The Anti-PUFA Elevator Pitch

Why Yes! I *Am* a Crackpot, As it Happens

Last night was choir. I do the tea for my choir, and I always buy a stack of biscuits to go with them.

Choirs are always well supplied with women, and are always short of men. A bit like my alma mater. And this is Cambridge.

So last night, I found myself chatting aimlessly to two women I barely know who are respectively a doctor and a life scientist.

And one of them said something fluffy about avoiding eating biscuits, blah blah health, blah blah weight, blah blah processed....

I was halfway through my seventh All-Butter Shortbread biscuit at the time:

https://www.sainsburys.co.uk/gol-ui/product/sainsburys-highland-all-butter-shortbread-fingers-200g (I yet keep faith, O my masters. Just saying...)

I am rather obviously overweight, so in retrospect it was no surprise that this thought had sprung into their mind, but I don't think they were trying to be cruel, they were just saying girl stuff, and I am so blind to female status plays that I didn't even notice.

Instead, God help me, I said:

"Oh I think these are fine! The only weirdness is ammonium bicarbonate, and I checked, and it's a very traditional raising agent and shouldn't even leave traces in the biscuits."

And the biochemist said, not unreasonably:

"But they're full of sugar and saturated fat!"

"Ah", I said, thinking, Oh crap. What a place for an angry argument…

"But animal fat is what we were designed to eat, and sugar is unambiguously bad for teeth but metabolically I think it's probably completely innocent."

You could see the crackpot lights going on in their heads. Oops.

So I had to think on my feet.

For months now, I've been trying to write an essay called "Why I am So Very Very Suspicious of Polyunsaturated Fats". But there's so much to say, and it's all so complicated, and so the essay just keeps being stillborn. I currently have three different drafts, and I'm trying to make a list of all the points from those three drafts to combine them into one huge super-essay with the most important things at the top, but it's just not happening.

And suddenly I needed an Elevator Pitch. So I extemporised in roughly the following manner:

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Anti-PUFA Elevator Pitch

Animal fats are what we were evolved to eat. It's possible that they're bad for us, but I think you'd need very strong clear evidence to believe that they're harmful. And I haven't seen any.

Polyunsaturated fats, on the other hand, are a most unnatural food for a tropical omnivore. You don’t really get them in the tropics at all. It's clear that we can digest them in small quantities, and in fact they're essential, in very very small quantities.

But as a staple food they’re weird chemicals.

Humans are a very very very complicated chemical reaction.

If you try to run a chemical reaction on the wrong substrate, it will behave differently.

Consider a car:

If it's a petrol car, it will run badly if you put diesel in it. If it's a diesel car, it will run badly if you put petrol in it.

Petrol and diesel are very very similar.

Or consider heavy water:

Chemically heavy water is almost exactly the same as water.

But if you drink too much of it you will die. And it’s not that it’s radioactive. It just behaves slightly differently to the water your tissues expect.

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There's absolutely no reason to believe that humans will run better on the wrong fuel.

In particular, animal fats have one double bond for every two molecules.

Polyunsaturated fats have two or three double bonds in every molecule.

When we burn fat for energy, we use a different metabolic pathway to break the double bonds.

What if that pathway is somehow rate limited? What if it just can't handle the load?

What if it sends the wrong signals about how much energy is being liberated and corrupts the signal about how much stored energy you've got?

What if partially burned fuel clogs up your metabolism, like partially burned fuel clogs up car engines if the proportions aren't right?

Double bonds are unstable at body temperatures, and prone to oxidation. That's why mammals and tropical plants don't use them. What if that causes trouble?

(Suddenly I had their interest... They actually seemed intrigued... So I started ranting:)

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Medically, we know there's a problem. Before 1900, no one anywhere in the world had problems with obesity, heart disease, type 2 diabetes, or any of the other host of horrors known as the 'diseases of modernity'.

We know that weight must be controlled by a homeostatic mechanism, like everything else in biology. Hunger and satiety are the signals sent by the homeostat controlling your fat levels. That almost has to be true in all animals.

We know that there were people before 1900 who had plenty to eat. They ate animal fats and sugar, and they didn't get fat, they didn't get heart attacks, they didn't get type 2 diabetes.

They did not eat polyunsaturated fats.

But modern people eat so much polyunsaturated fat that the chemical composition of our bodies has changed. And the effect is not small. Fat stores. Cell membranes. All lipids. Not the right lipids any more. Mitochondrial membranes even.

We know that "Dieting Doesn't Work".

No one ever fixed their weight issues with "Eat Less, Exercise More". You can starve yourself thin, but you can't starve yourself healthy.

The consensus is that the problem is ultra-processed food. But what does that even mean? What is it about the processing?

What's the one thing you find in almost all processed food?

If you try to give up PUFAs, you'll find that ultra-processed and 'contains vegetable oil' are almost the same thing.

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(My friends looked interested, and thoughtful. They're both clever women. I stopped there. Because I am a crackpot. I am not a madman.)

Anyone medical has heard an awful lot of crackpot theories about hypothyroidism.

The field is infested by cranks. A lot of people think that they're hypothyroid. But they're not. We can test for hypothyroidism. The tests are very good and the problem is as well understood, and the treatment is as good, as anything in medicine.

Anyone medical fears anyone who's 'tired all the time'. They're constantly dealing with patients who are always fatigued.

They do all the tests they can think of, and they can't find anything wrong. They can't help.

The consensus medical view is that 'tired all the time' is a psychological problem. Medicine writes off anything that it doesn't understand as a psychological problem. It's a tradition. Syphilis was a psychological problem once.

So here's the bit I didn't say, because I was trying to convince them there might be something to the idea, rather than alienate them:

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All over the Western world, everywhere the modern diet is eaten, there's an 'Epidemic of Hypothyroidism'.

But it's not an epidemic of hypothyroidism. The symptoms are everywhere, but the disease isn't.

Low body temperature, a vast array of symptoms of general failure of all bodily processes. But very few actual cases of thyroid problems.

What we really have is an 'epidemic of slow metabolism'.

And I have seen many scattered tiny bits of evidence that polyunsaturated fats are wrecking people's metabolism in a hundred different ways. And so the thought occurs…..

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But that is the quiet part. I did not say it out loud.