Dietary Fat & Diabetes Prevention.

The information on this page has been compiled and edited from previously published articles, by Dr. Connie Guttersen.  The articles are not intended as health advice, nor do they necessarily reflect the views and opinions of the California Olive Committee. Always consult your physician on matters of health and wellness.

by Connie Guttersen, RD PhD.

Scientific evidence indicates that specific types of dietary fat are important for preventing type 2 diabetes. Monounsaturated fats may be beneficial for glucose and insulin homeostasis, as well as improving insulin sensitivity. (4,5). Other studies have concluded that a high intake of saturated fat and trans fat adversely affects glucose metabolism and insulin resistance. (6) In another study, a multicenter study of 162 healthy men and women showed that a diet high in saturated fat (18% of the energy) decreased insulin sensitivity when compared with a diet high in monounsaturated fat (21% of energy) with the same total fat content. (7)

The mechanisms by which specific types of dietary fat affect insulin sensitivity are not fully understood. One explanation may be that the fatty acid composition of the phospholipids in the muscle cell membranes is directly related to insulin sensitivity. In addition, specific types of fatty acids in the cell membrane could influence insulin action via altering the insulin receptor binding or influencing the ion permeability and cell signaling. In summary, changes in dietary fatty acid composition alters the fatty acid composition of the phospholipids in cell membranes, perhaps modulating insulin action and sensitivity. Most of the clinical and epidemiological studies have observed no effect of total fat intake on insulin sensitivity and risk of type 2 diabetes. As for the effects of particular types of fatty acids, past findings have been inconsistent. Much of the inconsistency is due to the nature of the methodology, duration of the study, and sample size. However, more recent studies with better design do suggest that specific types of dietary fat rather than total fat as percentage of energy play an important role in the development of type 2 diabetes.

A ground breaking study, published by the Harvard School of Public Health researchers in the Journal of the American Medical Association further confirmed the protective effects of monounsaturated fats against type 2 diabetes. (8) This study followed 83,000 female nurses for 16 years. The women in the study completed food frequency questionnaires approximately every four years between the years of 1980 and 1996 and had no history of diabetes, cancer, or cardiovascular disease. The results show that consuming one tablespoon of peanut butter or a full serving of peanuts or other nuts (1 ounce), five or more times a week is associated with a 20 to 30% reduced risk of developing type 2 diabetes, respectively. The relationship between consuming these monounsaturated sources is linear; higher consumption provides a greater protective effect. Further analysis of the Nurses Health Study, published in a recent issue of Circulation: Journal of the American Heart Association, found that eating fish regularly reduced the risk of heart disease in diabetic women by as much as 64%. (9) This reduction was most evident when the fish was consumed five or more times per week. It is well known that fish oil or omega three fatty acids reduce the risk of irregular heartbeats, decrease blood triglycerides levels, improve function of blood vessels, and reduce blood clot formation. These effects are particularly important for reducing the risk of cardiovascular disease among individuals with diabetes. The researchers of this study also concluded that the association between the higher fish consumption in diabetic women and better heart health can also be extended to diabetic men.

 

REFERENCES:

1. The Diabetes Prevention Research Group: Reduction in the evidence of type 2 diabetes with life-style intervention or metformin. New England Journal of Medicine. 2002;346:393-403
2. The Diabetes Prevention Program: Design and methods for a clinical trial in the prevention of type 2 diabetes. Diabetes Care. 1999;22:623-34.
3. Uusitupa, M. et al. The Finnish Diabetes Prevention Study. Br. Med J Nutr. 7/2000. 83;10:S137-42.
4. Vessby B. Unsitupa, M. et al Substituting dietary saturated for monounsaturated fat impairs insulin sensitivity in healthy men and women: The KANWU study. Diabetologia. 2001;44:312-319.
5. Heine RJ, Mulder C, et al. Linoleic acid enriched diet: Long term effects on serum lipoprotein and apo-lipoprotein concentrations and insulin sensitivity in non-insulin dependent diabetic patients. Am J Clin Nutr.1989 49:448-456.
6. Salmeron J, Hu FB., Manson JE, et al. Dietary fat intake and risk of type 2 diabetes in women. AM J Clin Nutr. 2001;73:1019-1026.
7. Christiansen E, Schneider, S. et al. Intake of a diet high in trans monounsaturated fatty acids or saturated fatty acids: Effects on postprandial insulinemia and glycemia in obese patients with NIDDM. Diabetes Care. 1997: 20:881-887
8. Jiang R, Manson J, Liu S, Willett W, Hu, F. Nut and peanut butter consumption and risk of type 2 diabetes in women. JAMA. 2002;288:2554-2560.
9. Hu, F. et al. Fish and long chain omega 3 fatty acid intake and risk of coronary heart disease and total mortality in diabetic women. Circulation. 2003; 107:1852-1857.
10. Salmeron, J. et al. Dietary fiver, glycemic load, and risk of non-insulin dependent diabetes mellitus in women. JAMA. 1997;277 (8):472-77.