alpha-carotene and Arteriosclerosis

Recent epidemiologic and animal model data suggest that oxygenated carotenoids are protective against early atherosclerosis. We assessed the association between atherosclerotic progression, measured by carotid intima-media thickness (IMT), and plasma levels of oxygenated and hydrocarbon carotenoids, tocopherols, retinol, and ascorbic acid.. Participants were from an occupational cohort of 573 middle-aged women and men who were free of symptomatic cardiovascular disease at baseline. Ultrasound examination of the common carotid arteries, lipid level determination, and risk factor assessment were performed at baseline and 18-month follow-up. Plasma levels of antioxidants were determined at baseline only. Change in IMT was related to baseline plasma antioxidant levels in regression models controlling for covariates. In models adjusted for age, sex, and smoking status, 18-month change in IMT was significantly inversely related to the 3 measured oxygenated carotenoids (lutein, beta-cryptoxanthin, zeaxanthin; P<0.02 for all) and one hydrocarbon carotenoid, alpha-carotene (P=0.003). After adjusting for additional cardiac risk factors and potential confounders, including high-sensitivity C-reactive protein, these associations remained significant (P<0.05).. These findings suggest that higher levels of plasma oxygenated carotenoids (lutein, zeaxanthin, beta-cryptoxanthin) and alpha-carotene may be protective against early atherosclerosis.

Topics: Adult; Age Factors; Antioxidants; Arteriosclerosis; beta Carotene; Carotenoids; Carotid Artery, Common; Fasting; Female; Follow-Up Studies; Humans; Lipoproteins; Los Angeles; Lycopene; Male; Middle Aged; Predictive Value of Tests; Prospective Studies; Regression Analysis; Sex Factors; Smoking; Surveys and Questionnaires; Tunica Intima; Tunica Media; Vitamin A; Xanthophylls; Zeaxanthins

the evidence of a potential beneficial role of antioxidants in preventing atherosclerotic disease is not entirely consistent.. to assess the longitudinal association of serum total antioxidant capacity and serum antioxidants with the presence of subclinical carotid atherosclerosis.. Prospective case-control study nested within an historical cohort. Cases were 150 individuals with elevated carotid intimal-medial thickness measured by B-mode ultrasound at the first two examinations of the Atherosclerosis Risk in Communities Study (1987-92). Controls were 150 age-gender-matched individuals with low carotid intimal-medial thickness. Serum antioxidant vitamins, uric acid, and serum total antioxidant capacity were measured in frozen serum samples collected from the same individuals in 1974 (13-15 years prior to the determination of case-control status).. Compared to controls, atherosclerosis cases had significantly higher levels of serum total antioxidant capacity in 1974 than controls. This difference was almost entirely explained by increased serum concentration of uric acid in cases. In contrast with cross-sectional results, uric acid serum concentration in 1974, was significantly higher in cases than in controls, even after adjusting for the main cardiovascular risk factors. Cases had significantly lower levels of alpha-carotene in the 1974 sera than controls, but no other differences in serum antioxidant vitamin concentrations were observed.. The higher serum uric acid concentration seemed associated with elevated total serum antioxidant capacity among individuals with atherosclerosis. This finding is consistent with experimental evidence suggesting that hyperuricemia may be a compensatory mechanism to counteract oxidative damage related to atherosclerosis and aging in humans.

Topics: Antioxidants; Arteriosclerosis; Bilirubin; Carotenoids; Carotid Artery Diseases; Case-Control Studies; Cohort Studies; Female; Humans; Longitudinal Studies; Male; Middle Aged; Prospective Studies; Reference Values; Retrospective Studies; Uric Acid; Vitamins

Interaction of peroxynitrite, the product of the reaction between nitric oxide and superoxide, with carotenes (lycopene, alpha-carotene, and beta-carotene) and oxocarotenoids (beta-cryptoxanthin, zeaxanthin, and lutein) was studied both in homogeneous solution and in human low-density lipoproteins (LDL). All carotenoids prevented the formation of rhodamine 123 from dihydrorhodamine 123 caused by peroxynitrite, suggesting that the carotenoids react with peroxynitrite. Oxocarotenoids were as effective as biothiols, known scavengers of peroxynitrite, whereas lycopene, alpha-carotene, and beta-carotene exhibited a considerably more pronounced effect. Moreover, peroxynitrite caused a loss of carotenoids in LDL as was revealed by HPLC. The concentration of peroxynitrite causing half-maximal loss of carotenoids in LDL ranged from 13 +/- 3 to 68 +/- 3 microM for lycopene and lutein, respectively. Again, oxocarotenoids were less reactive in this system. A correlation between efficiency of carotenoids in the competitive assay with dihydrorhodamine 123 and the concentration of peroxynitrite causing half-maximal loss of carotenoids in LDL was observed (r(2) = 0.91). These findings suggest that carotenoids can efficiently react with peroxynitrite and perform the role of scavengers of peroxynitrite in vivo.

Topics: Arteriosclerosis; beta Carotene; Carotenoids; Cryptoxanthins; Fluorescent Dyes; Free Radical Scavengers; Humans; In Vitro Techniques; Lipoproteins, LDL; Lutein; Lycopene; Nitrates; Rhodamine 123; Spectrometry, Fluorescence; Xanthophylls; Zeaxanthins

A large number of studies have contributed to the hypothesis that carotenoids, vitamins A and E are protective against atherosclerosis by acting as antioxidants. The aim of this study was to assess the relationship between plasma levels of carotenoids (alpha- and beta- carotene, lutein, lycopene, zeaxanthin, beta-cryptoxanthin), vitamins A and E, and atherosclerosis in the carotid and femoral arteries.. This prospective and cross sectional study involved a randomly selected population sample of 392 men and women aged 45-65 years. Carotid and femoral artery atherosclerosis was assessed by high-resolution duplex ultrasound.. alpha- and beta- carotene plasma levels were inversely associated with the prevalence of atherosclerosis in the carotid and femoral arteries (P=0.004) and with the 5-year incidence of atherosclerotic lesions in the carotid arteries (P=0.04). These findings were obtained after adjustment for other cardiovascular risk factors (sex, age, LDL (low density lipoproteins), ferritin, systolic blood pressure, smoking, categories of alcohol consumption, social status, C-reactive protein). Atherosclerosis risk gradually decreased with increasing plasma alpha- and beta-carotene concentrations (P=0.004). No associations were found between vitamin A and E plasma levels and atherosclerosis.. This study provides further epidemiological evidence of a protective role of high alpha- and beta- carotene in early atherogenesis.

Topics: Adult; Aged; Arteriosclerosis; beta Carotene; Carotenoids; Carotid Arteries; Cross-Sectional Studies; Female; Femoral Artery; Humans; Incidence; Italy; Male; Middle Aged; Osmolar Concentration; Prevalence; Prospective Studies; Risk Factors; Ultrasonography