Kefir and Sauerkraut Every Day: What Studies Show

Key points

Kefir, yoghurt and fermented vegetables are simple foods that gut bacteria like. In a human trial over 10 weeks the diversity of gut bacteria grew and some inflammation markers in the blood fell. You can start gradually, and by the end of 10 weeks bloating did not differ on average from baseline.

How to use it

A glass of unsweetened kefir or yoghurt at breakfast and a quarter cup of sauerkraut with lunch is already two servings. Choose products with no added sugar. If you rarely ate fermented foods before, start with one serving a day and add a second a week later.

Sauerkraut contains a lot of salt, so with high blood pressure and other salt limits keep the portion small and ask your doctor.

A real-life example

A man of 45 sits down to dinner with his wife. Instead of sweet yoghurt he takes a glass of kefir, and with the meat puts a bowl of sauerkraut on the table. It is not a diet or a course: within a week such a plate becomes a habit, and the gut gets its share of bacteria and fibre.

What the studies showed

In a randomised trial healthy adults ate fermented foods for 10 weeks: kefir, yoghurt, fermented vegetables and others, on average 6.3 servings a day by the end. There were 18 people in the group. The diversity of their gut bacteria grew, and the growth held with fewer servings. Of 93 measured inflammation markers, 19 fell from baseline (Wastyk H Cell 2021. PMID 34256014^[1]).

The main predefined measure, the cytokine response score, did not change. So the trial did not show that fermented foods change the overall immune response, and results for individual markers should be treated as preliminary (Wastyk H Cell 2021. PMID 34256014^[1]).

In the group on a high-fibre diet overall bacterial diversity stayed stable, but the set of bacterial enzymes that break down fibre changed. So the two approaches work in different ways (Wastyk H Cell 2021. PMID 34256014^[1]).

Who should see a doctor first

See a doctor for severe abdominal pain, persistent bloating, blood in the stool or weight loss without a reason. If you are on a salt-restricted diet, have bowel, kidney or heart disease, or have a greatly weakened immune system, discuss fermented foods with your doctor. Prescribed treatment is not changed on your own.

Bottom line

Unsweetened kefir or yoghurt and a little sauerkraut every day is an inexpensive habit with which gut bacteria diversity grew in a small trial. Start with one serving and add gradually.