Vitamin E may affect the life expectancy of men, depending on dietary vitamin C intake and smoking

Background: Antioxidants might protect against oxidative stress, which has been suggested as a cause of aging. Methods: The ATBC Study recruited males aged 50-69 years who smoked at least 5 cigarettes per day at the baseline. The current study was restricted to participants who were followed up past the age of 65. Deaths were identified in the National Death Registry (1445 deaths). We constructed Kaplan-Meier survival curves for all participants, and for four subgroups defined by dietary vitamin C intake and level of smoking. We also constructed Cox regression models allowing a different vitamin E effect for low and high age ranges. Results: Among all 10,837 participants, vitamin E had no effect on those who were 65 to 70 years old, but reduced mortality by 24% when participants were 71 or older. Among 2284 men with dietary vitamin C intakes above the median who smoked less than a pack of cigarettes per day, vitamin E extended life-span by two years at the upper limit of the follow-up age span. In this subgroup, the survival curves of vitamin E and no-vitamin E participants diverged at 71 years. In the other three subgroups covering 80% of the participants, vitamin E did not affect mortality. Conclusions: This is the first study to strongly indicate that protection against oxidative stress can increase the life expectancy of some initially healthy population groups. Nevertheless, the lack of effect in 80% of this male cohort shows that vitamin E is no panacea for extending life expectancy

Vitamin E supplementation and pneumonia risk in males who initiated smoking at an early age: effect modification by body weight and dietary vitamin C

Peer reviewe

Vitamin E supplementation may transiently increase tuberculosis risk in males who smoke heavily and have high dietary vitamin C intake : Reply by Hemilä and Kaprio

Peer reviewe

Cohorts

Cohort studies are essential for conducting large studies of multiple exposures and outcomes in humans. Recently, the ability to combine data from multiple cohorts in, for example, meta-analyses, and the willingness in the genetics community to collaborate to enable replication studies has led to many new insights into the genetic and environmental determinants of human health and behaviors. The contribution of Professor Nicholas Martin to the development of cohort studies, particularly of twin and twin-family studies, over a period of several decades is reviewed. He has contributed to the development and use of both Australian and international resources. The contributions of Australian twin studies to genomewide association projects are multiple, and across multiple domains, from biomarkers, lifestyle and behavior to disorders and disease.Peer reviewe

Vitamin E supplementation may transiently increase tuberculosis risk in males who smoke heavily and have high dietary vitamin C intake

Peer reviewe

Modification of the effect of vitamin E supplementation on the mortality of male smokers by age and dietary vitamin C

"The Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study (1985-1993) recruited 29,133 Finnish male cigarette smokers, finding that vitamin E supplementation had no overall effect on mortality. The authors of this paper found that the effect of vitamin E on respiratory infections in ATBC Study participants was modified by age, smoking, and dietary vitamin C intake; therefore, they examined whether the effect of vitamin E supplementation on mortality is modified by the same variables. During a median follow-up time of 6.1 years, 3,571 deaths occurred. Age and dietary vitamin C intake had a second-order interaction with vitamin E supplementation of 50 mg/day. Among participants with a dietary vitamin C intake above the median of 90 mg/day, vitamin E increased mortality among those aged 50-62 years by 19% (95% confidence interval: 5, 35), whereas vitamin E decreased mortality among those aged 66-69 years by 41% (95% CI: -56, -21). Vitamin E had no effect on participants who had a dietary vitamin C intake below the median. Smoking quantity did not modify the effect of vitamin E. This study provides strong evidence that the effect of vitamin E supplementation on mortality varies between different population groups. Further study is needed to confirm this heterogeneity."The Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study (1985-1993) recruited 29,133 Finnish male cigarette smokers, finding that vitamin E supplementation had no overall effect on mortality. The authors of this paper found that the effect of vitamin E on respiratory infections in ATBC Study participants was modified by age, smoking, and dietary vitamin C intake; therefore, they examined whether the effect of vitamin E supplementation on mortality is modified by the same variables. During a median follow-up time of 6.1 years, 3,571 deaths occurred. Age and dietary vitamin C intake had a second-order interaction with vitamin E supplementation of 50 mg/day. Among participants with a dietary vitamin C intake above the median of 90 mg/day, vitamin E increased mortality among those aged 50-62 years by 19% (95% confidence interval: 5, 35), whereas vitamin E decreased mortality among those aged 66-69 years by 41% (95% CI: -56, -21). Vitamin E had no effect on participants who had a dietary vitamin C intake below the median. Smoking quantity did not modify the effect of vitamin E. This study provides strong evidence that the effect of vitamin E supplementation on mortality varies between different population groups. Further study is needed to confirm this heterogeneity.Peer reviewe

Subgroup analysis of large trials can guide further research: a case study of vitamin E and pneumonia

BACKGROUND: Biology is complex and the effects of many interventions may vary between population groups. Subgroup analysis can give estimates for specific populations, but trials are usually too small for such analyses. PURPOSE: To test whether the effect of vitamin E on pneumonia risk is uniform over subgroups defined by smoking and exercise. METHODS: The Alpha-Tocopherol Beta-Carotene Cancer Prevention Study examined the effects of vitamin E (50 mg per day) and β-carotene (20 mg per day) on lung cancer in 29,133 male smokers aged 50-69 years using a 2 × 2 factorial design. The trial was conducted among the general community in Finland during 1985-1993; the intervention lasted for 6.0 years (median). In the present study, we tested the uniformity of vitamin E effect on the risk of hospital-treated pneumonia (898 cases) by adding a dummy variable to allow each subgroup its own vitamin E effect in a Cox model covering all participants. RESULTS: Vitamin E effect was not uniform over eight subgroups defined by baseline smoking (5-19 vs ≥20 cigarettes per day), age of smoking initiation (≤20 vs ≥21 years), and exercise during leisure time (yes vs no). Vitamin E decreased pneumonia risk by 69% (95% CI: 43% to 83%) among participants who had the least exposure to smoking and exercised during leisure time. Vitamin E increased pneumonia risk by 79% (95% CI: 27% to 150%) among those who had the highest exposure to smoking and did not exercise. LIMITATIONS: Although the evidence of heterogeneity is strong, it is not evident to what extent the estimates of effect or the limits between the subgroups can be extrapolated to other populations. CONCLUSION: Subgroup analysis of large trials should be encouraged, though caution is needed in the interpretation of findings. The role of vitamin E in susceptibility to pneumonia in physically active nonsmokers warrants further study. TRIAL REGISTRATION: ClinicalTrials.gov NCT00342992.Peer reviewe

Traumatic brain injury, collision sports participation, and neurodegenerative disorders : narrative power, scientific evidence, and litigationd

Non peer reviewe