Ilana Katz MS, RD, CSSD
Since a big part of my work with athletes involves reducing the risk of Gastrointestinal (GI) distress I thought a different perspective of the GI environment and how to nurture it would be rather informative. The organisms and their metabolic processes themselves, the majority of which live in the colon, are referred to as microbiome and they dramatically effect human health in general, not just for athletism. The microbiome is made up of trillions of microorganisms ranging between bacteria, fungi, viruses, and others., all of which impact the immune system.
The microbiome multitasks between maintenance of immunity, digestion, hormonal and nutrient balance by:
- maintaining optimal gut flora (by fighting pathogens and embracing working microorganisms)
- activates anti-inflammatory responses1
- uptake of hormones2
- detoxifies environmental negatives (such as drugs, chemicals, unnatural “food” items eg. artificial sweetener, sugar alcohols, etc.)1
- synthesizes essential nutrients (particular to the gut are biotin, folate and vitamin K)1.
Inflammation and digestion, and most other functions mentioned above, differs greatly between individuals, and is mostly influenced by stress, age, past infections (antibodies), gender (and within gender experience of natural birth, breast feeding, etc.), medications, lifestyle habits (smoking, alcohol, etc.). and most importantly, diet3.
It is thus safe to say that almost every chronic (and probably acute too) inflammatory response is affected by changes in the microorganism composition of the gut. There is no blueprint for an ideal breakdown of gut microbiome but the diversity of the microorganisms has shown an increase in symbiosis – the mutually beneficial relationship between them.
Lower level symbiosis results from higher than necessary caloric intake, highly processed foods, saturated fat, refined sugar, and soda (chemicals) whereas microbial diversity and therefore increased likelihood of positive symbiosis result from dietary intakes such as coffee, tea, red wine, fruits and vegetables, nuts and buttermilk.4 Stress would be the biggest contributor to low diversity and reduced symbiosis as well as high triglycerides, irritable bowel symptoms (diarrhea) and intestinal inflammation.5
In research on dietary effects of microbiome, the summary states that eating plant-based foods and nuts are related to reduced bowel inflammation and aid in healthy cholesterol management5. The typical American diet of low earth based nutrients, high saturated fats, high refined sugars and high in processed animal proteins negatively reduces gut microbial diversity, symbiosis and overall gut health.
So what is it about the earthy foods that assist in a positive microbiome? Simply, the content of fiber. Why? Because although fiber is the undigestible carbohydrate for humans it provides the gut microorganisms with essential “food” for them to produce enzymes. These enzymes in turn, breakdown these undigested carbohydrates in process of fermentation.6 Fermentations’ end-product is butyrate, the preferred food-source for cells in the large intestines. The healthier cells are then able to maintain the intestinal wall health, reducing risk of other major chronic disease states such as colon cancer, colitis and Chron’s disease.
Why then are people with a diagnosis of inflammatory bowel diseases (IBD) like Chron’s and colitis advised to keep their diet lower in fiber? It may be a case of which came first, their dysbiotic colons, or the fact that fibrous foods can cause abdominal pain, bloating, cramping, diarrhea, and obstructions.7 Symptoms of IBD could then be reduced by limiting fiber however the vicious circle of health impacted colon and dysbios will ensue. It is therefore in the best interest of a person struggling with GI distress to seek professional help within the dietetic realm to work on tolerance of fiber. Because GI distress should not mean a low fibrous diet, dietitians will often teach such patients to increase fiber progressively, maintain excellent hydration processes and learn new techniques such as juicing, blending, other cooking methods to pre-breakdown tough fibrous skins of earthy produce, and removing completely undigestible seeds.
So far, I have focused mostly on the digestion of fibrous carbohydrates. But when talking about microbial flora it is important to consider that some undigested animal protein lands up in the colon too. Unlike plant based proteins, the fermentation of animal protein does not result in butyrate and the formation of healthy enzymes, instead they are fermented by colonic bacteria and produce potential toxins such as ammonia, and hydrogen sulfide.8 These toxins inhibit butyrate formation that would otherwise protect the colon lining from harmful entry of microbial invasion. The toxic gases thus increase inflammation responses further risk GI distress and chronic bowel diseases. Not only do they inhibit the growth of anti-inflammatory bacteria, but they also support the growth of pro-inflammatory bacteria3. Furthermore, hydrogen sulfate results in foul smelling gas, a common side effect of high protein, low fibrous diets. From a dietetic standpoint, if the diet is high in meat, by simply adding a variety of colorful, and fibrous vegetables could reduce the protein fermentation.
In summary, whether you are an athlete looking to reduce the risk of gastrointestinal distress while training/racing, or an individual wanting to reduce irritable bowel syndrome, or just an individual trying to keep the gut healthy, diet is the major factor determining microbiome make-up. The best diet for a healthy flora in the colon is simply a whole food diet with a variety of non-processed macronutrients (fibrous carbohydrates, lean protein and unsaturated fat), favoring plant-based more than animal proteins, non-excessive alcohol (favoring red wine) and the elimination of refined and processed sugars, artificial sweeteners and sodas.
- Gut Microbiome for health. http://www.gutmicrobiomeforhealth.com/en/about-gut-microbiome-info/
- Camilleri MD., Serotonin in the Gastrointestinal Tract. Curr Opin Endocrinol Diabetes Obes. 2009 Feb; 16(1):53-59.
- Brown K, et al. Diet-induced dysbiosis of the intestinal microbiome and effects on disease. Nutrients. 2012;4:1095-1119.
- Conlon MA, Bird AR. The impact of diet and lifestyle on gut microbiota and human health. 2015;7:17-44.
- Zhernakova A, et al. Population-based metagenomics analysis reveals markers for microbiome composition. Science. 2016;565-569.
- Rose DJ, et al. Influence of dietary fiber on inflammatory bowel disease and colon cancer: importance of of fermentation patterns. Nutr Rev. 2007:65:51-62.
- Limdi et al. Dietary practices and beliefs in patients with IBD. Inflamm Bowel Dis. 2016:22:164-172.
- Yao CK., etal. Insights into colonic protein fermentation and its health implications. Ailment Pharmoco ther. 2016;43:181-196.