Serum sterol responses to increasing plant sterol intake from natural foods in the Mediterranean diet
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Phytosterols in natural foods are thought to inhibit cholesterol absorption. The Mediterranean diet is rich in phytosterol-containing plant foods.
Aim of the study
To assess whether increasing phytosterol intake from natural foods was associated with a cholesterol-lowering effect in a substudy of a randomized trial of nutritional intervention with Mediterranean diets for primary cardiovascular prevention (PREDIMED study).
One hundred and six high cardiovascular risk subjects assigned to two Mediterranean diets supplemented with virgin olive oil (VOO) or nuts, which are phytosterol-rich foods, or advice on a low-fat diet. Outcomes were 1-year changes in nutrient intake and serum levels of lipids and non-cholesterol sterols.
Average phytosterol intake increased by 76, 158 and 15 mg/day in participants assigned VOO, nuts and low-fat diets, respectively. Compared to participants in the low-fat diet group, changes in outcome variables were observed only in those in the Mediterranean diet with nuts group, with increases in intake of fibre, polyunsaturated fatty acids and phytosterols (P < 0.020, all) and significant (P < 0.05) reductions of LDL-cholesterol (0.27 mmol/l or 8.3%) and the LDL/HDL-cholesterol ratio (0.29 mmol/l or 11.5%). Variations in saturated fat, cholesterol or fibre intake were unrelated to LDL-cholesterol changes. In the whole group, changes in serum sitosterol-to-cholesterol, which reflect those of dietary phytosterol intake and absorption, correlated inversely to LDL-cholesterol changes (r = −0.256; P = 0.008). In multivariate analyses, baseline LDL-cholesterol, increases in serum sitosterol ratios and statin use were independently associated with LDL-cholesterol reductions.
Small amounts of phytosterols in natural foods appear to be bioactive in cholesterol lowering.
KeywordsPhytosterols Mediterranean diet Nuts Olive oil Cholesterol
The PREDIMED study is supported by grants from the Spanish Ministry of Health (FIS) RTIC G03/140, PI04/1828, PI04/1837, PI 04/2239, PI05/1839, PI06/0365, PI 07/240 and RTIC RD06/0045. The authors sincerely thank the participants in the study, the PREDIMED personnel for excellent assistance, and Fundación Patrimonio Comunal Olivarero and Hojiblanca SA, Spain; California Walnut Commission, Sacramento, CA, USA; Borges SA and Morella Nuts SA, both from Reus, Spain for generously donating the VOO, walnuts, almonds and hazelnuts, respectively, used in the study. CIBER Fisiopatologia de la Obesidad y Nutricion is an initiative of ISCIII, Spain. Emilio Ros is a non paid member of the Scientific Advisory Board of the California Walnut Commission. Emili Corbella provided expert assistance with statistical analyses.
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