Whole Grains and Heart Disease Risk

We know from one study that those who eat the most whole grains tend to have a lower Body Mass Index, a lower weight, and a lower waist circumference compared to those who eat the least whole grains. Whole grains have also been associated with a lower fasting insulin score (12/19/07) and an overall lower risk of death among type 2 diabetics (5/26/10). These are indirect indicators that more whole grains in your diet can help reduce your risk of diabetes and heart disease.

A group of researchers in Scotland recently published a study focused on the effect of higher whole-grain food intake on fairly healthy individuals (Am J Clin Nutr 2010; 92(4): 733-40). They recruited over 200 men and women between the ages of 40 and 65 with Body Mass Indices between 18.5 and 35 (normal to obese). Anyone with known heart disease, asthma, high blood pressure or fasting blood glucose, and those with thyroid conditions were excluded, but those with only moderately high cholesterol or other signs of metabolic syndrome were included in the study.

For 4 weeks the study participants followed what the researchers term a "refined diet," meaning a diet high in refined cereals and white bread. Then the participants were randomly assigned to one of three diets that they followed for 12 weeks: the first group continued the "refined diet," the second replaced three servings of refined grains with three servings of whole wheat products, and the third group replaced three servings of refined grains with one serving of whole wheat and two servings of oat products.

At the beginning of the study, at the end of the first four weeks and then again midway through the test period and again at the close of the study, the researchers measured the participants' blood pressures and cholesterol levels while also monitoring their overall health, weight and level of physical activity.

Interestingly, systolic blood pressure (the top number in your blood pressure score) declined in all three groups - but those in the whole grain groups saw their number drop significantly more: between 5 and 6 points compared to between 1 and 2 points for the "refined diet" group. This was true even though the participants' weight, level of physical activity, and Body Mass Indices remained the same.

However, more whole grains did not appear to have any effect on triglycerides or HDL cholesterol (the good cholesterol). Further, and surprisingly, the "refined diet" group actually reduced their overall cholesterol and their LDL cholesterol (the bad cholesterol) by a clinically significant amount.

What this means for you

These reductions in blood pressure are comparable to taking blood-pressure-lowering medications. While more whole grains may not have an effect on your cholesterol directly, they're more satisfying than refined grains, which can help you manage your weight. Here are some suggestions for getting more whole grains in your diet.

First posted: October 6, 2010