Last week several news outlets ran the story that eating meat can be as bad for you as smoking. A link to The Guardian article is here. As someone who has worked in the health and fitness industry for 10 years I’m quite accustomed to seeing sensationalist headlines about almost every aspect of the industry. As I become more learned these headlines provoke one of two reactions in me. They either make me laugh/angry at the sheer ridiculousness of them, or they make me question whether all my learning and philosophies to date are erroneous. Either way, they prompt me into looking at the research behind the headline so I can then soothe my clients’, or indeed my own, fears.
I felt compelled to do my best in critiquing the research behind the story for two reasons. Firstly, I recommend most of my clients increase their protein intake, and secondly, since I’ve started blogging, no research quite so contrary to popular nutritional protocol has been reported on so heavily. So, in a sense, this is my big moment to put my blog to good use.
So, let me begin this post in earnest with a disclaimer. I’m rubbish at looking at research and interpreting what it all means. After I read the study (which is available HERE) I could see a couple of things that weakened its claims, but I didn’t want to attempt to write a full on critique of it as I simply don’t have the skills to do so. I wouldn’t be fair if I just said I didn’t like the study simply because it doesn’t agree to my own nutritional practices. I decided to wait until a few other, better respected bloggers got their teeth into it before I put anything on my page. With that in mind, all I am doing here is summarising a few very well written articles that have looked into the research and discussed its pros and cons. I thought that would make it nice and simple for my thousands of followers to understand the research and how it was done.
The articles I read were by Denise Minger at Raw Food SOS (who has a great book out by the way – Death by Food Pyramid), Zoë Harcombe at Zoë Harcombe dot com, and Examine.com which is a great resource when trying to find research on any thing health and fitness related. I got all these links from the blog of Michael R Eades which is another fantastic place to do some reading. I highly recommend you read all these pieces if you are into this kind of thing. If you’re not, and just want to know if eating meat will indeed kill you, my summary is below:
- It was in fact two studies. One looked at humans, the other looked at mice. The human study was an observational epidemiological study which only ever proves correlation and not causation. It shows that something happened with a group of people (in this case they had a higher than ‘normal’ protein intake), and then something else happened (in this case cancer mortality increased). It shows only association and DOES NOT show one caused the other. The mice study was then used to explain the association. At no point in the human study was a high protein intake shown to cause anything.
- The human study took 6381 people over 50 and tracked them over an 18 year period. Only one food diary was taken though, at the beginning of the study. So, the assumption is made that they ate the same way for 20 years based on one day’s worth of data, and that all participants recalled that day’s worth of eating perfectly. Not ideal in my opinion.
- The group was then split into those who ate low protein, mid protein and high protein, with no control for quality of protein or quality of food in general. When looking at the whole group, no association was found between any of the protein groups and overall mortality, diabetes, cancer or CHD. It was only when the group was split into 50-65 year olds, and 65 years and older that some associations presented themselves. The high protein 50-65 year olds had more instances of mortality and cancer. But, the high protein over 65 year olds had less instances of mortality and cancer. Not unexpected given the law of averages. So, the headline could have just as easily been “Protein will save you in old age” as opposed to “protein will kill you in middle age”.
- The study also looked at the source of people’s protein – animal or plant, and claims that the people who ate more sources of animal protein had higher instances of mortality (although that is then reversed when you reach 65). The guy who ran the study is the founder of a plant based meal replacement product, which could tell you all you need to know about the motives of the research.
- The mice study centres around a hormone called IGF-1 which increases when we have a higher protein diet. Mice were injected with cancer and the speed and size of their tumours was then assessed. The mice on a lower protein diet showed smaller tumour growth. Not surprising given that IGF-1 makes all cells grow, be it cancer cells or muscle cells. There was no difference between the mice consuming plant protein versus animal protein. The food the mice were fed after being given cancer should also be noted: Corn starch, casein, maltodextrin, sucrose, soy bean oil and cellulose – every mouses dream meal. Basically a hodge podge of processed goodness.
- The statistics used to fuel the fire of the headlines were based on relative risk, not absolute risk. As an example of the difference between the two, if you buy one lottery ticket you have 1 in 14 million chance of winning. If you buy a second ticket, you have a 2 in 14 million chance (provided the numbers are different!). Relatively you have doubled your chances of winning the lottery. Using absolutes, you have gone from a 1 in 14 million chance to a 2 in 14 million chance of winning – i.e. keep saving. Zoe Harcombe breaks the stats down brilliantly with this POST. I urge you to read it if you’re interested. I would only do it a disservice to try and summarise it, as I am quite frankly, far too thick. Essentially the stats don’t hold up as the sample group is far too small.
If you read the articles I have linked to you will find out a hell of a lot more, but hopefully I have explained the key problems with the study. I’m sure it was great research, but it certainly didn’t warrant the scaremongering headlines that came out as a result. The study doesn’t show that a high protein diet causes cancer in humans, and it certainly isn’t as bad as smoking. Any time an observational epidemiological study in nutrition is used to generate a headline, be aware that they a fraught with problems and only ever show correlation, and not causation. In my opinion, you cannot make any link from one day’s worth of ‘I-hope-you’re-being-honest’ style food diarying to health 20 years later.
Hence my post title – Know Your Enemies. First off, know what foods are genuinely bad for you. To keep it simple, place everything processed into the enemy category. Processed foods will harm you, no doubt. They will interact with your body and its cells in a way that we have not yet evolved to handle. Secondly, always take sensationalist news headlines with a pinch of salt. The media don’t have the same agenda as you or I, or anyone else trying to stay fit and healthy. They want people to read their publications first and foremost, so wild claims in headlines are great for attention seeking. They may also have other reasons behind deciding to run a news story. The news isn’t necessarily what is happening, it is what the news companies want us to know what is happening.
Keeping learning, don’t believe everything you hear and read and keep your food as natural and as whole as possible. They are the main things I would take away from these recent news stories. And hopefully one day, when I get through uni I will actually learn to dissect some research for myself.