Meat is bad for you. Wait, it’s OK

Contrary to decades of work, researchers from Dalhousie and McMaster Universities recently found that red meat, including bacon, is not harmful. It wasn’t a new study but rather a “study of studies,” a meta-analysis of existing studies.

image: Foreman Grill Recipes

It was a perfectly flawed study. Perfect because it offered a veneer of the scientific method; flawed because of what it didn’t include.

It didn’t include studies that found the opposite of their conclusion. Those well-researched studies found a link between meat consumption and coronary heart disease, heart attack, Type 2 diabetes, cardiovascular death and all-cause mortality. That’s quite an exclusion.

As well, the researcher’s conclusions were contrary to those of the World Health Organization, the Canadian Cancer Society, the American Institute for Cancer Research, and the American Heart Association. Their findings also diverged from Canada’s new Food Guide which suggests eating less animal protein.

Why did the researchers not include studies that concluded the opposite of their report? They weren’t funded by the cattle or pork industry. The reason that they didn’t include the studies was technical. The self-selected 14 member panel decided that these findings were not of sufficient quality.

What they did include is suspect. For example, they included one trial that dominated their analysis; a trial involved almost 49,000 women. But that trial was designed to examine dietary fat intake, not meat intake says nutritionist Leslie Beck (Globe and Mail, October 2, 2019).  It seems to me that a study purporting to investigate the relationship between meat consumption and health shouldn’t include fat consumption.

And the researcher’s findings were flawed in another way. They did not distinguish between the consumption of red meat and processed meat, despite evidence that processed meat such as bacon is more harmful.

It’s not surprising that their study should come to the conclusion that it did. Obviously, what’s included will determine the outcome.

The researchers at Dalhousie and McMaster Universities were exhaustive in a peculiar way. They were exhaustive in the number of findings: they conducted not just one review but five.

Three of the reviews analyzed more than 100 observational studies involving more than six million participants. These types of studies link associations between consumption and health by following people for decades to see if participants who became ill or died.

Another of the five reviews analyzed randomized controlled trials, studies that show cause and effect of eating more or less red meat.

The researchers were thorough enough to appear scientific but blind in excluding accepted knowledge. They couldn’t see the forest for the trees.

The authors acknowledged their lack of confidence in their data. They conceded that their recommendation was weak but judging by the headlines they received, you wouldn’t know it.

Finally, studies on groups of people don’t necessarily predict outcomes for individuals. Leslie Beck says:

“A large body of evidence suggests that a high intake of red and processed meat increases the risk of ill health. I acknowledge that the risk on an individual level may be small, and that it’s your overall diet that matters most when it comes to health, not one food.”

Lies, damn lies, and category 1 carcinogens

The World Health Organization recently placed processed meat in category 1 of carcinogens, along with radioactive elements and asbestos. That’s the list of agents “carcinogenic to humans.” They also placed red meat in 2A which includes Glyphosate (Roundup) and lead compounds which are merely “probably carcinogenic to humans.”

bacon

Is eating bacon more likely to cause cancer than exposure to an herbicide? No. Agents aren’t listed according to risk. The criterion used is: do they or do they not cause cancer. The categories are grouped by experts according to certainty from the most evident all the way down to category 4, “Probably not carcinogenic to humans” of which there is one item, Caprolactam (used to make nylon).

Risk is determined by how much you are exposed to the carcinogen. André Picard, public health reporter for the Globe and Mail explains:

“The expert group does hazard identification, not risk assessment. Practically, that means they determine, yes or no, whether something may cause cancer, but not how potent it is at a causing cancer,” and adds, “It’s important to remember, however, that not every exposure to a potential carcinogen will cause cancer: Frequency, intensity and potency matter.”

All agents in a category don’t carry the same risk. If they did, people would be dropping like flies from eating meat. Compared to other items, they are not.

Eating processed meat and smoking tobacco, both in category 1, don’t have the same mortality rate. Processed meats result in 34,000 deaths worldwide annually whereas smoking causes about one million cancer deaths. Also in category 1, asbestos kills more than 100,000 and alcohol causes 600,000 cancer deaths a year.

Also misleading is the way percentages are used to translate statistics. For example, two slices of bacon are reported to increase your risk of colorectal cancer by 18 per cent. Eating a 4 ounce steak will result in a similar increase. But when risks of colorectal cancer are low to begin with, a small percentage increase of a small risk is still a small risk. The actual numbers expose this fallacy, explains Pickard:

“Based on these 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.”

In other words, the increased risk is 10 out of 1,000. If you are one of those 10 persons who acquire cancer from eating meat, it’s tragic but as a risk assessment it’s not that bad.

Risk assessment is complicated by the toxicity of the agent, the amount of the agent you are exposed to, the length of time exposed to it, the way you are exposed (inhaled, ingested, topically applied), and your genetics.

The categories are useful in determining what to avoid, if possible. But some things are almost unavoidable. Like living: walking in the sun (ultraviolet rays), working (painter, hairdressers and shift-workers), eating (barbequing at high temperatures), camping (wood smoke), and travelling (cosmic rays from flying in a plane, breathing vehicle exhaust).

Unavoidable, like being alive: the naturally produced hormone estrogen has been linked with cancer, especially when combined with the artificial hormone progestin.