Love your cooties!

There is something that bugs me and that is how scared people have become of bacteria. Our homes have to be clinically clean and our food completely sterile. All kinds of bacteria have been grouped together and are marketed as this deadly threat towards humanity. Then we happily fight them with disinfectants and antibiotics. This is such a grave misconception! Sure there are bad bacteria, but there are just as many harmless and even healthy bacteria that are essential for our survival. Did you know that only 10% of the cells in a body of an adult are actually human? The rest are microorganisms such as bacteria, and without them you probably wouldn’t even be alive.

The biggest community of bacteria is found in your intestines. It is the most complex microbiome in our body (a microbiome is like a miniature ecosystem of microorganisms). Our gut flora helps us break down the food we eat and stop foreign, bad bacteria from establishing themselves in our intestines. A healthy gut flora thus improves our immune system. The microorganisms of our intestines are known as our gut microbiota. Out of these organisms about 40 species are constantly present (80% of the microbiota). The rest vary depending on outside factors such as travel, antibiotics and short-term diet changes. But long-term changes in your diet can affect the core microbiota. What you eat is the most important factor determining what bacteria you have in you. The most common bacteria in the human gut are of the groups Firmicutes and Bacteriodetes.

Studying the gut microbiota is not the easiest thing to do. To determine which bacteria are present, the classical way is to isolate them and grow them outside of the body. But the inside of a human is hard to replicate, and only 20-40% of the gut microbiota can be cultivated. New technology has made it possible to study the bacteria using DNA-techniques on fecal samples. Isn’t science glamorous? Anyhow, studies have shown that the gut flora of a vegan differs from that of an omnivore. Vegans have a larger proportion of Bacteriodetes, whilst omnivores have more Firmicutes. Vegans also generally have a lower pH in their intestine preventing the growth of certain bacteria, such as E. coli, that don’t like acidic environments.   

Enough with all the biology-lingo you might be thinking. Well, I studied biotechnology for three years, so I find this fascinating. But I’m getting to the part about what all this means for your body and health. Our gut flora can either make or break us. Studies have been conducted on the correlation between obesity and microbiota. They showed that the bacteria in the gut of an obese person could absorb more energy and also be the cause of chronic, low-grade inflammations. The inflammation affects insulin signals, which in turn can lead to more fat being stored but also type 2 Diabetes. So who are these mean bacteria? Well it turns out that the microbiota of an obese person consists of more Firmicutes and Actinobacteria and less Bacteriodetes. Which is the opposite of the average vegan microbiota.

A vegan’s gut flora has been showed to contain lower levels of inflammatory bacteria and more of the bacteria that protect the body. One of these good guys is F. prausnitzii, low levels of which have shown correlations to obesity, inflammation and intestinal disorders. It is believed that one of the reasons vegans have more of the good bacteria is because of a higher intake of fiber. Eating a lot of fiber will change the environment of the intestines: lower the pH, make it harder for pathogens to adhere and change the fermentation pattern of the bacteria there.

Finally, there is one difference in a vegan’s microbiota that I find pretty amazing. You might recall hearing that red meat will increase the risk for cardiovascular disease. The reason for this has been thought to be changes in cholesterol levels, but recent studies show that it might rather depend on the bacteria in your gut. Meats, and even eggs, contain a substance called choline. Bacteria in the gut can convert choline to trimethylamine, which the liver then turns into trimethylamine N-oxide, TMAO. Sorry about all the chemistry here, but I simply find it too fascinating not to mention. It is not known how, but TMAO is a contributing factor to atherosclerosis. Atherosclerosis is basically the thickening of the artery walls. If this happens close to your heart, you have a heart attack. So in this study they examined another substance, carnitine, which is similar to choline and present in red meat. In the study omnivores were given large steaks to eat. The levels of both carnitine and TMAO were then measured, and both turned out to be present at elevated levels. Omnivores were then given antibiotics to knock out their gut bacteria, and then again a steak to eat. This time the level of carnitine was again very elevated, but the level of TMAO had not changed as significantly. Finally, a vegan was persuaded to eat a steak and this gave the same result. Higher carnitine but not TMAO (vegans given a carnitine supplement were also tested to make the study a bit more reliable). The conclusion of this was that specific bacteria were needed for the body to produce the unhealthy TMAO, and that those bacteria were not present in vegans. Pretty cool, confess.

It must be said that studying microbiomes isn’t easy; neither is studying the effects of and differences between vegan and omnivore diets. Surveys in the US show that about 50% go vegan because of the health benefits. This means that half of all vegans might actually care a bit more about their health than the average person. And true, vegans in general work out more, drink less alcohol and smoke less than others. This means that it can be hard to know if differences between the health of vegans and omnivores actually are because of food, or lifestyle in general.

Different people feel good from eating different things, this I strongly believe in. But that what we eat impacts our health, and that this is largely through the bacteria in our gut, is proven. Going vegan is a way of taking care of the good critters inside of you, and keeping the bad ones away. It is pretty amazing that we have bacteria to thank for so many things working in our bodies. I say trust your gut, and take care of your gut by eating food that’s good for you! Feed those good bacteria!