An investigation of the relationship between antioxidant vitamin intake and coronary heart disease in men and women using logistic regression analysis

Oxidant injury and antioxidant prevention: role of dietary antioxidants, minerals, and drugs in the management of coronary heart disease (Part II)

Antioxidants, trace minerals, and certain amino acids enhance antioxidant defense of the body by improving intracellular redox status, vascular endothelial function, and nitric oxide secretion. Antioxidant supplementation has been suggested for primary and secondary prevention of coronary heart disease.

Beta-carotene and risk of coronary heart disease. A review of observational and intervention studies

The production of free radicals may favour the processes of atherosclerosis, and antioxidant vitamins (including beta-carotene), which partly prevent such processes, might favorably influence cardiovascular disease (CVD); thus, their supplementation might be a useful tool in the prevention of coronary heart disease (CHD). The relationship between beta-carotene and CHD has been investigated in several observational studies, including ecological, cohort and case-control studies. Six cohort studies reported relative risks (RR) of CHD between 0.27 and 0.78 for high beta-carotene levels (plasma/serum levels and dietary intake), but four more recent ones reported RR around unity (range 0.84 to 1.19). The evidence from case-control studies supports a role of beta-carotene in the prevention of CHD (odds ratios, OR, between 0.37 and 0.71), with a possible stronger protection for current smokers. The four published randomized clinical trials of beta-carotene supplementation found RR close to unity (range 0.96 to 1.26) for the relation between beta-carotene and CHD. The apparent discrepancy between observational and intervention studies may depend on several factors. The benefit reported in some observational studies may be related to consumption of foods rich in beta-carotene rather than beta-carotene itself, as foods rich in beta-carotene are usually rich also in other antioxidant vitamins and micronutrients, or to time-related factors, i.e., longer supplementation in intervention studies. Thus, a reasonable recommendation for the prevention of CHD for the general population is to consume a balanced diet with emphasis on antioxidant rich fruit and vegetables and whole grains.

Effect of dietary catechin and vitamin E on aortic fatty streak accumulation in hypercholesterolemic hamsters

Male golden Syrian hamsters were fed for 16 weeks on a hypercholesterolemic diet containing, per kg, 150 g of lipids (90 g butterfat, 35 g vitamin E-stripped corn oil and 25 g fish oil), 2 g cholesterol and either 3 IU vitamin E (3 IU E), 3 IU vitamin E and 200 mg catechin hydrate (3 IU E-200 Cat) or 30 IU vitamin E (30 IU E). More fatty streaks, measured by Oil Red O staining, were deposited in aortas of hamsters fed 3 IU E than in those fed either 3 IU E-200 Cat or 30 IU E. Lipid staining increased with plasma low-density lipoprotein cholesterol (LDL-C) in all animals. At the same concentration of LDL-C, animals fed either 3 IU E-200 Cat or 30 IU E developed less fatty streaks than those fed 3 IU E. Plasma LDL-C and total cholesterol were highest in hamsters fed 3 IU E and LDL-C and total cholesterol in animals fed 3 IU-200 Cat were not different from those fed either 3 IU E or 30 IU E. This study showed the importance of circulating plasma LDL-C on atherogenesis and the inhibitory effect on this process of both dietary vitamin E and catechin.

Vitamins E plus C and interacting conutrients required for optimal health. A critical and constructive review of epidemiology and supplementation data regarding cardiovascular disease and cancer

Antioxidants are crucial components of fruit/vegetable rich diets preventing cardiovascular disease (CVD) and cancer: plasma vitamins C, E, carotenoids from diet correlate prevalence of CVD and cancer inversely, low levels predict an increased risk of individuals which is potentiated by combined inadequacy (e.g., vitamins C + E, C + carotene, A + carotene); self-prescribed rectification of vitamins C and E at adequacy of other micronutrients reduce forthcoming CVD, of vitamins A, C, E, carotene and conutrients also cancer; randomized exclusive supplementation of beta-carotene +/- vitamin A or E lack benefits except prostate cancer reduction by vitamin E, and overall cancer reduction by selenium; randomized intervention with synchronous rectification of vitamins A + C + E + B + minerals reduces CVD and counteracts precancerous lesions; high vitamin E supplements reveal potentials in secondary CVD prevention. Plasma values desirable for primary prevention: > or = 30 mumol/l lipid-standardized vitamin E (alpha-tocopherol/cholesterol > or = 5.0 mumol/mmol); > or = 50 mumol/l vitamin C aiming at vitamin C/vitamin E ratio > 1.3-1.5; > or = 0.4 mumol/l beta- (> or = 0.5 mumol/l alpha+ beta-) carotene.

CONCLUSIONS

In CVD vitamin E acts as first risk discriminator, vitamin C as second one; optimal health requires synchronously optimized vitamins C + E, A, carotenoids and vegetable conutrients.

Cell density and antioxidant vitamins determine the effects of hyperoxia on proliferation and death of MDCK epithelial cells

Epithelial cells are prone to oxidant injury, which could change epithelial cell homeostasis and lead to degenerative diseases. We examined the effects of hyperoxia on death and proliferation off Madin-Darby canine kidney (MDCK) epithelial cells and antioxidant vitamin protection. Subconfluent and near-confluent MDCK cells were cultured under normoxia or hyperoxia for two days. We measured cell number and viability, mitochondria enzymatic activity, thymidine incorporation, necrosis [lactate dehydrogenase (LDH) release], and apoptosis (DNA fragmentation and morphological changes). When the cells were subconfluent, hyperoxia decreased the number of adherent cells, mitochondrial enzymatic activity, and thymidine incorporation, but neither LDH release nor apoptotic changes increased compared with normoxic controls. In normoxia, near-confluent cells had lower nonadherent cell numbers, mitochondrial enzymatic activity, and thymidine incorporation than subconfluent cells; hyperoxia further decreased the latter two parameters and increased apoptotic changes and LDH release in near-confluent cells. Vitamin E protected mitochondrial enzymatic activity, apoptotic changes, and LDH release against hyperoxic injury but did not affect changes in thymidine incorporation with hyperoxia. Vitamin C partially protected the mitochondrial enzymatic activity and thymidine incorporation in subconfluence, but not in near confluence. These results indicate that cell density is a major determinant of the effects of hyperoxic injury and the profile of antioxidant vitamin protection.

Beta-carotene intake and risk of nonfatal acute myocardial infarction in women

There are indications that beta-carotene, but not pre-formed vitamin A, is protective on the risk of acute myocardial infarction (AMI). The relationship between nonfatal AMI and the intake of beta-carotene and retinol was investigated in a case-control study conducted between 1983 and 1992 in northern Italy on 433 women with nonfatal AMI and 869 controls in hospital for acute, non-cardiovascular, non-neoplastic, non-digestive, non-hormone related conditions. Odds ratios (OR), with their 95% confidence intervals (CI), were computed by unconditional multiple logistic regression analysis, including terms for age, education, body mass index, smoking, alcohol and coffee drinking, menopausal status, hormone replacement therapy and history of diabetes, hypertension and hyperlipidemia. The risk of AMI was inversely related to beta-carotene intake, with an OR of 0.5 (95% CI: 0.3 to 0.8) for the highest quintile of intake compared to the lowest (chi2 trend = 10.53, p < 0.01). Retinol intake was not associated with AMI, with an OR of 0.9 (95% CI: 0.6 to 1.3) for the highest quintile of intake compared to the lowest. Analysis in separate strata of covariates indicated that the inverse association of beta-carotene intake with risk of AMI was appreciably stronger in younger, lean women with no history of diabetes or hypertension, and in current smokers. The results of this study indicate that the risk of nonfatal AMI in women is inversely related to intake of beta-carotene containing foods, but not foods containing retinol.

Carotenoids and retinoids: a review of research, clinical, and public health applications

Traditionally, the carotenoids and retinoids have been regarded as dietary sources of vitamin A and have been evaluated regarding their respective physiologic roles in vision, growth, immune system integrity, and prevention of vitamin A deficiency. In the 1990s, however, vitamin A deficiency is no longer widespread in Western countries. Therefore, the role of carotenoids and retinoids is evolving to encompass treatment and prevention of conditions such as cancer and cardiovascular disease, which are prevalent in Western societies. This review summarizes current research concerning the therapeutic utility of vitamin A and its analogues and their roles in the prevention of cancer and cardiovascular disease.

Association of serum vitamin levels, LDL susceptibility to oxidation, and autoantibodies against MDA-LDL with carotid atherosclerosis. A case-control study. The ARIC Study Investigators. Atherosclerosis Risk in Communities

Oxidative modification of LDL is believed to be a crucial step in atherosclerosis. Thus, antioxidant vitamins may have a role in the prevention of coronary disease. We examined the cross-sectional association of serum vitamin levels, the susceptibility of LDL to hemin-induced oxidation (lag phase to conjugated diene formation), and the malondialdehyde-LDL (MDA-LDL) to native LDL radioactivity binding ratio with carotid intima-media thickness (IMT), a measure of asymptomatic early atherosclerosis. The participants in this observational study were 231 asymptomatic age-, sex-, race-, and field center-matched case-control pairs selected from the Atherosclerosis Risk in Communities (ARIC) study cohort on the basis of B-mode carotid artery ultrasonograms obtained from 1986 through 1989. Cases exceeded the 90th percentile of IMT, and control subjects were below the 75th percentile of IMT for all arterial segments. Biochemical analyses were performed on fasting frozen (-70 degrees C) serum specimens collected from 1990 through 1992. In conditional logistic regression adjusting for age, blood storage time, total cholesterol, and log-triglyceride concentrations, serum beta-cryptoxanthin and lutein plus zeaxanthin levels were inversely related to the extent of atherosclerosis (odds ratio [OR] per 1-SD increase: 0.75, 95% confidence interval [CI]: 0.59-0.94; and OR per 1-SD increase: 0.76, 95% CI: 0.59-0.95, respectively). Increases in alpha-carotene and lycopene were associated with nonsignificantly lower odds of being a case, whereas beta-carotene, retinol, and alpha-tocopherol were unrelated to IMT. Although not reaching statistical significance, the lag phase and autoantibodies against MDA-LDL were positively associated with asymptomatic atherosclerosis. After adjustment for potential confounders, only the inverse association of lutein plus zeaxanthin with asymptomatic atherosclerosis was maintained. This study supports a modest inverse association between circulating levels of some carotenoids, particularly lutein plus zeaxanthin, and carotid IMT. These findings suggest that these carotenoid compounds (regarded as biomarkers of fruit and vegetable intake) may be important in early stages of atherosclerosis.

An investigation of the relationship between antioxidant vitamin intake and coronary heart disease in men and women using discriminant analysis

Smoking, high blood pressure and elevated blood cholesterol are the well-established 'classical' risk factors for coronary heart disease (CHD) in men and women. However, it is also well-known that there is a considerable degree of residual variation in CHD after these factors have been taken into account. Consideration of antioxidant vitamin status may help to reduce this unexplained variation. Here, discriminant analysis is applied to the baseline cross-sectional data from the Scottish Heart Health Study. The problem of possible behavioural changes after diagnosis for CHD is addressed by analysing diagnosed and undiagnosed CHD cases separately. Results show that the combined dietary intakes of the antioxidant vitamins C, E and carotene (assessed using a food frequency questionnaire) differentiate CHD prevalence as well as do the classical risk factors. For women, stepwise discriminant analysis shows that the effect of the antioxidant vitamins on CHD is removed by adjustment for the classical risk factors and age. For men, however, the antioxidant vitamins still contribute to the discriminant function. It is concluded that dietary antioxidant vitamins appear to have a significant effect on the prevalence of CHD, especially amongst men. The benefits and problems of using discriminant analysis in this practical context are discussed, including the assumptions that need to be tested.