Kefir is a milk product rich in probiotics - live bacteria, which given in sufficient amounts, may improve health. Probiotics are found in supplemental forms or in foods such as yogurt, kombucha tea and sauerkraut. Kefir is produced by the action of ten probiotics, which is five times the amount that most yogurts contain.

Kefir, which originated in Europe and Asia, has been used for hundreds of years to promote health, and has much promise as a preventive food. It is prepared by inoculating cow, goat, or sheep's milk with kefir grains. Kefir grains are formed from a combination of bacteria and yeasts in a substrate of lipids, proteins and sugars.

The kefiran present in kefir reduces serum cholesterol levels in rats. Kefir is also known to have antioxidant and antimutagenic properties.

The effect of kefir can be changed by fermenting it for shorter or longer periods. Kefir which is matured for longer has an increased folic acid content. It also has a sourer flavor and most people prefer to consume it with some form of sweetening, such as sugar or honey.

Kefir is believed to keep the stomach and immune system strong and stable.