Probiotics: Bacteria in Your Diet May Enhance Your Health

Wednesday, October 11, 2006 - 1:59pm

By Donna Feldman, MS, RD

The human digestive tract is home to millions of bacteria. Some researchers estimate that humans have more bacterial cells than body cells. But when it comes to health, bacteria usually have a bad reputation. For example, if you've ever suffered from "turista" (the intestinal ailment that strikes people who travel to other countries), you're well aware of the effect of unwelcome bacteria on your digestion.

While there are over 400 species of bacteria in humans, not all cause problems. Research suggests that friendly bacteriaprobiotics, may help digestion, immunity, allergies and cancer.

What are probiotics?

The United Nation's Food and Agriculture Organization defines probiotics as live microorganisms...which confer a beneficial health effect on the host. In other words, for bacteria to be considered a probiotic, it must be beneficial to humans. As a result, if food manufacturers labels a food as containing probiotics, the benefits must be proven by research.

In the United States, no health claims for probiotics have been approved, but this hasn't stopped the recently surging sales of probiotic products. Yogurt and yogurt-type drinks are especially popular probiotic-containing foods. In the European Union, there are even stricter rules requiring companies to prove the health claims about probiotics. New research efforts are focused on proving the beneficial effects, so that food producers can add these health claims to food labels.

Benefits of probiotics

Anecdotal evidence suggests friendly bacteria help a variety of digestive problems, from turista to irritable bowel syndrome to diarrhea. Scientists also believe probiotics could:

  • Reduce carcinogens
  • Enhance immunity
  • Decrease allergies.

However, none of these benefits have been proven, mainly because the research is complicated and time consuming. What's so complicated? Well, each species of bacteria may come in several different strains. If one strain shows a beneficial effect, researchers can't assume other strains will have the same effect and must test each strain individually.

At the moment, most probiotic-enhanced foods and supplements contain varieties of lactobacillus or bifidobacterium, which are the best known probiotics. As research continues, other types of bacteria may also prove beneficial.

What happens when probiotics are ingested

The concept sounds simple enough. Eat friendly bacteria and they will eventually arrive in your intestine and enhance your overall health. However, the reality is more complex. For starters, the bacteria may not survive the digestive enzymes in your stomach and upper small intestine. The probiotics industry is working to solve this problem by making more viable products so the cultures survive the digestive process. Then, there's the problem of the bacteria needing to eat, which is where prebiotics come in.

Food containing probiotics

Probiotics are not bacteria; they are food for friendly bacteria. The best-known of these are fructooligosaccharides (FOS), a class of sugars that are indigestible by humans. FOS are derived from edible plants like Jerusalem artichokes, and can now be found in a range of specialty food products from yogurt to ice cream to lollipops. FOS can also be purchased separately in capsule or powdered form. Consuming prebiotic-containing products encourage the growth of friendly bacteria in the digestive tract.

Further probiotic research needed

Despite the lack of research-based proof, some health care providers routinely recommend probiotic foods, like yogurt, for diarrhea caused by antibiotics or infection. Someday, friendly bacteria, along with prebiotics, may very well be shown to enhance your health in a variety of ways. Evidence for benefits will lead to an explosion of food products that contain pre- and pro-biotics, or combinations of them termed "synbiotics." But until the evidence is in, yogurt and other foods with friendly bacteria will still be available, and you should be cautious about anecdotal claims that portray probiotics as a panacea.