Beneficial Bacteria in your Body

Microbiologists are excited about recent studies showing that the bacteria in our guts, throat, genital organs and on our skin can have newly discovered beneficial roles in health. We have some 500 different strains of bacteria in our intestinal tract; the average healthy adult carries about 5 pounds of them. From the mouth to the colon, they help us break down and digest our food and allow for its absorption. They also synthesize a range of vitamins, from the B group to vitamin K.

About 70% of our immune system resides in the lining of the gut; signals from good bacteria influence immune cell development and susceptibility to infections and inflammatory diseases. Researchers at the University of Pennsylvania have shown that when mice are treated with antibiotics to reduce numbers of beneficial bacteria, they have an impaired antiviral immune response and delayed clearance of systemic viruses or influenza in the airways. The researchers concluded that signals from beneficial bacteria stimulate immune cells in a way that is optimal for antiviral immunity.. This may be a way that good gut bacteria reduce your susceptibility to colds and flu.

The same researchers also looked at allergic lung inflammation, similar to asthma in humans, and found that mice given antibiotics had higher levels of basophils in their white blood cells, and elevated seum IgE – seen in allergic disease. Researchers at the University of British Columbia found that mice treated with the antibiotic vancomycin reduced the diversity of microbes in the gut and increased the susceptibility of the animals to experimentally induced asthma. They conclude that normal bacterial populations can positively influence the response to allergens in the environment, making inflammation and asthma less likely. The bacterial multitudes in our bodies may have functions never before appreciated.

Antibiotics are life-saving drugs in many situations, including streptococcal throat infections (that can lead to heart valve damage), bacterial meningitis, bacterial pneumonia, urinary tract infections, et al. The purport of this column is not to criticize their use when needed, but to underline the importance of beneficial bacteria in the gut.

Research on the ‘microbiome’ is a hot topic currently, with exciting implications for human health. Microbiome is defined as the totality of microbes in the body (bacteria, viruses and fungi), their genetic elements and environmental interactions. What you can do right now to keep your microbiome in good shape is to feed your helpful intestinal bacteria the right food. Sugary foods that are low in fiber allow the ‘bad’ microbes to thrive. Avoid them. Certain foods are known as ‘prebiotics’ can help our beneficial bacteria. Examples are whole grains, oats, bananas, garlic & onions, artichokes and asparagus. In addition, many people take a ‘probiotic’ supplement that contains beneficial bacteria, and also eat fermented foods such as yogurt, kefir, and sauerkraut. Make sure the yogurt you buy contains living cultures, and avoid ones that are sweetened – it’s better to add fruit yourself. You can buy probiotic capsules at many grocery stores. Look in the refrigerated section and keep the capsules refrigerated at home to preserve the life of the bacteria therein.

If you take antibiotics for a bacterial infection, it’s a good idea to take a probiotic to restore your beneficial bacteria. This may help to prevent serious diarrhea after antibiotic use, which can occur when bad bacteria such as Clostridium difficile take over. Wait at least 2 hours after taking the antibiotic, so it can be absorbed into your bloodstream, before taking the probiotic. If you have asthma, a probiotic supplement might help – talk to you doctor about this.

Sadja Greenwood, MD, MPH - back issues on this blog. Write me a comment, and I'll answer you.