This is a link to an NPR story that explains why I’ve changed my diet to be largely vegetarian. This article describes all of the biology that shows that humans are not designed to be every day carnivores. It is safe to have a meat meal every now and again but our daily diet should be plant based and may include fish and shellfish.

References

It’s all about critters

As you know, our digestive track is on the outside, topology speaking. The exterior surfaces secrete acids and enzymes that digest our food. The intestines absorbs nutrients from the food we eat. We live in symbiosis with a diverse colony of bacteria that help us to digest our food and, occasionally, some that are less than helpful. Most obviously, eating spoiled food introduces the bacterial that cause garbage gut, a technical term well known to those of us having dogs in the household.

It turns out that what we eat establishes conditions that allow different types of bacteria to be our guest helpers. Researchers have found that the gut bacteria colony changes in composition pretty quickly with a change in diet. This change completes in about four days. Unfortunately, some of the colony produce toxins as a byproduct of metabolizing the food we eat. It is this process that causes garbage gut when we eat spoiled food.

The catch is that eating unspoiled food can produce toxins that have less immediately obvious effects. Bacteria present in regular meat eaters metabolizes a specific amino acid into a specific toxic metabolite that the gut can absorb. That metabolite is responsible for establishing the conditions that spawn arteriosclerosis plaques. The involvement of the metabolite in plaque formation is partially understood.

TMAO

TMAO is the acronym for trimethylamine-N-oxide. Bacteria present in regular meat eaters produce this compound by metabolizing lecithin (a popular mold release agent in baking) and L-carnitine, an amino acid commonly found in meat. L-carnitine takes its name from the Latin root for meat, carnitas in Spanish and is present in animal meat and eggs.

The liver metabolizes TMAO into several harmful substances that are believed to have a role in plaque formation. Without TMAO, these substances are not found.

The interesting bit is that high TMAO levels are present only in frequent meat eaters. Those who seldom eat meat (both vegetarian and vegan) are able to consume lecithin and L-carnitine without producing TMAO. Those who eat meat invariably have TMAO in their bloodstream.

Some get the double whammy

Most body builders eat a high meat diet (yes, chicken counts but fish doesn’t). Many also take supplemental L-carnitine. Individuals eating a diet high in meat and supplementing L-carnitine, are in double jeopardy by throwing fuel on the fire with their L-carnitine supplementation. As we will see, high meat consumption and L-carnitine supplementation explains the high mortality rate to stroke and heart disease among strength athletes.

Several high profile boutique cardiologists were, before this was known, recommending L-carnitine supplementation as was a leading ubiquitous supplement seller. They are no longer making these recommendations.

The Detective Work

One quarter of all fatal first heart attacks occur in patients with none of the traditional risk factors for coronary artery disease. Researchers have long suspected diet but were looking at the obvious cholesterol rather than in the shadows. Recently, researchers realized that it couldn’t be LDL, HDL, and triglycerides because these were similar in the two populations. So, they began looking for something that was common in the heart disease population but uncommon in the healthy population. They compared the blood of patients with similar lipid profiles but with and without the disease. The difference turned out to be TMAO. Patients with heart disease had high levels of TMAO. Healthy patients had low levels of TMAO.

From where did the TMAO come?

The researchers fed a diet of red meat and eggs to subjects. They found TMAO. They placed the subjects on one of the antibiotics commonly used to treat garbage gut and the TMAO level dropped sharply. So red meat, eggs, gut bacteria and TMAO are now strongly linked and bacteria are known to produce TMAO from these foods. We don’t know which bacteria or exactly how TMAO initiates plaque formation but we don’t need to know. Those that seldom eat meat and eggs had low TMAO levels and low rates of coronary artery disease and stroke.

We Know Why Boutique Low Fat Vegan Diets Reverse Heart Disease

Dr Dean Ornish and Dr Neal Barnard, among others, advocate a strict vegan no added fat diet. This diet has dramatically lowered blood lipids in patients that adhere to it and most undergo remission of their blockages. We now know that these diets worked by lowering TMAO and we now know that these benefits can be achieved while eating a more normal vegetarian or vegan diet. No red meat, low TMAO. Regular meat, high TMAO. It’s that simple.

Personal Conclusions

You can eat nuts. You can put oil on your salad. You can have steak or chicken for Sunday dinner. But fish would be better and oysters, clams, scallops, etc are OK. Even when fried as long as you don’t eat beef, pork, or chicken, regularly. Once a week is probably OK because consumption for several days is required to change the gut bacteria to a harmful population.