The Care and Feeding of Gut Bacteria

diet myth

The Diet Myth: The Real Science Behind What We Eat

by Tim Spector

Weidenfeld and Nicholson (2015)

Book Review

The Diet Myth is all about looking after our intestinal bacteria – which are ultimately responsible for the proper functioning of our digestive, immune, endocrine and nervous system. As Professor Tim Spector explains, all mammals co-evolved over millions of years with the bacteria that inhabit their intestines. Because these bacteria produce a number of vital biochemicals that our bodies are genetically incapable of producing, without them the species homo sapiens would not exist. This relatively recent discovery has led many scientists to classify the microbiome (the collective name given to gut bacteria) as a vital organ like the brain, liver or kidneys.

Civilization hasn’t been kind to our intestinal bacteria. For various reasons (overuse of antibiotics, processed foods and pesticides like Roundup), urban life has caused us to lose half of the septillions of gut bacteria we started out with. Nearly all the chronic illnesses that plague modern society (obesity, heart disease, stroke, diabetes, cancer, autoimmune disease, depression, autism, schizophrenia and possibly drug addiction and alcoholism) can be traced to loss or malfunction of intestinal bacteria.

For this book, Spector has chosen to focus on dietary research into foods that improve the health and diversity of our remaining gut bacteria. He blames the myriad of contradictory diet fads on the reality that each human being has their own distinct collection of bacteria. This means the foods that keep them healthy depend on the preferences of their particular bacteria.

Fortunately he’s able to make a few general recommendations that seem to apply to most people.

According to Spector, people with the most diverse profile of gut bacteria are the healthiest. The best way to promote this diversity is through a diverse fiber-rich diet that includes:

  • At least 20 different food types per week
  • A daily serving of 5 vegetables and 2 fruits
  • Daily servings of probiotic foods (fermented foods, such as yogurt, sauerkraut and miso, raw milk and unpasteurized cheeses) that contain beneficial bacteria.*
  • Daily servings of prebiotic foods rich in polyphenols that gut bacteria love**
  • A strict limitation on red meat,*** sugar, refined carbohydrates, transfats (hydrogenated fats found in vegetable oils, margarine and Crisco) and processed foods

Research also indicates that lifestyle factors such as exercise (athletes have the most diverse microbiomes) also promote bacterial diversity (and good health). As does episodic fasting.****


*These mainly provide different strains of lactobacillus and bifidobacteria that crowd out harmful inflammatory gut bacteria.

**Foods rich in polyphenols include dark chocolate, coffee, green tea, turmeric, red wine, onions, garlic, (uncooked) extra-virgin olive oil, roasted nuts, Jerusalem artichokes, chicory root, leeks, asparagus, broccoli, bananas, wheat bran and fermented fruits and vegetables.

***Citing numerous studies, Spector totally debunks the claim that red meat is harmful due to its fat content. He maintains the risk associated with red meat is the conversion (by gut microbes) of L-carnitine to trimethylamine oxide, which causes plaque build-up in arteries (in Europeans – this effect appears to be absent in other ethnic groups). He recommends that Europeans limit their intake of red meat to ½ serving or less per day. Those who eat more than this have a 10% increase in mortality. Those who eat one daily serving or more of processed meat (sausages, ham, salami, etc) have a 40% increase in mortality.

****When people fast, a gut organism caused Akkermansia cleans up gut inflammation by feeding off the intestinal lining. Research reveals specific benefit from the 5/2 diet in which people fast two days a week and eat normally the other five.

Intestinal Bacteria and Chronic Illness

bacteria

(This is the second of 2 posts about a possible link between intestinal bacteria, obesity, and other chronic illnesses.)

The most enlightening article I’ve seen about micrbiota (gut bacteria) research is an April 2013 article from Mother Jones. It explores the possibility that insulin resistance (see previous post) is actually an “inflammatory” process caused by the production of “endotoxin” by unhealthy gut bacteria.

The Major Health Implications of Dysbiosis

Owing to a doubling of obesity rates since 1980, this strikes me as a reasonable hypothesis. The mass marketing of antibiotics by Big Pharma, Food Inc (in livestock feed), and Monsanto (in genetically modified organisms) has led to epidemic levels of dysbiosis (a derangement in gut bacteria) in the industrialized world. In addition to skyrocketing obesity rates, the developed world has also experienced a significant increase in other dysbiosis-related conditions, including cancer, diabetes, and degenerative and autoimmune disease. It would also explain why children born to obese mothers (we acquire gut bacteria from our mothers) are more likely to suffer from asthma, attention deficit disorder, and autism.

The article cites research from the University of Washington showing that foods high in saturated fats and sugar promote the growth of endotoxin-producing inflammatory bacteria. Endotoxin, in turn, causes inflammatory damage to the the hypothalamus, the brain’s appetite center. When this occurs, people lose the ability to feel full and eat to excess.

The Mother Jones article also references studies in which volunteers improved their insulin sensitivity, as well as losing weight, by reducing their level of “inflammatory” bacteria. They accomplished this by consuming diets rich in fermented foods containing healthy, anti-inflammatory bacteria.

Most interesting of all are studies showing that bariatric (weight loss) surgery helps some patients and not others depending on their ability to grow a healthier microbiota (gut bacteria colony) following their procedure.

The Care and Feeding of Intestinal Bacteria

After suffering a sudden onset of so-called “irritable bowel” syndrome 20 years ago, I have a strong personal interest in dysbiosis. The Sydney GI specialist I consulted says the only effective treatment for most IBS sufferers is to re-establish a healthy microbiota.

The end of the article offers a number of suggestions how to accomplish this. The bottom line is to consume a diet rich in 1) fermented foods with live bacterial cultures and 2) complex carbohydrate and fiber-rich foods these organisms thrive on. Studies show that treatment with whole foods is always preferable to taking probiotics. Fermented foods contain literally thousands of strains of bacteria that work collaboratively with one another. Probiotic capsules, in contrast, contain a dozen strains at most and are likely to be destroyed by stomach acid

Examples of helpful fermented foods include sauerkraut (only if it’s made via fermentation), miso (fermented soybean paste), kefir (a fermented drink), and some yoghurts. To ensure the bacterial cultures are live, it’s best to ferment these foods yourself or get them from a reliable health food store. It’s also essential to check the label to make sure they aren’t pasteurized (pasteurization kills bacteria).

The foods these bacteria like to munch on include onions, garlic, potatoes, bananas, yams, apples, oranges, whole grains, Jerusalem artichokes, legumes and cruciferous vegetables (cabbage, broccoli, and cauliflower).

Looking after the new bacteria in my intestine is almost like having a new pet to care for. I can already tell from my symptoms which foods they really like: yam, cooked apples, and avocado. Luckily I’m pretty keen on them myself.

photo credit: www.cihr-irsc.gc.ca via photopin cc