Can ‘fizzy’ milk really keep your gut fighting fit?

Some experts say kefir helps you fight off disease AND lose weight, so we ask...

THE sharp tang of kefir may not be to everyone’s taste, but the fermented milk drink has a growing legion of fans.

Kefir, available in dairy and non-dairy versions, is high in the ‘good’ bacteria thought to contribute to improved gut health, reducing the risk of disease and supporting weight loss. It is a source of nutrients such as vitamins A, B, K and calcium.

Adding good bacteria to the diet helps rebalance the microbiome — the community of bugs in our guts.

Plain yoghurt is also a fermented product that naturally contains the bacteria Lactobacillus bulgaricus and

Streptococcus thermophilus. Meanwhile, products sold as ‘probiotic’ yoghurt will usually have more beneficial bacteria added, such as Lactobacillus casei and types of Bifidobacteria.

But kefir usually has a larger range of potentially health-giving bacteria — with 12 or more varieties rather than the typical one or two added to probiotic yoghurts. Another difference — thought to be responsible for kefir’s superior health benefits — is that it often also contains beneficial yeast (which is why it can be fizzy).

‘It’s this micro-organism diversity that can make kefir superior to more simple fermented foods such as yoghurt,’ says Professor Paul Cotter, a microbiologist at Teagasc Food Research Centre in Cork, who studies the health benefits of fermented foods.

A review last year by Professor Cotter, published in the journal Nutrients, suggested that consuming kefir or kefir micro-organisms is linked to reduced inflammation, improved cholesterol levels and healthy blood pressure.

Meanwhile, a 2015 study in the journal PLoS One suggests peptides (broken-down protein) that form during the making of kefir can reduce the clotting that contributes to heart attacks, and improves the absorption of calcium.

Kefir is produced when kefir ‘grains’ are added to milk to initiate fermentation. They look like gooey mini cauliflower florets and contain different bacteria and yeast.Once the milk is fermented, the grains are removed. The liquid left is the kefir. It’s this process that helps distinguish the better products. Many don’t use this technique, as it’s difficult to mass-produce, says Professor Cotter.

‘One popular way to scale up involves using a small amount of the kefir produced to start fermenting a new batch. It’s still quite good, as the consumer is drinking real kefir microbes.’

Other products are made by fermenting milk with a few ‘beneficial’ bacteria extracted from kefir grains.

‘In this case, they would be very similar to drinking probiotic yoghurt,’ adds Professor Cotter.

You can identify a good kefir product as its label will say it’s made with actual kefir grains. It will also list some of the ‘good’ bacteria, but look out for yeasts, in particular Kluyveromyces marxianus or Saccharomyces. It is easy to make kefir (see box), but beware if you buy one.

‘Some kefirs contain lots of added sugar, flavouring and fruit purees, which as well as impacting calories and oral health, may reduce the wider health benefits of the beneficial bacteria and yeasts,’ says dietitian Helen Bond. ‘The yeast Kluyveromyces marxianus, has been shown in animal studies to bolster immune function,’ adds Bond.