Now that research has demonstrated the human microbiome and its resident microorganisms, including bacteria, viruses, fungi, and protozoa that live in our intestinal tracts, play an important role in modulating the risk of several chronic diseases, including cognitive decline and heart disease, everyone from researchers to bio-hackers to runners are looking for ways to populate their guts with right kind of bugs. 

It’s becoming clear that diet plays a significant role in shaping our microbiome, with experiments showing that dietary alterations can induce robust microbial shifts within a short period of time, maybe even fewer than 24 hours. Given this association, there may be significant therapeutic utility in altering microbial composition through diet to overturn gut dysbiosis (i.e. where the bad guys crowd out the good fellows).

Over the years, several research papers have suggested that consuming higher amounts of dietary protein, especially while keeping overall calorie intake under control, can have benefits. Historically, it’s been thought that eating more protein can improve satiety, which makes it easier to reign in calorie intake. Since protein has a higher thermic effect of feeding, the number of calories your body burns digesting and processing food than carbs and fat, this could also help make it easier to trim your waistline. 

But a few scientists have uncovered a novel way that protein may help you crush a body composition goal—and it’s a more robust microbiome. 

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Can eating more protein do your microbiome some good?

There is mounting evidence that the microbiome can play a surprising role in body weight. And a recent study in the journal Nutrients suggests going bigger on protein while dieting for weight loss might be one method to fertilize your gut with critters that make it easier to maintain weight loss and stay healthy.

Scientists at the David Geffen School of Medicine at UCLA randomly assigned 80 overweight or obese participants to follow either a calorie-restricted high-protein diet (protein making up 30% of total calories) or a calorie-restricted lower-protein diet (protein totaling just 15% of total calories) for two months. Fecal samples were taken before the dietary intervention as well as at weeks one, two, four, six and eight to test for changes in the gut microbiome. At the end of the trial, it was discovered that people who ate a greater percentage of their daily calorie allotment from protein had a greater diversity of microorganisms in their digestive tract than their peers who consumed less protein. 

There were also some positive changes in microbial composition for both groups on the weight loss diets: Population numbers of beneficial bacteria such as Bifidobacterium spp. were bumped up while species including Prevotella_2 spp. that are thought to contribute to health concerns like heart disease were lowered. But it appeared that the high protein diet had a more pronounced effect on this shift. 

The protein you eat is then metabolized primarily by microbial fermentation in the intestine, so it may serve as a food source for the bugs you want more of within. Evidence shows consuming a protein supplement while following a calorie-controlled diet can spur on bacteria that metabolize amino acids. 

Interestingly, these outcomes were seen predominantly in white and African-American subjects and not Hispanics. The Hispanic subgroup may have started the trial with already a greater microbial diversity in their guts, so they were less responsive to the high protein diet. However, research shows that lower microbiome diversity in Hispanics is associated with a greater risk for obesity.

The upshot is that alterations in the gut microbiome may influence weight loss success with different types of diet. Perhaps this is why making sure not to skimp on protein is why some people report success losing weight when following a higher-protein diet. It’s also worth noting that there was an emphasis in both diet regimes that participants consume high-fiber carbohydrates such as whole grains and fruits, which the investigators believe was responsible for an uptick in numbers of Akkermansia spp. in each diet group. A greater abundance of these gut bacteria has been linked to improved body composition. That means protein and fiber could be a dynamic duo for gut health and to help show that stubborn belly fat who’s boss.

Of course, there are a few questions that remain to be answered. Would the same impact on the microbiome occur if higher protein consumption is not paired with some sort of calorie restriction to help create an energy imbalance? Also, does someone need to be overweight or obese to experience a benefit to their microbiome from a calorie-restricted, high-protein diet? Can someone with a fairly healthy microbiome and body weight to begin with glean any benefits from going pro-protein? Is it the weight loss itself or the consumption of protein that is plays a bigger role in microbiome diversity? And does the ratio of plant-based to animal-based protein in a higher protein diet play a role? Likely, a high protein diet in the context of an overall lousy diet won’t do the microbiome any favors. The science of the microbiome is rapidly evolving so we could have more answers shortly.

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The best protein for better gut health

If you’re aiming to ramp up your protein intake, there might be no better way to do so (while also bolstering the beneficial critters in your gut) than to work more plant-based proteins into your diet. 

The advantage of plant-based proteins is they come bundled with dietary fiber, which is metabolized to short chain fatty acids by the micro-critters in your gut. These microbial-derived fatty acids appear to have profound health impacts, including reducing inflammation. This might be a major reason why research shows people who eat plant-heavy diets are less prone to many of today’s biggest ills. A 3-ounce serving of tempeh has about 20 grams of protein and 7 grams of fiber, while a cup serving of black beans has 15 grams of both. It’s worth noting that the combo of protein and fiber makes these foods extra filling, which may put the brakes on overeating to help your efforts to maintain a healthy body weight that, in turn, will end up fostering a healthier microbiome.

But there’s no need to go plant-only. There is some evidence that an omnivorous diet may encourage a greater microbiome diversity than a vegetarian diet. Perhaps a greater diversity of foods in the diet, including some animal proteins, leads to a greater diversity of bugs that fertilize your digestive tract.

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