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Prebiotics and Probiotics 

The digestive tract is home to more than 500 species of bacteria, comprising about 100 trillion bugs altogether. Collectively, they are tremendously important for overall health.We give these bugs a home; in exchange, they do a variety of things for us. For instance, they help digest food, synthesize certain vitamins, and play an important role in immune defense.These bugs also act as a barrier to help our bodies filter and appropriately absorb nutrients from what we eat.

There are ‘good’ bugs called probiotics, which we can constantly replenish.These probiotics also need nourishing food  to help them grow. Prebiotics are the fiber-rich foods that probiotics feed and grow on. As an added bonus, a compound

called butyric acid is produced when the probiotics break down prebiotic foods in the colon. Butyric acid is the preferred form of fuel for the cells that line the colon, and it serves to acidify the environment as well, making it harder for harmful bacteria to survive.

Two of the main probiotic bacteria that reside in the digestive tract are Lactobacilli and Bifidobacteria.These can be taken in the form of supplements or included in the diet in the form of fermented (or probiotic) foods.The table below lists examples of common probiotic and prebiotic foods.













Fermented foods can also be made at home.Though the probiotic content will vary by batch, home fermenting is a safe way to ensure that you are ingesting beneficial bacteria, as various cultures around the world have done for centuries.




Specific strains and their effects: 

4 Major types of phyla exist in our gut.

1. Bacteroides

2. Firmicutes

3. Proteobacteria

4. Actinobacteria




Popular probiotic strains such as lactobacillus acidophilus, plantaris, casei, bacillus, streptococcus thermophilus etc. are derived from the above 4 major phyla. 




Microbiome and Obesity:

Studies show that obese individuals have a higher bacteroides to firmicutes ratio in their gut as compared to their lean counterparts. An optimal firmicutes to bacteroides ratio increase the production of short chain fatty acids which in turn improves metabolism. It is not clearly understood if this is a contributing cause or effect. It is postulated that this is partly due to,healthier diets containing abundance of plant sources which thin individuals eat which promote growth of fermicutes.

Microbiome and Gut related diseases (Irritable Bowel Syndrome, Inflammatory Bowel Disease):

Several studies show that loss of a healthy gut microbiome is correlated with symptoms of IBS (irritable bowel syndrome). Often, building a healthy microbiome with appropriate diet can help resolve IBS symptoms. Certain strains such as lactobacillus and bifidobacter are particularly helpful in improving IBS symptoms. 

Microbiome and Recurrent Urinary Tract Infections:

Recurrent urinary tract infections are usually a result of E. coli predominance. A healthy gut and urogenital microbiome can help prevent recurrent urinary tract infections. Two microbiome strains lactobacillus rhamnosus and lactobacillus fermentum have been shown to be effective against recurrent urinary tract infections and bacterial vaginosis. 

Microbiome and the Immune System:

A healthy gut microbiome is crucial to developing and maintaining robust immune system. Several strains incluidng bacteroides, firmicutes and bifidobacter infantis are capable of inducing the production of regulatory T cells through the expression of the gene FOXP3. These regulatory T cells are needed for appropriate immune function. 

Microbiome and Heart Health:

Unhealthy foods such as processed meats increase the production of TMAO (Trimethyl amine oxide). TMAO is a chemical which promotes atherosclerosis or blocking of the arteries. A healthy gut microbiome, which is fed by plant based fiber helps remove or block the production of TMAO. Lactobacillus has shown to lower cholesterol and increase HDL levels in humans. 

Microbiome and Brain Health: 

Gut microbiome exerts its influence on brain function through a strong gut brain axis. Several strains of healthy gut microbiome such as prevotella are depleted in people with brain disorders such as Parkinson's disease, autism and Alzheimer's disease. It is not clear yet if this imbalance is a cause or result of such disorders. 

Microbiome and A Variety of Additional Health Conditions:

Gut microbiota plays an important role in regulating and controlling several health conditions such as allergies, asthma, skin conditions, mood disorders etc. Research is still mounting on use of specific strains for these conditions. A healthy microbiome down regulates disease activity and helps lower the need for conventional treatments. 

Does everyone need probiotics?


Though everyone needs a healthy microbiome, not everyone needs to supplement with store bought probiotics. Actually, some conditions get worse when probiotic supplements are used. A few include

1. SIBO (Small intestinal bacterial overgrowth)

2. Severe dysbiosis

3. Intestinal obstruction

4. Adhesions 

5. Acute intestinal infection

Below are probiotic strains which have been scientifically studied and have been shown to be effective in above conditions when used alongside standard treatment. 

1. Bifidobacter longum

2. Bifidobacter infantis

3. Bifidobacter breve

4. Lactobacillus plantaris

5. Lactobacillus acidophilus

6. Lactobacillus casei

7. Lactobacillus bulgaris

8. Streptococcus thermophilus


How to Become a Pro at Building Your Microbiome

Just as by eating a well balanced whole foods based diet we can avoid the need for vitamins and micronutrient supplementation, a healthy microbiome can be built using the following approach.

1. Eat a variety of plant based, fiber containing whole foods.

2. Eat 1-2 servings of prebiotics containing or fermented foods as shown in the table above. 

3. Limit processed foods and artificial sweeteners.

4. Avoid antibiotics unless absolutely necessary.

5. Exercise daily to promote a healthy gut microbiome. 



By doing above, you may not need supplemental probiotics. However, if you have any health conditions (some of which are mentioned above) or have symptoms ( general symptoms which should first be reviewed by your health care professional include  irritable bowel, gas, bloating, indigestion, mood problems, recurrent infections, allergies, skin conditions, food sensitivities, etc.) which suggest that you have an imbalance in your microbiome, consider the following strains after consulting with your health care professional.  

For additional information on gut health, visit the page on leaky gut



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