Written by Susan Sweeny Johnson, PhD, Biochem. Researchers have shown that the intake of cereal fiber and magnesium could be inversely associated with diabetes risk.
About 90–95% of all North American cases of diabetes are type II, and about 20% of the population over the age of 65 has diabetes mellitus type II. Diabetes of all types costs the US $92 billion annually. Fifty-five percent of Type II diabetics are considered obese.
Type II Diabetes develops in adults as a result of high sugar and fat consumption over a period of time which decreases the sensitivity of body cells to the hormone insulin. Many cases can be controlled without insulin if the patient exercises regularly and consumes a low sugar, low fat diet also increasing fiber consumption as recommended by the American Diabetes Association. (1) Fiber consumption is thought to reduce blood sugar by preventing the absorption of sugar from the digestive tract or perhaps indirectly increasing liver sensitivity to insulin indirectly through the metabolites of intestinal bacteria. (2-4)
In this study, researchers conducted two tests to look at the effects of different types of fiber on the onset of type II diabetes and confirm the role of magnesium in this process. First, they did a prospective study of 9,702 men and 15,365 women aged 35 to 65 years who were observed for incident diabetes from 1994 to 2005. They looked at the relative risk of developing diabetes compared to their reported diets which they analyzed for total fiber, insoluble fiber, soluble fiber, cereal fiber, fruit fiber, and vegetable fiber as well as magnesium. Second, they looked at other published studies and analyzed them statistically to see if there was any significant correlation between types of fiber or amount of magnesium in diet and onset of diabetes.
The results were reported as relative risk (RR)*. In the first large prospective study, higher cereal fiber intake was inversely associated with diabetes risk (RR for extreme quintiles**, 0.72), while fruit fiber (0.89) and vegetable fiber (0.93) were not significantly associated. Magnesium intake showed no significant correlation. In the second analysis of other published studies, higher cereal fiber intake was again associated with lower diabetes risk (RR for extreme categories, 0.67), but there were no significant associations for fruit (0.96) and vegetable fiber (1.04). However there was a significant inverse association for magnesium consumption (RR for extreme categories, 0.77).
In the highest quintile where the risk of developing diabetes was the lowest, the subjects consumed an average of 27.9 grams of total fiber per day including 16.6 grams of cereal fiber from whole-grain products primarily breads. Increasing intake of magnesium and whole-grain products in the diet appears to help prevent development of type II diabetes.
*Relative Risk: The ratio of observed cases of diabetes to the statistically predicted number for the population. No change would be reported as a RR of 1.00. Relative Risks below 1.00 indicate a negative correlation and above 1.00 indicate a positive correlation.
** Subjects were divided into five groups based on the amount of nutrient compared. The lowest quintile consumed the least fiber, the highest quintile consumed the most on average.
Source: Schulze, Matthias B., Mandy Schulz, Christin Heidemann, Anja Schienkiewitz, Kurt Hoffmann, and Heiner Boeing. “Fiber and magnesium intake and incidence of type 2 diabetes: a prospective study and meta-analysis.” Archives of Internal Medicine 167, no. 9 (2007): 956-965.
© 2007 American Medical Association. All rights reserved.
Posted August 27, 2008.
References:
- Bantle JP, Wylie-Rosett J, Albright AL, et al. Nutrition recommendations and interventions for diabetes–2006: a position statement of the American Diabetes Association. Diabetes Care. 2006;29:2140-2157.
- Mann J. Dietary fibre and diabetes revisited. Eur J Clin Nutr. 2001;55:919-921.
- Torsdottir I, Alpsten M, Holm G, Sandberg AS, Tolli J. A small dose of soluble alginate-fiber affects postprandial glycemia and gastric emptying in humans with diabetes. J Nutr. 1991;121:795-799.
- Montonen J, Knekt P, Ja¨rvinen R, Aromaa A, Reunanen A. Whole-grain and fiber intake and the incidence of type 2 diabetes. Am J Clin Nutr. 2003;77:622-629.
