Whole Grain

From The Experts

Heart Disease

In 2010 the American Society for Nutrition held a symposium on the health benefits of wholegrains. It stated that current scientific evidence “suggests that wholegrains have a beneficial effect on cardiovascular disease (CVD) risk reduction” (Jonnalagadda et al., 2011)3

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).2

Individual studies have looked at a variety of risk factors for CVD and the effects wholegrains can have on them:

The Ministry of Health recommends we 'eat plenty of breads and cereals, particularly wholegrains' (Ministry of Health, 2003). A randomised control trial showed three servings of wholegrains per day over 12 weeks significantly reduced systolic blood pressure by 6 mmHg. High blood pressure (hypertension) is a risk factor for CVD (Tighe et al., 2010).8

Another risk factor for CVD is atherosclerosis, which can be demonstrated by the carotid intimal medial thickness (CIMT). After following 1625 subjects aged 40-69 years for 5 years it was shown that there is an inverse association with wholegrain intake and CIMT, suggesting wholegrains may protect against atherosclerotic CVD (Mellen et al., 2007).5

Individuals with type 2 diabetes have a greater risk of CVD than the general population. In the nurses’ health study, in which 7822 women with type 2 diabetes were assessed over 26 years, wholegrain intake was associated with reduced CVD specific mortality. It also looked at specific parts of the wholegrain and showed women consuming the most bran had a 35% lower risk of CVD mortality than those consuming the least bran (He et al., 2010).1 The bran is often removed during the refining process, so wholegrains are a better source of bran than refined grains.

Heart failure is a subtype of CVD and a recent study has shown individuals that consume more wholegrains have a lower incidence of heart failure than those that consume less wholegrain. The findings suggest that there is a 7% lower risk for each additional serving of wholegrains per day (Nettleton et al., 2008).7

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)4 examined the intakes of breakfast cereals reported by over 86,000 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. HE, M., VAN DAM, R. M., RIMM, E., HU, F. B. & QI, L. 2010. Whole-grain, cereal fiber, bran, and germ intake and the risks of all-cause and cardiovascular disease-specific mortality among women with type 2 diabetes mellitus. Circulation, 121, 2162-8.
  2. JENSEN, M. K., KOH-BANERJEE, P., HU, F. B., FRANZ, M., SAMPSON, L., GRONBAEK, M. & RIMM, E. B. 2004. Intakes of whole grains, bran, and germ and the risk of coronary heart disease in men. American Journal of Clinical Nutrition, 80, 1492-9.
  3. JONNALAGADDA, S. S., HARNACK, L., LIU, R. H., MCKEOWN, N., SEAL, C., LIU, S. & FAHEY, G. C. 2011. Putting the whole grain puzzle together: health benefits associated with whole grains--summary of American Society for Nutrition 2010 Satellite Symposium. Journal of Nutrition, 141, 1011S-22S.
  4. LIU, S., SESSO, H. D., MANSON, J. E., WILLETT, W. C. & BURING, J. E. 2003. Is intake of breakfast cereals related to total and cause-specific mortality in men? American Journal of Clinical Nutrition, 77, 594-9.
  5. MELLEN, P. B., LIESE, A. D., TOOZE, J. A., VITOLINS, M. Z., WAGENKNECHT, L. E. & HERRINGTON, D. M. 2007. Whole-grain intake and carotid artery atherosclerosis in a multiethnic cohort: the Insulin Resistance Atherosclerosis Study. American Journal of Clinical Nutrition, 85, 1495-502.
  6. MINISTRY OF HEALTH 2003. Food and Nutrition Guidelines for Health Adults: A Background Paper. Wellington: New Zealand: Ministry of Health.
  7. NETTLETON, J. A., STEFFEN, L. M., LOEHR, L. R., ROSAMOND, W. D. & FOLSOM, A. R. 2008. Incident heart failure is associated with lower whole-grain intake and greater high-fat dairy and egg intake in the Atherosclerosis Risk in Communities (ARIC) study. Journal of the American Dietetic Association, 108, 1881-7.
  8. TIGHE, P., DUTHIE, G., VAUGHAN, N., BRITTENDEN, J., SIMPSON, W. G., DUTHIE, S., MUTCH, W., WAHLE, K., HORGAN, G. & THIES, F. 2010. Effect of increased consumption of whole-grain foods on blood pressure and other cardiovascular risk markers in healthy middle-aged persons: a randomized controlled trial. American Journal of Clinical Nutrition, 92, 733-40.