29 October 2019

Healthy diets and the planet

There is, as with society in general, increasing concern about planetary health amongst the medical profession. While clearly climate change can damage health it is not always immediately apparent how doctors themselves can help people make changes. Two main areas stand out: physical activity that reduces the use of vehicles; and a healthy diet that helps reduce the carbon cost of producing our food.

So, what is the evidence that a healthy diet’ is better for the environment. All depends on how you define healthy of course. A new paper published in PNAS° has analysed it further, indeed, it’s described as the most sophisticated analysis to date” in the Guardian but I’m guessing that’s reporting on the authors’ view in the press release.

They looked at 15 food groups, five major health outcomes, and five aspects of environment degradation. The food groups associated with the best health are all, with the exception of fish, the best for the environment. This lovely graphic from the Guardian° shows it best.

It’s easy to criticise journalists for their reporting of science - reducing complex research articles to short articles is always a bit fraught. And, to be fair to those who criticise, it is often done very badly indeed. The Guardian, while not completely immune from the siren call of clickbait, has to be commended for this graphic that rather brilliantly summarises the key findings. It reproduces one that is provided in the paper itself but it is good to see.

And one important point to make and I nearly missed myself - the y-axis is logarithmic. Those towards the top are orders of magnitude worse than those at the bottom.

The graphic also serves another function when it comes to giving dietary advice. The nature of evidence on diets doesn’t always sit well with the one-to-one consultation but encouraging people to consider pushing their diet towards that bottom left corner is a helpful message.


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