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Oct232009

The Meat of the Matter: Red Meat and Cancer

 

Written by Tom Nikkola - Director of Nutrition & Weight Management

"Red meat is strongly linked to cancer" reads the headline in a recent medical journal. Many such headlines have been found in newspapers, magazines and other article sources. Does the consumption of red meat really cause cancer?

Since the 1960s, meat has been associated in some research studies with higher levels of various cancers. Interestingly, there have been many studies that have shown no association either. Does one of the most popular sources of dietary protein in many countries really cause cancer? The most likely answer to the question is "maybe, but it depends." If you remember from last week's article, the definition of red meat is not black and white when you review what the literature says about meat consumption. The spectrum of "meat" can range from a highly-processed hot dog to a cut of grass-fed beef steak. 

 

 

 

 To date, there has not been a clinical trial done to compare a group of people who refrain from red meat and compare it with those that do eat it for an extended period of time. Because of the cost of such a study and the challenge in controlling all the necessary variables, it's unlikely such a study would take place. Instead, the studies that have been done are epidemiological studies. They generally look at a group of people with higher cancer rates and compare that group, or groups, with another group, or groups of people with lower rates of cancer. Then they look at individual variables, such as total meat consumption and attempt to draw conclusions. Another way to do the study is to look at meat consumption in various populations and then compare the occurrence of cancer. The results of these studies have been mixed. Many studies have been done that show no effect of meat consumption on cancer risk, but they do not usually make new headlines.

 

 

Study Difficulty

Researching meat's effect on disease risks, including cancer, is a difficult task. Since the studies are epidemiological studies, they rely on food frequency questionnaires, which are known to be limited in their accuracy. As an example, one could ask a group of Americans about how often they eat red meat and compare meat consumption with another group from a country like China where there may be lower rates of various cancers and ask. There are several disadvantages to this type of study. They leave many questions unanswered, such as: What kind of red meat was it? Was it processed? How was it processed? Was it grass-fed meat or commercial meat? Then, the even more significant questions come into play, like: What about overall calorie consumption? What processed carbohydrates might be a part of the diet in one group and not the other? What other lifestyle variables are possible? What was fruit and vegetable consumption like? Is it possible that the health associated with plant-based diets comes more from high intakes of fruit and vegetable intake rather than limited meat consumption? 

Cancer is more common in more developed nations, which tend to eat more meat, but also tend to eat more processed foods, sugar, less fruits and vegetables, might drink more alcohol, endure more daily stress, etc. So, to look at various populations and compare one piece of the diet and attempt to link it to a disease is a bit of a stretch. If we were able to so easily tie such associations together, we might also say that bottled water causes cancer because more developed countries, where cancer is more prevalent, drink more bottled water than less developed nations. Obviously no one would want to make that claim because it doesn't make sense.

 

 

What about meat could lead to cancer?

If studies have not yet shown a direct cause of cancer, does that mean there is no concern about meat consumption? Not necessarily. Carcinogens created during high-temperature cooking of meats can be part of the equation that could lead to colon cancer. According to Sally Fallon, "colon cancer occurs when vegetable oils and hydrogenated fats, along with certain carcinogens, are acted on by certain enzymes in the cells lining the colon." With the higher prevalence of vegetable oils and hydrogenated oils in American diets, the addition of carcinogens from meat cooked at high temperatures could increase the risk of cancer. Of course, this includes three variables - vegetable oil, hydrogenated oils and carcinogens. It's possible that if vegetable oils were not part of the diet, the carcinogens might have no effect.

Excess consumption of preservatives is another possible cause of the higher relation of meat consumption and cancer. Although they have been suggested to be safe when consumed in moderation, if people eat a diet mostly composed of processed, preservative-filled meat, they could increase their risk of certain cancers. If preservatives were a concern for cancer risk, a simple solution would be to avoid processed meats containing preservatives. This is as simple as reading a label and choosing wisely.

Gary Taubes, in his book Good Calories, Bad Calories presents another possible explanation.  Because many of the cancers occur in "endocrine-dependant organs," a disruption in the body's normal hormonal balance could increase the risk of cancer. An imbalance of hormones could occur from a diet of highly refined carbohydrates, which affects the body's ability to regulate the hormone insulin. It's possible this could lead to other hormonal disruptions. Also, more studies are pointing to the fact that increased levels of body fat tend to also release additional hormones that could affect the normal balance of hormones in the body. As mentioned above, cancer occurs at higher rates in more developed nations where obesity is higher and more processed carbohydrates are consumed. Higher meat consumption happens to also occur in these populations. In this case though, meat would be guilty only by association. Along those same lines is the question about the hormones used in commercial meats. Although they are supposedly safe, they can be easily avoided. If there was even a small possibility that the hormones passed along in animal products, it is not worth it to take the chance. Choose hormone-free products.

Finally, the majority of today's commercial beef is fed a corn-based diet, which dramatically changes the nutrient profile of the meat. When cows are fed corn, they have a much higher concentration of omega-6 fatty acids. Omega-6 fatty acids have been shown to increase inflammation. Cows fed their natural diet of grass have much more omega-3, which is anti-inflammatory.

 

Summary

To ensure you get the best nutrition possible, while avoiding any cancer-related risks, there are some simple steps you can take to improve your diet:

  • Avoid preservatives. If you're going to eat processed meats, be sure to purchase preservative-free meats. Even if they are okay to eat in the diet in moderation, they're not necessary, so go without them.
  • Look for hormone-free meat and dairy products. Specifically, look for packaged meat that says "raised without the use of hormones or antibiotics." A label that claims "raised naturally" or "antibiotic free" does not always mean it was raised without any hormones or antibiotics.
  • As much as possible, try to purchase meat products that were fed a natural diet during their life cycle. Grass-fed, free-range beef, pastured pork and chicken, etc. When animals are fed their natural diet, the nutrient profile of the meat is improved dramatically. If you are not sure where to shop for farm-raised, natural foods, check out Eat Well Guide. All you need to do is enter your zip code and you'll find farms, stores, farmers markets and restaurants in your area that offer these foods.
  • Eat plenty of vegetables and fruit. See Add Some Color to Your Day for more details.
  • Reduce stress and get plenty of exercise

As long as you make wise choices about the type of meat you eat and how it was raised, it can be an important part of a well-rounded nutrition program.

References:

Taubes, G. Good Calories, Bad Calories. 2007. Anchor Books, New York, New York.

Pollan, M. The Omnivore's Dilemma. 2006. Penguin Group, New York, New York. 

Fallon S, Enig M. It's the Beef. Wise Traditions. The Weston A. Price Foundation Newsletter. Spring, 2000

Brody J. Paying a Price for Loving Meat. The New York Times. April 27, 2009

Eades M. Meat and mortality. The Blog of Michael R Eades, M.D. March 24, 2009

Hansen W. Is red meat's bad name justified? Los Angeles Times. November 10, 2008

This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.

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