Vitamin Paradox

Vitamins Good Vitamin Pills Bad

I've always been puzzled by vitamin pills.

One of the few things we actually know about human nutrition is that there are some chemicals which we need in tiny quantities which we can't ourselves make.

The classic example is vitamin C, ascorbic acid, which is a crucial part of metabolism and involved in several metabolic pathways in animals and in plants.

There's vitamin C in almost every kind of fresh food, exactly because it's so crucial in most living creatures.

Most animals and plants synthesize vitamin C as required, but the great apes, along with several other types of animals, have lost the ability to make it, presumably because it was at some point so omnipresent in some ancestor's diet that there was no selection pressure against random mutations that destroyed the synthesis pathway.

Absent active pressure maintaining the pathway and selecting out the broken genes, the breakage spread, but the species carried on without noticing. Unnecessary pathways are often destroyed by such random drift, possibly because there's usually some other minor advantage to losing the gene. Once a pathway is broken like this, it's very difficult to get it back.

If you somehow manage to remove all sources of vitamin C from your diet you'll get the horrible disease scurvy, which is fatal. It takes some work to do this, but sailors living on ship's biscuits used to manage it on a regular basis, and it was a curse to polar explorers even in the early part of the twentieth century. (A fascinating story, which some raccoons in a lab coat discuss here: https://slimemoldtimemold.com/2022/01/11/reality-is-very-weird-and-you-need-to-be-prepared-for-that/)

One interesting thing about vitamin C is that it comes in two forms (stereoisomers). Chemically they're the same, but they're mirror image molecules. One form is the scurvy-curing wonder-drug, the other form is inert and does nothing helpful in the body. But in most ways, the two forms behave the same.

Several other vitamins have been discovered, and mostly the story is the same.

Of particular interest is vitamin B12, the most chemically complicated of all the vitamins, which can only be obtained from animal sources. We do know how to synthesise it from scratch, but it's never actually done, because the synthesis is so complicated.

Vegetarians, vegans, and other people who don't eat much animal-derived food are often at risk of vitamin B12 deficiency, and as might be imagined, it has many horrible effects.

It's often said that the reason for eating a varied diet is to make sure that you're exposed to sources of all the vitamins, including presumably some we don't know about.

So the puzzle is, why aren't vitamin pills good for people? Usually we've got excellent control over the amounts of such things circulating in our bodies. We have to have, because you never know how much of the things you're going to get from your diet day to day, so you need to be able to conserve quantities of everything vital in case you run short, and you need to be able to get rid of excess amounts.

You need a very lot of vitamin C to give yourself an overdose. I don't think it's even possible to do it by eating normally, you need to take large quantities of the synthesized vitamin.

Vitamin homeostasis needs to be good, and so it should be good.

So if you take vitamin pills, assuming they don't contain ludicrously high quantities, they shouldn't do any harm, and they might even do some good, by fixing shortages you're not aware of.

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But this seems not to be the case. There've been various trials of multivitamin pills, and if anything they seem harmful. All-cause mortality rises.

I think we're currently advised not to take vitamin supplements, but to get our vitamins by eating a varied diet.

This makes no sense to me.

After all, when someone has a measurable deficiency of some vitamin, the pills will raise the levels of the vitamin in their bodies.

Chemicals are chemicals. They don't remember where they came from. The idea that natural vitamins are good, but synthetic vitamins are bad, is the same sort of magical thinking that says that processed food is bad because of the processing.

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This is a paradox. And paradoxes are always worth paying attention to. There's clearly something interesting going on.

I wonder if it's the same sort of thing that might be going on with PUFAs.

Just like there are two forms of vitamin C, one of which does the business, and one of which does nothing, maybe there are various forms of the other vitamins.

Suppose, e.g. B12 derived from certain sources isn't quite right.

So if you get it from e.g. liver, it's fine and does what it's supposed to do, but if you get it from e.g. algae, it doesn't.

It can be quite hard to make a test that responds to only one form of a chemical. A test that can detect a deficiency of a certain vitamin might actually respond to another form of that vitamin that is not quite right.

What if there are forms of various vitamins that are close enough to register as the vitamins on various chemical tests, but which don't quite do what they're supposed to in the body?

So you'd get a vitamin deficiency, and you'd see that on a vitamin level test.

And you'd fix it with a vitamin supplement, and you'd see that you've fixed it and your test results would be normal.

But what you've actually done is to fill yourself with something slightly wrong. It might not work at all, or it might do most of what you want it to do, but not quite right, leaving you with some strange symptoms, which may not be the same symptoms as the deficiency was giving you.

Maybe that's why even vegans who take their supplements and track their vitamin levels usually seem a bit unwell.

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Even worse, suppose you take a multivitamin supplement on general precautionary principles.

Because you're getting lots of the wrong substance from the pills, the wrong stuff might be crowding out the right stuff.

In fact, even if you are getting all the right stuff from your food, and in ample quantities, if you take high doses of synthetic vitamins, you might be crowding out the good stuff, giving yourself problems that you wouldn't have had if you hadn't taken the supplement.

It would explain why vitamins from food are good for you, but synthetic multivitamin supplements are bad for you, quite neatly.

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So I'm getting a bit reluctant to take vitamin supplements, and even to eat 'fortified' foods.

Putting something that's like the thing you're supposed to be eating, but not actually the thing you're supposed to be eating, is exactly the problem I think we're seeing with PUFAs.

Your systems are designed to work well on exactly the substances that your ancestors encountered. Slight variations on those substances might be very bad.

In fact that's the way to bet. You don't put diesel in a petrol engine. You don't put petrol in a diesel engine.