Your overall health depends on the healthy functioning of your digestive system; not only does it pull nutrients from food to nourish the body, but it participates in protecting it against disease.

The bacteria that populate the digestive tract play a major role in both of these functions. Imbalances in the types of gut flora - friendly vs. harmful - can lead to digestive upsets which, if left unchecked, can lead to far more serious health problems. One such disease is Irritable Bowel Syndrome. Irritable Bowel Syndrome, or IBS, is the most common, chronic medical condition in the Western world. Approximately 40% of those with IBS have symptoms severe or frequent enough to disrupt their daily lives.

Convincing evidence shows that probiotics can speed recovery from infectious diarrhea. They may also ease symptoms of irritable bowel syndrome. and in some cases, for people with Crohn’s disease. And although some findings for ulcerative colitis are promising, they not conclusive, according to a Yale University workshop on the clinical use of probiotics.

Probiotics come in a variety of forms, from powders and capsules to foods such as yogurt, dairy drinks, infant formulas, cheese, and even snack bars that are supplemented with specific probiotic organisms.

Yogurt is the most familiar source of probiotics -- "good" bacteria like lactobacillus or bifidobacteria that keep a healthy balance in your gut. Studies suggest that probiotics can help ease lactose intolerance. They also may help tame gas, diarrhea, and other digestive problems. You can pay extra for special digestive yogurt brands, but any with "live and active cultures" listed may help. Kefir, sour cream, cottage cheese and some soft cheeses can also be found with live and active cultures.

Acidophilus milk (milk that has been fermented with bacteria such as lactobacillus acidophilus) sometimes called sweet acidophilus milk and buttermilk (milk that is cultured with lactic acid bacteria) are also rich in probiotics. Raw milk (milk that has not been pasteurized) is rich in probiotics, but is not always available. Raw milk cheese would also be a source of probiotics.

Sauerkraut (fermented cabbage) contains the beneficial microbes leuconostoc, pediococcus, and lactobacillus. Choose unpasteurized sauerkraut because pasteurization (used to treat most supermarket sauerkraut) kills active, beneficial bacteria. Sauerkraut (and the similar but spicy Korean dish, kimchi) is also loaded with immune-boosting vitamins that may help ward off infection.

Sourdough bread contains lactobacilli, a probiotic which may benefit digestion. Look for good old fashioned (or homemade) breads, as not all commercial varieties will contain live cultures. Any of these forms may be effective for some digestive problems as long as they contain the beneficial organisms in adequate numbers. Dosage is very important, as well as viability and choosing a broad spectrum of bacteria strains.

For example, the suggested dosage for infants with colic is 15 billion CU units daily. Divide this over 5 feeding daily, the supplemental dosage per feeding would be an estimated 3 billion. Capsules can be opened and the contents added to their milk (powders are also available). If breast feeding (which is strongly recommended), probiotics can be added to milk that has been pumped.

Mother’s milk should naturally contain adequate probiotics but if the mother or infant had been given anti-biotics for any reason, all probiotics have been destroyed as well. This can create huge digestive disturbances for the infant who’s digestive system is not yet fully developed and needs the added probiotics to digest the milk.

Pets also need adequate probiotics in their diet. Gas, diarrhea and other episodes of digestive upset often greatly benefit from adding probiotics to their food or to a small bowl of yogurt (which all animals seem to love). Dosages will depend on the size of the dog or cat, keep in mind a 10 pound infant may need 15 billion cu daily.

If you don’t feel probiotics are helping, here are some things to consider:

Is the dosage high enough?
Some people seem to feel eating a serving of yogurt a day should be adequate to relieve them of their digestive distress. In most cases, the required level of bacteria is simply not there. Even the brands promoted for digestive health only contain about 1 billion CU per serving. This might be enough for a healthy person as a maintenance,but not for someone experiencing difficulty. If you are taking capsules, try increasing the dosage, it’s almost impossible to overdose.

Are the bacteria viable?
For example, many brands require refrigeration (it will tell you on the label if it does). If it was not kept refrigerated, there is a good chance that many if not all of the probiotics are no longer living and cannot help you.

Are you taking a brand with a variety of strains?
Certain strains appear to be helpful only for certain conditions. The strains that appear to be most effective in treating infectious diarrhea, for instance, include Lactobacillus GG and Saccharomyces boulardii. Try changing brands to one that contains a larger variety of strains.

Enemies of probiotics in the body include anti-biotics, stress, and acidic pH. In addition, severe colon cleanses and enema can flush out important probiotics leading to imbalance.