It is commonly said that the dog is man’s best friend. Some very small and inconspicuous creatures have every right to dispute that statement. They are symbiotic bacteria often referred to as the “Normal Flora” of the body. A symbiotic relationship is one in which two dissimilar organisms live intimately together for their mutual benefit. Some of the more common symbionts in the human body are Lactobacillus Acidophilus, Lactobacillus Casei, Bifidobacterium bifidum, Streptococcus thermophilus and Saccharomyces boulardi. Not exactly household names, but they are still some of our closest friends.

What do these little symbionts do for us? Many things. They reinforce mucosal barriers in the mouth, intestinal tract & vagina to prevent the invasion of disease causing organisms. Canker sores, peptic ulcers, diarrhea and vaginal infections are far less common when optimum numbers of symbiotic bacteria are present. In the intestinal tract they block the entrance of undigested proteins that can cause allergy symptoms if absorbed.

These tiny friends protect us from harmful germs in many ways. First, they physically crowd out disease causing organisms. They prevent germs from multiplying in our bodies by manufacturing acidic compounds such as lactic acid and short chain fatty acids. They take nutrients away from harmful organisms and destroy disease causing bacteria and yeast. In addition, they produce natural antibiotics called microcins and bactericins.

Our symbionts not only protect us from invaders, the actually synthesize nutrients including vitamin B-12, biotin and vitamin K. They also improve the nutrient quality of foods such as yogurt and cheese, using fermentation to produce folic acid, niacin and riboflavin. They improve digestion of dairy products by providing lactase to split lactose (milk sugar) into glucose and galactose.

Finally, these tiny creatures stimulate our immune function by increasing the body’s release of a substance called IgA. It is no wonder that an individual who does not have an healthy population of symbiotic bacteria on board is far more susceptible to infections than someone who has nurtured and respected them.

The importance of maintaining our normal flora is made clear by the fact that officials at the US Centers for Disease Control estimate that foodborne disease may be responsible for 5,000 deaths, 325,000 hospitalizations and 76 million cases of GI illness in the United States each year. Many, perhaps most, of the deaths and hospitalizations could be prevented by the presence of adequate numbers of symbionts in the intestinal tract.

The two greatest enemies of our normal flora are chlorinated water and antibiotics. Both kill off the sensitive symbiotic bacteria leaving us vulnerable to attack by disease causing organisms. We should therefore drink purified water and use antibiotics only when reasonable alternatives are unavailable. The antibiotic that is least likely to damage the normal flora is azithromycin.

Populations of symbiotic bacteria are available as “probiotics.” These are sold as capsules or granules. In most cases it is recommended that they be refrigerated to preserve their viability. Some are available in a spore form that does not require refrigeration and is better able to survive the acidic environment of the stomach. Look for expiration dates & certification of organism’s name & number of cells (CFU) colony forming units.

Capsules usually contain 1-2 billion cells, granules 2-4 billion cells per 1/2 teaspoon. Since we are invariably exposed to chlorinated water on occasion it is advisable to take 1-2 billion CFUs of Lactobacillus acidophilus alone or in combination with other symbiotic bacteria twice daily for several days each month. It is very important to restore these bacteria after taking any antibiotic. Taking 2-4 billion CFUs 3 times daily for 2 weeks after completing an antibiotic course is recommended.

Whole wheat, onion, garlic, leek and banana contain substances called fructooligosaccharides that support the growth of friendly bacteria. Including these foods in the diet regularly will help support the presence of a healthy number of these organisms.