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 carotenoid-rich foods. Smokers have a high risk of cardiovascular disease and low dietary intake and plasma concentrations of carotenoids. The aim of this study was to determine the carotenoid response of smokers and nonsmokers to increased intake of 300-400 g of vegetables and its effect on LDL oxidation.


METHODS
After a depletion period of 8 days, 34 healthy females (18 nonsmokers, 16 smokers) were supplemented with beta-carotene- and lutein-rich (green) and lycopene-rich (red) vegetable foods, each for 7 days.


RESULTS
Baseline concentrations (mean +/- SD) of plasma beta-carotene (0.203+/-0.28 micromol/L vs. 0.412+/-0.34 micromol/L; P <0.005) and lutein (0.180 +/-0.10 vs. 0.242+/-0.11 micromol/L; P<0.05) but not lycopene (0.296+/-0.10 vs. 0.319+/-0.33 micromol/L) were significantly lower in smokers compared with nonsmokers. After supplementation, the change (supplementation minus depletion) in plasma beta-carotene (0.152+/- 0.43 vs. 0.363+/-0.29 micromol/L in smokers vs. nonsmokers; P = 0.002) and LDL lutein (0.015+/-0.03 vs. 0.029+/-0.03 micromol/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 red-vegetable supplementation, plasma and LDL lycopene concentrations were increased in both groups, but only nonsmokers showed a significant increase in the lag-phase (44.9+/-9.5 min at baseline, 41.4+/-6.5 min after depletion, and 49.0+/-8.9 min after supplementation; P<0.01) compared with depletion.


CONCLUSIONS
In this short-term intervention study, a dietary intake of >40 mg/day of lycopene by a group of nonsmoking individuals significantly reduced the susceptibility of LDL to oxidation, whereas an equivalent increase in lycopene by a group of smokers showed no such effect.
Chopra
M
M
Northern Ireland Centre for Diet and Health, School of Biomedical Sciences, University of Ulster, Coleraine, County Londonderry, Northern Ireland BT52 1SA, United Kingdom. M.Chopra@ulst.ac.uk
O'Neill
M E
ME
Keogh
N
N
Wortley
G
G
Southon
S
S
Thurnham
D I
DI
D000328:Adult; D002338:Carotenoids / Q000097:blood* / Q000737:chemistry; D004032:Diet; D005260:Female; D005638:Fruit / Q000737:chemistry; D006801:Humans; D066298:In Vitro Techniques; D008074:Lipoproteins / Q000737:chemistry*; D008077:Lipoproteins, LDL / Q000378:metabolism*; D014975:Lutein / Q000737:chemistry; D000077276:Lycopene; D008875:Middle Aged; D010084:Oxidation-Reduction; D012907:Smoking / Q000097:blood*; D014675:Vegetables / Q000737:chemistry; D019207:beta Carotene / Q000737:chemistry
D008074:Lipoproteins; D008077:Lipoproteins, LDL; D019207:beta Carotene; D002338:Carotenoids; D000077276:Lycopene; D014975:Lutein