“Eat your damn whole grains!” If you’ve ever known a nutritionist, there’s a pretty good chance they might utter some variation of this advice. Whole grains, they say, are so much better than those nutrient depleted refined grains because the whole grain is full of vitamins and minerals which are removed during the refining process.
Nevermind that some studies have suggested whole grains may not actually provide us with many of these nutrients in a usable form (1,2,3,4). The nutrients are there, but whole grains commonly have anti-nutrients along with their nutrients, so the whole thing is a bit of a paradox–whole grains provide more nutrients, as well as more compounds that inhibit our ability to get these nutrients.
So what about about all these studies showing whole grains are super healthy for you? Correlations, my dear Watson. These are epidemiological studies capable of observing trends, not determining what causes what. A simple explanation for the perceived advantage of whole grains in these studies could be due to the healthier habits of whole grain eaters. Studies have shown people who choose whole grains generally have healthier habits in general–less smoking, more physical activity, and greater consumption of fruits and vegetables, for example (5,6,7).
So what do controlled studies say about whole grains compared to refined grains? This is where things get interesting.
A number of studies have compared refined to whole grains by feeding them to various groups of people and observing the effect on markers of health. A few studies have found that consuming whole grains appears to to lower blood pressure more than refined grains (8,9). Interestingly, in both of these studies (one on white and brown rice, the other on white and whole wheat), the group consuming the refined grains actually had lower LDL cholesterol at the end of the study. A similar study also found that whole grain bread increased LDL in one subset of the subjects and increased triglycerides in another (10).
I should point out that in these studies no other difference on other important health marker were found.
From here, we have a mixed bag. In studies comparing whole grains to refined grains, one found whole grains decreased CRP (11), while another found whole grains increased LDL oxidation (12). One study found whole grains improved insulin sensitivity (13), while another found whole grains increased BMI (14).
How does one look at these studies and determine which type of grain is better for you? I certainly don’t know. Thankfully, there was a controlled study which evaluated this issue and actually measured diseases and death. It’s called the Diet and Reinfarction Trial, or DART. In it, heart disease survivors were advised to either start consuming more whole grains, or just continue eating refined grains.
By the end of the trial there was an increase in the number of deaths, cardiovascular disease deaths, and cardiovascular events (these were not quite statistically significant results). Basically, eating whole grains did nothing for these people and may have contributed to a number of deaths.
Are you doubting the “whole grains are better for you” mantra yet?