What is Kefir?
Kefir is a fermented milk drink with the consistency of thin yoghurt. It is prepared using kefir grains, small gelatinous crystals made up of various species of lactobacilli and yeast enclosed in a matrix of proteins, lipids and polysaccharides. Water kefir is similar to dairy kefir and utilises sugar water or fruit juice in place of milk. Different grains are used to produce water and milk kefir. Both beverages are sour and slightly effervescent due to the production of lactic acid and carbon dioxide, and are often flavoured.
Fermented foods have recently experienced a surge in popularity, and as a result, an increasing number of people are becoming aware of the many benefits of this probiotic beverage.
Where does Kefir Come From?
Kefir is one of the oldest fermented milk products known, and it is thought to have originated with shepherds in the Caucasus mountains of Russia two thousand years ago. Milk kefir has spread to the west in the last 100 years or so. It is thought that water kefir originated more than two hundred years ago in Mexico, where the grains form naturally on the pads of the Opuntia cactus.
Kefir can be prepared at home by adding the appropriate kefir grains to milk, juice or sweetened water. Fermentation is allowed to proceed at room temperature for between 12-72 hours depending on the type of kefir, desired consistency and ambient temperature. After this time, the grains are strained from the product and reused. Strained water kefir is often fermented a second time in an airtight vessel with added sugar, to produce a sweet, effervescent beverage.
Kefir grains may be obtained commercially, or shared between members of a community.
As popularity grows, ready-made, commercially produced milk kefir is increasingly available for purchase.
Kefir is considered to be a 'nutriceutical' food, and both types of kefir are primarily known for their probiotic benefits and used to maintain digestive health. Because the microorganisms used in the culture break down lactose, kefir is a suitable source of dairy for lactose intolerant people, and research suggests that kefiran, the polysaccharide present in kefir grains, may help alleviate symptoms of lactose intolerance (1). Recent research has uncovered a relationship between digestive and metabolic health, and kefir has shown some benefit in the treatment of cardiometabolic diseases, potentially playing a role in reducing cholesterol, blood pressure, and normalising sugar metabolism (2). Recent research suggests that regular consumption of probiotics such as kefir can strengthen the immune system (3), and early research has even shown that kefir may have anticancer properties (4).
Kefir Benefits for Bodybuilding
Kefir is used by an increasing number of athletes. While it has not been shown to have any direct ergogenic effects, many sportspeople believe that the immune system benefits of kefir are able to counteract the effects of fatigue and a heavy training schedule (5). Kefir is high in good quality dairy protein, provides a number of vitamins and minerals, and it is a particularly rich source of calcium. It is also a good source of tyrosine, which can have calming and cognitive benefits (6), and milk kefir is relatively high in energy, which can assist weight gain. The general benefits of kefir assist in creating a solid foundation of health upon which optimal strength and muscle gains can be made.
Kefir Cons, Negatives & Side Effects
The most common side effects of kefir consumption are digestive complaints, including diarrhoea, constipation and cramping. These are more likely to occur when kefir is first started, and are likely to abate with regular consumption.
People trying to lose weight should be aware that milk kefir is a relatively high energy food, particularly if sweetened or flavoured.
Because kefir contains live microorganisms, it may be unsuitable for people who have a suppressed immune system.
The fermentation process has the potential to produce biogenic amines like tyramine or histamine in milk kefir. Because of the natural variability in the microorganisms that make up kefir grains, it is impossible to say what amount of each of these substances will be present. Tyramine can cause migraines, and is of particular risk for people using monoamine oxidase inhibitors (MAOIs) for the treatment of conditions including depression, because tyramine has the potential to cause a hypertensive crisis. High amounts of histamine can cause illness that resembles allergic reaction. This type of side effect is thought to be very rare, and there are no documented occurrences in the scientific literature.
Kefir Dosage and Timing
Kefir can be enjoyed at any time of day. To minimise gastrointestinal symptoms, many people recommend gradually introducing kefir to the diet, starting with very small doses (say, one tablespoon twice a day) and gradually building this dosage up. There is no regular recommended dosage, but one small glass per day is common. Some people believe that drinking more than this will not afford any extra benefit, but this guideline is regularly exceeded by people who enjoy the taste of kefir, with no adverse effects.
If kefir seems too complicated or you're not a fan of the taste, there are a number of high quality probiotic supplements available that can give similar benefits. A number of antioxidant and superfood supplements contain probiotic bacteria to optimise gut health, and if you're looking for a protein powder with these benefits, the Reflex range combines the benefits of a top quality dairy-based protein with a probiotic blend.
(1)Guzel-Seydim ZB, Kok-Tas T, Greene AK, Seydim AC. Review: functional properties of kefir. Crit Rev Food Sci Nutr. 2011 Mar;51(3):261-8
(2) Astrup A. Yogurt and dairy product consumption to prevent cardiometabolic diseases: epidemiologic and experimental studies. Am J Clin Nutr. 2014 May;99(5 Suppl):1235S-42S.
(3) Ashraf R, Shah NP. Immune system stimulation by probiotic microorganisms. Crit Rev Food Sci Nutr. 2014;54(7):938-56.
(4) Rizk S, Maalouf K, Baydoun E. The antiproliferative effect of kefir cell-free fraction on HuT-102 malignant T lymphocytes. Clin Lymphoma Myeloma. 2009;9 Suppl 3:S198-203.
(5) Nichols AW. Probiotics and athletic performance: a systematic review. Curr Sports Med Rep. 2007 Jul;6(4):269-73.
(6) Noori N, Bangash MY, Motaghinejad M, Hosseini P, Noudoost B. Kefir protective effects against nicotine cessation-induced anxiety and cognition impairments in rats. Adv Biomed Res. 2014 Dec 6;3:251.