In his later years Metchnikoff observed that many people in his native Russia lived vigorous and healthy lives well into old age. He attributed that to the Russian habit of eating fermented milk products, a.k.a. yogurt. Aware that such products contained bacteria, Metchnikoff hypothesized that eating what he called “good” bacteria prevented “bad” bacteria from taking over in the deep recesses of the body. In fact, Metchnikoff believed that the key to longevity involved maintaining a favorable internal environment in the intestines, preventing putrefaction induced by bad bacteria.
Since Metchnikoff’s time, science has learned much more about the health benefits associated with maintaining a healthy balance of bacteria in the body. The sheer numbers are amazing: Anywhere from 300 to 500 different species of beneficial bacteria, numbering in the trillions, are found in the large intestine.1 Scientists suggest that the number of such bacteria is 10 times more than the number of cells in the human body.
The gut environment is dynamic. Just as a human society consists of good citizens and bad citizens, so does the intestine, except the “citizens” are bacteria. The good bacteria are termed probiotics, meaning “prolife,” and the bad are antibiotics, meaning “against life.” Most people are unaware of the health benefits provided by probiotics until they take antibiotic drugs.
Antibiotics may be lifesavers, but they kill both bad and good bacteria. When enough probiotic, or beneficial, bacteria are destroyed by a drug, symptoms attributed to the antibiotics often appear. The main one is diarrhea, which occurs because the probiotics are not keeping the bad bacteria in the gut in check. When antibiotic drugs wipe out all bacteria, the bad bacteria often come back first. The body responds by attempting to rid itself of bacterial imbalance—hence diarrhea.
These days probiotics, including the lactobacillus that converts carbs into lactic acid, are most readily available in dairy-based foods and supplements. Another primary probiotic is bifidobacterium. Two other common probiotics are Streptococcus thermophilus and saccharomyces, the latter being not a bacterium but a beneficial yeast organism.
Various factors affect the composition of bacteria within the body: age, immune status, stress, alcohol intake. Certain indigestible carbohydrates, collectively known as prebiotics, also positively influence both overall health and the population of bacteria in the gut.
Probiotics keep us healthy through various mechanisms. They defend against pathogens, or disease-causing organisms, by producing such antimicrobial compounds as cytokines and butyric acid. Both increase gut acidity, making it inhospitable for invading or potentially dangerous bacteria.2 Probiotics also compete with pathogeni19bacteria for binding and receptor sites, just as the drug Nolvadex blocks the cellular binding sites for estrogen. Probiotics are a second line of defense for the immune response because they help maintain the mucosal barrier of the gut, which prevents organisms from invading. If that line of defense is compromised, serious disease or death can result.
To qualify as a true probiotic, bacteria must exert a beneficial effect on the host, which is you. They must survive the formidable barriers to absorption, such as the high acid content of the stomach and the degrading effects of bile. They must be able to adhere to the lining of the large intestine and favorably affect the microbial balance of the gut.
Studies show that true probiotics exert a number of protective effects. They oppose a bad-guy bacterium called Helicobacter pylori, which causes ulcers and is involved in gastric cancer.3 Maintaining a favorable microbial balance helps to prevent such maladies as traveler’s diarrhea, inflammatory-bowel disease, irritable-bowel syndrome and a rotoviral diarrhea common in children.4
Probiotics can prevent the bloating that results from eating either too much food or any amount of bad food. Much bloating is caused by gases that bad bacteria release in the gut. The same bacteria cause halitosis, or bad breath, which may be counteracted by taking probiotics. By increasing gut acidity, probiotics promote intestinal motility, or the movement of food through the intestine. That, in turn, promotes increased nutrient uptake and prevents constipation.5
Probiotics enhance immunity not only by helping to maintain the vital gut mucosal barrier but also by producing cytokines, the proteins that activate immune cells, including the macrophages that engulf and digest invading organisms and the natural killer T cells that attack viruses and incipient tumors in the body.
Some preliminary evidence shows that probiotics help prevent cancer. In one study lactobacillus acidophilus blocked colon cancer in rats. Other strains of probiotics have blocked cancers of the colon, liver, small intestine and breast in animal studies. Some research shows that probiotics appear to prevent recurrence of bladder cancer in humans.
There is emerging evidence of a positive probiotic effect against cardiovascular disease. A probiotic strain called Lactobacillus reuteri decreased total cholesterol and blood triglyceride levels by 38 percent and 40 percent, respectively, while increasing the HDL-to-LDL ratio by 20 percent after only one week. Other studies show that probiotics may lower elevated blood pressure.
People who experience adverse symptoms when they eat dairy products may be gratified to know that probiotics help break down and digest lactose, or milk sugar, by producing the enzyme lactase, which digests lactose. That explains how those who cannot tolerate milk without experiencing bloating and gastrointestinal discomfort can safely eat yogurt or other fermented milk products. The probiotics in the yogurt break down the lactose before it causes problems.
Probiotics produce short-chain fatty acids, such as butyrate, propionate and acetate. They act as fuel for the cells that line the intestine and appear to protect against mutagenic cell changes that can lead to cancer.
Recent research suggests that probiotics may be a useful adjunct to therapy for manic-depressive illness. People suffering from that condition have elevated levels of pro-inflammatory cytokines, increased oxidative stress and altered gastrointestinal function. They have decreased nutrient uptake and are often deficient in omega-3 fatty acids. More important, they usually also have an overgrowth of bacteria in their small intestines, which limits nutrient uptake.
They also experience higher levels of stress, which is known to decrease levels of beneficial bacteria. That’s important because one effect of probiotics is to modify immune response; in depressed people, the immune response is out of whack. Probiotics lower levels of inflammatory cytokines, decrease oxidative stress through antioxidant activity and improve nutrient uptake by lowering levels of bad intestinal bacteria.
Some research shows that the type of fat you eat affects your body’s probiotic levels. One example is research showing that omega-6 fatty acids, such as various vegetable oils, inhibit probiotic-bacteria growth. Omega-6 fats are also potent inflammatory agents in the body and are linked to cancer development and out-of-control oxidative reactions. By contrast, omega-3 fatty acids, or fish oils, promote the growth of probiotics, decrease inflammation and promote probiotic adhesion to the intestinal wall, which is essential to their function. The combination of omega-3s and probiotics may promote positive effects on mental health.
A common question is whether it’s best to get probiotics from the food you eat or in dietary supplement form. Some scientists prefer the food route for synergistic reasons. For example, eating whey proteins promotes the body’s probiotic uptake, and some whey-protein supplements now contain probiotics, which makes nutritional sense. The buffering effect against stomach acid that occurs when you put food in your stomach also promotes probiotic uptake.
In order to get the benefits of probiotics in your diet, you’d need to drink about a liter, or just over a quart, of acidophilus milk per day. Keep in mind that probiotic effects are transient; they don’t stay too long in the body and are swept out with other bacteria. So you need to get them in there on a regular basis. Taking several strains of supplemental probiotics should easily get you to beneficial levels.
The question of whether probiotics are in any way toxic is a sensible one, as we’re dealing with bacteria and yeast organisms.6 Some studies indicate that a person with compromised immunity needs to be careful when using probiotics because they can lead to excessive immune stimulation. Prebiotics, which are indigestible carbohydrates that promote bacterial fermentation and probiotic growth, can cause problems simply because they can’t be digested.7 Too large a dose of prebiotics can draw water into the gut and cause excessive gas, bloating, abdominal pain and diarrhea.
Perhaps the main problem with probiotics is that you may not be getting what you pay for. In a study presented at the annual meeting of the American Society for Microbiology in 2001, Belgian scientists reported on 55 commercial probiotic products. Included in the study were 25 dairy supplements and 30 powdered products. More than a third of the powdered products contained no live bacteria, while the liquid products all did. Only 13 percent of the supplements, however, contained all the strains listed on the label. A third of other products contained bacteria not listed on the label, though they proved harmless.
The best type of supplement is a combination of liquid dairy-based probiotics and prebiotics called synbiotics. Keep such supplements refrigerated to maintain maximum potency.
Bodybuilders and other athletes often overlook the importance of maintaining an efficient digestive system, as promoted by probiotic supplements. But let’s face it: If you suffer from gastrointestinal illnesses, your nutrient uptake is likely to be compromised. When that happens, you can gulp down the most expensive, high-tech supplements available and still get zero benefit. Probiotics will help you maintain a healthy gut environment, aid immunity and promote health and muscular gains.
References
1 Koop-Hoolihan, L. (2001). Prophylactic and therapeutic uses of probiotics: a review. J Am Dietetic Asso. 101, 229-238.
2 Isolauri, E., et al. (2004). Probiotics. Best Practice and Res Clin Gastroentr. 18, 299-313.
3 Zubillaga, M., et al. (2001). Effect of probiotics and functional foods and their use in different diseases. Nut Res. 21, 569-579.
4 Rolfe, R. (2000). The role of probiotic cultures in the control of gastrointestinal health. J Nutr. 130, 396S-402S.
5 Guarner, F., et al. (2003). Gut flora in health and disease. Lancet. 361, 512-519.
6 Marteau, P., et al. (2004). Tolerance of probiotics and prebiotics. J Clin Gastroenterol. 38, S67-S69.
7 Van Loo, J. (2004). Prebiotics promote good health. J Clin Gastroenterol. 38 Supp. 2, S70-S75.
©,2013 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited.
