Influence of increased fruit and vegetable intake on plasma and lipoprotein carotenoids and LDL oxidation in smokers and nonsmokers

Background Epidemiological studies suggest a cardioprotective role for caro tenoid-rich foods. Smokers have a high risk of cardiovascular disease and l ow dietary intake and plasma concentrations of carotenoids. The aim of this study was to determine the carotenoid response of smokers and nonsmokers t o increased intake of 300-400 g of vegetables and its effect on LDL oxidati on. Methods: After a depletion period of 8 days, 34 healthy females (18 nonsmok ers, 16 smokers) were supplemented with beta -carotene- and lutein-rich (gr een) and lycopene-rich (red) vegetable foods, each for 7 days. Results: Baseline concentrations (mean a SD) of plasma beta -carotene (0.20 3 a 0.28 mu mol/L vs 0.412 +/- 0.34 mu mol/L; P <0.005) and lutein (0.180 /- 0.10 vs 0.242 +/- 0.11 <mu>mol/L; P <0.05) but not lycopene (0.296 +/- 0 .10 vs 0.319 +/- 0.33 <mu>mol/L) were significantly lower in smokers compar ed with nonsmokers. After supplementation, the change (supplementation minu s depletion) in plasma beta -carotene (0.152 +/- 0.43 vs 0.363 +/- 0.29 mu mol/L in smokers vs nonsmokers; P = 0.002) and LDL lutein (0.015 +/- 0.03 v s 0.029 +/- 0.03 mu mol/mmol cholesterol; P = 0.01) was significantly lower in smokers than nonsmokers. Green-vegetable supplementation had no effect on the resistance of LDL to oxidation (lag-phase) in either group. After re d-vegetable supplementation, plasma and LDL lycopene concentrations were in creased in both groups, but only nonsmokers showed a significant increase i n the lag-phase (44.9 +/- 9.5 min at baseline, 41.4 a 6.5 min after depleti on, and 49.0 a 8.9 min after supplementation; P <0.01) compared with deplet ion. Conclusions: In this short-term intervention study, a dietary intake of >40 mg/day of lycopene by a group of nonsmoking individuals significantly redu ced the susceptibility of LDL to oxidation, whereas an equivalent increase in lycopene by a group of smokers showed no such effect. (C) 2000 American Association for Clinical Chemistry.