Evolutionary Psychiatry

The hunt for evolutionary solutions to contemporary mental health problems.

Diet and Aggression: Trans Fats

Pesky trans fats could affect our behavior


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Our brains are high energy, fatty powerhouses of sparking neurons and amazing thought. In order for them to work properly, brains need the right sort of vitamins, minerals, and the right sort of fat. In the early 20th century, scientists figured out a way to make oils into more solid fats by partially hydrogenating them. This procedure was useful to make cheaper fats for mass consumption and processed foods with a long shelf-life and palatable consistency. Unfortunately, trans fats are also deadly and the FDA has declared them unsafe in any amount. Most of the data used to try to get trans fats out of the food supply is about heart disease, but trans fats are also probably rotten for the brain.

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Beatrice Golomb is one of my favorite researchers.  She runs studies trying to sort out how statin treatment might affect the brain and maybe cause cognitive difficulties. More recently, she shows up as the primary author on a cool little observational study linking trans fats and aggression.

The weaknesses of the study:  observational, food frequency questionnaires (FFQs), not too many confounders accounted for (I'll get to that later).  The strengths:  decent sample size (>1000), long follow up, prospective (meaning following and measuring people from the beginning rather than retrospective, which means looking back and is pretty much the least reliable way to run a study).

In this research, a bunch of ordinary folks already signed up for a statin study (who weren't on any lipid lowering meds during this study) were co-opted to track trans fat intake as well.  Researchers use the same people for different studies all the time.  This study was done back before the FDA required the amount of trans fat to be labeled, so people could eat “donettes” in blissful ignorance and manufacturers had little incentive to get rid of the nasty stuff. 

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So, what did they find?  Well, amount of trans fat reported consumed in the beginning of the study FFQ correlated linearly with aggression scores measured years later. The researchers accounted for aggression at baseline, sex, age, alcohol consumption, education, smoking, and exercise. In fact, dietary trans fats were more predictive of later aggressive behaviors than any of the other known confounders, and predicted aggression similarly in women and men. Dietary trans fats were also associated with depression.

What is a plausible biochemical mechanism of trans fats causing crankiness?  Well, the neurons need plenty of omega 3 to keep the lights on, so to speak, and trans fats interfere with omega 3 metabolism. In addition, trans fats on their own seem to cause inflammation, cell energetics problems, and oxidative stress.  Yuck.

What don't I like about the findings and discussion of this study?  I've looked at a number of other studies about diet and aggression.  The most rigorous are the Diet and Violence studies done in prisoners, showing boosting micronutrient intake an several replicated randomized controlled trials significantly reduced violent acts.  There is also another throwaway observational study linking soda consumption to adolescent violence.

We all know that trans fats in the American diet circa 1999 were of the garbage processed food variety. Literal junk disguised as tasty treats, though synthetic vitamins might have been sprayed on the flour used as dictated by law. So trans fats consumption is not only a marker of mere trans fat consumption, but also nutrient poor, calorie rich crapola that will decrease the amount of micronutrients one would take in. At the same time, the energetics of the cells are compromised by the trans fats and the omega3 levels are torched. One doesn't typically enjoy a meal of wild-caught pacific salmon and donettes, after all.

I do find it very plausible that synthetic trans fatty acids are terrible for your brain and behavior. And very plausible that processed foods cause problems too. Here is what irks me about the government guidelines for food.  By adding the focus on total fat reduction, polyunsaturated fatty acids and whole grains, they steer folks away from nutrient-rich whole foods and towards convenience foods engineered to meet government guidelines, like low fat whole grain fish crackers and electric green yogurt "food." I’m sorry, but guidelines making us reach for the “whole grains” type of processed sugary honey nut o-shaped cereal over spinach and eggs or plain greek yogurt and blueberries (for example) are misguided.

I wish the government food plate looked more like this one.  I think we all agree trans fats are nasty, and this study is one more reason to look upon them with a wrinkled nose and suspicion. While most manufacturers have taken most of the trans fats out of the food, keep an eye on those labels, and watch out at restaurants, who aren’t yet required to label them. Several towns such as Philadelphia and New York City have banned them, however. Some microwave popcorns and other processed foods were still loaded with trans fats as of January 2012. Do your very best to avoid trans fats. Your heart and brain will thank you.

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Emily Deans, M.D., is a psychiatrist with a practice in Massachusetts.

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