Probiotics: The Friendly Bacteria

Probiotics: The Friendly Bacteria

By Kris Gunnars, BSc

The bacteria in your body are said to outnumber your body’s cells at a 10-to-1 ratio. However, a recent study says that the ratio is closer to 1-to-1. According to these estimates, you have 39–300 trillion bacteria living inside you. Whichever estimate is most accurate, it’s certainly a large number.

Much of these bacteria reside in your gut, and the majority are quite harmless. Some are helpful, and a small number can cause disease.

Having the right gut bacteria has been linked to numerous health benefits, including the following:

  • • enhanced immune function
  • • healthier skin
  • • improved digestion
  • • reduced risk of some diseases
  • • weight loss 

Probiotics, which are a certain type of friendly bacteria, provide health benefits when eaten.

They’re often taken as supplements that are supposed to help colonize your gut with good microorganisms.


What are probiotics?

Probiotics are living microorganisms that, when ingested, provide a health benefit. However, the scientific community often disagrees on what the benefits are, as well as which strains of bacteria are responsible.

Probiotics are usually bacteria, but certain types of yeasts can also function as probiotics. There are also other microorganisms in the gut that are being studied, including viruses, fungi, archaea, and helminths.

You can get probiotics from supplements, as well as from foods prepared by bacterial fermentation.

Probiotic foods include yogurt, kefir, sauerkraut, tempeh, and kimchi. Probiotics should not be confused with prebiotics, which are carbs — often dietary fibers — that help feed the friendly bacteria already in your gut.

Products that contain both prebiotics and probiotics are referred to as synbiotics. Synbiotic products usually combine friendly bacteria along with some food for the bacteria to eat (the prebiotics), all in one supplement.

The most common probiotic bacteria are Lactobacillus and Bifidobacteria. Other common kinds are Saccharomyces, Streptococcus, Enterococcus, Escherichia, and Bacillus.

Each genus comprises different species, and each species has many strains. On labels, you’ll see probiotics identified by their specific strain, the species, subspecies if there is one, and a letter-number strain code.

Different probiotics have been found to address different health conditions. Therefore, choosing the right type — or types — of probiotics is essential. Some supplements, known as broad-spectrum probiotics or multi-probiotics, combine different species in the same product.


Importance of microorganisms for your gut

The complex community of microorganisms in your gut is called the gut flora, gut microbiota, or gut microbiome.

The gut microbiota includes bacteria, viruses, fungi, archaea, and helminths — with bacteria comprising the vast majority. Your gut is home to a complex eco-system of 300–500 bacterial species.

Most of the gut flora is found in your colon, or large intestine, which is the last part of your digestive tract. Surprisingly, the metabolic activities of your gut flora resemble those of an organ. For this reason, some scientists refer to the gut flora as the “forgotten organ”.

Your gut flora performs many important health functions. It manufactures vitamins, including vitamin K and some of the B vitamins. It also turns fibers into short-chain fats like butyrate, propionate, and acetate, which feed your gut wall and perform many metabolic functions.

These fats also stimulate your immune system and strengthen your gut wall. This can help prevent unwanted substances from entering your body and provoking an immune response.

Your gut flora is highly sensitive to your diet, and studies show that an unbalanced gut flora is linked to numerous diseases. These diseases are thought to include obesity, type 2 diabetes, metabolic syndrome, heart disease, colorectal cancer, Alzheimer’s, and depression.

Probiotics and prebiotic fibers can help correct this balance, ensuring that your “forgotten organ” is functioning optimally.


Impact on digestive health

Probiotics are widely researched for their effects on digestive health. Evidence suggests that probiotic supplements can help cure antibiotic-associated diarrhea.

When people take antibiotics, especially for long periods of time, they often experience diarrhea — even long after the infection has been eradicated. This is because the antibiotics kill many of the natural bacteria in your gut, which shifts the gut balance and allows harmful bacteria to thrive.

Probiotics may also help combat irritable bowel syndrome (IBS), a common digestive disorder, reducing gas, bloating, constipation, diarrhea, and other symptoms.

Research regarding the effectiveness of probiotics supplementation for the treatment of IBS is mixed. A recent review reported that seven of the studies indicated IBS improvement with probiotic supplementation, but four did not.

Research indicates that multi-strain probiotic supplements seem to bring most IBS improvement, especially when taken for longer than 8 weeks.

Some studies also note benefits of probiotic supplementation against inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis. Again, researchers say further research is needed before the treatment is confirmed to be effective.


Impact on weight loss

Some research indicates that people with obesity have different gut bacteria than those who are lean. Research shows a connection between gut microbes and obesity in both infants and adults. It also shows that microbial changes in the gut are a factor in developing obesity as an adult.

Therefore, many scientists believe that your gut bacteria are important in determining body weight. While more research is needed, some probiotic strains appear to aid weight loss.


Other health benefits

There are many other benefits of probiotics. They may help with
the following conditions:

  • • Anti-aging. Though research is extremely limited, there’s evidence that probiotics have the potential to extend lifespan by increasing the ability of cells to replicate themselves. 
  • •  Blood cholesterol: Several probiotics have been shown to lower total and LDL (bad) cholesterol levels, although the research remains controversial.
  • • Blood pressure: Probiotics may also cause modest reductions in blood pressure.
  • • Depression and anxiety: The probiotic strains Lactobacillus helveticus and Bifidobacterium longum have been shown to reduce symptoms of anxiety and depression in people with clinical depression.
  • • Immune function: Several probiotic strains may enhance immune function, possibly leading to a reduced risk of infections, including those that cause the common cold.
  • • Inflammation: Probiotics reduce systemic inflammation, a leading driver of many diseases.
  • • Skin health: There’s some evidence that probiotics can be useful for acne, rosacea, and eczema, as well as other skin disorders. 

This is only a small slice of probiotics’ benefits, as ongoing studies indicate a wide breadth of potential health effects



In addition to their potential effects on weight loss, digestion, and neurological disorders, probiotics may improve heart health, immune function, and symptoms of depression and anxiety.




Download the full issue of the March-April 2024 Healthy Options News Digest here.


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