How Good for You Is Kefir?

Kefir is pretty good for you, wrote Elena Conis in a Los Angeles Times article titled Kefir is nutritious but larger health claims are on shakier ground. Beware the silly and exaggerated claims of the propagandist food faddists.

What is kefir? For those who don't know:

Kefir grains.

Kefir's closest cousin is yogurt, also made by fermenting milk with bacteria. But kefir is fermented with more and different types of bacteria, in addition to yeast, which means the final product has more of the beneficial microorganisms, or "probiotics," that first made yogurt a popular health food. Probiotics can control the growth of harmful bacteria and aid digestion, and some even manufacture vitamins in the gut.

Conis wrote that at base, kefir has some desirable nutrients, saying "The drink is a good source of calcium, protein and potassium (and less desirably, in its fruit-flavored forms, sugar)."

It's the more advanced claims that haven't been proven for humans.

Whether the drink is any more immune-boosting than, say, spinach, or any other nutrient-dense food, remains to be seen. Claims that kefir can help cure cancer stem from findings that the drink, or some of its components, hindered tumor cells in test tubes and lab animals. In vitro, kefir has been shown to slow the growth of breast cancer cells. In mice injected with cancer cells, it has slowed the development of tumors and increased the activity of such immune system cells as so-called natural killer and T-helper cells. A 2007 Japanese study suggested the drink may do the same in humans: 19 adults who drank kefir daily for three weeks had unusually active natural killer cells.

But such research is challenging to interpret. It not only has focused largely on rodents but also has used kefir products made with limited bacterial starter cultures to pinpoint which culture may be responsible for the potential benefits. The effects that grocery-store kefir might have on cancer patients haven't been studied in rigorous clinical trials.

Some commercials kefirs add even more probiotics to the mix, as I wrote in Probiotic Kefir Healthier Alternative to Yogurt

What's more important for those of us who are lactose intolerant is that kefir is as good or better than yogurt in reducing symptoms.

If there's one thing kefir may be most likely to do, it's aid in digestive health. Like yogurt, kefir contains lactase, the enzyme that breaks down lactose, the dominant sugar in milk. In a 2003 study of 15 adults unable to digest lactose, Ohio State University researchers found that drinking kefir reduced lactose maldigestion symptoms -- including bloating, stomach pain and gas -- by 70%. French researchers produced similar findings; they've also shown that kefir can speed recovery from diarrhea in infants.