Over the years you have come across claims with every type of diet imaginable, from low fat to high fat, low carbohydrate to high carbohydrate, and even extreme diets bordering on the illogical that ask you to shun pomegranates if you have type A blood. Why pick on pomegranates? Granted they are tough to peel and make your hands all messy, but to never eat them because you have a certain type of blood type? Give me a break!
Anyway, I digress. How important is fat, or the lack thereof, in relation to health and disease? Recent studies indicate that the extreme position of consuming very little fat can lower mood, and even lead to violence and suicide.
Reducing fat intake in those who are McDonald's junkies is certainly a worthwhile goal. Most members of the medical establishment, health writers in the media, and other fitness experts stress the importance of a reducing excessive fat intake. But, tipping the scale too much of the low end can lead you to the local health food store or pharmacy urgently groping for a bottle of St. John's wort.
"Alterations in mood after changing to a low-fat diet," was the title of the article published recently in The British Journal of Nutrition. Ten male and ten female healthy volunteers aged between 20 and 37 years of age had their mood monitored while reducing their fat intake. The amount of total calories they consumed remained constant. For the first month, each volunteer consumed a diet containing 40 percent energy as fat, and the second month half of the subjects changed to a low-fat die consisting of 25 percent of calories from fat. Changes in mood and blood lipids were tested before, during, and after the conclusion of the study. At the end of the second month, the volunteers who had remained on the 40 percent fat diet had a slight decline in anger and hostility while those on the lower fat diet had an increase in hostility. The researchers state, "The results suggest that a change in dietary fat content from 40 percent down to 25 percent of energy may have adverse effects on mood.
Another study released to the media in March got a lot of media attention through releases in Associated Press and Reuter's News Service. The findings, published in the March 15 issue of the American College of Physicians' Annals of Internal Medicine (128(6):478-487), were based on computer-database surveys of more than 30 peer- reviewed medical reports and analyses from the United States and Europe. The investigators discovered that men with blood cholesterol levels of less than 160 milligrams per deciliter had a homicide, suicide or fatal accident rate 50 to 80 percent higher than those with the highest cholesterol levels. Women with low cholesterol levels were nearly 30 percent more prone to violent death.
Dr. Beatrice Golomb, staff physician at San Diego Veterans Affairs Medical Center in California, said the findings suggest a link between low cholesterol and violent death. She said it is possible that low cholesterol is accompanied by a reduction in the brain chemical serotonin, which is believed to control violent behavior. ``We know that low-serotonin people are more likely to commit suicide, especially by violent means, and homicide,'' explained Golomb, who also works as a research professor of psychiatry at the University of Southern California.
Wells AS, Read NW, Laugharne JDE, Ahluwalia NS. Alterations in mood after changing to a low-fat diet. British Journal of Nutrition 79:23-30, 1998.
Comments: The importance of the amount of fat in the diet, the right proportions, the right fats, and so on will be debated for years and decades to come. I don't propose to have the correct answers, but until we learn more about this topic, I'm avoiding extremes. I don't count the grams of fat in my diet, but I do eat eggs two or three times a week, eat fish at least twice a week, have a soy drink and soybeans almost every day, and I try to limit the amount of whole milk, cheese, and butter. About once or twice a month I'll have chicken or meat.
In March of this year I attended the Natural Health Expo in Anaheim, California. One evening, I was having dinner with a few people who were attending the show. After my meal of halibut and vegetables, I ordered a fruit plate and I agreed with two other people at the table to split a chocolate cake in three portions. Well, this didn't sit too well with one of the health fanatics seated at the table. He observed, since I was a prominent physician in the health community, that I should be a good example by not eating the dessert. I told him that everyone has their own level of comfort in what how flexible they wish to be in their dietary choices, and I wasn't going to live my life based on how I thought people would react to what I ate. Many years ago I made the philosophical decision that I didn't want to go on the rest of my life never having a piece of pie or chocolate cake. I think having a piece of delicious dessert once in a while is perfectly acceptable compromise for me.
The type of fat we normally ingest has, of course, a lot to do with mental health than just the quantity of dietary fat intake. A good book on this topic is The Omega Plan by Artemis Simopoulos, M.D. and Jo Robinson (HarperCollins, 1998).
Dr. Golomb, is quoted in the above Reuter's article saying that low cholesterol levels may reduce serotonin levels and hence influence mood. I think another possibility that we should consider is that very low cholesterol levels could reduce the production of pregnenolone and other steroid hormones such as progesterone, DHEA, and the sex steroids. All of these hormones have an influence on mood and behavior.