Kefir
Kefir as a functional food: a systematic review of 16 human studies, the limited evidence on cholesterol and blood pressure, and why high-quality trials are still needed.
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Overview
Kefir is a fermented milk drink made with a mix of bacteria and yeasts. Water kefir and plant-based kefirs are different products and this page covers fermented-milk kefir, the form the systematic review studied. [1]What the research shows
A 2023 systematic review of randomized controlled trials of oral kefir consumption included 16 studies (18 publications). [1]| Outcome | What the review found | How firm |
|---|---|---|
| Oral bacteria (Streptococcus mutans) and dental caries risk | Potential as a complementary therapy | Limited |
| Helicobacter pylori eradication therapy | Potential as a complementary therapy alongside treatment | Limited |
| Adult dyslipidemia and hypertension | May aid treatment, "although evidence was very limited" | Very limited |
| Safety | Assessed in only 5 of the 18 publications | Gap |
| Study quality | 12 studies had an overall high risk of bias | Weak |
[1]
The authors conclude kefir appears safe for generally healthy people, but that efficacy and safety data from high-quality human trials are needed before recommendations for conditions of the oral and gastric microbiota or metabolic health. [1] We do not claim more than that.
Live cultures
Kefir contains live microorganisms when sold unpasteurized or not heat-treated after fermenting, but a fermented food is not automatically a probiotic. [2] See Probiotics, prebiotics and fermented foods.Safety and individual considerations
- Dairy allergy applies to milk kefir.
- Pregnancy: choose pasteurized products and ask a clinician about live-culture foods (see Safety). [3]
- With a weakened immune system, ask a clinician before starting live-culture foods. Proper evidence for kefir-specific infection risk was not found in the sources we read.
Related
Yogurt · Yogurt vs kefirFrequently asked questions
Does kefir lower cholesterol?
The 2023 review says kefir may aid treatment of dyslipidemia, but evidence was very limited. [1]
Is kefir safer than yogurt?
We did not find a source comparing them. Safety was assessed in only 5 of 18 kefir publications. [1]
References
- Kairey L et al. The effects of kefir consumption on human health: a systematic review of randomized controlled trials. Nutr Rev 2023. PMID 35913411.
- Marco ML et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods. Nat Rev Gastroenterol Hepatol 2021. PMID 33398112.
- Clemson Cooperative Extension. Food Safety for Pregnant Women and Their Babies. Extension fact sheet.