Whole Grain

From The Experts

Heart Disease

As early as 1998, researchers from the University of Minnesota examined the relationship between the consumption of wholegrain foods and Ischemic Heart Disease (IHD) in over 31,000 women (Jacobs et al, 1998). Over 9 years, women consuming approximately one serving of wholegrain foods per day had a 30% lower risk of developing IHD compared to women who rarely consumed wholegrains, after accounting for a range of other factors that may contribute to a lower risk of heart disease.

Since then, several other large prospective studies have been published finding that increased wholegrain intakes are associated with a 20%-40% lower risk of Coronary Heart Disease (CHD) in men and women (http://gograins.grdc.com.au/)

A protective effect of wholegrain consumption in men has also been observed. As part of the Health Professionals Follow-Up study of over 42,000 men, it was observed that men consuming the most wholegrain foods had an approximately 20% lower risk of developing Coronary Heart Disease (CHD). In addition, heart disease risk was reduced by 6% for each 20g increment in wholegrain intake (Jensen et al, 2004).

In a study of over 11,000 US adults, consumption of approximately three serves of wholegrains per day was associated with a 28% lower risk of developing coronary artery disease (CAD), compared to consuming less than one serving per day (Steffen et al, 2003). Interestingly, the consumption of refined cereal grains (such as refined grain breakfast cereals, wheat breads and pasta, bagels, muffins, biscuits and cookies) was associated with a trend to increased risk of CAD.

Stroke is a leading cause of death and disability in populations. As wholegrains have previously been associated with lower risk of mortality, including mortality from coronary artery disease, researchers from Harvard Medical School reanalysed data from over 75,000 US women participating in the Nurses' Health Study to assess the association between wholegrain intakes and the risk of Ischemic Stroke over a 12 year period (Liu et al, 2000). After accounting for age, smoking and known risk factors for heart disease, women consuming the most wholegrains had a 30% lower risk ischemic stroke compared to women eating the least wholegrains.

To examine the effects of wholegrains in other population groups, researchers from the University of Minnesota examined the relationship between wholegrain intakes and the risk of ischemic stroke in a cohort of almost 12,000 US men and women (Steffen et al, 2003). Although a reduction in risk for ischemic stroke was observed in subjects consuming three or more servings of wholegrains per day, this was no longer significant after adjusting for a range of factors, such as BMI, blood pressure and medication usage.

Hypertension is a risk factor for cardiovascular disease, including stroke. It has been suggested that the various nutrients found in wholegrains (such as soluble fibre, minerals, folate and vitamin E) contribute to the protective effects on stroke (Liu et al, 2000). To determine the effect of wholegrains on blood pressure, researchers from the United States examined the effect on blood pressure in adults consuming 45g oats per day, as part of an energy reduced diet (Saltzman et al, 2000). After 6 weeks, subjects consuming the oats had a significant reduction is systolic blood pressure compared to the control group. In another study investigating the benefits of oats on blood pressure, 73% of adults who consumed oat-based cereals (compared to refined wheat cereals) for 6 weeks were able to reduce by half or eliminate their medication, compared to only 42% in the control group (Pins et al, 2002). The authors concluded that the consumption of wholegrain oats may significantly reduce cardiovascular disease risk.

Breakfast cereals are a major contributor to wholegrain (and refined grain) intakes in many studies (Jensen et al, 2004; Liu et al 2003). In a study to examine the effect of wholegrain and refined grain breakfast cereals on the risk of cardiovascular disease, researchers from Harvard University (Liu et al, 2003) examined the intakes of breakfast cereals reported by over 92,000 male Physicians in the US. The researchers found that over the five years of the study, men who consumed one or more servings of wholegrain breakfast cereals per day had a 20% lower risk of CVD compared to men who rarely consumed wholegrain breakfast cereals. However, there was no effect observed in men who consumed one or more servings of refined grain breakfast cereals per day. The authors of this study concluded that it is important to distinguish between wholegrain and refined grain cereal products for the prevention of chronic diseases.

References

  1. Jacobs DR, Meyer KA, Kushi LH et al, Wholegrain intake may reduce the risk of ischemic heart disease death in post-menopausal women: the Iowa Women's Health Study, Am J Clin Nutr 1998;68:248-257.
  2. Jensen MK, Koh-Banerjee P, Hu FB et al, Intakes of wholegrain, bran and germ and the risk of coronary heart disease in men, Am J Clin Nutr 2004;80:492-499.
  3. Liu S, Manson JE, Stampfer MJ et al, Whole Grain consumption and risk of Ischemic Stroke in women, A prospective study, JAMA 2000;284(12):1534-1540.
  4. Liu S, Sesso HD, Willett WC et al, Is intake of breakfast cereals related to total and cause-specific mortality in men? Am J Clin Nutr 2003;77:594-599.
  5. Pins JJ, Geleva D, Keenan JM et al, Do wholegrain oat cereals reduce the need for antihypertensive medications and improve blood pressure control? J Fam Pract 2002 (51(4):353-359.
  6. Saltzman E, Krupa Das S, Lichtenstein AL et al, An oat-containing hypocaloric diet reduces systolic blood pressure and improves lipid profile beyond effects of weight loss in men and women, J Nutr 2000;131:1465-1470.
  7. Steffen LM, Jacobs DR, Stevens J et al, Associations of wholegrain, refined-grain, and fruit and vegetable consumption with risks of all-cause mortality and incident coronary artery disease and ischemic stroke: the Atherosclerosis Risk in Communities (ARIC) Study, Am J Clin Nutr 2003;78:383-390.