The Dose Response Effect of Almonds on Serum Vitamin E, Plasma Lipid Fractions and Erythrocyte Phospholipids
The purpose of this study was to determine if two different amounts of almonds added to a heart healthy diet would increase vitamin E concentrations in healthy men and women, and reflect positive fatty acid profiles in serum lipids and erythrocytes. Twenty three subjects participated in a crossover metabolic study for a 14 week period. Subjects consumed one of three diets for 4 weeks each, a control diet, a low almond diet and a high almond diet after a 2 week run-in period. All meals were prepared in the test kitchen, and almonds were added to the experimental diets by replacing 10% (low almond) or 20 % (high almond) of the total calories for each subject. Blood samples were taken after each 4 week period. Serum α-tocopherol concentrations increased in subjects consuming the low and high almond group, and a dose response effect was found. A 1 % increase of energy from almonds resulted in a 0.5μmol/L increase in α-tocopherol in plasma and a 0.005μmol/L increase in red blood cells in subjects that did not take vitamin E supplements prior to the study. Both (β- and γ-tocopherol decreased as a result of the almonds added to the diet. Serum fatty acids were determined in phospholipid, triglyceride, cholesteryl ester and free fatty acid fractions as well as erythrocyte phospholipid fractions. Serum phospholipids were the most responsive fraction, and the addition of almonds to a heart healthy diet significantly decreased the concentration of palmitic acid (C16:0), a saturated fatty acid in plasma phospholipids and triglycerides. Fatty acids were compared using relative percent and absolute concentration methods. Oleic acid (C18:1), a significant fatty acid in almonds increased in cholesteryl ester, phospholipid and triglyceride fractions when calculated as relative percent, but no change was found with absolute concentrations. Traditionally in the literature, relative percent is used almost exclusively. Further studies are needed in this area. In conclusion, the addition of almonds in the diet increased serum α-tocopherol concentrations and improved the fatty acid composition of serum and erythrocyte membrane lipids.
Laboratory and Basic Science Research, Lipids, Nutrition, Diet; Nutrition; Prunus -- metabolism; Vitamin E -- biochemistry; Antioxidants -- metabolism; Erythrocyte Membrane -- chemistry; Fatty Acids, Monounsaturated; Dietary Fats, Unsaturated -- blood; Lipids -- metabolism; Cardiovascular Diseases -- prevention & control.
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