Phytosterols from natural foods may decrease cholesterol absorption
MedWire News: Habitual dietary intake of naturally occurring phytosterol in moderate doses is associated with improved lipid profile and reduced intestinal cholesterol absorption, Spanish research shows.
Supplementary phytosterols are known to modify cholesterol absorption efficiency, and recent studies have found evidence that phytosterols from the usual diet affect serum total and low-density lipoprotein (LDL) cholesterol levels and whole-body cholesterol metabolism.
The Mediterranean diet is rich in naturally occurring phytosterols, and has been linked to a reduced incidence of cardiovascular disease.
To investigate whether naturally occurring phytosterols in the usual diet affect intestinal cholesterol absorption and improve serum lipid profiles, Iva Marquez-Lopez, from the University of Zaragoza, and colleagues measured serum levels of surrogate cholesterol absorption markers and LDL cholesterol levels in 85 healthy Spanish volunteers aged 18-66 years.
Usual food intake over the previous year was assessed by a food frequency questionnaire, from which total phytosterol intake was estimated and classified into tertiles (<459, 459-512 and >512 mg/day).
The estimated daily intake of phytosterols and cholesterol was 489 mg (median) and 513 mg (mean), respectively.
Serum levels of LDL cholesterol decreased significantly across increasing tertiles of phytosterol intake, from 4.10 mmol/l (158.30 mg/dl) in the first tertile to 3.51 mmol/l (135.52 mg/dl) in the third tertile.
Cholesterol absorption efficiency was estimated using the surrogate marker ratio of sitosterol to cholesterol, adjusted for sitosterol intake. The adjusted sitosterol-to-cholesterol ratio decreased significantly across increasing tertiles of phytosterol intake, from 7.06 to 4.80 x103 mmol of sterol per mol of cholesterol and mg of sterol intake, in the first and third tertiles, respectively.
Writing in the journal Nutrition, Metabolism & Cardiovascular Diseases, the researchers conclude: "Moderate doses of phytosterols in the habitual diet appear to be bioactive and might have a protective effect on the lipid profile, via decreasing cholesterol absorption."
However, they caution: "We regard the present study as an exploratory research showing suggestive results about the phytosterols' bioactivity that should be validated by using direct cholesterol-metabolism quantification methods."
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By Joel Levy