The number of Australians with gut problems seems to have increased in recent years. Most of these individuals do not have Coeliac disease, proven food allergies or inflammatory bowel disease but suffer frequent abdominal pain, bloating and bowel disturbances. Emerging research is pulling together an understanding of the complex interaction between the gut, the food we eat and the role of the gut bacteria. We share with you some ideas on why there has been a rise in gut problems and offer some possible solutions.
Note: If you have persistent gut symptoms, please seek medical advice.
In recent years there has been a great deal of speculation about the pre-agricultural diet and what type of diet is best for the genetic heritage that evolution has given us. What we can tell you is that the humans have a herbivore type gut, very similar to that of apes and monkeys. The relatively smaller size of the human gut can be attributed to our long evolutionary history of cooking food, which reduces the digestive work required. More in Humans are Herbivores.
We evolved in tandem with our gut microbiome, the bacteria and other microbes that inhabit our gut. They are just as much a part of our digestive system as our own cells. They feed on dietary components that are not absorbed in the small intestine, such as dietary fibre and resistant starch. The microbiome pays its fare by providing us with energy and nutrients that would otherwise have been lost. The large bowel or colon is essentially a fermentation vat. This explains the gas .
We have all heard of “good bugs” and “bad bugs” thanks largely to the food industry marketing of probiotic supplements. Recent medical research is finding links between the type of gut bacteria present and certain diseases such as Crohns disease. More recently Faecal Transplants have been successfully used to eradicate clostridium difficile infection. However the current paradigm is still very much about putting the right kind of bacteria into the gut with little consideration of the type of growth medium, the food. This is like planting rice seeds in a wheat paddock with no irrigation and expecting to grow a crop of rice. “Good bugs” can only thrive and persist on the right food mix, the “pre-biotic”. A recent study (David et al 2014) found that it only takes three days of an all plant based diet vs an all animal product diet to produce a completely different balance of gut bacteria. More in Gut Microbiome.
Animal protein foods not only lead to a less favourable gut microbiome but their constituents can also damage the gut lining. Some of these such as saturated fat and endotoxins have a direct inflammatory effect while other such as methionine and carnitine produce inflammatory bacterial products. The loss of the bulking effect of dietary fibre further contributes to these effects. When the gut lining, which is only one cell thick, is damaged by this combination of “bad” gut microbiome and animal protein foods it loses it integrity and leaks like a sieve. Potential allergens and proteins that may trigger autoimmune disease are then able to pass into the blood stream. This state is known as “Leaky gut syndrome” and is thought by some to be responsible for many diseases including auto-immune diseases. More in Leaky gut syndrome (under construction).
Dietary fibre is essential to gut health and is protective against other diseases such as heart disease, diabetes and breast cancer. Our page, Nutrient Density explains that adequate dietary fibre cannot be obtained by simply adding a supplement or particular food to an otherwise low fibre diet. Many gut problems are simply symptoms of inadequate dietary fibre. Constipation is not always apparent as one can have a transit time, from eating to elimination, of 5 days but still be “regular”. There is a group of Greger videos in the Resources section below which covers this in more detail. More in Fibre (under construction).
There is a group of carbohydrates known as FODMAPs which can ferment too quickly and produce large amounts of gas leading to abdominal pain and distension. A low FODMAP diet can often reduce these symptoms but may not be addressing the underlying cause of why the gut is so sensitive to gas. An inflamed gut lining, a “bad” mix of gut bugs and inadequate dietary fibre may be behind many FODMAP intolerances including whole wheat. Avoiding wheat, other whole grains, or even all starches, will reduce gas production and relieve symptoms for some people but it will not cure the unhealthy gut situation. In fact the gut health is likely to be worse as fibre intake is further reduced and “good” gut bacteria are starved of fermentable carbohydrates. See FODMAPs.
Many individuals suffering from gut problems protest at the suggestion that their overall diet could be causing the problem. After all, they may be lean and healthy and following the advice of experts to eat more fish, chicken, yoghurt and olive oil, whilst restricting carbohydrates. What’s more, the gut problems may not have followed a change in diet. The onset of gut problems may be delayed for months or years following a change in diet or a habitual low starch diet. There may be a tipping point, an irreversible shift to one side of a precarious balance in an already stressed system that follows some event such a course of antibiotics (see Blaser 2011) or an episode of gastroenteritis. Once the gut bacteria and gut lining have gone past this tipping point they may not readily recover due to positive feedback mechanisms which maintain the new dysfunctional state.
A whole foods plant based diet is part of the solution for most gut problems. Having said this, we wish to make it clear that none of the information we provide is intended to be taken as medical advice and that persistent gut symptoms should be assessed by a qualified health practitioner. There are some resources below that may interest those who have been diagnosed with Crohns disease, Diverticular disease or Ulcerative colitis.
The transition to a whole foods plant based diet may be problematic for some. It can take several months to adapt to the higher dietary fibre content and greater bulk of whole plant foods. Focusing on increasing the intake of starchy foods (eg grains, potatoes) may be better tolerated than trying to eat large amounts of fruits and raw vegetables. The FODMAP information may assist in choosing a less gassy range of whole plant foods during this transition phase but is likely to be less of an issue in the long term. Legumes in particular may need to be introduced gradually – which may mean abandoning the standard plate model of a “protein” food comprising a quarter of the plate. There is plenty of protein in the rest of the plate.
While there is no question that those with Coeliac disease must avoid all gluten containing grains, wheat, barley and rye, the evidence does not support the avoidance of wheat as a general health measure. Those avoiding wheat can easily choose other whole grains. Most are able to tolerate oats. We have said little about food intolerances which we suspect are often (but not always) secondary to an unhealthy gut. An elimination diet can be helpful during recovery from severe gut problems and when there is strong suspicion of true food intolerances. Our page on Elimination diets has been provided for informational purposes only. Link to Elimination diets (under construction).
- McDougall, J. A. (2006). Dr. McDougall’s Digestive Tune-Up. Summertown, Tenn.: Healthy Living Publications (book)
- Dr Michael Klaper: Digestion Made Easy (video) – rent or buy through Vimeo
- Allergic Reactions to Food – John McDougall, MD, includes ‘Foods to eat on an elimination diet’ (scroll to bottom of page for list of foods)
- The Hungry Microbiome: why resistant starch is good for you (video) – This CSIRO animation shows how resistant starch moves through the intestine, feeds the healthy bacteria of the gut Microbiome, nourishes the cells lining the colon and helps prevent cancer.
- David, L.A. et al. (2014). Diet rapidly and reproducibly alters the human gut microbiome. Nature, 505(7484), 559-63.
- Blaser, M. (2011). Stop the killing of beneficial bacteria. Nature, 476(7361), 393-394. – Reports on the effects of repeated courses of antibiotics.
- Boosting Gut Flora Without Probiotics (blog post) – Dr Michael Greger
- Junk food binge alters community of microbes in the gut in less than a day – Reports on a study showing how switching from a low-fat, plant-based diet to high-fat, high sugar alters the microbes in the gut in less than a day.
- Food Mass Transit (video) – Dr Michael Greger [key paper: Burkitt 1972]
- Stool Size Matters (video) – Dr Michael Greger
- Stool Size and Breast Cancer Risk (blog post) – Dr Michael Greger
- Bowel movements: the scoop on poop (blog post) – Dr Michael Greger
- How Fiber Lowers Cholesterol (video) – Dr Michael Greger
- Relieving Yourself of Excess Estrogen (video) – Dr Michael Greger
- Colitis (Severe), Inflammatory Bowel Disease, Ulcerative Colitis, Crohn’s Disease – Dr John McDougall Common Health Problems
- Finding Relief for Inflammatory Bowel Disease (IBD) – Linda Carney, MD
- Preventing Crohn’s Disease With Diet – Dr Michael Greger (2014, 5 min. video)
- Treating Crohn’s Disease With Diet – Dr Michael Greger (blog post) and this video: Dietary Treatment of Crohn’s Disease (4 min.)
- Dr. John McDougall Medical Message: Diverticulosis (3 min. video) and his associated web page: Diverticular Disease (Diverticulosis & Diverticulitis).
- Diverticular Disease and Diet – Dustin Rudolph, Pharmacist
- Diverticulitis and Happy Endings – Linda Carney, MD.
- Crowe, F. L., Balkwill, A., Cairns, B. J., Appleby, P. N., Green, J., Reeves, G. K., . . . Beral, V. (2014). Source of dietary fibre and diverticular disease incidence: a prospective study of UK women. Gut, 63(9), 1450-1456.
Gluten, wheat & grains:
- *NEW Sept. 2014* An excellent series of 3 videos from Dr Michael Greger:
1. Is Gluten Sensitivity Real?;
2. Gluten-Free Diets: Separating the Wheat from the Chat (if you only have time to watch one video, make it this one);
3. How to Diagnose Gluten Intolerance
- For the Love of Grains – Dr John McDougall (2008)
- Gluten-free Diets Are Harmful for the General Population (Except for one percent) – Dr John McDougall (2013)
- Brouns, F. J. P. H., van Buul, V. J., & Shewry, P. R. (2013). Does wheat make us fat and sick? Journal of Cereal Science, 58(2), 209-215.
- van Buul, V. J., & Brouns, F. J. P. H. (2014). Health effects of wheat lectins: A review. Journal of Cereal Science, 59(2), 112-117.
- The following is a half hour audio interview with naturopath and plant based diet advocate, Dr Pam Popper, in which she discusses the role of gut inflammation:
Perfect Digestion – Interview with Dr. Pam Popper
- The Leaky Gut Theory of Why Animal Products Cause Inflammation (4 min. video) and associated blog post: How Does Meat Cause Inflammation?
- Carnitine, Choline, Cancer and Cholesterol: The TMAO Connection (9 min. video) – features two landmark studies linking animal foods, gut bacteria, inflammation, cancer and heart disease.
- Andrew Neuman: Recovered from Severe Ulcerative Colitis (written story)
- Plant-Based Diet Has Me Winning My Long, Hard Battle with Ulcerative Colitis – Somer M. (written story)
- Ryan Schultz, DVM (veterinarian) Cures Himself of Crohn’s Disease (written story)
- Sondra Berk: Suffered with Crohn’s Disease for Years (13 min. video)
- C. Scott Campbell: IBS (Irritable Bowel Syndrome) (written story)
- Jeff Kristad: Irritable Bowel Syndrome (written story)
- Joan Isa: Hiatal Hernia, GERD, Indigestion (written story)
- Herbie of the Week: Tommy (He Reversed All of His Medical Issues With a Plant-Based Diet!) – diagnosed with diverticulitis and pre-cancerous polyps
Page last updated 26 February 2015