Kefir is produced from white “grains” formed from a specific and complex mix of lactic acid bacteria and yeasts living in a symbiotic relationship. These “grains” are inoculated into a variety of milks — mainly cow, goat, or sheep milk. Traditionally, kefir was made in goatskin bags that were hung near a doorway where the bag would be knocked by anyone passing through; which would help keep the milk and kefir grains well mixed. It’s known by many names, including “Prophets’s millet”, as it’s said that the Prophet Mohammed gave the grains to a selected tribe as a symbol of eternal life.
Several modern studies have shown that regular consumption of kefir is associated with improved digestion, improved tolerance of lactose, as well as cholesterol-lowering and blood-pressure-lowering effects. It also regulates blood sugar and is antibacterial, anti-inflammatory, antioxidant, and anti-cancer; it reduces allergies and eczema and has healing properties.
Nutrition
The nutritional composition of kefir varies according to the milk, the microbiological composition of the grains used, the time/temperature of fermentation and storage conditions. It contains a range of vitamins including the B group (including B12), and A, C, D and E. Minerals such as calcium, potassium, phosphorus, sodium, copper, zinc, molybdenum and manganese are found in kefir. Along with these are essential amino acids and conjugated linoleic acid in amounts similar to those in the milk in which it was fermented.
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Kefir contains a complex and highly variable community of lactic acid bacteria and yeasts. Lactobacillus species are always predominant but the quantity and variety can vary between batches and the type of milk used. Kefir also contains a beneficial polysaccharide, kefiran (a glucose-galactose compound), which is synthesised by the lactobacilli present.
During fermentation the lactose is broken down (mainly to lactic acid). Also formed are pyruvic acid, acetic acid, acetoin, citric acid and amino acids. Ethanol is also produced and kefir can be as high as 1–2 per cent alcohol.
Kefir vs yoghurt
Kefir and yoghurt both contain the nutrients from the milk in which they are fermented. They both have a slightly sour taste and can contain live probiotic cultures. Kefir can be substituted for yoghurt in many dishes.
Kefir, however, has a thinner consistency (it’s usually sold as a drink) and it typically contains three times the level of live probiotic cultures than yoghurt. To make kefir, milk is fermented with the SCOBY (symbiotic culture of bacteria and yeasts) — a mix of 20–30 different types of probiotic bacteria and yeasts; most yoghurts are made using only a few. A higher probiotic count confers greater health benefits for the digestive and immune systems.
Preparation
In a glass or plastic container, 2–10 per cent kefir starter grains are added directly to milk, agitated regularly to mix and left to ferment (in the dark) for about 24 hours at 25–30°C. The better-quality milks produce a better-quality product — organic raw milk is ideal. The fermented milk is then strained off the grains and they are added to a fresh batch of milk to repeat the process.
If left to ferment for several days, a secondary fermentation occurs whereby the level of B vitamins, especially folic acid, rises and it becomes increasingly sour. The shelf life of unrefrigerated kefir is up to 30 days.
Kefir can also be grown in water and sugar or in water and dried fruit or juice, ginger beer, coconut water or other sugary liquids, which, while still health-promoting, have a different microbial composition. It can also be grown on soy milk, coconut milk or rice milk but may cease growing if the medium does not contain all the growth factors necessary for its survival.
Therapeutic uses
While much of the research on kefir is still focused on in vitro or animal studies, there’s increasing interest in clinical trials and these are already confirming the benefits in humans.
Digestive system
Kefir is antimicrobial to pathogens such as E. coli, listeria and salmonella in the gut. It assists in the assimilation of cholesterol by absorbing 40–84 per cent of the cholesterol content of foods. Kefir also has the ability to remove carcinogenic compounds from the foods we eat and it improves the gut mucosal immunity.
Fatty liver & metabolic syndrome
There has been substantial research on the damaging effects of high-fructose corn syrup in the development of fatty liver disease and metabolic syndrome. Kefir can improve the symptoms of NAFLD (non-alcoholic fatty liver disease), including bodyweight, energy intake, inflammatory reactions and fatty liver in high-fructose corn syrup-induced fatty liver (in animals). This is promising for clinical research.
Cardiovascular
Regular consumption of kefir has been shown to reduce high blood pressure and tachycardia while lowering blood cholesterol.
Cancer
Research has shown that kefir has great potential for cancer prevention and treatment, with the polysaccharide and peptide components inhibiting proliferation of and inducing apoptosis in tumour cells. This appears to be most effective in colorectal, breast and lung cancers and lymphoblastic leukemias.
Immune system
Kefir has an immunomodulatory activity, improving immunity by stimulating antibody production and increasing natural killer cell activity. Its anti-inflammatory activity reduces allergies, asthma and eczema.
Bone metabolism
Kefir improves bone metabolism in osteoporotic patients. In a clinical trial bone density increased with six months of kefir ingestion.
As a healthy fermented food, kefir is recommended for all ages, from infants to the elderly and from athletes to infirm people.
