To some extent, you could be forgiven for not knowing more about your microbiota, which has been best defined by researchers writing for the journal, Scientist, as “the ecological community of… microorganisms that literally share our body space.” In total, an adult human has roughly 100 trillion microorganism cells making up his or her microbiota. That compared to the roughly 10 trillion human cells typically making up our bodies. Microorganisms, then, outnumber our own cells by 10 to one in our own bodies. So, in a sense, we may be better described as a petri dish, incubating colony upon colony of microorganisms than any lofty definition of a human being.

Your Microbiota and You

In general, our microbiota aren’t just commensal or existing in a neutral state of mere co-existence. Our microbiota exist in and on our bodies in relatively stable but stunningly diverse communities made of specific species in harmonious equilibrium with one another and us. Mutualism is what generally defines our relationship with our microbiota. We help them survive and they, in turn, return the favor.

Take the human hand as illustrative. The hand microbiome differs literally from one centimeter to the next. This means that the microorganisms that live on your palm are substantially different than those on the back of your hand. These are different still than those on your fingers and each finger is different from the next, even differing significantly in each of the spaces between the fingers. All of these microorganisms thrive on the skin and help crowd out other harmful, pathogenic microorganisms that can cause disease. You may well owe your clear skin to your microbiota.

The human digestive system contains similarly complex communities of microorganisms. The colon alone is estimated to have as many as 1,000 different microorganism species representing trillions of cells. These microorganisms are thought to be systemically important, converting dietary fiber into short-chain fatty acids, a nutrient that is as essential as many hormones excreted via the human endocrine system. As a result, many scientists now consider the digestive microbiota as a de facto human endocrine organ. It’s the only organ in our bodies that doesn’t share our DNA and dysfunction of this organ is thought to lead to various inflammatory and autoimmune diseases. Furthermore, each of the microorganisms in our digestive system generally provides some service (like the decomposition of fiber into short-chain fatty acids) in the aid of digestion, although it’s still unclear what exactly each microorganism does and how.

The Revealed Importance of Digestive Microbiota

Depending on your diet, the balance of your digestive microbiota can change. Eat more meat relative to plant-based proteins (such as legumes, nuts, seeds and whole grains) and the microorganisms that assist in the digestion of animal proteins thrive to the exclusion of those that digest plants. Eat more plant-based proteins and the reverse happens. Unfortunately for us humans (but less so for our livestock cousins), our digestive microbiota responsible for plant digestion are the special extra endocrine organ. So by eating too much meat, in the long run, you’re killing not just your circulatory system (by increasing your risk for cardiovascular disease) and stomach (by increasing your risk for cancer) but you’re also killing your digestive microbiota, but in this case, immediately. Your microbiota can die off much more quickly than your arteries or stomach. Likewise, however, it can also recover more quickly if you improve your habits.

How Much Meat is Too Much?

This is all not to worry you into going vegetarian or vegan. I’m not making a moral argument here about animal cruelty nor am I making an environmental case that meat eating is inefficient and detrimental to the environment. While those arguments are certainly true, what I’m doing is different. I’m appealing to your better judgement as it might apply to the way you feel right now and how that relates to your diet.

Many, however, may find new health science somewhat dubious given the contradictory information circulating in the media. First, sugar was good and fat was bad. Now fat is good and sugar is bad. Coffee can simultaneously kill you and extend your life. Fish is good except some fish is bad and others are great. Unless they’re endangered, of course. It’s enough to make you tune out, I get it.

But this is different. The science we have on this topic is more robust. Multiple studies have not only shown the same results in a laboratory setting, but also studies of long lived peoples around the world, the so-called Centenarian studies, have shown that cultures in which a disproportionate number of people live to 1oo years or more share some common traits. These traits include things you’d expect like good genetics, a culture of non-smoking, light to no alcohol consumption, strong family and social networks along with consistent moderate physical activity. But, as you may have guessed by now, they also include plant-heavy diets, rich especially in plant-based protein like legumes and nuts and impoverished in the area of meat.

Okinawans, the people of the Pacific archipelago prefecture of Japan, for example, enjoy some of the highest life expectancies of any population on Earth, as well as some of the highest proportions of Centenarians. Okinawans also enjoy 97 percent of their lives, on average, free from disability. In fact, their rates of cardiovascular disease, cancer, stroke and dimentia are all vastly lower than Western societies and indeed all societies. The weekly meat consumption among Okinawan Centenarians over the course of their lives has notably been about two to three servings per week. That is, Okinawan Centenarians, forged in the frugality of World War II, eat a small morsel of meat with every meal or forgo meat entirely for certain meals, like breakfast. In meat’s place are plant-based proteins.

So, to answer the question, “How much meat is too much?,” the answer very well may be, “Whatever you’re currently eating.”

Caloric Balance

But before you run out and start eliminating meat from your diet, it’s worth considering what that’s going to look like. Even if you get a sufficient amount of protein from plant-based sources, you still have to consider where you’re getting your overall calories from.This is something most people fail to consider.

As it turns out, there are only three kinds of calories in food: Protein, carbohydrate and fat calories. As a rule of thumb for the average person, a balanced diet should contain about an equal proportion of calories from each source, a third from each. Since people who eat meat tend to eat a lot more of it than they need as a protein source, when they reduce meat consumption, they tend to hold plant-based protein sources to sufficiency and distribute the remainder of calories between carbohydrates and fat. This is a mistake because your caloric balance of a third from each source is thereby upset, which may also upset the balance of your digestive microbiota in a similar way that the shift to meat did. It also isn’t usually very healthy to eat all those carbohydrates and fat.

The solution is either to just reduce the total amount of calories you eat by perhaps one quarter or be sure to eat as much plant-based protein as you were eating meat on a calorie-for-calorie basis, all else being equal. Unfortunately, it’s not obvious to everyone how you do this. Luckily, I have some recipes for you!

Three recipes to get your digestive microbiota raving:
Simple Summer Stew
Quick Pasta Recipe
Three Vietnamese-Inspired Soups
French Country-Style Chicken Stew
Two Braised Chickpea Recipes
A Very Fancy Miso Soup
Mixed Vegetable and Tofu Soup

Have a question? Ask me anything!