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Updated 30 October 2015

Let's get some perspective on meat and cancer

The news that we're at an increased cancer risk of colorectal cancer from eating processed meats has caused quite a stir. But, as two South African dietitians point out, there's no proof that removing meat from your diet will protect you against cancer.

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A review of around 800 epidemiological studies by the WHO's International Agency for Research on Cancer (IARC), released on Monday 25 October, showed that eating processed meats like hot dogs, biltong, sausages or bacon can lead to bowel cancer in humans.

They classified processed red meat as a “Group 1” carcinogen (“carcinogenic to humans”) and regular red meat as a “Group 2A” carcinogen (“probably carcinogenic to humans”).

They stated that for an individual, the risk of developing colorectal (bowel) cancer increased by 18 percent for every 50 gram portion of processed meat they eat each day.

Based on the WHO estimates, about 66 in every 1,000 people who eat a lot of red meat or processed meat will develop colorectal cancer in their lifetime; by comparison, 56 of every 1,000 who eat very little meat, processed or otherwise, will develop colorectal cancer.”

Health24's DietDoc, a registered dietitian with a doctoral degree in Nutrition and Biochemistry, responds:

We have been saying for years that eating processed meat in large quantities is harmful. The WHO has announced that any processed meat if eaten in excess of 50 g per day, is as harmful as smoking and Plutonium, so 50 g/day appears to be the limit.

I have always recommended that readers who ask me on the Message Board restrict their biltong intake to 30 g per day!

This is because biltong can be regarded as a snack food and I believe that all snacks should be consumed in quantities of about 30 g (a small handful).

How this will impact the Banting craze will be interesting to watch because many people interpret Banting as carte blanche to eat large quantities of processed meats (‘cold meats’, salami, bacon, all sausage, including boerewors, even the low-salt ones, as well as biltong). The foods contain nitrates, which are added as preservatives and to give the product a red colour.

Nitrates and nitrites can produce nitrosamines in the body which have been known as mutagens (agents that potentially cause genetic mutations) and carcinogens for a very long time.

Ironically, the highest intake of nitrates in the average human diet is from drinking water and vegetables irrigated with water rich in nitrates.

Read: Nitrates in fruit and veg protect the stomach

Unfortunately high-fat, highly coloured sausages and polonies are popular foods for less affluent members of the South African population and are widely sold by street food vendors. An example is the ‘Quarter’ (a quarter loaf of white bread filled with fried eggs, fried sausages, bacon, cheese, atchaar, and other delights).

As one man sitting in a UK pub said this morning on TV: “Yesterday it was sugar, and now they want us to give up our bacon and eggs! Not a chance!”

With all these conflicting and dire warnings about food, beverages and the environment, I can only reiterate what dietitians have been saying for years:

“Eat a balanced diet that consists of a variety of foods, and do not overdo your consumption of any one food or drink.”

The Food-Based Dietary Guidelines say it all.

Prof Hettie Schönfeldt of the Institute of Food, Nutrition & Well-being at the University of Pretoria on how the report relates to South Africans:

  • The Report represents the opinion of a selected group of scientists, not the consensus in the scientific community.
  • This evaluation does not introduce any new evidence. It is based on existing scientific literature.
  • The majority of South Africans consume mostly chicken, then beef, followed by pork, lamb or mutton and processed meat (BFAP, 2015).
  • On average South Africans eat notably less protein-source foods (11 to 18%) compared to recommended levels by the World Health Organisation (WHO) which state that 20% of total dietary energy should be from protein (Mchiza et al., 2015).
  • Food energy of South Africans is mainly derived from carbohydrates such as maize meal and bread (between 57% and 69%) (Mchiza et al., 2015), which is significantly higher than the recommended 45%. This may be linked to affordability rather than to choice.
  • Animal protein, such as red meat, is a favourite food in our diets but the portions at a population level still remain smaller than those recommended by the South African Food-Based Dietary Guidelines. 
  • A surprisingly high intake of eggs and sardines was reported in a recent study in Gauteng investigating meat consumption (Vermeulen et al., 2015), and the total intake of red meat, white meat, fish and eggs remained less than the recommended intake of up to 90g per day.
  • Furthermore, South Africans consume approximately 4.2kg of processed meat per person per year, which equals 12g processed meat per day, which is less than 1/3 of a sausage per day.
  • Red meat plays an important role in a balanced diet, as it contains high biological-value protein and important micro-nutrients such as B Vitamins, iron (both free iron and haem iron), and zinc. Some segments of the population, such as children, teen girls and women of childbearing age, may benefit from an additional serving of meat.
  • There is no evidence that removing meat from your diet protects you from cancer. In fact a major long term study by the Oxford University, UK (Key et al., 2014), has shown no difference in colorectal cancer rates between meat eaters and vegetarians.
  • South African red meat contains less fat than red meat in most first world countries, and the composition of red meat indicates a reduction in total fat content over time. For example research results found that the average fat content of target grade beef decreased from 32% in 1949 to 18% in 1981, and then again to 13% in 1991 (Naude, 1994), and currently it is only 11.3%, according to a study performed at the University of Pretoria (UP) (Hall, 2015). The reduction in fat is directly linked to consumer demand for leaner products.

The International Meat Secretariat recommendations on how to cook meat

  • Stay by the grill or braai and flip the meat more often to avoid overcooking and possible charring of the meat surface.
  • Avoid direct exposure of the meat to an open flame.
  • Panfry red and processed meat over medium instead of high heat.
  • Marinate meat in marinades containing citrus juice like lemon or lime and add spices such as garlic or onion.
The best way to minimize your cancer risk is to live a healthy lifestyle, which includes:
  • Do not smoke.
  • Maintain a healthy weight.
  • Enjoy regular physical activity.
  • Eat red meat along with plenty of vegetables and whole grains.
  • If you do, drink alcohol responsibly.

Read more:

Braai-mad South Africans takes meat warning with a pinch of salt

High-protein diet may up cancer and diabetes risk

Genetic link between meat and colon cancer risk

References used by DietDoc:

- Feeley A, Pettifor JM, Norris SA (2009). Fast-food consumption among 17-year-olds in the Birth to Twenty cohort. South African Journal of Clinical Nutrition, Vol 22(3):118-123.

- Mahan LK, Escott-Stump S, Raymond JL (2012). Krause’s Food & the Nutrition Care Process. 13th Edition, Elsevier Publishing, New York.

 
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