Are Grains Pro-Inflammatory or Anti-Inflammatory?

Consistent with recommendations from leading heart disease and cancer authorities, I recommend at least three servings of whole grains a day. A meta-analysis of 11 studies estimated that this would translate into a 17 percent lower overall risk for mortality (though amusingly, the paper typo’d it “risks for morality.” Angel food vs. Devil’s food cake perhaps?)

No surprise, though, given that whole grain consumption has been associated with a lower risk of dying from cardiovascular disease, cancer, diabetes, and inflammatory diseases in general. Eating more whole grains could potentially save the lives of millions of people around the world every year. 

My first thought was that this may be a substitution effect. Just like the halo around fish consumption may be less about the pros of fish than the cons of what you might otherwise have ordered, do whole grains look good just because refined grains are so bad? To my surprise, when I dug up the half dozen studies that looked at refined grain intake and mortality, the only one that found a significant link was a pooling of Harvard cohorts that, if anything, found a protective association. Of course, this could be a bit of substitution effect as well, as those eating lots of refined grains are probably not on lower carb diets, which, even after adjusting for other lifestyle factors, have been associated with dying prematurely from cancer, heart disease, stroke, and all causes put together. 

Whole grain consumption is also associated with successful aging, as measured by a variety of functional and clinical components. Is this all just a Big Barley conspiracy? Studies funded by industry groups like the Cereals & Grains Association were not significantly more likely to come to favorable conclusions, as opposed to, for example, the dairy or sugary beverage industries, for which industry funding increased the odds of favorable conclusions more than seven-fold. A recent review of such shenanigans concluded that “dairy intake recommendations made in dietary guidelines should account for the potential influence of industry sponsorship on evidence of health effects.” When, in its latest dietary guidelines, Canada did just that, dairy was removed as a separate food group. Water became the beverage of choice. 

Observational studies consistently correlate whole grain consumption with lower levels of inflammation. Each daily serving is associated with approximately a 7 percent lower CRP level, but randomized, controlled trials to prove cause and effect only found anti-inflammatory benefits in certain subgroups. For example, whole grains only appeared to reduce IL-6 levels in unhealthy individuals, for example, or reduce CRP among those who started out with elevated levels. Oats, however, contain a unique class of anti-inflammatory compounds called avenanthramides.

Avenanthramides are thought to be responsible for the fresh odor and flavor of oats, as well as the ability of oatmeal lotion to relieve skin itching and irritation. Studies on human skin fragments from plastic surgery subjected to inflammatory chemicals reveal that oatmeal extract can suppress inflammation—so much that oatmeal now appears to be the treatment of choice for certain serious chemotherapy-induced skin rashes. The avenanthramides are suspected to be the active component, since they can directly attenuate inflammation in muscle cells in vitro, and drops in inflammatory mediators IL-6 and CRP are only seen after eating high versus low avenanthramide oats after muscle-inflaming exercise, like running downhill.