The simple truth is that you can’t live without bacteria. In fact, they live all over your skin and in your GI tract. According to the NIH Human Microbiome Project, there are 10 microorganisms for every human cell. They account for up to 3% of your body mass. That means someone who weighs 150 lb carries nearly 5 lb of that weight as bacteria!

Gut Bacteria and the Human Body

Of course, you don’t want the kind of bacteria makes you sick. That’s why we treat infections like pneumonia, strep throat, and cellulitis. But don’t let that fool you. Many bacteria in the body are beneficial. They affect your immune system, mental state, and metabolism. The question is do you have the right balance of bacteria in your body to reap those benefits?

Take Home Message:
Not all bacteria are bad. Some bacteria have health benefits.

Firmicutes and Bacteroidetes

Although there are other types of gut bacteria, 90% of them fall into one of two types:  Firmicutes and Bacteroidetes. Studies show that infants and the elderly tend to have low ratios of Firmicutes to Bacteroidetes (F/B) while adults have higher ratios. More interestingly, people who are obese tend to have high F/B ratios while those who are lean have lower ratios. When you look at it that way, it is healthier to have a higher proportion of Bacteroidetes than Firmicutes bacteria.

The effect these bacteria have on your body is reflected by how many short fatty chain acids (SFCAs) they produce, especially butyric acid (i.e., butyrate).

• SCFAs release “good” cytokines that strengthen the immune system and reduce inflammation.
• They influence secretion of peptides like glucagon-like peptide 1 [GLP-1] and peptide tyrosine [PYY] that help regulate appetite.
• SCFAs modulate production of serotonin in the gut and affect the permeability of the blood-brain barrier that allows the “feel good hormone” to reach the brain.

Notably, most of the butyrate-producing bacteria are in the Bacteroidetes group. Also, when more Bacteroidetes bacteria are present, a thicker film is able to form over the colon, protecting it from damage. Firmicutes bacteria, on the other hand, are more likely to produce methane that can cause gaps between cells and that can thin the mucus barrier that protects the colon.

Take Home Message:
You want to improve the ratio of Firmicutes to Bacteroidetes bacteria in your gut. The more Bacteroidetes the better.

How A High Protein Diet Affects Gut Bacteria

What we eat affects the balance of gut bacteria in our body.

Diets rich in protein can be an issue. Most protein is digested before it enters the colon. Keep in mind that when you take antacids or antibiotics, larger amounts of undigested protein are going to reach the gut. When this undigested protein is processed by gut bacteria in the colon, ammonia and hydrogen sulfide are produced. These substances can be toxic to the colon and trigger inflammation.

When bacteria break down protein, they also release large amounts of amino acids and SCFAs like acetic acid and propionic acid that then get absorbed back into your body. This reabsorption can add an extra 200 calories to your diet every day! Not only that but these SCFAs do not have the favorable profile of butyric acid. In fact, they could promote the deposition of fat in the body.

Take Home Message:
High protein diets are more likely to trigger inflammation in your gut and may make you hold onto calories.

How a High Fiber Diet Affects Gut Bacteria

You may be better off eating a diet rich in fiber with fruits, vegetables, and resistant starches like barley, chickpeas, green bananas, legumes, lentils, oats, and plantains. Unfortunately, that may mean turning to some foods that might make you gassy. The gas is a result of microbial fermentation and that is actually a good thing. This fermentation process assists in the proper release of insulin.

The nondigestible elements in these foods also stimulate the growth of good bacteria, decrease oxidative stress in the colon, and modulate gut hormones in a way that will help better control your appetite by decreasing ghrelin, increasing PYY, and improving leptin sensitivity.

A plant-based diet or a Mediterranean diet may provide you the most benefit. This is not to say that you should never eat meat or that you should become a vegetarian. You may want to keep your protein intake in check and incorporate more fruits and vegetables into your diet every day.

Take Home Message:
Diets high in fiber and resistant starch increase the growth of good bacteria and help to control your appetite.

Should You Take Probiotics?

The easy answer is to get more healthy bacteria into your gut but how? Probiotics are live microorganisms you can ingest for a health benefit. The two main groups you will hear about are Lactobacillus and Bifidobacterium.

Probiotics can be found in everyday food items, and this may be the best way to go. Your body is better able to digest and process them. Consider eating foods like buttermilk, kefir, kimchi, miso, tempeh, and yogurt regularly. Fermented foods have also been shown to help people with diabetes and heart disease. Their gut bacteria changes to increase Bacteroidetes and decrease Firmicutes species. Studies show these people tended to have reduced insulin resistance and required fewer medications.

If you are going to purchase and take a probiotic supplement, be careful. Many of them will not be of any benefit to you and they could cost a pretty penny. The ones that work best usually contain calcium and that means they will require refrigeration. You also need one that has enough bacteria in it. Many of these supplements do not have bacteria at high enough concentrations to survive the acid in your stomach. Look for products that have > 2 billion CFU per daily dose.

Take Home Message:
It is better to get probiotics in your diet. If you prefer to take a supplement, take one with calcium in it and one with at least 2 billion bacteria per dose.

 

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