Food and the Brain: Good Fats, Bad Fats

Food Brain & Fats

This is a guest blog post by Jennifer Lee, Ph.D.

Omega-3 essential fatty acids have an important role in the mammalian nervous system.  They seem to be crucial for healthy neuronal structure and function.  And the healthy structure and function in our brains is what allows for healthy behavior.  Plenty of research has been conducted on the role of diets and behavior, particularly in children, with a lot of interest in the ever-controversial role of sugar.  But let’s turn our attention to fats, for a moment.

Essential fatty acids comprise parts of phospholipids and cholesterol esters, which are imperative in the structure and development of synaptic and dendritic cell membrane structures in the brain.  When lacking in essential fatty acids, such as omega-3s, our brain uses non-essential fatty acids to do its job instead.  Or, at least, it attempts to do its job… when we don’t feed our brains well, and the only fats we consume are bad fats, the brain resorts to using what is available.  And this leads to changes in membrane-bound receptors and certain neurotransmitters.  Which leads to psychological and behavioral changes.  Bad fats = bad news.

Researchers have noticed that the tremendous shift in the Western diet away from omega-3 essential fatty acids parallels the large rise in psychiatric disorders, including ADHD and depression.  For this reason, a wide array of studies have found that essential fatty acids might have a significant effect on the neurotransmission of serotonin and associated behavioral disorders.  Here is a cursory review of a few of these findings:

One study found that fatty acid plasma levels were lower in children with ADHD than other children of the same age and sex.  The same thing was found in studies of rats and monkeys with behavioral hyperactivity.  In other studies, children with dyspraxia, dyslexia, and ADHD showed behavioral improvement due to the addition of essential fatty acids in their diets.  Another study looked at violent male subjects with antisocial personality and found low omega-3 plasma concentrations.  This agrees with yet another study that found lower hostility and depression scores in those of hundreds of subjects who consume a diet high in fish.  A study of prison inmates found a significant reduction in aggressive and violent behaviors after supplementation with essential fatty acids.  The same result was found in another study of clinical populations of subjects suffering from various personality disorders.  The list goes on and on.

So how might essential fatty acids affect behavior?  Because they affect our physiology, and the physiology of our brains especially.  Physiological studies of lab animals (rats, pigs, etc.) found that diets deficient in essential fatty acids result in more serotonin receptors in the frontal cortex.  This might sound like a good thing, but actually, more of these types of serotonin receptors means less free-floating serotonin: a condition thought to contribute significantly to depression.  Other studies show that frontal cortex concentrations of serotonin, tryptophan, dopamine, homovanillic acid, and noradrenaline––stuff we want to have at healthy levels in our brains––are nearly doubled in animals supplemented with daily essential fatty acids compared to animals fed substandard diets.

In sum, a number of clinical disorders and behavioral problems have demonstrated an association with decreased levels of omega-3 fats.  Even more, correcting this deficiency by supplementation leads to clinical improvement, probably by way of the transmission of serotonin and other neurotransmitters.  Unfortunately, science is not ready to make a statement that good fats will calm a hyperactive child or make a depressed person happy.  But hey, they can’t hurt!

Information in part from “Essential fatty acids and their role in the treatment of impulsivity disorders,” Prostaglandins, Leukotrienes and Essential Fatty Acids 71 (2004) 211-16.

Jennifer Lee is a behavioral scientist who received her Ph.D. in psychobiology and learning.  She is a psychology instructor, researcher, and writer in studies of human and animal behavior.


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  • Jeanette Chen

    Isn’t the balance of omega 3 and omega 6 fatty acids also important?

    • Jennifer Lee

      Yes, very much.  According to this research, we have too much omega-6 in our (Western) diets and not enough omega-3.  There is a particular ratio that is thought to be healthiest: something like 3:1 omega-6:omega-3 (can’t remember the exact numbers here), and apparently in our diets we tend to get somewhere more like 17:1.

  • Brian

    Which is why all the processed oils are not really (or at all) good for you, even though they are low in saturated fat. This is also why we are hearing more and more about pasture-raised ruminant animals, because they are shown to have a much higher level of omega 3′s in them. Fish, and salmon specifically is, of course, one of the best sources… or fermented cod liver oil.

    Good article. Thanks for sharing!

  • Knowfoodnow

    Your article about how essential fatty acids may impact behavior is fascinating. I wrote about identifying foods with good fats vs bad fats here:

    • Jennifer Lee

      Thanks for linking that here, I am referring Leefred (above) to your article.

  • Jim

    This seems to be based on some very sparse evidence. The Mayo clinic site says
    “ Promising initial evidence requires confirmation with larger, well-designed trials.”

    • Janice D.

      Jim I have research results of my own to report and they are opposite from the stupid scientists. I find omega-3 to make my kids more hyperactive. Lately I have been dosing them with this kind of nasty fish oil and they get pretty agitated when they hear me rummaging in the cabinet to get the magic fish oil. Real hyperactive, so much so they are getting nearly impossible to catch and force medicine into. I didn’t know such small kids could scream and fight so hard. This will become a greater problem as they get bigger and I get older. I’m thinking of giving up on the fish oil and just let them eat PBJ sandwiches if that’s what they want. Stupid omega-3.

    • Jennifer Lee

      Some of the studies I mentioned had small sample sizes, and some were quite large.  They were all well-designed.  But yes, this is a new line of research, so we would need additional studies to support the authors’ claims.  It would be nice if all initial evidence came from large, well-designed studies, but that is often not the case.  Large studies require large funding, and the funding agencies have their own agendas… you can see how that ends up affecting science.  Many lines of research actually start with modest studies and don’t explode until the right people with plenty of resources take an interest. 

  • Leefred

    Thanks for sharing this. Can you please provide a simple list of “good” and “bad” fats and foods for us laypeople?

    • Jennifer Lee

      Check out Marsha Hallet’s article:

      Basically, good fats come from nuts, beans, and fish.  Bad fats come from animal fat and processed foods (what I call “fake fats”, like hydrogenated oils).  The harder part to remember is regarding “vegetable” fats (I put vegetable in quotes because they’re not all technically vegetables).  For example, avocado oil is good (thank god), but vegetable shortening is a definite no-no.

      • Brian

        Saturated fat isn’t as bad as the popular press would have you believe. There is really not a lot of good science that proves saturated fat is bad for you. This is my opinion, but health has more to do with the quality of food you eat more than the macronutrients and micronutrients. Eat a nice diverse set of whole foods from their most natural origion, and you will be far better off than the average person eating SAD. So what I mean by this is organic locally raised vegetables and fruits, pasture raised meats, wild fish…

        • Daniel Donovan

          This person has a PhD? ………..

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