Antioxidant vitamins and mineral supplementation, life span expansion and cancer incidence: a critical commentary

Purpose

Experimental evidence indicates a strong connection between oxidative damage, cancer, and aging. Epidemiological observations suggest that a diet rich in fruits and vegetables is associated with lower incidence of some cancers and longer life expectancy; since fruits and vegetables contain natural antioxidants, a considerable effort has been dedicated to understanding their effects in experimental studies and in human trials.

Results

A: Effects of antioxidant-containing food and supplements on oxidation damage in humans. Intervention trials employing a variety of biomarkers have shown either a slight decrease in oxidation damage or no effect. B: Effects of selected antioxidants on mortality and cancer incidence. β-carotene and α-tocopherol, alone or in combination, increase cardiovascular and all-cause mortality or have no effect. In some studies, β-carotene and retinyl palmitate significantly increase the progression of lung cancer and aggressive prostate cancer. Protection against cardiovascular mortality or no effect of vitamin E has been reported, with an increase of all-cause mortality at dosages greater than 150?IU/day. Selenium showed beneficial effects on gastrointestinal cancer and reduced the risk of lung cancer in populations with lower selenium status. For multivitamin and mineral supplementation, no significant reduction of mortality or cancer incidence was observed, but some reports indicate a possible preventive effect in cervical cancer.

Conclusions

The majority of supplementation studies indicate no variation of general mortality and of cancer incidence or a detrimental effect on both. Antioxidant supplements so far tested seem to offer no improvement over a well-balanced diet, possibly because of the choice of the substances tested or of an excessive dosage. However, new natural or synthetic compounds effective in vitro and in experimental studies might still be worth investigating in human trials.     

Rethinking suicide: notes toward a critical epidemiology.

Where the genesis of "disease" owes much to causes that are social and economic in nature, epidemiology holds unrealized potential as a tool of social criticism. A particularly interesting example is provided by suicide and suicide research. Methodological difficulties are explored in detail, major findings reviewed, and the dominant interpretations of such findings criticized. Research has consistently pointed to the risks of marginal or minority status, unemployment, weak community supports, situational crises, and the pressures people are subjected to during periods of economic depression. It is argued that the sociostructural implications of such research have been systematically ignored, attention being devoted instead to more efficient management of the suicidal individual--this in spite of the lack of success of suicide prevention centers. Initial steps toward an alternative framework are outlined, with emphasis laid on the need to disaggregate the suicide act. It is further suggested that self-destruction is a far commoner--indeed, integral--part of our social environment than the bare rack of suicide statistics would suggest.     

Global disparities in health and human rights: a critical commentary.

Widening disparities in health and human rights at a global level represent the dark side of progress associated with escalation of economic and military exploitation and exponential population growth in the 20th century. Even the most basic universal human rights cannot be achieved for all under these circumstances. The goal of improved population health will be similarly elusive while medical care is commodified and exploited for commercial gain in the marketplace. Recognition of the powerful forces that polarize our world and commitment to reversing them are essential for the achievement of human rights for all, for the improvement of public health, and for the peaceful progress required to protect the "rational self-interest" of the most privileged people on earth against the escalation of war, disease, and other destructive forces arising from widespread poverty and ecological degradation.     

Invited commentary: a challenge for physical activity epidemiology

Numerous epidemiologic studies report an inverse association between increasing levels of regular physical activity and reductions in major morbidity and mortality. Clinical guidelines emphasize the importance of specific amounts of regular physical activity, yet the majority of US adults do not meet these recommended levels. There are comparatively less data on nonexercise, or lifestyle, physical activity that may occur throughout the day in an unstructured setting with variable duration and frequency. In this issue (Am J Epidemiol 2007;165:1343-1350), both regular exercise and other forms of nonexercise physical activity are examined in relation to total and cause-specific mortality in Chinese women. This work illustrates several important issues in physical activity epidemiology regarding the identification, measurement, and analysis of nonexercise components of physical activity. Unlike semiquantitative food frequency questionnaires for studies of individual foods and nutrients, physical activity epidemiology lacks a prevailing measurement tool and analytical technique by which to examine nonexercise physical activity. Our challenge is therefore to more accurately and consistently measure these more subtle components of nonexercise physical activity to better understand its potential clinical effects and role in disease prevention.     

Invited commentary: topical threats to epidemiology

Epidemiologic studies are subject to social and cultural influences, which can influence the way samples are identified or included and information is collected. In this commentary, the author highlights issues related to several factors that may influence current research methods, such as changes in telephone use and new ethical guidelines. Technologic developments that have the potential to provide new opportunities for sample selection and data collection are also outlined. Epidemiologists need to be flexible and responsive to changes that may influence their research methods and should use their training and judgment to assess the likely impact of any potential biases or influences, so that study quality is maintained.     

Invited commentary: The context and challenge of von Pettenkofer's contributions to epidemiology

Max von Pettenkofer is largely remembered for swallowing cholera vibrio, trying thereby to falsify the claim of his rival, the contagionist Robert Koch, that the bacillus he had isolated was cholera's sufficient cause. In this issue of the American Journal of Epidemiology, Alfredo Morabia reminds us that von Pettenkofer was more than this futile gesture. He was a 19th century public health leader whose multifactorial theory of cholera etiology deeply influenced the dominant anticontagionist school of disease transmission. His authority was undercut by the massive 1892 cholera epidemic in Hamburg, Germany. As it took off, the German government sent in Koch, who successfully contained the epidemic through interventions that von Pettenkofer regularly repudiated-quarantine, disinfection, and the boiling of water. The authors situate the antagonism between these two individuals within a broader scientific and political context that includes the evolution of miasma theory and debates over the role of governments confronted by epidemic disease. They also note that Koch's approach, which focused narrowly on the agent and its eradication, was missing key elements required for applying germ theory to public health. As scientists later incorporated biologic, host, and environmental factors into the germ theory paradigm, they reintroduced some of the complexity that had previously characterized the miasma model.     

Patient empowerment in the United States: a critical commentary

Whilst there is no consensus amongst analysts regarding how best to define 'patient empowerment', at the very least, this concept entails a re-distribution of power between patients and physicians. Empowered patients attempt to take charge of their own health and their interactions with health care professionals. Empowerment can occur at different levels (micro, meso, and macro) and patients have different ideas about what it means to 'take charge' and 'be empowered'. Some patients simply want to be given information about their conditions whilst others want to have full control over all medical decision-making. Some empirical evidence suggests that active patient participation in health care is associated with better patient outcomes. This field is ripe for future studies which both help to develop theoretical models of patient empowerment and articulate the conditions under which patient empowerment occurs.     

Diaries as a source of suffering narratives: A critical commentary

In this article, the ways in which diaries can be used as narratives of risk are explored. It is noted that unsolicited diaries appear to be an especially valuable resource for researchers who wish to explore the nature of suffering. They also provide a way of avoiding some of the moral dilemmas created when researchers solicit narratives of suffering and represent accounts which contextualize suffering within a personal biography. Such texts provide a mechanism for accessing not only contemporary accounts of suffering but also accounts from previous generations thus allowing researchers to explore the ways in which narratives of suffering have developed over time. These points are illustrated via an analysis of stroke survivors' accounts of their stroke and the traumatic experience of knowing themselves to be under threat and at risk of dying.     

The epidemic of endometrial cancer: a commentary.

Vital statistics show that a rise in incidence of endometrial cancer began in the mid-1960s on the West Coast of the United States. This rise was continuous and reached a peak in 1975. Elsewhere, incidence rates for endometrial cancer rose during the 1970s. It now seems evident that much of the rise in all areas of the country was due to replacement estrogen treatment. We estimated from data obtained from the Commission on Professional and Hospital Activities-Professional Activity Study of Ann Arbor, Michigan, that over 15,000 cases of endometrial cancer were caused by replacement estrogens during the five-year period 1971--1975 alone. This represents one of the largest epidemics of serious iatrogenic disease that has ever occurred in this country. With the substantial fall in estrogen sales starting in January 1976, there has been an associated decline in the incidence rates of endometrial cancer nationwide.