If you want to stay well, you need a strong immune system to protect you against disease and keep you from getting sick. Your gut acts as a huge immune organ, your first line of defense against infection, so you need an ample supply of probiotics, beneficial bacteria that live in the intestinal tract and help guard it. Your immune cells depend on their partnership with probiotics to help them shield the body from harm.

Wiping Out Infection Probiotics can help immune systems fend off invaders, but new research shows their potential in keeping wounds free from infection. Applied to wounds infected with Staphylococcus aureus, probiotics seem to keep the bacteria from binding to the human cells. More studies are necessary, but current results show how probiotics may be used against antibiotic-resistant infections.

Billions of Immune Helpers
While your body consists of about ten trillion cells, the bacteria that live within us add up to close to a hundred trillion cells. The vast majority of these bacteria live in the digestive tract. Accompanying them are most of your immune receptors, which patrol the digestive tract, destroying invaders that could make you ill. Along with probiotics and immune cells, the mucous membrane lining in the digestive tract protects the body from invaders.

When bacteria or other microbes contact this wall, immune cells determine whether it is a desirable probiotic or an undesirable intruder. If accredited as friendly, the immune cells leave them alone. In fact, friendly bacteria even get fed – your sticky mucous membranes incorporate sugars that probiotics use for nutrition. But if the bacteria or microbes are seen as potential sources of trouble, the mucus ensnares them, and passes them through the intestines where they are eventually excreted.

Barrier Defense
Research on probiotics demonstrates that they have multiple functions that help mucous membranes and immune cells protect against infection. For example, a study in France found that strains of bifidobacterium helped decrease harmful bacteria, kept them from invading cells and killed off some types of salmonella, a bacteria that frequently causes food poisoning (Gut, 2000; 47:646-52). In Germany, when scientists gave a group of people a probiotic supplement for three months, they found that they suffered colds that were, on average, 2 days shorter than those caught by other folks (Clin Nut, v.24 (4), pp 481-491). These researchers found that after only two weeks of supplements, the probiotics helped activate defense cells in the immune system.

Probiotic Deficits
Because the immune system depends so heavily on the help of its probiotic partners, anything that threatens these helpful little friends also threatens our health. Changes in the American diet and lifestyle during the past few decades have not made life easy for beneficial bacteria and may be one important reason our health overall has suffered. As Gary B. Huffnagle, PhD, points out in The Probiotics Revolution (Bantam), “During the past forty or fifty years, Americans have inadvertently performed a massive experiment by making two significant lifestyle modifications: greatly increasing our use of antibiotics and substantially changing our diet. Together these changes have produced an invisible epidemic of insufficient probiotics.”

Fifty years ago, Americans used to eat plenty of whole grains with fresh fruits and vegetables. But our more recent reliance on processed foods, which contain little of the fiber that probiotics need to feed, has favored the growth of yeast and harmful bacteria and gradually starved out many of our beneficial organisms. Meanwhile, our use of antibiotics has also wiped out much of the probiotic bacteria in the gut.

Promoting Immunity The beneficial probiotic bacteria in our digestive system have several crucial functions that help prevent pathogenic microbes from making us sick. Probiotics take food from pathogens. By consuming nutrients available in the gut, probiotics deprive disease-causing organisms the fuel they may use for reproduction. A fiber-rich diet helps those probiotics thrive. Probiotics occupy prime real estate. By attaching to cells in the walls of the digestive tract, probiotics deny pathogens access to important gastrointestinal property. Deprived of a place to live, they are more easily passed through the digestive tract for excretion. Probiotics make their own antibiotics. Probiotics can make natural substances that hinder the spread of disease-causing organisms. Plus, probiotic byproducts can make the digestive tract more acidic, which disrupts pathogenic reproduction.

Fermentation Benefits
In the colon, probiotic bacteria make important fatty acids from the cell walls of fruits and vegetables. Vadivel Ganapathy, a professor at the Medical College of Georgia, believes that eating dietary fiber provides necessary food for the bacteria to survive. Research shows the fatty acids made by probiotics help keep immune cells vigilant. If the probiotics decline, so does the supply of the fatty acids, and possibly your overall health. The body’s defenses are centered in the digestive tract where immune cells and probiotic bacteria team up to resist infection. Whenever we are exposed to harmful bacteria, yeast or parasites, our immune cells in the digestive tract can shield us. Probiotics aid this process by boosting the effectiveness and activity of these immune warriors. That’s why, when you keep the gut well supplied with probiotics, you make an invaluable contribution to your present and future health.