The microbiome is a hot topic on the internet. What can we do to promote a healthy gut? We are only a google search away from getting answers, but how do we separate sound advice from hype? Here are some perspectives I gained recently from surfing the internet.
First, a response to my review of Let Them Eat Dirt
The current way of looking at the “eat dirt” philosophy is called the “old friends” hypothesis. This hypothesis incorporates an evolutionary view of the development of our immune system. Our immune system co-evolved with our microbiome, the immune system allowing us to tolerate and even benefit from the microbiome. This all occurred in the millions of years pre-agricultural era. Most of our serious infectious agents are only about 10,000 years old and evolved after our having settled into population centers (for easy transmission) and a life close to herd animals (for rapid evolution of herd diseases into human pathogens). Paleolithic humans did not experience epidemic disease because they lived in dispersed groups and did not have herd animals (they did have plenty of other infectious diseases). So our immune system evolved to contend with microflora and parasites in the environment (water, soil, animals) and actually depends on exposure to this microflora (and parasites) to develop normally. Therefore, the paleolithic microflora are the “old friends”. Lack of exposure to the old friends is associated with diseases of the immune system. However, “eating dirt” or “raw water” (there is now a raw water movement) is not a good answer, as in our present world these may have the more recently evolved disease agents such as Salmonella, pathogenic E coli, and others. For a better explanation read the article.1 If the Eat Dirt book did not discuss the old friend hypothesis it is not providing scientifically informed advice. Dr. Joe Frank, Professor Emeritus of Food Microbiology, University of Georgia
Investigating microbial diversity in our guts
One of the more interesting articles I have read online is on the human food project and what we should eat to encourage a healthy microbiome. In reading the article, I didn’t learn that much about what I should eat beyond more fibrous foods, but the emphasis is on eating less fatty foods which comprise the Western diet. Maybe fat should still be the enemy rather than sugar which has emerged as the new one. Of most interest, however, are the ongoing American Gut and Human Microbiome projects. A better understanding of variation in the human microbiome will provide greater insight into what constitutes a healthy gut and the role of microbial populations in the development of chronic diseases.
A diet for a heathy gut
As we might expect there is a book out titled The Microbiome Diet: The Scientifically Proven Way to Restore Your Gut Health and Achieve Permanent Weight Loss. For a clearer picture of the plan, a diet website describes it as a calorie-restrictive, low-carb diet. The advantages of the diet mentioned by the website include encouraging a wide variety of unprocessed foods and no need to count calories or watch portion sizes. The downside is that the diet requires more food-preparation time than most diets and requires a number of nutritional supplements. The diet features 4Rs to good intestinal health. The one that confuses me most is to “Replace stomach acid and digestive enzymes.” I will have to read the book to get a better perspective on how that is possible. I plan to discuss this diet and others on this blogsite later this year. Is this diet really scientifically based or merely a way to take advantage of the current interest in our guts in popular media stories?
The next fad diet craze may be low in FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols). These diets have been designed to treat patients with IBD (Irritable Bowel Disease). Since such diets relate to the gut, it would seem reasonable that they be recommended to improve gut health. Unfortunately, these diets are not for everybody and are likely to cause more problems than they solve in our quest for magical solutions for conditions that don’t exist in healthy people. Such warnings have not stopped people from going gluten-free.
The food industry comes to the rescue
A primary focus of the food industry with respect to probiotics is in fermented dairy products, such as drinkable yogurts for young children. Probiotics can also be incorporated into dry powders to be dissolved in milk. Chocolate products have been considered, but probiotics are currently being incorporated into foods with a healthy image.
Probiotics are not the only biotics we need to consider for a healthy gut. These bugs must be fed properly if we are to keep them around. Prebiotics, like chicory root, may provide a part of the solution, but high-fiber diets can result in production of gas and bloating. The challenge to food product developers wishing to incorporate prebiotics into formulated foods is adding ingredients to keep the good microbes happy while minimizing gas production.2
I am not sure that the scientific community is ready to provide specific dietary guidelines for a healthy gut or that enough is really understood about the relationship between gut health and obesity. I am hoping to have a researcher in this area provide a guest article on this site in a few weeks. We must also acknowledge that occasional consumption of single products containing prebiotics or probiotics will NOT magically transform our gut from a sketchy one to perfection overnight. Lifestyle changes will probably be required to complement our new diet. In any event we need to be very careful about the interpretation of the latest study reported in the news.
Next week: Are we becoming victims of the merchants of certainty? Reading too much into the results from a single study.
1 Rook, G.A.W., C.A. Lowry and C.L. Raison, 2013. Microbial ‘Old Friends’, immunoregulation and stress resilience. Evolution, Medicine & Public Health 2013:26-64.
2 Slavin, J. 2013. Fiber and prebiotics: Mechanisms and health benefits. Nutrients 5:1417-1435.
Even my dog is on probiotics