What are Probiotics? – Types, Foods, Supplements, Benefits & Side Effects

Probiotics are bacteria that help keep the balance of microorganisms in the intestines. We generally associate the word bacteria with ‘disease,’ but in fact, our body has both good and bad kind of bacteria. Probiotics are considered the good bacteria as they provide many health benefits (1). Some of the common probiotic foods are yogurt, kimchi, natto, buttermilk, kombucha, pickles, etc.

There are myriad health benefits of probiotics such as weight loss, immunity boost, healthy skin, healthy heart, sharp mental health, etc.


In this article we will learn more about probiotics, how they work, best probiotic supplements and how they benefit our health.

What are probiotics?

The term ‘probiotics’ is derived from the Greek and means ‘for life.’ According to the World Health Organisation, probiotics are live organisms which when consumed in the right amounts, confer health benefits to the host (2).

According to the National Center for Complementary and Integrative Health, probiotics are live organisms (mainly bacteria) similar to the microorganisms found in the human gut (3). The benefits of probiotics include reduced inflammation, improved digestion, and healthy skin.

You can find probiotics in supplements and some foods like yogurt and cheese.

How do probiotics work?

We all have good bacteria that live in our gut. Sometimes when we take antibiotics, the beneficial bacteria in our gut also die. Probiotic supplements help in replacing the beneficial bacteria. They help balance the good and the bad bacteria in the gut to ensure that the body continues to work well.

Probiotics also help the good bacteria crowd out the bad bacteria from the intestines, and this prevents infection and inflammation.

Probiotics help in the digestive process as they help to body to extract nutrients from the food. Some probiotics also perform the vital role of hormone production.

Different types of probiotics

There are two primary species of probiotic bacteria.

1. Lactobacillus

This species has 18 different bacteria strains, and they inhabit your small intestine, mouth and the vagina.

Lactobacillus bacteria produce lactase, the enzyme that breaks down lactose. They also produce lactic acid, which helps control the population of harmful bacteria. Lactobacillus bacteria also help in the absorption of minerals.

2. Bifidobacterium

This species has eight different strains. They live in your colon. They support the immune system and limit the growth of harmful bacteria in the intestine. They also help to break down lactose into nutrients for the body.

3. Saccharomyces boulardii

This is the yeast that is found in probiotics. It helps to fight digestive problems like diarrhea.

Importance of gut flora

The human gut contains 100 trillion bacteria, ten times the number of cells that are in the body. These bacteria, also known as gut flora, affect our health in many ways.

They help build the body’s immune system, prevent diseases and also extract energy from the food we eat. Most gut flora is found in the colon, the large part of the digestive tract. Here are some ways how the gut flora affects our health –

  1. Bifidobacteria that grow inside the intestines of babies help to digest the healthy sugars in the breast milk and assist in the growth (4).
  1. Certain bacteria in our gut help in the digestion process as they help digest fiber and produce short chain fatty acids. Fiber is helpful in preventing weight gain, diabetes, heart disease and the risk of cancer (5).
  1. Our gut flora also controls how our immune system works. Our gut microbiome can control the way our body responds to medicine by communicating with the immune cells (6).
  1. The gut bacteria also affect the functioning of the brain. According to recent research, the gut microbiota also influences the brain function and behavior.

Balancing the good bacteria and the bad bacteria is vital for good health. Consuming probiotic-rich food and supplements can help maintain this balance and ensure that our gut microbiota works perfectly (7).

How to eat more probiotics?

While many people opt for probiotic supplements, there are many natural sources of probiotics that you can have to keep your gut healthy. Here are some of the healthiest probiotic-rich foods are –

1. Yogurt

Yogurt is made from milk which is fermented by good bacteria – lactic acid bacteria and bifidobacteria. Eating yogurt can help improve bone health and reduce blood pressure (8).

It also helps prevent diarrhea caused by antibiotic use and helps relieve the symptoms of irritable bowel syndrome (9).

Make sure you buy yogurt that comes from goat milk, sheep milk or A2 cow’s milk. Avoid yogurt that is labeled low fat or fat-free as it may contain added sugar.

What is probiotics and popular sources infographic

2. Sauerkraut

Made from fermented cabbage, sauerkraut is high in organic acids that support the growth of good bacteria. It is an excellent source of lactic acid bacteria – Lactobacillus.

Sauerkraut is also a good source of fiber and vitamins C, B and K. It contains sodium, iron and manganese and antioxidants like lutein and zeaxanthin (10).

3. Kefir

The work Kefir comes from a Turkish work Keyif, which means ‘feeling good.’ Kefir is a drink that is made up of milk and fermented kefir grains.

Kefir grains are cultures of lactic acid bacteria and yeast and look a bit like cauliflower. Kefir contains many strains of good bacteria and yeast, which makes it a potent probiotic (11).

4. Kimchi

This spicy Korean dish is made from cabbage, mixed with chili pepper flakes, salt, ginger, garlic, and scallion. It contains Lactobacillus kimchii, a lactic acid bacterium which can benefit digestive health (12). Kimchi also contains vitamin K, B2, and iron.

5. Natto

This Japanese dish contains fermented soybeans. It has extremely powerful probiotic Bacillus Subtilis which is known to improve digestive and cardiovascular health and bolster the immune system. Natto also helps to prevent osteoporosis in women (13).

6. Buttermilk

Buttermilk is the leftover liquid from making butter. This fermented drink is low in calories and fat and contains nutrients like vitamin B12, riboflavin, calcium, and phosphorus.

7. Miso

Miso has been a part of Japanese and Chinese diets for thousands of years. Made by fermenting soybeans with salt and a fungus called koji, miso has been traditionally used to stimulate the digestive system.

Miso is an excellent source of protein, fiber, vitamins, minerals, vitamin K, manganese, and copper. Studies have shown that miso soup can lower the risk of breast cancer and stroke (14, 15)

8. Kombucha

Kombucha is a fermentation of black or green tea. It is fermented by SCOBY a colony of bacteria and yeast which give it probiotic properties. Its health benefits include improved digestive and immune system and liver detoxification.

9. Kvass

Kvass is a fermented drink made by fermenting rye or barley. It can also be created with beets, fruit, and carrots.

10. Pickles

Pickles are cucumbers that are fermented in their own naturally present lactic acid and salt solution. The healthy probiotic bacteria in pickled cucumbers can improve digestive health. They are also a good source of vitamin K.

How to choose the correct supplement?

Though you can get all the probiotics you need from the food you eat, there are times when your body needs a boost. If you’ve been sick and have taken a course of antibiotics, there are chances that the antibiotics may have killed both the good and the bad bacteria.

Unless you are looking for a specific type of probiotic, you should choose a broad-spectrum probiotic that contains a mix of different strains of bacteria.

Opt for a reputable brand with excellent reviews. Purchase a supplement that has a higher number of probiotics – from 15 billion to 100 billion.

Bacillus coagulans, Saccharomyces boulardii, Lactobacillus rhamnosus are some of the strains of bacteria that make it to the gut and are more effective.

Health benefits of probiotics

Let us see some health benefits of probiotics in detail.

1.  Improve digestive health

Probiotics have been helpful in the treatment and prevention of gastrointestinal diseases. Studies indicate that probiotics are useful in treating diarrhea, ulcerative colitis and Crohn’s disease (16).

2. Can improve mental health

Many studies have linked probiotics with psychological health (17). According to a review of 15 separate studies, Bifidobacterium and Lactobacillus bacteria can reduce anxiety, depression, obsessive-compulsive disorder, memory and autism (18).

Benefits of probiotics infographic

3. Boost immunity

Probiotics help boost immunity by inhibiting the growth of harmful bacteria (19). Probiotics encourage the production of antibodies and boost immune cells.

4. Help lose weight

Probiotics prevent the absorption of fat in the intestine. They also increase the levels of hormones like GLP-1, which make you feel fuller for longer and burn more calories (20).

5. Healthy skin

According to some studies, probiotics help prevent skin problems like pediatric atopic dermatitis and eczema (21). They also help prevent acne and keep the skin looking healthy.


6. Improve heart health

Probiotics help improve heart health by lowering LDL and blood pressure. The lactic acid producing bacteria are especially helpful in reducing cholesterol levels.

Side effects of probiotics

Though most studies have found that probiotics have minimal side effects, they can cause some unpleasant digestive problems like bloating, gas and diarrhea. Yeast-based probiotics can cause constipation and increased thirst.

Some people can also develop an allergic reaction to probiotics with symptoms like itching, redness, watery eyes and a runny nose.

Over to you

Probiotics are live organisms which are beneficial to the host when consumed in the correct amount. They have many health benefits like an improved digestive system, better heart health and can also help you lose weight. Though probiotics are present in many foods that we eat, they can be taken as supplements as well.


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