Correlation between plasma levels of lutein and oxidized low density lipoproteins: a short human intervention study
The development of vegetable functional food products that provide benefits beyond their traditional nutritional value raised increasing interest. In fact several studies have shown that diet plays a role in the development of human diseases associated with oxidative damage (diabetes, cardiovascular disease and metabolic syndrome). Aim of the study was to evaluate the effects of daily intake of a frozen vegetable product containing pigmented vegetable such as red and green spinach, red and green chicory, red and green leaf chard (Italsur srl Notaresco, Italy) on plasma lipids and oxidized low density lipoproteins (ox-LDL). Furthermore, the bioavailability of lutein and β-carotene contained in the vegetable products, was investigated. The study included healthy volunteers (n=49, age ranged from 23 to 73 years), who consumed a daily portion (300g) of the vegetable product for 2 weeks.
The significant increase of plasma lutein (mean value from 0.27±0.13 to 0.40±0.17 µg/ml, p<0.001) and β-carotene (mean value from 0.31±0.12 to 0.56±0.17 µg/ml, p<0.001) after intake of vegetable product demonstrated that these phytonutrients are highly bioavailable. A significant reduction of plasma levels of total cholesterol (TC) (mean percentage reduction -6.4% with respect to baseline, p<0.05) and LDL-cholesterol (LDL-C) (mean percentage reduction -9.4% with respect to baseline, p<0.05) was observed after dietary intervention. Our results demonstrated also a significant decrease in plasma concentration of oxidized LDL (ox-LDL) after treatment (mean percentage decrease -21.9 %, with respect to baseline) (p<0.05). Evaluation of ox-LDL represents a useful biochemical marker of lipid peroxidation, therefore the results demonstrated a decrease of lipoprotein peroxidation after the daily intake of the vegetable product. A significant negative correlation has been established between plasma levels of lutein and of ox-LDL (r=0.69, p<0.001). Our results suggest that lutein may play a role in the protective effect against oxidation of LDL. In conclusion the increase of plasma carotenoids after dietary treatment for two weeks is associated with a physiological effect against lipid peroxidation of lipoproteins.
The significant increase of plasma lutein (mean value from 0.27±0.13 to 0.40±0.17 µg/ml, p<0.001) and β-carotene (mean value from 0.31±0.12 to 0.56±0.17 µg/ml, p<0.001) after intake of vegetable product demonstrated that these phytonutrients are highly bioavailable. A significant reduction of plasma levels of total cholesterol (TC) (mean percentage reduction -6.4% with respect to baseline, p<0.05) and LDL-cholesterol (LDL-C) (mean percentage reduction -9.4% with respect to baseline, p<0.05) was observed after dietary intervention. Our results demonstrated also a significant decrease in plasma concentration of oxidized LDL (ox-LDL) after treatment (mean percentage decrease -21.9 %, with respect to baseline) (p<0.05). Evaluation of ox-LDL represents a useful biochemical marker of lipid peroxidation, therefore the results demonstrated a decrease of lipoprotein peroxidation after the daily intake of the vegetable product. A significant negative correlation has been established between plasma levels of lutein and of ox-LDL (r=0.69, p<0.001). Our results suggest that lutein may play a role in the protective effect against oxidation of LDL. In conclusion the increase of plasma carotenoids after dietary treatment for two weeks is associated with a physiological effect against lipid peroxidation of lipoproteins.
