Good Bacteria for the Human Body: Types & Sources

Instructor: Lauren Posey

Lauren has taught intermediate reading in an English Language Institute, and she has her Master's degree in Linguistics.

Bacteria are everywhere, and we often think of them as harmful. This is not always true. In this lesson, you will learn about some types that are actually beneficial to the human body.


When you think of the word 'bacteria,' what comes to mind? You might think of harmful germs that carry disease and infection. While it is true that there are bacteria that make you very sick, not all bacteria are bad.

There are millions of microscopic bacteria, too small to see with the naked eye, that live inside the human body. These tiny organisms help us with actions we do every day, like digesting food.

Inside the Body

Some types of bacteria occur naturally inside the body. This means that, if everything is working normally, we don't have to eat any particular food or diet supplement in order to have these helpful organisms.


Bifidobacteria are one type of bacteria that occurs naturally in the body. They live in the intestines and help break down the food you eat, which allows your body to use the nutrients for energy. One side effect of their work is that they release gas. So just remember the next time you feel gassy, that just means the bacteria in your intestine are doing their job!

Bifidobacteria help keep your gut healthy and working properly, and they prevent issues like constipation and diarrhea. For the most part, they grow naturally in the gut. However, if necessary they can be taken in the form of a supplement.

Escherichia coli

Another useful bacteria is Escherichia coli, or E. coli. E. coli often gets a bad name because there are strains of it that can make people sick if they eat it. However, there are many different strains, and some of them grow naturally in the human intestine. These are beneficial, not harmful.

E. coli can keep harmful bacteria from thriving in the body

E. coli helps with food digestion as well, and it uses up nutrients that some harmful bacteria need to live. This means the harmful bacteria cannot take hold in our bodies, and so E. coli is keeping us healthy! These helpful bacteria also take up space in our gut, making it impossible for harmful bacteria to take hold and grow.

Outside the Body

There are also types of bacteria that do not occur naturally in the body, at least not in any great quantity. Some of these help us by fermenting food before we eat it, which creates foods like yogurt, sour cream, and cheese. These bacteria are helpful inside the human body as well, but since they do not grow there naturally, we have to get them by eating certain types of foods.

Lactic Acid and Yogurt

One of these useful outside bacteria is Lactobacillus acidophilus, which is often referred to simply as 'lactic acid.' This is one of the bacteria that ferments milk into yogurt, cheese, and other such foods. When it is going through the fermenting process, the lactic acid is essentially pre-digesting the food. This makes it easier for us to digest after we eat it.

Eating foods like yogurt and cheese is one way to get helpful bacteria into our bodies

Lactic acid is also beneficial if your normal intestinal bacteria count is low, which can happen after taking antibiotics. The lactic acid bacteria take up space in the digestive tract, preventing harmful bacteria from settling in.

Yogurt also contains other beneficial bacteria. In fact, some studies have shown that eating yogurt with active bacterial cultures (which most yogurt has) can be good for your immune system.

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