Cholesterol dip? Probiotics have no impact on lipid profile, finds study

The study used a probiotic strain developed and trademarked by Chr. Hansen. ©iStock

The Bifidobacterium animalis supsp. lactis probiotic strain does not improve the lipid profile or total faecal short-chain fatty acids (SCFAs) in healthy adults, researchers say.

Published in Nutrition Journal, a team of researchers investigated the impact the strain had on the overall lipid profile of healthy, young adults. 

The study, funded by a grant from the Dairy Research Institute, used three probiotic forms: pre-fermentation and post-fermentation, incorporated into a yogurt smoothie and a capsule.

“We hypothesised that BB-12 would improve the lipid / lipoprotein profile and increase faecal SCFA concentrations in healthy young adults,” the researchers wrote.

They said their hypothesis was in light of other studies that had demonstrated the cholesterol-lowering effects of some probiotics.

“In vitro and animal studies demonstrated that specific probiotics have hypocholesterolemic effects through possible mechanisms that include deconjugation of bile acids by bile salt hydrolase, production of SFCAs, and assimilation of cholesterol and fatty acids into the cell surface of the organism, which makes cholesterol less available for absorption into the circulation.”

They did acknowledge, however, that results from human studies remained “inconsistent”.

BB-12 in humans

The study, involving 30 healthy adults (19 female and 11 male) aged between 18 and 40, found that the BB-12 probiotic strain — well documented for enhancing immune response and supporting bowel function — did not improve lipid profiles or significantly change total faecal SCFA concentrations.

The researchers said the lack of impact could be related to the specific strain used, as other strains had in the past demonstrated an impact on cholesterol; in particular, Enterococcus faecium.

The only noteworthy change the BB-12 protein caused, they said, was in pre-fermentation form, where it significantly increased the excretion of acetate — the most abundant SCFA in the colon. However, the reason remained unclear.

However, this increase was also seen with the placebo treatment, and they surmised that other yogurt smoothie ingredients like milk solids, strawberry purée and pectins must have caused the change.

The researchers said findings also showed a negative association between the faecal excretion of SCFAs and blood lipids / lipoproteins, specifically that total cholesterol and LDL cholesterol were negatively correlated with all faecal SCFA levels.

This, they said, could be explained by previous research demonstrating that SCFAs suppress cholesterol synthesis by down-regulating gene expression involved in intestinal cholesterol biosynthesis.

Study details

Each smoothie or capsule contained 3.16 x 109 CFUs (colony-forming units)/day of BB-12, and participants were blinded when drinking the smoothies but not when taking the capsule, although all treatments were blinded to the researchers.

During the four-week study period, participants were not allowed to use antibiotics, stool softeners, probiotics or any cholesterol-lowering medication or supplements, and after each four-week intervention, there was a two-week washout period.

Daily log sheets and weekly check-ins were completed to verify treatment compliance, and each participant was asked to complete 24-hour dietary recall and physical activity records for three days during the last week of each treatment period.

Eligibility criteria included a BMI of 20 to 35 kg/m2 and a delayed transit time of more than 24 hours (between bowl movements). Exclusion criteria included smoking, elevated blood pressure above 140/99mm Hg or any history of stroke, diabetes or liver disease, among others. Women were excluded if they were lactating, pregnant or planned to get pregnant during the study.

The researchers acknowledged that the sample size used in the study was relatively small and predominantly Caucasian, which “precludes extrapolating the findings to the population at large”.

 

Source: Nutrition Journal

https://doi.org/10.1186/s12937-017-0261-6

 

“Effect of Bifidobacterium animalis subsp. lactis BB-12 on the lipid/lipoprotein profile and short chain fatty acids in healthy young adults: a randomized controlled trial”

Authors: Yujin Lee, et al.

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