Analysis of the AHS-1 data has been ongoing for about a decade. As investigators have pieced together answers to their questions, new directions for investigation have been suggested by the outcomes.
A basic profile of the study population showed an average age of 51 for men and 53 for women. The proportion of subjects who had been diagnosed by a physician as hypertensive was close to that expected for an adult population. Although a modest number of subjects admitted to past cigarette smoking — usually before joining the Adventist Church — there were virtually no current smokers in the population.
Other profile information includes:
- A large proportion claimed to exercise with at least moderate frequency.
- The population, made up of nearly two-thirds women, tended to be well-educated.
- More than 50% of respondents said they ate meat less than once a week.
Link to Cancer Prevention
One area investigated was a possible link between diet and cancer. Data from the original Adventist Mortality Study provided good evidence that Adventists enjoy moderately lower rates of many cancers. The differences in risk could be due to dietary habits.
Investigators have suggested a number of mechanisms that might explain the way certain foods could alter the risk of contracting various types of cancer. First, it is possible that certain nutrients alter the cellular environment in important ways. Some nutrients, including Vitamin E, ß-carotene (a form of vitamin A), and Vitamin C have antioxidant properties. Since there is evidence that oxidation of important intracellular chemicals may alter the control of cell differentiation and proliferation, such antioxidants may influence carcinogenesis.
Second, it has been suggested that foods we eat may alter hormone production, though little direct evidence exists for this idea. However, it is well-known that certain tumors, particularly those involving genital organs, respond to hormone levels and may actually be promoted by them. Interestingly, there is some evidence that soybeans alter sterol metabolism in ways that may be important for cancers such as breast cancer.
Third, it is clear that certain dietary articles can influence the rate that materials pass through the gastrointestinal tract — and, by this action, alter the nature and duration of contact between the surface epithelium and certain intra-luminal chemicals. This may influence the risk for bowel cancer.
Commonly, researchers tend to associate consumption of specific nutrients with the risk of cancer. Investigators for the Adventist Health Study have initially followed a different course, preferring to look at individual foods or food groups rather than specific nutrients. Reasons for this include:
- From a public health perspective, the examination of foods — rather than nutrients by themselves — has attraction because people tend to shop for foods rather than nutrients.
- Although specific nutrients have shown to be active agents, foods are literally comprised of hundreds of such chemicals. Therefore, it seems presumptuous to focus on the few nutrients commonly tabulated in dietary tables.
- Because each food is a peculiar mix of nutrients and chemicals, it is possible that a particular food with its unique 'soup' of chemicals might have properties which either promote or prevent cancer.
Findings from the Adventist Health Study have shown certain clear indications of association between diet and cancer, though these relationships are found mainly in tissues of endodermal origin. These include the lungs, stomach, pancreas, colon, and bladder. (See a PDF summarizing cancer findings.)