Red and processed meat eaters face greater risk of disease

New research from the US published in the Archives of Internal Medicine, shows that individuals who eat more red meat and processed meat appear to have an increased risk of death from all causes and also from cancer or heart disease over a 10-year period. In contrast, a higher intake of white meat appeared to be associated with a slightly decreased risk for overall death and cancer death.

The Australian and British Science Media Centres rounded up comment from experts on the research, which was published yesterday.

The association between meat intake and risk of death was assessed among more than 500,000 individuals who were part of the National Institutes of Health-AARP Diet and Health Study in the US. During the 10 year follow-up period, one-fifth of men and women who ate the most red meat (a median or midpoint of 62.5 grams per 1,000 calories per day) had a higher risk for overall death, death from heart disease and death from cancer than the one-fifth of men and women who ate the least red meat (a median of 9.8 grams per 1,000 calories per day).

Experts respond:

Professor Ian Olver is Chief Executive Officer of Cancer Council Australia

“This large study provides further evidence to support the recommendations by groups such as the World Cancer Research Fund in demonstrating an association between a high consumption of red and processed meats and a increase risk of death from cancer. Such population studies demonstrate these relationships between red meat and cancer deaths but are not able to prove that one causes the other. They do however give impetus for further more specific research. With red meat for example the method of cooking is important. For example, more carcinogens would be expected to be produced from barbeque than by slow cooking. Also the other factor predisposing to cancer is the fat content of the meat.

“The main limitation of the study is the self reporting of diet which is known to introduce inaccuracies. The message for consumers is to eat a diet with a balance of all of the food groups and foods such as red meat in moderation.”

Dr David Topping is a Senior Research Scientist with CSIRO Food Futures and Preventative Health Flagships, based in Adelaide.

“The group is an internationally recognised one with the senior investigator (Arthur Schatzkin) having an international reputation. The study is large and the procedures used are recognised. The journal has high editorial standards. The data linking red and processed meat to greater cancer risk support the findings of other studies but the finding of lower risk with greater white meat intake seem to be rather at variance with previous findings but may relate to their definition of white meat (which seems to include tuna ie fish).

The key finding me is the marked difference in fibre intakes with greater meat consumption. The fibre intakes of those with the lowest intakes of red meat are relatively high by US standards (25 grams per day (g/d) for men and 21 g/d for women). Australian intakes are high ~27 g/d, on average. However, the intakes for those at the highest quintile of meat consumption are much less at 18.6 and 14.8 g/d, men and women respectively. Previous studies have shown a dose-dependent lowering of colo-rectal cancer risk for dietary fibre and a number of studies have shown protective effects of fibre against a number of conditions. One could interpret the data as being compromised by the lack of control for fibre. It is true that Australian fibre intakes are high but so are colo-rectal cancer rates but we interpret this as reflecting the types of fibre consumed here. A large CSIRO Preventative Health study is showing that the type of dietary fibre has a significant influence on biomarkers which indicate bowel health and could lower colo-rectal cancer risk.”Horizontal rule

Mark L Wahlqvist is Director of the Asia Pacific Health and Nutrition Centre, Monash Asia Institute, Monash University, Victoria

“The publication by Sinha et al in the Archives of Medicine in March 2009 about meat consumption and mortality in the US National Health Institutes – American Association of Retired Persons Study of some half million people, provides even more certainty that, in diverse populations, minimizing red meat intake and avoiding processed meats altogether is an important measure to reduce mortality from both cancer and cardiovascular disease. White meat in this study meant poultry and fish – for both men and women, it was protective against total mortality, cancer mortality and all other causes of death collectively assessed.

“This study was amongst White, Hispanic, Black, Asian and Native Americans. It is consistent with the Australian Health 2000 study (Victorian Anti-Cancer Council) of more than 30,000 Australian, Greek, and Italian born Victorians. It also provides similar information to a similarly large study across several European countries (EPIC, the European Cancer study). The corollary is that a plant-based diet is a preferred orientation for food intake in the human species and many studies support this conclusion.

“The US study has taken into account energy (calorie) intake and physical activity which, along with obesity, are now known to be increasingly important risk factors for several cancers like large bowel and breast, as they are for cardiovascular disease. Nevertheless, meat, especially processed meat, might be a greater risk in populations with low physical activity and obesity. The recent (2007) WCRF (World Cancer Research Fund) report on Diet, Physical Activity and Cancer would support this view.

“What then is the place of meat in the human diet? In small amounts, even about an ounce or 30g, it can make a significant difference to the risk of micronutrient (vitamins and minerals) deficiency, protecting against such deficiency. Fresh, lean red meat of these amounts is likely to be of more benefit than harm. For most of the world’s food insecure, this would be an advantage.

“But, if meat production, with its land, energy and water requirements and green gas emission potential, is to be sustainable, it will need to be a little for most and not a lot for a few!”

Dr Shawn Somerset is a Senior Lecturer and Nutrition Specialist in the School of Public Health at Griffith University, Queensland

“The average intake of meat in Australia is far in excess of the intake recommended by the International Agency for Cancer Research. The current official Australian Dietary Guidelines recommend ‘Include lean meat, fish, poultry and/or alternatives’, which is out of step with advice to reduce meat intake. Substantial revision of advice on meat consumption by nutrition professionals and health agencies in Australia is well overdue. ”

Glenys Jones, Nutritionist, MRC Human Nutrition Research (UK), said:

“This research is consistent with a growing number of studies looking at processed and red meat intake and their relationship to ill-health although it must be taken into account that these studies are observational and therefore it is not possible to adjust for all potential confounding factors. Interventions, if they were carried out, would not only reduce meat intake but also subsequently increase vegetable, bean and pulse intake, and this would result in an increase in dietary fibre intake, which has been positively linked to health.

“Meat is a good source of bio-available iron and other nutrients and is an important part of the diet. Evidence points to a diet containing modest amounts of meat being more beneficial to optimal health than those containing high amounts, particularly of meats that are fatty, burnt or processed with added salt and nitrates. Therefore for high meat consumers a message of moderation should be projected. There are also environmental benefits of reducing meat intake, in that the carbon and oxygen embedded in meat production is extremely high and with a population of 9 billion to feed by 2050, meat intake will need to reduce to produce sustainable diets.”

Ed Yong, Cancer Research UK’s health information manager, said:

“We’re now in a position where two of the world’s largest studies on diet and cancer have found that people are more likely to develop some cancers, if they eat too much red or processed meat.

“No one’s saying that people should avoid bacon or burgers completely, but evidence from large studies like this tells us that cutting down on these foods can reduce the risk of dying from cancer and other diseases. In this new study, people eating the most meat were eating about 160g of red or processed meat per day – approximately a 6 oz steak – while those who ate the least were only getting about 25g per day – approximately a small rasher of bacon.

“To help reduce your risk of cancer, Cancer Research UK recommends a balanced diet high in fibre, fruit and vegetables and low in saturated fat, salt and red and processed meat.”