BACKGROUND:A reader asked for information on kefir milk, sometimes also called the Tibetan fungus. The reader had been recommended kefir as a way to boost energy levels. It is also said to help maintain a healthy intestinal balance and to have other health-promoting effects.
Kefir is a fermented milk drink that originated with shepherds living in the Northern Caucasus region of Russia. A similar product was developed by shepherds in the Tibetan mountains, and hence its other name. Kefir was traditionally made with sheep, goat or cow’s milk. Kefir grains are added to the milk and allowed to incubate overnight at room temperature. These grains look like small cauliflower florets, but contain a combination of bacteria and yeast held together by a polysaccharide matrix. When they are mixed with milk, the lactose contained is fermented producing a sour, carbonated beverage that looks like thin yogurt. A small amount of alcohol is produced, with the final product usually containing about 1 per cent alcohol. During the fermentation process, new kefir grains are produced which can be filtered off and used in preparing the next batch of kefir.
EVIDENCE FROM STUDIES
Microbial analyses of kefir grains have found that they contain numerous Lactobacillus strains, Bifidobacteria species and yeast. Some of these are the same microorganisms as found in probiotic supplements. The precise composition of kefir grains depends on where they are produced, and this impacts the microbial content of the resulting kefir beverage. Many of the claims about kefir are similar to those made for probiotic yogurts and other products.
Chemical analyses of kefir have found that it contains lactic acid and several fatty acids. Kefir is reported to be a good source of B vitamins and other nutrients. However, its levels are similar to other dairy products. Some preliminary research suggested that kefir might lower cholesterol levels. A few small studies have found that drinking kefir milk has little or no impact on cholesterol or triglyceride levels.
While kefir is most commonly recommended to boost energy levels, to relieve intestinal complaints and for an antiallergenic effects, no studies of these effects in humans could be located. A study was published at the end of 2010 finding some beneficial immune effects, but this was conducted with cells, not people.
PROBLEMATIC ASPECTS
Some people get intestinal cramps and constipation when first taking kefir. These symptoms usually disappear after a few days of regular use. Although kefir grains reduce the amount of lactose in ordinary milk, they do not eliminate all the lactose. Those who are lactose intolerant are likely to have some gastrointestinal symptoms, though probably with reduced intensity compared with ordinary milk.
RECOMMENDATIONS
In Russia and parts of Eastern Europe and Scandinavia, kefir is a readily available health drink. Because of its sour taste, commercial products are often mixed with various fruits and other sweeteners. In the US, kefir has recently been appearing in trendy health food shops and restaurants.
Numerous types of kefir drinks are now available. In addition to those traditionally made from various animal milks, kefir drinks can be made from soy or coconut water. While these contain the minerals and other nutrients available in the starting drinks, evidence from research studies is not available to show whether the kefir formulations provide additional health benefits.
Kefir is a relatively nutritious drink, though its taste can be too sour for some. Kefir grains can be purchased for those who wish to make their own drinks. The jury is still out on whether kefir will become another fad health drink, or show itself to be particularly beneficial. Research is needed to show whether the claims made about it can be substantiated.
DÓNAL O'MATHÚNAhas a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University
