Red and processed meat-eating associated with breast cancer in post-menopausal women

This week’s hot nutrition news in the UK concerns a study which assessed the relationship between meat-eating and breast cancer. ‘Red meat ups breast cancer risk’ was, essentially, the way this study was headlined in the media. The brevity of such titles will usually not tell the full story, so I decided to take a closer look at this study and its findings.

In this study, researchers at the University of Leeds in the UK assessed the diets and risk of breast cancer in almost 34,000 pre- and post-menopausal women over about 8 years [1]. Meat consumption and risk of breast cancer was assessed in all women. The researchers also provided data for premenopausal and postmenopausal women taken alone.

This distinction turned out to be important, because the results in pre-menopausal and postmenopausal women were very different indeed.

For instance, high total meat consumption (defined as more than 103 grams of meat a day) in pre-menopausal women was associated with a 12 per cent increased risk of breast cancer compared to eating none. On the other hand, low meat consumption (defined as less than 62 g of meat per day) was associated with a 32 per cent reduced risk of breast compared to eating none at all.

Also, looking at the intake of different types of meat, higher intakes of red meat, processed meat, poultry and offal were not associated with a statistically significant increase in cancer risk.

In post-menopausal women it was a different story. Compared to eating no meat at all, even low levels of meat consumption were associated with a 52 per cent increased risk of breast cancer. High meat consumption was associated with a 63 per cent increased risk. This association was strongest for red and processed meat, hence the headlines. Poultry eating, on the other hand, was not significantly associated with risk of breast cancer in post-menopausal women.

However, it should be borne in mind that this study was a ‘epidemiological’ in nature, and cannot therefore be used to conclude that eating red or processed meat ‘ups breast cancer risk’. Just because two factors are associated, doesn’t mean one is causing the other.

Now, this study did attempt to account for other factors which may explain differences in breast cancer risk including age, weight, activity and fruit and vegetable consumption. However, accounting for such ‘confounding’ factors can be an imprecise science. For instance, breast cancer may be influenced by other factors that were not ‘controlled’ for that might influence the apparent association between meat eating and breast cancer risk.

Those still keen to take a cautionary approach here may like to consider avoiding any over-consumption of red and processed meat. That does not mean, however, that these foods cannot take some place in a healthy diet, though.

A broader view of the influence of meat-eating on health can perhaps be had by looking at overall risk of death in vegetarians and non-vegetarians-eaters. When attempts have been made to control for confounding factors, there has been found to be no statistical difference in mortality in those eating meat compared to vegetarians [2].

References:

1. Taylor EF, et al. Meat consumption and risk of breast cancer in the UK women’s cohort study. British Journal of Cancer 2007;96:1139-1146

2. Key TJ, et al. Mortality in British vegetarians review and preliminary results from EPIC-Oxford. Am J Clin Nutr 2003;78(suppl):533S-8S

8 Responses to Red and processed meat-eating associated with breast cancer in post-menopausal women

  1. Robin 6 April 2007 at 2:52 pm #

    What nobody seems to point out is that the human race has been eating red meat for a long, long time. The incidence of breast cancer, on the other hand, has been increasing steadily over the last 50 or more years. It may well be coincidental that the increase has been occuring at the same time as the use of the contraceptive pill and HRT.
    My wife has steadfastly refused to have a scan and, at nearly 65, may well have adopted a sensible approach when one considers the possible impact of high doses of XRays in breast scans.
    Generally, I’m glad I’m a man!

  2. Neil 6 April 2007 at 9:18 pm #

    or this study over 20 years which reckoned to find no association.

    http://aje.oxfordjournals.org/cgi/content/abstract/164/10/990

    I wonder what’s better, a trial with fewer participants, but tightly randomised and controlled,
    or more participants in a trial with more variables??

  3. Sara Neill 12 April 2007 at 2:49 pm #

    As I understand it, there is a difference in the risk of cancer from eating red meat that is organically reared, and that which is not – with organic meat being safer to eat. This is because the chemicals given to non-organic animals are stored in their fat, which is then eaten and absorbed by us.

    I don’t remember the study that showed this, but I would be interested to find out if I understood its findings correctly.

    Since our bodies are designed to consume meat I assume that is what is best for us. The ethics of killing and eating animals is another question entirely, of course.

  4. Dr John Briffa 12 April 2007 at 3:16 pm #

    Sara
    I’m not aware of any research that has looked at this explicity, though the idea you present makes sense to me. Also, the concept is supported by the evidence which shows that, gram for gram, processed meat (which usually contains potentially cancer-inducing preservative chemicals) is more strongly associated with cancer than non-processed meat.

  5. Diana 13 April 2007 at 1:53 pm #

    Large studies can throw up interesting links but they can also be not sufficiently sensitive to all the variables in the object of the study. An interesting example recently was that of dairy products ” now that the data has been further sub-divided recent studies show that low-fat milk is more damaging to human health than full-fat milk.

    Re red meat. Variables that could affect the result ” as well as organic/non-organic – could be how well the meat was cooked ie did the person regularly consume a lot of meat that had been burnt at the edges? Was the meat from grass-reared cattle? Intensively reared cattle fed on, for example, corn products apparently have a different mix of fats present in the meat. And D’Adamo proposes that your blood group will affect how your body reacts to different foods. Those who have ‘O’ group blood thrive on red meat and the ‘B’ group do so to a lesser extent. It does not suit ‘A’ and ‘AB’ blood groups.

  6. Sara Neill 13 April 2007 at 6:50 pm #

    THANK YOU FOR THAT. iT GIVES FURTHER FOOD FOR THOUGHT (PUN NOT INTENTIONAL.)

    SARA

  7. Tilly Baxter 17 April 2007 at 8:37 am #

    Is there any evidence I wonder that in countries where there is higher consumption of processed meats such as Germany, France and Italy, with their fantastic hams, pates and sausages of all kinds, of higher incidents of breast cancer?
    Tilly

  8. prakasham 11 December 2008 at 7:53 am #

    What are the difference between “red meat and processed meat”

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