What is kefir, how is it made, and is it healthy? Jo Lewin explains the benefits of drinking kefir and why it's a good source of probiotics and calcium
Kefir is a cultured, fermented milk drink, originally from the mountainous region that divides Asia and Europe. It is similar to yogurt – but a drink, with a tart, sour taste and a slight ‘fizz’. This is due to carbon dioxide – the end product of the fermentation process. The length of the fermentation time will affect the taste. Kefir is a good source of calcium and is rich in probiotic bacteria.
How is it made?
The method of making kefir is one of the main differences between kefir and yogurt. Traditional milk kefir uses kefir grains and whole cow’s milk – although now you can find it made from goat’s/sheep’s milk and coconut milk too. Kefir grains are not actually grains at all but are small gelatinous beads that look like grains containing a variety of bacteria and yeasts. The grains are placed in a glass jar/bowl, soaked in milk, covered and left at room temperature for a minimum of 24 hours. This enables the bacteria and yeast to ferment the lactose (natural sugar in milk) into lactic acid, activating the bacteria to proliferate and grow.
After around 24 hours at room temperature, the grains are strained from the kefir and transferred to a fresh batch of milk and used again to enable them to keep reproducing - this cycle can be carried on indefinitely. The strained kefir is now ready to drink.
The grains will multiply as long as they are kept in fresh milk at the right temperature. When the product is put in the fridge the cool temperature inhibits the fermentation process.
Is it safe to make kefir at home?
As kefir is a fermented product, strict guidelines must be adhered to in order to ensure that it is safe for consumption – if made incorrectly it has the potential to make you ill. We advise buying kefir from a reputable source and taking care to follow the on-pack storage instructions, rather than making it at home.
Milk is a good source of protein and calcium, and kefir is no different. However it has the added benefits of probiotics. Probiotics are known as ‘friendly bacteria’ that can ease IBS symptoms such as bloating and digestive distress in some people.
Read more about probiotics.
The fermentation process also helps to break down the lactose in milk so there is some evidence to suggest that kefir may be tolerated by those who suffer from lactose intolerance. You should speak to your GP if you think you may be lactose intolerant.
Kefir grains contain around 30 strains of beneficial bacteria. Some of the major strains include the lactobacillales – or lactic acid bacteria (LAB).
Lactobacillus kefiri, which is one LAB unique to kefir, has been shown in a study to inhibit the growth of some harmful bacteria such as salmonella, h-pylori and e-coli and is used in some gut inflammatory disorders. However, many of the health claims associated with kefir require further research.
Does kefir improve digestion?
Some people find that kefir improves their digestion due to its probiotic content. Probiotics can help restore balance in the gut, thereby improving digestion. As kefir is rich in probiotic bacteria, it can be beneficial to include it in the diet for the prevention and treatment of gastrointestinal disturbances.
Some studies have found that kefir is better tolerated in those with lactose intolerance. However, people with lactose intolerance should consult their GP before introducing kefir to their diet.
Those with Irritable Bowel Syndrome (IBS) should consult with a GP before taking probiotics as in some cases, they can make symptoms worse.
Does kefir help you to lose weight?
Obesity has been linked to an imbalance in gut bacteria. However, which strain of bacteria has an effect is less clear. Some evidence suggests that the lactobacillus species, or LAB group, like those found in kefir are associated with changes in weight.
However there is some evidence that shows that probiotics do not decrease body weight or affect weight loss/BMI. Clearly this is an area for further research.
Does kefir promote better bone health?
Traditional kefir made from cow's milk is a good source of calcium and vitamin K, which are both important for bone health. As we get older, our bones become weaker, which can increase the risk of osteoporosis and fractures, especially in post-menopausal women. Kefir, along with other dairy products, is a useful source of dietary calcium.
Does kefir reduce inflammation?
Inflammation is involved in a number of diseases such as inflammatory bowel or rheumatoid arthritis. The anti-inflammatory/immunomodulatory effects of probiotics have been reported in some studies, although this is an emerging area of research. It does appear that the LAB bacteria are anti-inflammatory but whether that translates directly to kefir is still unknown.
Are there any side effects?
As the process used to make kefir can vary between brands, it is hard to monitor its strength, so some products may be stronger sources of probiotic bacteria than others. For those who are not used to probiotics or fermented foods it is sensible to start with a small amount and increase slowly. Some report digestive symptoms such as bloating, constipation or diarrhoea when introducing probiotics to the diet. Anyone with a compromised immune system should speak to a health professional before taking probiotics.
What about water kefir?
Water kefir is made in a similar way to milk kefir. The kefir grains are placed in sugared water and the same fermentation process occurs (as in milk). The fermentation produces beneficial bacteria while reducing the sugar content of the drink. It's important to note that the grains are different – water kefir is made with specific grains that rely on water, and will not work in the same way if put in milk or milk substitutes. Cane sugar or fruit juice can be used to sweeten the water. Water kefir is a great alternative source of probiotic bacteria for those who are following a dairy-free diet but does not contain the same protein and calcium content that's provided by milk.
Kefir was recently featured in BBC’s Trust Me I’m A Doctor.
More healthy guides...
This article was last reviewed on 31st August 2017 by registered nutritionist Kerry Torrens.
Jo Lewin works as a Community Nutritionist and private consultant. She is a Registered Nutritionist (Public Health) registered with the UKVRN. Visit her website at www.nutrijo.co.uk or follow her on Twitter @nutri_jo.
A registered nutritionist, Kerry Torrens is a contributing author to a number of nutritional and cookery publications including BBC Good Food magazine. Kerry is a member of the The Royal Society of Medicine, Complementary and Natural Healthcare Council (CNHC), British Association for Applied Nutrition and Nutritional Therapy (BANT).
All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website terms and conditions for more information.