Red Meat and Bowel Cancer

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Full Name: Kannivelu Badrinath
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Red Meat and Bowel Cancer

Post by Badri »

Last week the WHO reported that cured and processed meats like bacon, sausage, hot dogs and ham cause cancer. These foods were added to their top tier list of substances (that includes alcohol, cigarettes, asbestos, and arsenic) that cause cancer. For very many years we have known that bowel cancer is more common in the west than in the East. We often wondered if this was because the rich westerners ate a lot more meat compared to the poor easterners. There was however no conclusive proof until now.

The present report focusses on processed meat like ham, sausage, hot dog etc. The group of 22 scientists from the WHO's International Agency for Research on Cancer in Lyon, France evaluated more than 800 studies from several continents about meat and cancer. Based on that evaluation, they classified processed meat as "carcinogenic to humans" and red meat as "probably carcinogenic."

The North American meat industry is protesting about this report arguing that cancer is a complex disease not caused by single foods. The American Cancer Society has long urged people to reduce consumption of red meat and processed meat. The WHO estimates that a 50-gram portion of processed meat eaten daily increased the risk for bowel cancer by 18 percent. The report also links red meat to cancer. It classifies beef, lamb and pork as "probable" carcinogens

Several years ago the Harvard Health published important information about the effects of long-term meat consumption. It indicated that a high consumption of meat is linked to an increased risk of cancer in the lower colon and rectum. Conversely it also reported that the long-term consumption of large amounts of fish and poultry appeared protective.

The best evidence on the topic comes from two studies published in 2005, one from Europe and the other from the United States. The European research tracked 478,000 men and women who were free of cancer when the study began. The people who ate the most red meat (about 5 ounces a day or more) were about a third more likely to develop colon cancer than those who ate the least red meat (less than an ounce a day on average). Their consumption of chicken did not influence risk one way or the other, but a high consumption of fish appeared to reduce the risk of colon cancer by about a third.

Scientists have offered a number of explanations for the link between red meat and colon cancer. One theory blames heterocyclic amines (HCAs), chemicals produced when meat is cooked at high temperatures. HCAs may play a role, but since high levels can also be present in cooked chicken, they are unlikely to be the whole explanation. Preservatives have also been implicated in the case of processed meats; nitrates are a particular worry, since the body converts them to nitrosamines, which are carcinogenic.

Scientists from England offered a new explanation. Their investigation recruited healthy volunteers. The volunteers ate one of three test diets for a period of 15 to 21 days. The first diet contained about 14 ounces of red meat a day, always prepared to minimize HCA formation. The second diet was strictly vegetarian, and the third contained large amounts of both red meat and dietary fibre.

Stool specimens from the 21 volunteers who consumed the high-meat diet contained high levels of N-nitroso compounds (NOCs), which are potentially cancer-causing chemicals. The 12 volunteers who ate vegetarian food excreted low levels of NOCs, and the 13 who ate meat and high-fibre diets produced intermediate amounts.

These results are interesting enough on their own, but the researchers went one step further. They were able to retrieve cells from the lining of the colon that are shed into the stool. The cells from people eating the high-meat diet contained a large number of cells that had NOC-induced DNA changes; the stools of vegetarians had the lowest number of cells with damaged genetic material, and the people who ate high-meat, high-fibre diets produced intermediate numbers of damaged cells.

The study from England showed that large amounts of red meat can produce genetic damage to colon cells in just a few weeks, but it does not prove that red meat causes cancer. None of the cells were malignant, and the body has a series of mechanisms to repair damaged DNA. Still, the research fits with earlier epidemiologic data raising a red flag about red meat.

Instead of counting on your body to repair your damaged DNA, do everything you can to prevent damage in the first place.
You don’t have to give up red meat to stay healthy, but the evidence suggests that you’d be wise to limit your consumption. Two 4-ounce portions a week should be safe; even then, choose lean cuts, trim away excess fat, and avoid charring your meat on a grill. Limit processed, cured, and salted meats as much as possible.

Dr. Kurt Straif Epidemiologist at International Agency for Research on Cancer said in a statement -“For an individual, the risk of developing colorectal (bowel) cancer because of their consumption of processed meat remains small, but this risk increases with the amount of meat consumed”.

My view on this topic: We have known for many years that bowel cancer is more common in the west than in the East. The evidence now suggests that this is probably because of increased consumption of red meat by the west. The WHO have gone overboard to list meat as "carcinogenic to humans" and red meat as "probably carcinogenic. They have listed bacon, sausage, hot dogs and ham along with cigarettes, asbestos, and arsenic as carcinogenic. This cannot be right. However as there is evidence now that excessive intake of meat can cause bowel cancer, it would be wise to limit the amount of red meat one consumes and try and avoid processed meat as much as possible. Eating a roast or moderate amount of meat once or twice a week is unlikely to cause any harm.
Last edited by Badri on 09 Nov 2015 05:10, edited 1 time in total.
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Full Name: Govind Mohan
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Re: Red Meat and Bowel Cancer

Post by gmohan »

Very good coverage Badri, of this much debated aspect of Meat and cancer risk.

An earlier WHO study also implicated Processed meat and Type 2 Diabetes Mellitus.

few points to also consider:

The average Briton consumes about 70G of meat daily.
A caucasian consumes about 100g of Protein per day . Daily recommended Protein intake is about 46 G for a Caucasian woman and ,56G for a Caucasian man.

The suggestions are that for optimal health and longevity, the most calories consumed should come from : Fresh fruit and vegetables,nuts and seeds ( e.g. Flax seeds).
Beans of all types and whole unrefined grains.

A good source of Omega 3 oils from fresh fish ( not farmed fish) has positive effect on Vascular health- Walnuts have a high content of Omega3 .

G Mohan.
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