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Hydrolysis of phytosterol esters in the intestine is required for their cholesterol lowering effects
Author(s) -
Brown Andrew W,
Carden Trevor J,
Hang Jiliang,
Dussault Patrick H,
Carr Timothy P
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.585.7
Subject(s) - phytosterol , chemistry , hydrolysis , stearic acid , cholesterol , food science , absorption (acoustics) , aqueous solution , sterol , biochemistry , chromatography , organic chemistry , physics , acoustics
Phytosterol esters lower cholesterol with different efficacies depending the fatty acid moiety of the ester. We hypothesized that differential hydrolysis of phytosterol esters affects the distribution of free cholesterol between the aqueous and oily phases of intestinal contents, altering its availability for absorption. Hamsters were fed an atherogenic diet (Control), or the Control with 5%: free phytosterols; phytosterols esterified to palmitic, oleic, or stearic acids; or phytosterols etherified to stearic acid, thus representing different levels of expected hydrolysis. Contents were collected from the proximal intestine, aqueous and oily phases were separated, and lipids were analyzed by GC. Cholesterol absorption was measured by the dual isotope method. As expected, the amount of free phytosterol in the phases differed among treatments: (free phytosterol = oleate esters) > (palmitate esters = stearate esters) > (stearate ethers = Control). However, no differences were observed in the partitioning of free cholesterol between the aqueous and oily phases. The relative amounts of free phytosterols in the oily and aqueous phases were highly correlated (r=0.87), with the amount of free phytosterol being negatively correlated with cholesterol absorption (r=−0.72, p<0.0001). These results imply that it is the free, rather than esterified, phytosterol that decreases cholesterol absorption. Grant Funding Source : Supported by USDA‐NIFA grant 2007‐35200‐18298 and the University of Nebraska Agricultural Research Division Hatch Act Funds