Last month an update was published on the intriguing suggestion that low levels of salicylic acid—the active component in aspirin—naturally found in plant foods may in part explain the health benefits of a plant-based diet. Some scientists go as far as to suggest those who don't eat enough fruits and vegetables may be suffering from "salicylic acid deficiency," a condition with "important public health implications." Others even propose reclassifying it as an essential micronutrient, "Vitamin S."
Many chronic disease processes involve inflammation, including our top three killers—heart disease, cancer, and stroke—so doctors prescribe a daily aspirin to those for whom the benefits are thought to outweigh the risks. About 1 in 10 people on chronic low-dose aspirin develop stomach or intestinal ulcers, which in rare cases can perforate the gut and cause life-threatening bleeding. My NutritionFacts.org video Aspirin Levels in Plant Foods suggests that the low levels of salicylic acid in fruits (particularly nectarines), vegetables (particularly asparagus), and herbs and spices (especially mint, cumin, thyme, and paprika) may provide the best of both worlds.
The way aspirin and salicylic acid work is by helping our body keep inflammation in check by reducing the assembly of the enzyme responsible for producing inflammatory compounds from something called arachidonic acid, an omega-6 fatty acid that both we and other animals make. In my NutritionFacts.org video-of-the-day yesterday, Chicken, Eggs, and Inflammation, I explain that arachidonic acid is like cholesterol, in that our bodies make all we need for optimal function. The problem is that so do the bodies of birds and mammals, and so when we consume those other animals the level of arachidonic acid in our blood may climb too high.
For example, inflammation in our brain caused by dietary arachidonic acid may explain why those eating plant-based diets appear less stressed and depressed (see my NutritionFacts.org video Plant-Based Diet & Mood) and why eliminating chicken, fish, and eggs may improve symptoms of mood disturbance, depression, and anxiety within two weeks (see Thursday's Improving Mood Through Diet). Arachidonic acid may also play a role in cancer, asthma, inflammatory bowel disease, rheumatoid arthritis, and other autoimmune disorders (see Friday's Inflammatory Remarks about Arachidonic Acid).
This morning's NutritionFacts.org video-of-the-day Chicken’s Fate is Sealed documents the meat industry's attempts to lower the arachidonic acid level in chicken muscles through genetic manipulation and the egg industry's attempts to lower arachidonic acid levels in hens by feeding hens blubber from baby harp seal pups clubbed to death in the Canadian seal hunt. But any arachidonic acid from chicken and eggs is in excess of what our body needs.
In summary, plant-based diets are anti-inflammatory diets because "Vitamin S" and other anti-inflammatory phytonutrients in plants may help prevent the body from overproducing inflammatory compounds, and also because plant-based diets minimize one's intake of inflammatory precursors in the first place.
-Michael Greger, M.D.