Health experts call bacteria “good” and “bad”. Bad bacteria make us sick. Good bacteria help us digest food, and a few other things. Let me propose another view. Any bacteria (i.e., bacterial species) will make us sick if it becomes too numerous — so all bacteria are “bad”. All bacteria protect us against other bacteria — so all bacteria are “good”. The terms “good” and “bad” are misleading. It is like saying a person is inherently rich or poor. Anyone, given a lot of money, becomes rich. Anyone whose money is taken away becomes poor. Low bacterial diversity or reduction of diversity makes it more likely that one bacterial species can overwhelm its competitors, producing sickness. When this happens, to say that the species (e.g., H. pylori) that became numerous “caused” the sickness (e.g., ulcers) is to seriously misunderstand what happened and how to prevent it from happening. We are taught that our immune system protects us from infection. We should be taught that bacterial diversity does the same thing.
The following story, from a reader of this blog, suggested these ideas:
My wife had a lot of problems, visceral fat that wouldn’t go away being one of the most obvious symptoms. Every time I convinced her to try a ketogenic (= very low carb) diet, she would get sick. I went to NYC to see Paul Jaminet speak. He suggested that she likely had some type of gut infection or dysbiosis. Not a bad theory, as she’d undergone prophylactic antibiotic treatment to clear up an H. pylori infection. (Yes, I know, but at the time it seemed like the thing to do.)
She started putting on weight after that, which is typical.
Finally she gave VLC [very low carb] one last try. She wound up getting inflamed lymph nodes in her thighs. Our doctor was wondering if she might have bovine tuberculosis or the bubonic plague, either of which would explain her symptoms. (The nodes were inflamed, black-and-blue, and sensitive. This is a typical symptom of bovine tuberculosis, and the disease spreads from the gut to the body through the bowel. As we consume raw milk, this wasn’t a crazy theory, but there have been no recorded outbreaks in Connecticut for years and years.) All the tests he did for an infection came back negative, but her symptoms clearly suggested she had one.
Finally she went to see a new OB-GYN. His nurse/dietician reaffirmed everything I’d been telling her, and she finally decided to go fully ketogenic. Once again, she got sick, but this time she decided to tough it out. Sure enough, after many weeks she started feeling better, and more importantly, the weight started coming off, and the visceral fat started reducing.
She did a stool test, and (I haven’t seen the results yet) we were told that she had the obesigenic gut biota. So she started an intensive probiotic regimen. This helped her one negative from the ketogenic diet: constipation.
She’s thrilled with the progress she’s seeing, and her few lingering issues after going primal 2.5 years ago seem to be resolving. The constant yeast infections have abated, and she’s planning a new wardrobe, heaven help me.
There are several interesting things here: 1. A very-low-carb diet made her sick. 2. This happened after antibiotic treatment. 3. Tests for infection were negative. 4. If she waited long enough, the low-carb-induced illness abated. 5. Probiotics helped. 6. Fermented foods didn’t help. At the time of Paul Jaminet’s diagnosis, says the reader, they were already eating plenty of fermented food: “Sauerkraut, yogurt, home-made kefir, the whole drill. No effect.”
How can these observations be explained?
With some general ideas. Each bacterial species keeps similar species in check by competing for the same resources (food and location). No two species need exactly the same things but there is plenty of overlap. For example, Species 1 needs Resources A and B, Species 2 needs Resources A and C. They keep each other in check by reducing the supply of A. Suppose C = carbohydrate. By reducing C, a very-low-carb diet reduces the number of Species 2, making more A available. This allows Species 1 to greatly expand. Maybe this expansion kills off Species 2. Armed with vast amounts of A, Species 1 out-competes other competitors. Its numbers greatly increase, causing sickness.
The notion that some bacteria are good and others are bad is absurd because all are safe in small amounts and all will cause sickness in large amounts. If any one person was replicated in millions or billions of copies it would cause enormous damage, waste and disruption, no matter who it was. Suppose I was genetically replicated so that there were hundreds of millions of me. I only like a few singers, such as Michelle Shocked and Cat Power. There would be a huge undersupply of records by those singers and a huge oversupply of other music. The music industry would collapse. I am a certain size. There would be a huge shortage of clothes of my size and a huge oversupply of clothing of other sizes.
The bacterial ecosystem is not self-correcting. It is the opposite: disruptions tend to spread. Suppose you eat too little carbohydrate. This reduces Species 2 (which needs A and C = carbohydrate). This means there is more Resource A for Species 1 (which needs Resources A and B). Species 1 increases. By virtue of increased numbers, it pushes down its competitors for Resource B. These weakened competitors, which also need D, E, and F, begin to lose battles for those resources against other bacteria that need D, E, and F. They decline in number. No longer with substantial competition for what it needs (A and B), Species 1 multiplies unchecked and causes damage until A and B run out. (Which may be why the reader’s wife, after a long illness, got better.) Fever fights infection because bacteria that grow best at one temperature (normal body temperature) do less well against competitors at a higher temperature.
The tests for infection failed to come up positive because they looked for too few bacteria. According to this view, there are thousands of bacteria inside us that can run out of control. You can test for only a tiny fraction of them. Fermented foods failed to help because they did not provide enough diversity.
We have a huge preference for diversity in what we eat. We much prefer a meal with three foods than one food, for example. The usual view is that this preference evolved because we need many nutrients (e.g., many vitamins) to be healthy. Now I wonder. Maybe the protective effect of bacterial diversity was the main reason. If so, taking a multi-vitamin pill is not going do much good, which is what research suggests.
These ideas are obviously supported by evidence that fermented foods improve health and antibiotics harm health, which I’ve covered many times. They are also supported by two recent studies with a different emphasis. One of them found that people with sinusitis had less bacterial diversity in their nose than people without sinusitis and that increasing diversity tended to prevent sinusitis. Someday the 2005 Nobel Prize for “showing” that ulcers are “caused” by H. pylori will seem as medieval as the 1949 Nobel Prize for prefrontal lobotomies.
The practical consequences of this view include: 1. Antibiotics should be a very last resort. When given, they should be followed by treatments that restore bacterial diversity. The reader’s story suggests restoration of diversity may not be easy. Plainly diversity should be tracked after antibiotics. 2. Epidemiological studies should not just ask how did the germs spread? They should also ask why were they allowed to do harm? Why didn’t natural defenses – the immune system and other bacteria – suppress them to harmless levels? To the epidemiological neglect of immune function we can add neglect of this line of defense. 3. There should be convenient ways to measure one’s bacterial diversity so each of us can learn where we are and what makes it go up and down. 4. Researchers should study what makes bacterial diversity go up and down. Here is a recent study about this: old people living in an old-age home, who ate a restricted diet, had less bacterial diversity than people the same age who lived independently and ate more varied foods.. 5. Researchers should learn the correlates of high and low diversity. Take a group of people, measure their bacterial diversity, track their health for six months.