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Does Red Meat Cause Colon Cancer?

Posted Oct 14 2008 4:01am

Colon cancer on four legs?

I was involved in a discussion recently where the statement of “red meat causes colon cancer” was spoken. Figuring that to be a gross overgeneralization, I decided to do some sleuthing and see what the record shows regarding red meat and colon cancer. I meandered over to Google, typed in “red meat” and came up with a screen full of search results. Of the first five hits, four are irrelevant (a comic strip called “Red Meat” and a honky tonk band called…”Red Meat”) and the fifth is to Wikipedia.

But the sixth result is where the fun begins: Eating Lots of Red Meat Linked to Colon Cancer. It’s also a prime example of how data is twisted to create news that sells.

The verdict: Eating large amounts of red or processed meat over a long period of time can indeed raise colorectal cancer risk. But the risks from such a diet are smaller than those from obesity and lack of exercise, both for colon cancer and for overall health. [my emphasis]

Now, go back and read the headline. Then reread this quote. Obesity and physical inactivity are greater risks to colorectal health, but the report focuses on the red meat. And most people read the headline and perhaps a couple paragraphs. Unfortunately the above quoted text wasn’t until the third paragraph. How ’bout them apples?

Digging Into The Data

Let’s look at several variables that I think are important when considering whether or not red meat as a whole is a bad thing for your rectum. Here is a quick list of three major ones:

  • How was the meat raised?
  • How was the meat processed?
  • How was the meat prepared?

Grass-fed vs. Conventional Meats
The type of meat makes a difference:

The general belief is a reduction of red meat intake [reduces colorectal cancer risk], and subsequent nutritional advice usually strongly recommends this. Paradoxically, beef together with whole milk and dairy derivatives, are almost the only sources for conjugated linoleic acid (CLAs) family. Furthermore CLAs are the only natural fatty acids accepted by the National Academy of Sciences of USA as exhibiting consistent antitumor properties at levels as low as 0.25 – 1.0 per cent of total fats.

Remember that Conjugated Linoleic Acids are found in much higher quantities in grass-fed meats vs. conventional grain-fed meats. Unfortunately, we’re not going to get beyond putting two and two together since no studies (that I’ve found) are comparing grass-fed to grain-fed meats in terms of cancer.

Processed vs. Fresh Meats
In most studies I’ve seen, there is little to no differentiation between “red meat” and “processed red meat”. Salami and pepperoni are red meat. Does that mean someone that eats a lot of pepperoni pizza has a high intake of red meat in studies? How does a steak compare to a sausage?

Processed meat intake, CYP2A6 activity, and risk of colorectal adenoma:

Our results suggest that nitrite and nitrate intake from processed meat intake increases the risk of colorectal adenoma after accounting for HCA and PAH. [2-fold increased risk in the highest, compared to the lowest, quartile]

Recall The Diet-Cancer Study? It found a 21% increase in colorectal cancer risk for each 1.7oz of processed (smoked, salted, cured, chemical preservatives) meat. Nitrates, present in most any preserved meat you’ll find in the grocery, have been found to increase colon cancer risk …even when water is the source.

It’s How You Cook It
There have been studies that looked beyond just total red meat intake to examine how the meat was cooked:

No associations were found for red roasted or for boiled meats.

Conclusion: Increased risk seems to be related to cooking temperature and close contact of the food to the heating source, because higher risks were observed for heavily browned surfaces when meats were barbecued or iron-pan cooked.

Note that how the meat is cooked is what determined risk in this study. Roasting or boiling showed no association with risk. That’s because high temperature cooking increases the creation of carcinogens known as heterocyclic amines. Low temperature cooking, on the other hand, do not promote heavy creation of HCAs.

Other Study Examinations

There have been three discussions on Weston A. Price regarding red meat and colon cancer.
Here is the first one:

Colon cancer was also tied to beef in an erroneous interpretation of the National Cancer Institute Japanese-Hawaiian study which actually showed macaroni, green beans and peas to have higher risk associated with colon cancer than beef or lamb.1

And the second:

Myth: Beef causes colon cancer

Truth: Argentina, with higher beef consumption, has lower rates of colon cancer than the US. Mormons have lower rates of colon cancer than vegetarian Seventh Day Adventists (Cancer Res 35:3513 1975)

Correct me if I’m wrong…if the hypothesis holds, shouldn’t the country with the highest beef consumption in the world also have the highest rates of colon cancer? And shouldn’t meat eaters (Mormons) have higher rates of colon cancer compared to vegetarians, especially when both groups are likely living squeaky clean lives in terms of drinking and smoking (considering religious restrictions)?

And number three:

Two American studies conducted in the 1990’s have found a higher risk of colon cancer among those who eat red meat.8 However, no study done in Europe has ever shown an association between meat consumption and cancer. 9

While two US studies have implicated meat consumption as a cause of colon cancer, there are several that contradict these findings. In 1975, Rowland Philips compared Seventh-Day Adventists physicians, who do not eat meat, with non-Seventh Day Adventist physicians, and found that the vegetarian doctors had higher rates of gastrointestinal and colon-rectal cancer deaths.10 National Cancer Institute data show that Argentina, with very high levels of beef consumption, has significantly lower rates of colon cancer than other western countries where beef consumption is considerably lower.11 A 1997 study published in the International Journal of Cancer found that increased risk of colon and rectal cancer was positively associated with consumption of bread, cereal dishes, potatoes, cakes, desserts and refined sugars, but not with eggs or meat. 12 [my emphasis]

Here are links to some the studies WAPF used in that last quote there:

So What’s The Word?

I think the data shows no issues from eating quality grass-fed meats, fatty or not. Grass-fed meats contain CLA, known to be an anti-cancer compound. Further, I think cooking “low and slow” is the safest way, along with avoiding chemically-preserved meats. I don’t think there’s anyway that anyone can say there is definitive proof that red meat is harmful, especially considering that nobody is looking at properly-raised meats.

What do you think about the association of red meat with colorectal cancer? Is there data that I’ve missed one way or the other?

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