from Scandinavia reported that young obese men demonstrated more cognitive impairments, i.e. lower I.Q. scores, than young normal-weight men. Studies also suggest that obesity predisposes people to depression and makes them less likely to respond to standard anti-depressant therapy. Blocking our brains' endogenous marijuana system with the drug rimonabant reduced the urge to eat high-fat foods; however, this drug produced depression and induced too many attempted suicides that the drug was pulled from clinical trials. These results suggest that obesity indirectly interferes with the normal role of our brain's marijuana neurotransmitter system in the control of diet, mood and cognitive abilities.
What these discoveries also teach us is that our brain's own marijuana neurotransmitter system is necessary for us to feel hunger, to experience happiness and to maintain the brain processes that prevent depression and cognitive decline. In total, these studies provide additional evidence that what we consume affects our mood and mental performance. Consuming more fish oil, or Omega-3 supplements, may offer an affective and safe approach to combating some of the consequences of a poor diet on brain function.
© Gary L.Wenk, Ph.D., author of Your Brain on Food (Oxford, 2010)
