This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.
How Much Dietary Fiber Do You Need?
According to the Institute of Medicine of the National Academies of Science in its dietary advisory, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients), Chapter 7: Dietary, Functional, and Total Fiber, most adults should consume 25 g to 38 g of dietary fiber daily.10 This recommendation was based on the Institute’s determination that this amount of dietary fiber could protect an individual from developing coronary artery disease. The Institute assumed that this amount also would be sufficient to promote bowel health.
Interestingly, the results of an analysis of the combined data obtained in the 76,947-woman Nurses’ Health Study and the 47,279-man Health Professionals Follow-Up Study also support the concept that adequate dietary fiber intake is absolutely necessary for colon health. As a result of their analyses these scientists concluded that every 5 g of dietary fiber consumed daily reduced the chances of developing colorectal cancer by about 9%.11
However, unlimited intake of soluble dietary fiber may not be prudent.12 Foods rich in soluble dietary fiber often contain compounds that prevent the digestion of dietary fat. Although this may seem appealing to some individuals who experience difficulty maintaining a healthy body weight, it is unhealthy and may decrease the absorption of essential fatty acids and fat-soluble vitamins. Similarly, soluble fiber intakes greater than 50 g/day may inhibit the digestion of dietary sugars – again, potentially attractive to the overweight but unhealthy. Increasing the amount of simple sugars and starches, such as corn starch, rice starch and potato starch that reaches the colon encourages the microbes to produce lactic acid, not butyrate. While the lack of butyrate produced may be directly unhealthy for the colon, the increased amounts of sugars and starches may also promote the growth of unhealthy bacteria and yeast, adversely affecting the healthy balance of bacterial flora in the guts. Maintaining a balanced amount of dietary fiber intake is thus necessary to obtain its benefits.
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10. Institute of Medicine of the National Academies. Food and Nutrition Board. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients), Chapter 7: Dietary, Functional, and Total Fiber. The National Academies Press, Washington, D.C., 2005, pp. 339-421.
11. Michels KB, Fuchs CS, Giovannucci E, Colditz GA, Hunter DJ, Stampfer MJ, Willett WC. Fiber intake and incidence of colorectal cancer among 76,947 women and 47,279 men. Cancer Epidemiol Biomarkers Prev 2005;14:842-849.
12. Chandalia M, Garg A, Lutjohann D, von Bergmann K, Grundy SM, Brinkley LJ. Beneficial effects of high dietary fiber intake in patients with type 2 diabetes mellitus. N Engl J Med 2000;342:1392-1398.