Kefir is a traditional dairy product that originates from the North Caucasus, Tibetan and Mongolian mountains. The name kefir originates from a Slavic word, keif, which means living and wellbeing, as its consumption has long been associated with health benefits. Modern research suggests that kefir has antibiotic properties, and may lower blood pressure as well as improving glucose tolerance.
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What is kefir?
Kefir is a drink made by fermenting sheep, goat or cows’ milk with a unique mixture of bacteria and yeasts. These microbes clump together to form kefir grains which resemble a cross between cauliflower florets and cottage cheese. After fermenting the milk, the kefir grains are strained out for reuse and were traditionally passed from generation to generation as a source of family wealth.
Over 300 microbial species have been isolated from kefir of different origins, including lactic and acetic acid bacteria (eg Lactobacillus kefiranofaciens, Lactobacillus kefiri, Lactococcus lactis) and yeasts (eg Candida kefyr). Fermented kefir milk has a sour taste and is similar to a thin but creamy, effervescent yogurt – those made from goat milk have a stronger taste than those made from sheep and cows’ milk.
Kefir contains vitamins A, B1, B2, B5, B6, B12, folic acid, biotin, C and K that derive from the milk, bacteria and yeasts. It is also good source of magnesium, calcium and phosphorus, which may partly explain its blood pressure benefits, and provides small amounts of zinc, copper, iron and manganese.
How does kefir lower blood pressure?
Kefir contains small protein chains (polypeptides) created from the milk proteins that are broken down during fermentation. It also contains a starchy polysaccharide called kefiran which is derived from the walls (capsules) of the bacteria present. These substances have biological actions and are small enough to be absorbed into the circulation intact. Drinking kefir has been found to:
- stimulate the production of new, healthy, blood vessel lining cells which improves arterial elasticity
- suppress inflammation
- improve nerve signalling systems between the gut and brain
- enhance the reflex baroreceptor control of blood pressure
- act as an ACE (angiotensin converting enzyme) inhibitor, although the exact kefir milk peptides that inhibit ACE have not yet been identified.
Most kefir studies so far have involved cell cultures and rodents. Researchers recently presented findings at the American Physiological Society meeting, for example, involving hypertensive rats; those whose diet was supplemented with kefir for nine weeks had significantly lower blood pressure than those not given kefir, and also had reduced gut permeability and lower circulating levels of endotoxins. They suggested that kefir may lower blood pressure through interactions between the gut and brain and by restoring normal nerve function needed for blood pressure control.
Will kefir lower your blood pressure?
Recent studies have found that the balance of gut bacteria is different in people with coronary heart disease compare to those without. Consuming probiotic foods such as yogurt and kefir may help to correct this imbalance, although this is far from proven.
Anecdotal evidence suggests that some people experience a beneficial lowering of blood pressure from drinking kefir regularly, but while there are plausible mechanisms to support this, it has not yet been confirmed in clinical trials.
There is preclinical evidence (cell and animal studies) to suggest that kefir may help to lower blood pressure, but this has not yet been studied in human clinical trials and it is not yet possible to say whether or not it is effective. Kefir is a nutritious drink, however, and has been consumed for over 4,000 years with a long tradition of promoting good health.
Kefir may improve glucose control
Kefir has been studied in a clinical trial to investigate its traditional use in improving diabetes control. A study involving 60 people with type 2 diabetes mellitus compared the effects of drinking either 600ml kefir per day, or a conventional fermented milk yoghurt (containing Streptococcus thermophiles and Lactobacillus bulgaricus) for 8 weeks. Significantly greater improvements were seen in fasting blood glucose and HbA1C levels in those drinking kefir compared to those drinking the yogurt milk.
Research suggests this beneficial effect on glucose control results from activating insulin signalling pathways to improve the uptake of glucose into skeletal muscle cells.
Do you drink kefir? Have you noticed an effect on your blood pressure control?
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