Effect of ?-tocopherol and ?-carotene supplementation on coronary heart disease during the 6-year post-trial follow-up in the ATBC study

AIMS

To evaluate the 6-year post-trial effects of alpha-tocopherol and beta-carotene supplementation on coronary heart disease (CHD) in the alpha-tocopherol, beta-carotene cancer prevention (ATBC) study.

METHODS AND RESULTS

29,133 male smokers, aged 50-69 years were randomised to receive alpha-tocopherol 50 mg, or beta-carotene 20 mg, or both, or placebo daily for 5-8 years. At the beginning of the post-trial follow-up, 23,144 men were still at risk for a first-ever major coronary event (MCE), and 1255 men with pre-trial history of myocardial infarction (MI) were at risk for MCE. Post-trial risk for MCE (n=2059) was 0.95 (95% confidence interval 0.87-1.04) among alpha-tocopherol recipients compared with non-recipients, and 1.14 (1.04-1.24) among beta-carotene recipients compared with non-recipients. The risk for non-fatal MI (n=993) was 0.96 (0.85-1.09) and 1.16 (1.03-1.32), and for fatal CHD (n=1066) 0.94 (0.83-1.06) and 1.11 (0.99-1.25), respectively. Among men with pre-trial MI no effects were observed in post-trial risk of MCE (n=257).

CONCLUSION

beta-Carotene seemed to increase the post-trial risk of first-ever non-fatal MI but there is no plausible mechanism to support it. Our findings do not advocate the use of alpha-tocopherol or beta-carotene supplements in prevention of CHD among male smokers.

Postintervention effect of alpha tocopherol and beta carotene on different strokes: a 6-year follow-up of the Alpha Tocopherol, Beta Carotene Cancer Prevention Study

BACKGROUND AND PURPOSE

In the Alpha Tocopherol, Beta Carotene Cancer Prevention Study, alpha tocopherol supplementation decreased risk of cerebral infarction by 14% (95% CI, -25% to -1%), and beta carotene increased risk of intracerebral hemorrhage by 62% (95% CI, 10% to 132%). We report here the 6-year postintervention effects of alpha tocopherol and beta carotene supplementation on stroke and its subtypes.

METHODS

A total of 29,133 male smokers, aged 50 to 69 years, were randomized to receive 50 mg of alpha tocopherol, 20 mg of beta carotene, both, or placebo daily for 5 to 8 years. At the beginning of the post-trial follow-up, 24 382 men were still at risk for first-ever stroke. During the post-trial follow-up, 1327 men experienced a stroke: 1087 cerebral infarctions, 148 intracerebral hemorrhages, 64 subarachnoid hemorrhages, and 28 unspecified strokes.

RESULTS

Post-trial risk for cerebral infarction was elevated among those who had received alpha tocopherol compared with those who had not (relative risk [RR], 1.13; 95% CI, 1.00 to 1.27), whereas beta carotene had no effect (RR, 0.97; 95% CI, 0.86 to 1.09). Alpha tocopherol supplementation was associated with a postintervention RR of 1.01 (95% CI, 0.73 to 1.39) for intracerebral hemorrhage and 1.38 (95% CI, 0.84 to 2.26) for subarachnoid hemorrhage. The corresponding RRs associated with beta carotene supplementation were 1.38 (95% CI, 0.99 to 1.91) and 1.09 (95% CI, 0.67 to 1.77), respectively.

CONCLUSIONS

Neither alpha tocopherol nor beta carotene supplementation had any postintervention preventive effects on stroke. The post-trial increase in cerebral infarction risk among recipients of alpha tocopherol may present a rebound of the reduced risk of cerebral infarction during the intervention.

Flavonol and Flavone Intake and the Risk of Intermittent Claudication in Male Smokers

The objective of this study was to investigate the association between flavonol and flavone intake and the risk of intermittent claudication in male smokers. The study population consisted of participants of the Finnish alpha-Tocopherol, beta-Carotene Cancer Prevention (ATBC) Study, who were free of intermittent claudication at study entry. These 25,041 male smokers were 50-69 years old at baseline. Participants completed a validated dietary questionnaire at baseline. The occurrence of intermittent claudication was assessed by annual administration of the Rose questionnaire. During the median follow-up of 4.1 years, 2412 new cases of intermittent claudication were observed. Dietary intake of flavonols and flavones was inversely associated with the risk of intermittent claudication when adjusted for cardiovascular risk factors (relative risk, RR in the highest vs. lowest quintile of intake 0.86, 95% confidence interval, CI: 0.75-0.98, p for trend 0.007). However, after further adjustment for intakes of vitamins C and E and total carotenoids, the association was attenuated (RR: 0.93, 95% CI: 0.81-1.08, p for trend 0.12). The risk of intermittent claudication was lower among men in the highest quintile of vegetable consumption (RR: 0.78, 95% CI: 0.69-0.89, p for trend 0.0001) and among wine drinkers (RR: 0.63, 95% CI: 0.41-0.98). Adjustment for flavonol and flavone intake only marginally changed these associations. In conclusion, flavonol and flavone intake was not independently associated with the risk of intermittent claudication.

Alpha-tocopherol (vitamin E) and beta-carotene supplementation does not affect the risk for large abdominal aortic aneurysm in a controlled trial

Antioxidants may retard atherogenesis and limit inflammatory processes involved in aneurysm formation. We evaluated effects of alpha-tocopherol and beta-carotene supplementation on incidence of large abdominal aortic aneurysm (AAA) in a randomised, double-blind, placebo-controlled trial. Subjects (n=29133) were 50-69-years-old male smokers, participants in the Finnish alpha-Tocopherol, beta-Carotene Cancer Prevention (ATBC) Study. They were randomised to receive either 50 mg/day of alpha-tocopherol, or 20 mg/day of beta-carotene, or both, or placebo in a 2x2 design. Incidence of AAA was evaluated from mortality and hospital registers. During 5.8 years of follow-up, 181 men were diagnosed with either ruptured AAA (n=77) or nonruptured large AAA treated with aneurysmectomy (n=104). Relative risk (RR) for AAA was 0.83 (95% confidence interval [CI] 0.62-1.11) among men receiving alpha-tocopherol compared with those who did not, and 0.93 (95% CI 0.69-1.24) among men receiving beta-carotene compared with those who did not. A modest though nonsignificant decrease in risk for nonruptured AAA was observed among alpha-tocopherol supplemented men (RR 0.71, 95% CI 0.48-1.04) compared with men not receiving alpha-tocopherol. For beta-carotene, RR for nonruptured AAA was 0.86 (95% CI 0.59-1.27) compared with men not receiving beta-carotene. Neither antioxidant affected risk for ruptured AAA. In conclusion, long-term supplementation with alpha-tocopherol or beta-carotene had no preventive effect on large AAA among male smokers.

Life-style factors and risk for abdominal aortic aneurysm in a cohort of Finnish male smokers

Prospective studies evaluating risk factors for abdominal aortic aneurysm are few. We studied the association of life-style factors with risk for abdominal aortic aneurysm among 29,133 male smokers 50-69 years of age, participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. During a mean follow-up of 5.8 years, 181 were diagnosed with ruptured abdominal aortic aneurysm or nonruptured abdominal aortic aneurysm plus aneurysmectomy. Risk for abdominal aortic aneurysm was positively associated with age [relative risk (RR) = 4.56, 95% confidence interval (CI) = 2.42-8.61 for > 65 vs < or = 55 years], smoking years (RR = 2.25, 95% CI = 1.33-3.81 for > 40 vs < or = 32 years), systolic blood pressure (RR = 1.92, 95% CI = 1.13-3.25 for > 160 vs < or = 130 mmHg), diastolic blood pressure (RR = 1.80, 95% CI = 1.05-3.08 for > 100 vs < or = 85 mmHg), and serum total cholesterol (RR = 1.85, 95% CI = 1.09-3.12 for > 6.5 vs < or = 5.0 mmol/liter). High-density lipoprotein cholesterol showed a strong inverse association with risk for aortic aneurysm (RR = 0.16, 95% CI = 0.08-0.32 for > 1.5 vs < or = 0.9 mmol/liter). High energy intake was associated with lower risk for aortic aneurysm (RR = 0.59, 95% CI = 0.38-0.94 for the highest quartile vs the lowest), whereas no associations with nutrients were evident. We conclude that classical risk factors for atherosclerotic diseases seem to be important in pathogenesis of large abdominal aortic aneurysms.

Prospective study of diet, lifestyle, and intermittent claudication in male smokers

The association between dietary and lifestyle factors and intermittent claudication was investigated in the Finnish Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. The cohort comprised 26,872 male smokers aged 50-69 years who were free of claudication at study entry. At baseline (1985-1988), subjects completed a diet history questionnaire. During a median follow-up period of 4 years (ending in spring 1993), 2,578 men reported symptoms of claudication on the Rose questionnaire, which was administered annually. Smoking status was assessed every 4 months. Smoking, systolic blood pressure, serum total cholesterol, and diabetes mellitus were positively associated with risk for claudication, whereas serum high density lipoprotein cholesterol, education, and leisure time exercise were inversely associated with risk. Dietary carbohydrates, fiber, and n-6 polyunsaturated fatty acids were inversely associated with risk for claudication, as were some dietary and serum antioxidants: dietary vitamin C (highest quartile vs. lowest: relative risk (RR) = 0.86; 95% confidence interval (CI): 0.77, 0.97), dietary gamma-tocopherol (RR = 0.89; 95% CI: 0.79, 1.00), dietary carotenoids (RR = 0.82; 95% CI: 0.73, 0.92), serum alpha-tocopherol (RR = 0.88; 95% CI: 0.77, 1.00), and serum beta-carotene (RR = 0.77; 95% CI: 0.68, 0.86). Smoking cessation reduced subsequent risk for claudication (RR = 0.86; 95% CI: 0.75, 0.99). The authors conclude that classical risk factors for atherosclerosis are associated with claudication. High intakes of antioxidant vitamins may be protective. Further research is needed before antioxidants can be recommended for the prevention of intermittent claudication.

The effect of alpha-tocopherol and beta-carotene supplementation on symptoms and progression of intermittent claudication in a controlled trial

We evaluated the effect of long-term supplementation with vitamin E (alpha-tocopherol) and beta-carotene on occurrence of claudication symptoms and risk for peripheral vascular surgery among men with intermittent claudication. Subjects, 50-69-year old male smokers, were participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, who reported intermittent claudication through a structured questionnaire (Rose) at study entry (n=1484). They were randomly assigned to receive either 50 mg/day of alpha-tocopherol, or 20 mg/day of beta-carotene, or both, or placebo, in a 2 x 2 design. During follow-up, claudication was evaluated by repeating use of the questionnaire once a year. Information on peripheral vascular surgery came from the National Hospital Discharge Register. We observed no effect of alpha-tocopherol and beta-carotene supplementation on claudication during a mean follow-up of 3.7 years. A slightly increased risk (odds ratio (OR) 1.60, 95% confidence interval (CI) 1.05-2.44) for vascular surgery was observed among beta-carotene supplemented men compared to those who did not receive beta-carotene. Alpha-tocopherol supplementation had no effect. In conclusion, long-term supplementation with alpha-tocopherol and beta-carotene showed no beneficial effect on symptoms and progression of intermittent claudication.