OT
Here's a very, very simple example of drawing conclusions from studies. I encountered this one just this morning on the blog of a doctor I follow and generally respect. He concludes from studies that whole grains are heart-protective. But what the studies compared was whole grains against processed grains, not against the absence of grains. Nothing it the studies demonstrates that whole grains have any absolute benefit. One might reasonable come away with the notion that refined grains may play a role in cardiovascular disease but asserting an absolute benefit for whole grains is an over-reach.
This is how memes and myths like the ones about fat that we were discussing get started and perpetuate. Whole grains are good for your heart, doncha know...
Whole Grains: Tried and True Protection for Heart & Brain
POSTED BY: Steve Parker | May 05, 2010 | 12:18 PM
One type of food has consistently been associated with lower risk of heart attacks and strokes: whole grains.
Heart disease, specifically coronary heart disease, is the leading cause of death in the developed world. Strokes are the No.3 killer, after cancer. "Cardiovascular disease" lumps together heart attacks, strokes, generalized atherosclerosis (hardening of the arteries), and high blood pressure.
I've been thinking - again - about the link between food and heart attacks after reading a 2009 review article by French epidemiologists who found no protection against heart attacks by eating fruits and vegetables. Now that we know that heart disease doesn't have much to do with our consumption of total fat, saturated fat, and cholesterol, you have to wonder if diet has any effect.
Dr. Frank Hu and others suggest that refined carbohydrates may be a major cause of heart disease. The refining of grains removes the bran and germ, leaving mostly starchy endosperm.
A 2008 review article in Nutrition, Metabolism and Cardiovascular Disease notes that whole grain consumption is associated with a 21% reduction in cardiovascular disease when compared to minimal whole grain intake.
Researchers at Wake Forest University found seven well-designed scientific studies that looked into the connection between whole grains and cardiovascular disease. The individual studies looked at groups of people, documenting baseline food intake via questionnaire, and watched for the development of disease over the ensuing years. These are called "prospective cohort studies," and are quite common in nutrition science. They are not perfect by any means, but sometimes they're the best we do.
They found that people eating at the high end of whole grain consumption (2 and a half servings a day) had 21% lower risk of developing cardiovascular disease compared to those rarely eating whole grains."Rare" consumption was an average of 0.2 servings a day. The lowered risk was similar whether the researchers were looking specifically at heart attacks, strokes, or fatal cardiovascular disease.
I'm sure that paleo diet advocates and anti-gluten folks will find fault with the conclusions from Wake Forest. But I find the evidence for a heart-protective effect of whole grains fairly persuasive. No, it's not absolute proof; we may or may not have that 10 or 20 years from now.
If you're concerned about developing coronary heart disease or stroke, perhaps because of family history, I'd seriously consider eating two or three servings of whole grain daily.
The Whole Grains Council has ideas to get you started.
-Steve Parker, M.D.
Disclaimer: All matters regarding your health require supervision by a personal physician or other appropriate health professional familiar with your current health status. Always consult your personal physician before making any dietary or exercise changes.
References:
Mellen, P.B, Walsh, T.F., and Herrington, D.M. Whole grain intake and cardiovascular disease: a meta-analysis. Nutrition, Metabolism and Cardiovascular Disease, 18 (2008): 283-290.
Dauchet L., Amouyel, P., and Dallongeville, J. (via MedScape). Fruits, vegetables and coronary heart disease. Nature Reviews Cardiology, 6 (2009): 599-608. doi: 1011038/nrcardio.2009.131 |
