- Dr. David Alfaro
I am a meat eating hypocrite
So this article came out today telling the world that red meat and cured meats are bad for you. Well too bad so sad. I love red meat. I love prosciutto. It makes me so happy. But, my love for yummy meats also makes me a hypocrite. If you have been reading my blog, you will have noticed that I do not like toxins and additives in my health products, but.....I happily eat "toxic" food? Hypocrite! Yes, I am, but I have made scientific, statistical evaluations on the risk/reward balance of meat consumption, and I am willing to accept the consequences.
Let us talk about meat and cancer.
The World Health Organization had 22 scientists meet at the International Agency for Research and Cancer in October of this year and published an article in The Lancet, a very reputable medical journal. All of this is VERY, VERY convincing. I mean, 22 scientists cannot be wrong! And it is The Lancet!
But when you read the article, you see that it is basically just a review of the research that has been out there for years already. Nothing new. I bet they got together and drank some great wine, ate some awesome charcuterie and had a nice rack of lamb, while they talked about the data that their underpaid, overworked research assistants slaved over for the last 2 years.
The authors quote statistics from a meta-analysis that is almost half a decade old, and if you really want to know what is going on, you have to go to the primary source, which I did.
This article is a meta-analysis, which means that the researchers read all of the papers that they could get their hands on, set specific inclusion criteria (to make sure they evaluated only the well designed studies), and then applied statistical methods to pool the results of all the papers to obtain a net result.
It is easy to get fooled by statistics, and it is even easier to take the numbers and to word them in a convincing manner. That is exactly what has happened in this situation. If we dig deeper into the numbers presented in this paper, we see a whole bunch of red flags.
The authors are looking at "relative risk"; what is the risk of getting cancer in people who eat meat, in comparison to those who do not. A value of 1 means that there is no difference. A value greater than 1 means that there is an increased risk, and a value lower than one means that there is a decreased risk.
Looking at some of the data in the article, we see that there is a HUGE variation in the relative risk, depending on where the reasearch was performed. In Europe the consumption of red meat was associated with a 29% increase in cancer risk, while in North America it was only 11% and in Asia it was -7%......yup, eating red meat protects you from colon cancer if you live in Asia. Just looking at those results, something is fishy!
There are many other curious statistical anomolies in the paper. For example, when analysed alone, meat was protective against rectal cancer in women (-10%), so were cured meats (-6%), but when analysed together, the risk was 212% higher! Two rights make a wrong? The data is littered with all of these things that just do not add up.
Then there is that whole correlation vs causation thing. The authers even admit that the research was primarily retrospective in nature, with very few interventional studies on humans existing. If we really wanted to measure the effect of meat on cancer we would have to grab a group of people who have never eaten meat, randomly assign them to a meat or non-meat group, then follow them FOREVER, and see which group had higher cancer rates. That kind of study is virtually impossible.
Nonetheless, a statistical conclusion is made: eating 100 g a day of red meat is correlated to a 17% increase in colorectal cancer, and eating 50 g a day of cured meats is correlated to an 18% increase.
What do these numbers mean?
That is just it. Neither article gives us the key information that we need to determine the impact of these results: the baseline risk. I do not understand how articles are allowed to be published when they are speaking in terms of relative risk, when they do not tell us what the baseline risk is in the populations they studied.
The impact of the results is VERY different, depending on the baseline risk. Say your base salary is $10 an hour, and eating meat increased your salary by 17%. That is an extra $1.70. Compare that to someone who makes $100 dollars an hour who gets the same 17% raise; that would be $17. I don't mean to be obvious here, but $17 is a way larger raise than $1.70. The same percent increase has a much larger effect because the baseline is higher.
To truly understand the significance of these numbers, we have to look at baseline risk of colorectal cancer.
What is the baseline risk of colorectal cancer in British Columbia?
In 2012, the rate of new colorectal cancers was 65.35 cases per 100 000 people, making it the third most common cancer in BC. A 17% difference in the risk of cancer could make a pretty significant impact on a POPULATION level.
Once again, however, we need to break down the numbers a little further. The incidence rate of 65.35 per 100 000 people, includes both those who overconsume meat and those who do not, and most of the cancers occur in people who are over 80 years old. That means that if we are looking at recommending the reduction of dietary meat consumption as a means of reducing the population risk of cancer, the effect is going to be less than 17% because the baseline risk includes people who are already low risk, and also includes older adults, who have increased incidences of cancer rates due to reasons other than eating red meat.
The key for me is breaking down the risk to a PER PERSON level. As a British Columbian, if the incidence of colorectal cancer is 65.35 per 100 000 people, across all age groups, it means that the risk is 0.0006535% per person. Now add that 17% relative risk that was found in the study: 0.000765% per person. The real life increase in risk is negligible because the baseline risk is so low and relative risk increase is also very low. PER PERSON.
The question I ask myself then is, am I willing to increase my risk of colorectal cancer from 0.0006535% to 0.000765% for the sake of eating that yummy, juicy steak on Friday after work? Or so I can pop some pancetta into my omelette on Sunday morning?
Yes, yes, yes, and infinity times infinity, plus infinity yes! Meat makes me happy. Bacon is amazing. We haven't even talked about all of the benefits of eating meat. The increase in risk is so negligible on a per person level, that the true impact of eating meat on an individual's chances of getting cancer is virtually zero. Yes, if we can reduce cancer rates as a population, the world would be a better place, but the reality is that there are other places to start.
Thanks for reading!
Dr. Dave
drdave@alfaropros.com
