Will a High Protein Diet Give you Cancer?

Will a High Protein Diet Give you Cancer?

The papers have been rife with the frightening results of yet another nutrition study this morning. Splashed across the Guardian, the BBC & The Telegraph websites are headlines such as High-protein diet ‘as bad for health as smoking’ & It’s time to kick the high-protein diet habit – before it kills you. And we’re talking front page stuff, they’re taking this seriously.

Should we take this seriously?

This struck a chord with me as I personally tend to keep my diet on the protein heavy side. I’m not an Atkins advocate, I’m more entrenched in Tim Ferriss’s slow carb camp with a few variations on the theme depending on my goals and how committed/lazy I’m feeling on any given week. And I know plenty of folks (perhaps you included) are in the same boat, whether it’s Atkins, paleo, slow carb or your own high protein variation. So are we all sailing towards higher rates of cancer together albeit with decent tone and slim or slimming waistlines?

What does the study tell us? This summary from the Guardian sums it up:

“The National Health and Nutrition Survey has been collating data on 6,381 people across the US, and found that diets rich in animal protein (as opposed to protein routinely taken from plant sources) could be as harmful to health as other vices such as smoking. Those under the age of 65 who regularly consume a lot of meat, eggs and dairy are four times more likely to die of cancer or diabetes”
Read the rest of that here:


It’s not that I have anything against these sorts of studies, it’s an important part of the learning process and simple correlation studies as this appears to be can throw up important questions and inspire more serious analysis. In other words sometimes the data can inspire the proper science.

I think if we take a few things that we ‘know’ and apply them to this study we may get a slightly more balanced view when compared to these rather scary headlines that seem to support the results of the study rather than question them as perhaps they might…

A high protein diet is defined by this study as anyone who is consuming 20% or more of their calories as protein daily. They’ve also suggested that these figures (the ones that suggest a four fold increase in the likelihood of cancer or diabetes) only apply when the protein taken is animal based; meat or dairy, and that plant based proteins don’t show the same correlation.

What I’m not seeing in this study is whether this correlation (between a high ‘animal’ protein diet and increased likelihood of cancer) applies when the 20% of calories taken as animal protein are coming from either of these 2 groups:

  1. Processed meats, dairy, low quality or meat of an unknown origin

  2. Lean meats (turkey etc), grass fed beef, meat sourced very locally

Not all high (animal) protein diets are the same…

I don’t know about you but I feel strongly that there may be a huge lifestyle factor at play between those two groups that could significantly affect that correlated assumption, not to mention the quality of the protein itself (along with all the added salt, hormones accompanying side dishes and who knows what else in that first group).

Am I surprised to hear there’s a correlation between group 1 and cancer? No. But group 2? I’m not so sure.

Having said all that I personally like to vary the type of protein I take (slow carb helps with that with the legume and lentil factor) but I think even the paleo approach should take this with a pinch of salt (but no more…) because a true stone age diet wouldn’t involve meat every day, and when it does, it won’t be a sausage or bacon, it’ll be a piece of lean, grass fed something good or a hormone free bird.

“What about the Insulin-like Growth Factor 1” I hear you cry…

There’s still an elephant in the ointment though: IGF1 – The growth hormone highly correlated with increasing likelihood of cancer. Our high protein diets might be great for muscle development and tone but at the same time are we promoting a hormone that could do us some serious damage in the longer term? If that’s the case then there is a potential saviour from this conundrum, intermittent fasting (my personal preference is for Michael Mosely’s 5:2 diet but there are plenty of valid variations) that has been shown to reduce all sorts of murky markers in your blood such as LDL Cholesterol (the bad one), triglycerides and good old IGF1.

I think this is more a question of the quality of what is being consumed, and what that might say about the demographic rather than simply how much ‘animal’ protein is being consumed. And allied to some preventative maintenance such as intermittent fasting to keep your blood work in order then I’m struggling to see any major dangers out of this report.

Of course I could have this completely arse backwards in which case you’ll correct me voraciously below….

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