In Vitro Cholesterol Uptake by the Microflora of Selected Kefir Starter Cultures

Abstract

Kefir, a fermented milk beverage, is recognized for its potential health benefits, including its cholesterol-lowering properties. This study demonstrated that selected kefir starter cultures, including Lactococcus strains and yeasts, significantly reduce cholesterol-binding capacity under simulated gastrointestinal conditions, underscoring the challenges of probiotic delivery. We compared the performance of these cultures under laboratory conditions (growth broths) and simulated digestive juice models. Lactococcus strains showed significant differences in cholesterol binding between the two environments, highlighting the limitations of relying solely on laboratory testing. Yeast cultures also exhibited greater cholesterol binding in their native broths, but their survival was limited in digestive models. Our findings suggest that effective probiotic formulations should prioritize strains with high cholesterol-binding capacity and robust survival rates throughout the digestive tract. This study provides valuable insights for future research on the mechanisms behind these functionalities and the potential of kefir yeast strains for use in human digestive models. Our results can be used to inform the development of improved probiotic formulations for cholesterol management.

Keywords: Lactococcus; cholesterol uptake; cholesterol-binding capacity; digestive model; kefir; survival rate; yeast.

Figure 1

Percentage of bound cholesterol in M17 broth and during simulated digestive juice passage [%] (n = 5). ^a–f—Means with different uppercase letters in the same column are significantly different (p < 0.05).

Figure 2

Amount of cholesterol permanently bound in M17 broth and during simulated digestive juice passage [%] (n = 5). ^a–e Means with different uppercase letters in the same column are significantly different (p < 0.05).

Figure 3

Percentage of bound cholesterol in yeast broth and simulated digestive juice passage [%] (n = 5). ^a–f Means with different uppercase letters in the same column are significantly different (p < 0.05).

Figure 4

Amount of permanently bound cholesterol in yeast broth and simulated digestive juice passage [%] (n = 5). ^a–d Means with different uppercase letters in the same column are significantly different (p < 0.05).