Whole grain consumption is associated with a 21% reduction in cardiovascular disease when compared to minimal whole grain intake, according to a 2008 review article in Nutrition, Metabolism, and Cardiovascular Disease.
Coronary heart disease is the No. 1 killer in the developed world. Stroke is No. 3. The term “cardiovascular disease” lumps together heart attacks, strokes, high blood pressure, and generalized atherosclerosis (hardening of the arteries).
Investigators at Wake Forest University reviewed seven pertinent studies looking at whole grains and cardiovascular disease. The studies looked at groups of people, determining their baseline food consumption via questionnaire, and noted disease development over time. These are called “prospective cohort studies.”
None of these cohorts was composed purely of diabetics.
The people eating greater amounts of whole grain (average of 2.5 servings a day) had 21% lower risk of cardiovascular disease events compared to those who ate an average of 0.2 servings a day. Disease events included heart disease, strokes, and fatal cardiovascular disease. The lower risk was similar in degree whether the focus was on heart disease, stroke, or cardiovascular death.
Note that refined grain consumption was not associated with cardiovascular disease events.
Why does this matter?
The traditional Mediterranean diet is rich in whole grains, which may help explain why the diet is associated with lower rates of cardiovascular disease. If we look simply at longevity, however, a recent study found no benefit to the cereal grain component of the Mediterranean diet. Go figure . . . doesn’t add up.
Readers here know that over the last four months I’ve been reviewing the nutritional science literature that supports the disease-suppression claims for consumption of fruits, vegetables, and legumes. I’ve been disappointed. Fruit and vegetable consumption does not lower risk of cancer overall, nor does it prevent heart disease. I haven’t found any strong evidence that legumes prevent or treat any disease, or have an effect on longevity. Why all the literature review? I’ve been deciding which healthy carbohydrates diabetics and prediabetics should add back into their diets after 8–12 weeks of the Ketogenic Mediterranean Diet.
The study at hand is fairly persuasive that whole grain consumption suppresses heart attacks and strokes and cardiovascular death. [The paleo diet advocates and anti-gluten folks must be disappointed.] I nominate whole grains as additional healthy carbs, perhaps the healthiest.
But . . .
. . . for diabetics, there’s a fly in the ointment: the high carbohydrate content of grains often lead to high spikes in blood sugar. It’s a pity, since diabetics are prone to develop cardiovascular disease and whole grains could counteract that. We need a prospective cohort study of whole grain consumption in diabetics. It’ll be done eventually, but I’m not holding my breath.
[Update June 12, 2010: The aforementioned study has been done in white women with type 2 diabetes. Whole grain and bran consumption do seem to protect them against overall death and cardiovascular death. The effect is not strong.]
What’s a guy or gal to do with this information now?
Non-diabetics: Aim to incorporate two or three servings of whole grain daily into your diet if you want to lower your risk of heart disease and stroke.
Diabetics: Several options come to mind:
- Eat whatever you want and forget about it [not recommended].
- Does coronary heart disease runs in your family? If so, try to incorporate one or two servings of whole grains daily, noting and addressing effects on your blood sugar one and two hours after consumption. Eating whole grains alone will generally spike blood sugars higher than if you eat them with fats and protein. Review acceptable blood sugar levels here.
- Regardless of family history, try to eat one or two servings of whole grains a day, noting and addressing effects on your blood sugar. Then decide if it’s worth it. Do you have to increase your diabetic drug dosages or add a new drug? Are you tolerating the drugs? Can you afford them?
- Assess all your risk factors for developing heart disease: smoking, sedentary lifestyle, high blood pressure, age, high LDL cholesterol, family history, etc. If you have multiple risk factors, see Option #3. And modify the risk factors under your control.
- Get your personal physician’s advice.
Steve Parker, M.D.
Extra Credit: The study authors suggest a number of reasons—and cite pertinent scientific references—how whole grains might reduce heart disease:
- improved glucose homeostasis (protection against insulin resistance, less rise in blood sugar after ingestion [compared to refined grains], improved insulin sensitivity or beta-cell function)
- advantageous blood lipid effects (soluble fiber from whole grains [especially oats] reduces LDL cholesterol, lower amounts of the small LDL particles thought to be particularly damaging to arteries, tendency to raise HDL cholesterol and trigylcerides [seen with insulin resistance in the metabolic syndrome])
- improved function of the endothelial cells lining the arteries (improved vascular reactivity)
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.
Reference: 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.
Oldways, the preeminent promoter of the Mediterranean diet, proclaims May to be “Mediterranean Month.” The idea is to spread awareness of the traditional Mediterranean diet. 
Diabetic Mediterranean Diet 