Antioxidants and disease: more questions than answers

Reactive oxygen species are widely believed to be involved in the etiology of many diseases as indicated by the signs of oxidative stress seen in those diseases. Conversely, antioxidants are believed to be protective. An important part of the supporting evidence is the consistently-seen inverse association between, on the one hand, intake of B-carotene and vitamin C and of fruit and vegetables, and, on the other hand, risk of cancer and coronary heart disease (CHD). However, the failure of supplemental p-carotene to prevent these diseases in intervention trials suggests that the associations for that nutrient reflect confounding rather than cause and effect. With respect to other antioxidants there is inconsistent evidence that supplements of vitamin E may have some ability to prevent cancer and CHD while selenium may prevent cancer. Overall, the role of oxidative stress in disease, especially cancer and CHD, has probably been overstated; other components of the diet (other nutrients, phytochemicals and dietary fiber) likely play a significantly greater role The possible benefits of supplements are discussed

Food Adverts on Children's Programs on TV in South Africa

I attended the conference from April 5 to 9. This conference was very valuable for my work for several reasons: I presented my poster, which was viewed by many people, I had a meeting with the series editor of Humana (one of my publishers) and several authors, I had valuable meetings with many people.Research in the U.S.A. since the early 1990s has shown that adverts that appear on children’s programs on TV are the antithesis of the recommended diet. They are mainly for fast foods and for foods rich in sugar and fat. There is almost no promotion of healthy food choices. Essentially all such previous research has been conducted in developed countries. In this study we examined food advertising on children’s TV in South Africa. We recorded 2 sets of children’s programs during weekdays: (1) 12 hours of programs (SABC2; 9 am-11 am); these are for children below school age, are mainly in English and Africaan, plus a small amount in Xhosa. Out of 47 ads none were for food. (2) 37.5 hours of programs were recorded on YoTV (SABC1; 3 pm-530 pm). This program is for children aged over approximately 7 years. It is mainly in English plus a small amount in Zulu. Out of 408 ads 69 (16.9%) were for food. Virtually all (97%) of the food ads fall into 2 groups: (1) 38 ads (55%) were for foods of generally poor nutritional value (fast food restaurants, highly refined breakfast cereals, candies, potato chips, and sugar-rich cold drinks); (2) 29 ads (42%) were for foods of generally good nutritional value (yoghurt and peanut butter). These findings suggest that food ads on children’s TV in South Africa is more evenly balance towards healthier foods than is the case in the U.S.A. Further investigation is required to form a clearer picture.Academic & Professional Development Fund (A&PDF

Dietary fats and coronary heart disease.

The prevention and treatment of coronary heart disease (CHD) necessitates vigorous dietary intervention so as 10 lower the serum cho1eslero11evel by at least 6%. Greater decreases in serum cholesterol can bring about reversal of atherosclerosis. The critical dietary change is the reduction in intake of saturated fat and cholesterol. Some of this fat may be replaced by unsaturated fats, especial1y monounsaturated fat (olive or canola oil). Fish and the omega-3 fats they contain may also be useful for the prevention of CHD. The benefits of omega-3 fats occur within a few months and probably involve an anti-thrombotic effect. There is evidence that the intake of rrans-fatty acids formed by the hydrogenation of oils should be reduced as they are associated with CHD. Hypolipidaemic drugs may be useful for persons at very high risk of CHD but should general1y be avoided for primary prevention

Nutrition and disease: challenges of research design

This review discusses research methodology in the relation between diet and disease. Medical research can be divided into two types: complex research (the detailed study of disease mechanisms using such methods as biochemistry and molecular genetics) and simple research (the investigation of the factors that cause or prevent disease using methods such as epidemiology, intervention trials, and analagous studies on animals). Although complex research has received the bulk of resources, the large majority of our information of practical value has come from simple research. This general principle is illustrated in the area of diet and disease by examples from various areas: selenium, carotenoids, and cancer; vitamin E,w-3 fatty acids, and coronary heart disease; dietary fat and obesity; dietary sodium and hypertension; and alcohol and stroke. Discussion then turns to aspects of the design of cohort (prospective) studies. Because of problems of sample size and relative lack of diversity, previous studies often failed to give clear-cut results. Suggestions are made concerning the design of cohort studies, notably the use of much larger numbers of subjects and with greater diversity in their diets. The problem of confounding also is discussed. Lifestyle factors often cluster together but cohort studies may not have fully unraveled this

Survey of nutrition knowledge of Canadian physicians

Objectives: Previous reports have indicated that physicians generally have little training in nutrition and a poor knowledge of the subject. A survey was carried out to determine the nutrition knowledge of physicians working in general practice. Methods: A questionnaire with multiple-choice questions was mailed to 248 physicians working in Alberta, Canada, mainly in Edmonton and Calgary. Non-respondents received a second questionnaire and a phone call. Results: Completed questionnaires were received from 36.1% (84 of 233 eligible physicians). The average correct response was 63.1%. The results indicate that physicians are generally aware of information which has been publicized in the medical press: which nutrients are antioxidants; the nutrient associated with the prevention of neural tube defects (folate); the preventive action of fruit and vegetables against cancer; the energy value of fat (9 kcals/g); and the recommended fat intake (under 30% of energy). By contrast they have a poor knowledge of other important topics in nutrition: the typical salt intake of Canadians; the association between excess protein intake and calcium loss; the type of dietary fiber helpful in lowering the blood cholesterol level (soluble fiber); and the nutrient which helps prevent thrombosis (omega-3 fat). Conclusions: These results support other data that physicians need more training in nutrition

Simplicity - the key to fruitful medical research

Medical research is here divided -into two broad categories. The great majority of research is "complex" and includes all studies of intricate body mechanisms. A minority of research is "simple" and deals mainly with direct relationships between human environmental or lifestyle factors and disease incidence (or with analogous studies on animals). In addition, it includes studies of simple body mechanisms. Examples are provided to demonstrate that most of our medical knowledge of practical benefit derives from simple research. This is particularly the case in the area of prevention

Refined carbohydrates - a cause of suboptimal nutrient intake.

During the refining of carbohydrate foods there is a sharp drop in the concentration of dietary fiber and of various vitamins and minerals. Estimates were made of the effect of refining on the total diet intake of fiber, selenium, folic acid, vitamins E and B6, choline, chromium, magnesium, zinc, manganese, copper, sodium and potassium. The health implications of this are discussed and it is concluded that the losses are likely to be detrimental