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Usually when we say “my gut tells me…” we’re referring to some vague hunch, something we can’t prove or trace the reasoning for. In today’s blog we’re standing those same words on their heads, to tell you how our gut– our digestive tract – can in fact provide solid proof for the health beneﬁts of whole grains.
While intake of whole grains has long been linked to prevention of chronic diseases associated with inﬂammation, no one has been quite sure how or why this is so. Researchers at the University of Nebraska carried out an interesting human trial, to investigate whether gut bacteria might explain the health beneﬁts of whole grains. The answer was yes!
Why gut bacteria? Before you start saying “eee-yew” or “Gee, I’m glad my job doesn’t require me to look at gut bacteria,” a few words on the gut might help. Increasingly, research shows that only 10% of the cells in our bodies are human – and the rest are bacteria, along for the ride. (Click here for a great Michael Pollan article on this.) Not surprisingly, our gut holds some of the greatest concentrations of bacteria. Don’t be alarmed: most of these bacteria are our friends, “good” microbes that help us digest our food and carry out many essential functions in our body. In fact, feeding our “good bacteria” helps crowd out the pathogens, or “bad bacteria” that may try to take hold in our systems.
The balance of “good” and “bad’ bacteria in our bodies plays a big role in maintaining good health – and diet is a major factor in determining which bacteria thrive in each person’s body. So these scientists decided to feed people a few diﬀerent whole grains, then see whether they could detect changes in the people’s gut bacteria.
Basics of the study. The study had 28 participants, 17 women and 11 men, who took part in what’s called a “randomized cross-over trial” – which means that everyone received a series of diﬀerent diet interventions, but not in the same order (in case order turned out to make a diﬀerence). While continuing to eat their normal diet, the people were asked to include about a cup of whole grains daily, through these three diet interventions:
60 grams per day of brown rice (about 1 cup cooked) or
60 grams per day of whole grain barley (again, about 1 cup cooked) or
30 grams of each (whole grain barley and brown rice, a half cup or so of each)
The trial started with a “baseline” week, so the scientists could measure participants’ normal gut bacteria. That was followed by four weeks on one of the diet interventions above, a two-week break (called a wash-out period), four weeks on another of the three diets, another two-week break, and then four weeks on the third diet.
Blood tests at the start of the study, and at the end of each four-week dietary intervention, measured glucose and insulin (markers of how well blood sugar is being managed), lipids (like cholesterol) and three indicators of inﬂammation (LBP, CRP and IL-6, if you’re technically inclined). In addition (this is where you can appreciate your own day job), scientists collected fecal samples from participants, and analyzed the microbes in them.
Whole grains cut inﬂammation. While there was a great deal of individual variation, the researchers found that overall:
whole grain consumption cut inﬂammation, especially IL-6 levels
it also improved management of blood sugar and fats
all three whole grain treatments resulted in immunological and metabolic improvements, but the one combining two grains did best
many improvements were especially signiﬁcant in women and in overweight subjects
One of the coolest things the scientists found was that important “good” bacteria associated with stamping out inﬂammation increased when participants ate whole grains. There was the “proof of mechanism,” right before their eyes. We’d like to draw attention to three key points in this study:
Not a whole lot of time. We think it’s pretty cool that these positive bodily changes were obvious In just four weeks of eating whole grains. Too often health steadies report ﬁndings like, “Those who eat six cups more vegetables every day for 47 years may reduce their risk of cancer by 6%” or some such. You know what I mean: the study shows that if you do something you’re not likely to do, and do it pretty much forever, there’s a tiny chance it might increase your lifespan by two weeks.
Not a lot of whole grains. Another important point to note is that these people were ﬁtting just one cup of cooked whole grains into their normal diets. No one was asking them to give up all their favorite foods. This is pretty do-able, right? The study shows that real-life, do-able amounts of whole grains, can make almost instant, provable changes in your body – changes that appear to have measurable links to better health. (Don’t miss the part where two grains were better than one –– just as we eat a variety of vegetables, we should eat a variety of whole grains, too.)
The whole is greater than the parts. Citing other research, the scientists made the important point that while whole grains signiﬁcantly increase bacterial diversity (a good thing), the same results have not been shown when people eat foods with prebiotics, resistant starches and/or dietary ﬁbers added. “The compositional complexity of whole grains, which contain a variety or carbohydrates and phytochemicals” could make a diﬀerence, according to the study. That’s a vote for eating foods as nature created them, and as our bodies evolved eating them – rather than pulling apart diﬀerent components and nutrients to make artiﬁcial “functional foods.” Real, minimally processed foods are functional enough, thank you very much.
Although this study was ﬁrst published (and added to our online health studies database) last year, we decided to blog on it today because there’s a widespread rumor out there that all grains – including intact whole grains – cause inﬂammation. Categorically not true, as this study demonstrates. Whole grains are part of the solution, not part of the problem.
A whole grain cookie is still a cookie, as we often say. Intact whole grains (real grain kernels, that haven’t been ground up or puﬀed or mixed with sugar) are still the healthiest choice, so make sure to work some intact grains into every meal: steel cut oats for breakfast, for instance; a whole grain salad or soup —- such as tabbouleh or mushroom barley soup — for lunch; and a whole grain pilaf or burger for dinner. Check out our recipes for inspiration. (Cynthia)