Research confirms the long-term advisability of eating foods with a low glycemic rating.
One of the latest installments of the famed Harvard Nurses Study (conducted since 1976) confirms the importance of the glycemic index. Researchers tracked the dietary habits and the health of 75,521 nurses for 10 years. The research team discovered that the consumption of carbohydrates with a high glycemic index was strongly associated with an increased risk of heart disease. They also discovered, although the data was not as strong, that “total carbohydrate intake, representing the replacement of fat with carbohydrate, appeared to be positively related to CHD [coronary heart disease] risk.”
The Harvard researchers concluded that eating foods high on the glycemic index leads to elevated blood-sugar and insulin levels, which in turn leads to hypertension, undesirable cholesterol and triglyceride levels and other risk factors for heart disease. Since this is the largest long-term epidemiological study being conducted in America, these conclusions will not go unnoted in the scientific community1.
This is a good time to disabuse you of the long-held notion that there was some enormous difference between so-called “simple” and “complex” carbohydrates. That theory held that simple carbs such as sugar and white flour sent glucose rushing into your bloodstream faster than complex carbs such as fruits, potatoes and whole grains. But the Nurses Health Study doctors and other researchers found that two foods that contribute most to elevating blood sugar to an excessive level (called the “glycemic load”) are baked potatoes and cold breakfast cereals. These foods were traditionally classified as complex, as opposed to simple, carbohydrates. However, they behaved just as simple carbohydrates do. So the glycemic index appears to be a better gauge of the impact of various carbohydrates on your blood sugar. As research continues to associate high-glucose load with increased risk of heart disease, we need to pay closer attention not only to the amount of carbohydrates consumed, but also to their position on the glycemic index.
Choosing your carbohydrate foods from the lower end of the glycemic index is fundamental common sense and has enormous potential as a tool for minimizing the risk factors associated with certain diseases. As the message spreads that hyperinsulinism is a factor in certain illnesses and disease, the glycemic index becomes an ever more important tool for selecting foods.
Interestingly, it has also been shown that reducing your glycemic load appears to diminish your risk of developing colorectal cancer2. One likely reason is that cancer cells feed off sugar. Another possibility is that sugar may compromise the integrity of the intestinal tract. Moreover, hyperinsulinism, in response to a high glycemic load, may increase the risk of cancer. Also, recent studies on women who have had breast cancer have shown that women with lower insulin production have a better survival rate and a decreased incidence of recurrence than women with higher insulin levels3-4.
Two other recent studies have shown that hyperinsulinism has also been associated with a higher risk for polycystic ovary syndrome5-6. It all goes back to lesson No. 1 in eating for health: Avoid glycemic load. Don’t cause your metabolism to struggle incessantly with high insulin levels, weight gain and looming cardiovascular and other health problems.
Selected References:
1. Liu, S., Willett, W.C., Stampfer, M.J., et al., “A Prospective Study of Dietary Glycemic Load, Carbohydrate Intake, and Risk of Coronary Heart Disease in US Women,” The American Journal of Clinical Nutrition, 71, 2000, pages 1455-1461.
2. Franceschi, S., Dal Maso, L., Augustin, L., et al., “Dietary Glycemic Load and Colorectal Cancer Risk,” Annals of Oncology, 12(2), 2001, pages 173-178.
3. Song, E.Y., Banerjee, M., Du, W., et al., “Diabetes but not Obesity is a Prognostic Factor for Disease-Free Survival in Women With Stage I, II, or III Breast Carcinoma Receiving Tamoxifen,” December 6-9, 2000, Program and Abstracts of the 23rd Annual San Antonio Breast Cancer Symposium, Abstract #120, San Antonio, TX.
4. Goodwin, P.J., Ennis, M., Trudea, M.E., et al., “Prognostic Effects of Circulating Insulin-Like Growth Factor Binding Proteins (IGFBPS) 1 and 3 in Operable Breast Cancer,” December 6-9, 2000, Program and Abstracts of the 23rd Annual San Antonio Breast Cancer Symposium, Abstract #118, San Antonio, TX.
5. Davison, R.M., “New Approaches to Insulin Resistance in Polycystic Ovarian Syndrome,” Current Opinion in Obstetrics and Gynecology, 10(3), 1998, pages 193-198.
6. Nestler, J.E., Jakubowicz, D.J., Reamer, P., et al., “Ovulatory and Metabolic Effects of D-Chiro-Inositol in the Polycystic Ovary Syndrome,” New England Journal of Medicine, 340(17), 1999, pages 1314-1320.
