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Dietary Fiber Is Key in Fighting Pathogens
A healthy, well-fed population of friendly bacteria in our colon can stave off nasty bugs
Jeff Leach (zinjboss)     Email Article  Print Article 
Published 2006-01-07 15:14 (KST)   
In a series of papers published last month by the New England Journal of Medicine (Dec. 8 issue: Vol 353, No 23, 2005) and the Journal of the American Medical Association (JAMA. 2005;294:2989-2995), researchers report the emergence of yet another drug-resistant bacteria created by an overuse of antibiotics in the United States.

The latest nasty culprit is Clostridium difficile -- C Diff to the rest of us -- which causes cramps, horrific diarrhea, and in some cases, death.

"We're very concerned," said L. Clifford McDonald of the U.S. Centers for Disease Control and Prevention in Atlanta.

In just a little over 50 years of antibiotic use, humans have artificially stimulated the frightening mutation and evolution of otherwise benign microbes. Unequaled in recorded biological history, this rapid evolution is occurring right before our eyes.

In our "pill for every ill" society, our greatest weapon against many of these super mutant pathogens remains our own resident population of friendly bacteria that occupy the entire length of the gastrointestinal system. From mouth to anus, and nearly the size of a professional tennis court in total surface area, the human gut represents our greatest exposure to the external environment -- providing endless "hiding" places for invading pathogens.

Numbering in the trillions, our indigenous colonies of friendly microbes are the first and last line of defense against invading pathogens and have served us well throughout our long evolutionary march to mammalian dominance. (1) A dominant, healthy and well-fed population of friendly bacteria in our gut -- mainly in our colon -- makes it difficult for invading pathogens to compete for necessary nutrients for survival. Numbers count in this biological warfare. However, our natural defenders require food to live and to maintain a dominant position in this critical ecosystem. That food is dietary fiber.

A person living in America today is likely to consume less dietary fiber than any previous generation in human history. Depending on gender, age, and activity level, our government recommends we only eat 25 to 38 grams a day -- give or take -- with the average American consuming only a fraction of that. Current U.S. guidelines for fiber intake are, from an evolutionary perspective, low fiber recommendations. Our not-so-distant ancestors consumed a diverse range of plants that provided 75, 100, and up to 150 grams of fiber a day -- sometimes more. (2)

Our diminishing dietary intake of fiber is literally starving our friendly evolutionary hitchhikers, inhibiting their ability to defend us against invading pathogens. This means more people get sick than should, which in turn provides for a greater number of opportunities for misuse and overuse of antibiotics for what are often run-of-the-mill infections. As a consequence, the rapid evolution of drug resistant strains is being artificially promoted and becoming frighteningly difficult to contain.

The role of dietary fiber in the cycle and emergence of drug resistant pathogens has received almost no attention. Actually, none. Any national policy that seeks to minimize our society's exposure to infectious disease through more controlled and appropriate use of antibiotics would be well served by an appreciation of the underlying evolutionary-determined dietary intake of fiber and its role in the human immune system.

Continuing to ignore basic evolutionary biological principles in future prevention strategies of this "shadow epidemic" (PDF) will cripple the future U.S. health care system and will result in the unnecessary death of many good people.

Our low dietary intake of fiber is in discordance with our evolutionary past and providing opportunities for everyday pathogens and an increasing number of drug resistant super bugs to establish a niche in our vast intestinal system. This is disrupting millions of years of evolution that resulted in a harmonious and symbiotic relationship between us and our permanent base of beneficial microbes.

Through this "evolutionary stable strategy," (3) our indigenous microbes have made it their evolutionary job to keep out invaders. Importantly, they have come to rely on a steady supply of fermentable substrates (fiber) coming down the pipe on a daily basis for growth and maintenance. With the average American consuming nearly 40 percent of daily calories from added sugars and fats, and another 30 percent to 40 percent from highly processed nutrient and fiber-poor grains, we have reached an "evolutionary tipping point" that is tinkering in not-so-good-ways with the very beneficial organisms that have allowed us to come so far. (4)

We cannot simply go from a species that evolved on a diet dependent on nutrient-rich fibrous plants, to one that eats almost no fiber. Our current low intake of dietary fiber is a socio-economic phenomenon that represents nothing more than the efforts of special interest that represent industries that have a monetary stake in seeing the "number of servings" for their "food groups" maintained or increased with the aid of policy makers in our nations nutritional guidelines. (5)

Unless we fix unbalanced agricultural subsidies that favor over production of select commodities and reign in the food industry that promotes over consumption of highly-processed foods laced with nutrient and fiber-poor sugars and added fats - and honestly address the gaps in nutrition education among consumers - our current fiber intake will remain at dangerously low levels.

As we are slowly seeing with industrialization and its byproducts, tinkering with delicate balances in nature has consequences.
(1) A nice overview can be found here: Gibson, G. R. and Roberfroid, M. B. 1995. Dietary modulation of the human colonic microbiota: introducing the concept of prebiotics. Journal of Nutrition, 125, 1401-1412.

(2) Brand-Miller, JC, Holt SHA. 1998. Australian Aboriginal plant foods: a consideration of the their nutritional compositional and health implications. Nutrition Research Reviews 11, 5-23

Murray, S.S., M.J. Schoeninger, H.T. Bunn, T.R. Pickering, and J.A. Marlett. 2001. Nutritional Composition of Some Wild Plant Foods and Honey Used by the Hadza Foragers of Tanzania. Journal of Food Composition and Analysis 13, 1-11.

Richards MP, Pettitt PB, Stiner MC, Trinkaus E. 2001. Stable isotope evidence for increasing diet breadth in the European mid-Upper Paleolithic. Proc Natl Acad Sci USA 98: 6528-6532.

(3) "Evolutionary stable strategy" is a term coined by Darwinian biologist Richard Dawkins in his book "The Selfish Gene"

(4) Adam Drewnowski and Nicole Darmon, American Journal of Clinical Nutrition, Vol. 82, No. 1, 265S-273S, July 2005

(5) U.S. Food Pyramid guidelines on nutrition: www.mypyramid.gov; see also: IOM (Institute of Medicine). 2002. Dietary Reference Intakes of Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: National Academy Press

Jeff Leach is an anthropologist who specializes in evolutionary trends in human nutrition and its application to modern health and well-being. You can read more at his Web site.
©2006 OhmyNews
Other articles by reporter Jeff Leach

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