Transcript: Improving Mood through Diet
In one of my videos last year, I reported on the finding that vegetarian men and women had significantly better scores on the Depression, Anxiety, Stress scale. Why were vegetarians significantly less depressed, anxious, and stressed than even healthy meat-eaters in this study? “[N]egligible arachidonic acid intake may help explain the favorable mood profile observed with vegetarian diets.” As I talked about last year, this arachidonic acid stuff in our diet produces inflammatory compounds, which may inflame our brain.
The omnivores ate nine times as much arachidonic acid as the vegetarians—which is not surprising, given that arachidonic acid is not found in plants. That’s why vegetarians and vegans have significantly lower levels of arachidonic acid flowing though their bloodstream. In fact, you can even measure it right out of saliva. They found significantly lower levels of arachidonic acid in vegetarian drool.
This was a landmark study, but it was also just a cross-sectional study—a snapshot in time. To prove cause and effect, they really needed to do an interventional study. So, they did. Presented at the American Public Health Association conference, they took a bunch of meat-eaters, and split them up into three groups. The control group maintained regular intake of flesh foods. The second group ate fish, but no other meat, and the third was put on a vegetarian diet with no eggs. The whole study lasted only two weeks, but what do you think they found?
If it were primarily the saturated fat inflaming the omnivores’ brains, then the moods of both the veg and fish groups would presumably improve. If arachidonic acid were the culprit, then presumably only the veg group would feel significantly better.
This is the amount of arachidonic acid, in blue, consumed per day by the end of the study. The fish-eaters were eating a lot more of those long chain omega-3s, though—EPA and DHA—so, maybe they were protected, even though they were consuming all that arachidonic acid in fish. Or, maybe no one would experience a change in mood at all in such a short time frame—just two weeks. Sometimes it takes drugs months to have an effect.
Here’s what they found. In terms of psychological benefits, the egg-free vegetarian group significantly improved—meaning greater reductions in both the Depression, Anxiety, Stress scale and the Profile of Mood States—a measurement of mood disturbance. Though the no-poultry fish group did marginally better than the control group, the difference was not statistically significant.
Conclusion: “The complete restriction of flesh foods significantly reduced mood variability in omnivores….Our results suggest that a vegetarian diet can reduce mood variability in omnivores. Perhaps eating less meat can help protect mood in omnivores, particularly important in those susceptible to [mood] disorders.”
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Dianne Moore.
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