Kefir consumption does not alter plasma lipid levels or cholesterol fractional synthesis rates relative to milk in hyperlipidemic men: a randomized controlled trial [ISRCTN10820810].
Level 2 - randomized trial
Randomized, blinded crossover clinical trial
PubMed 11825344 · doi:10.1186/1472-6882-2-1
What was done
Thirteen healthy, mildly hypercholesterolemic men participated in a blinded, randomized crossover trial consisting of two 4-week supplementation periods comparing kefir to milk. Blood samples were collected at baseline and after 4 weeks to measure plasma total, LDL, and HDL cholesterol, triglycerides, fatty acid profiles, and cholesterol fractional synthesis rates. Fecal samples collected at baseline, 2 weeks, and 4 weeks were evaluated for short-chain fatty acids (SCFAs) and bacterial content.
What was found
Kefir supplementation had no significant effect on total, LDL, or HDL cholesterol, triglyceride concentrations, plasma fatty acid profiles, or cholesterol fractional synthesis rates after 4 weeks (no numerical lipid values provided in abstract). Both kefir and milk increased fecal isobutyric, isovaleric, and propionic acids as well as total fecal SCFAs (p < 0.05). Kefir consumption increased fecal bacterial content in the majority of subjects.
Why it matters
Despite traditional use for perceived health benefits, these results do not support the use of kefir as a cholesterol-lowering agent in hypercholesterolemic individuals compared to regular milk.
Limits
The sample size was very small (n = 13) and restricted exclusively to men with mild hypercholesterolemia, limiting generalizability to women or broader populations. The intervention duration was short (4 weeks), and the abstract omits exact numerical values and confidence intervals for the primary lipid outcomes.