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An oldie-but-goodie from Dr. McDougall:

Just To Be On The Safe Side: Don’t Take Vitamins, John McDougall, MD, 24 February 2022

The only supplement he advises taking is vitamin B12. Even if someone eats meat they can be low, especially if they are older, owing to less efficient absorption. Eating meat won’t cure a vitamin B12 deficiency, you have to supplement.

Anyway, I like this exerpt:

In an effort to improve on Mother Nature’s creations, and to make big fat profits, scientists and entrepreneurs have developed thousands of products based on isolated concentrated nutrients. The enterprise begins by finding a pharmacologically active ingredient in a common food. Through science and manufacturing technology this substance is purified, then replicated into large quantities, and sold to the customer as a “potent, but natural remedy.” Familiar examples of such concentrates include isolates of soy and whey proteins, omega-3 fish and flaxseed oils, and vitamins and minerals. These magic bullets are delivered to the consumer in the form of pills, powders, liquids, nutrition bars, “health” drinks, and fortified foods. They are supposed to offset the effects of destructive habits and fix the customers’ bad health, naturally (like with no side effects) and almost effortlessly.
…
Tens of thousands of proteins, fats, carbohydrates, fibers, vitamins, minerals and other phyto (plant)-chemicals are present in proper amounts, kinds, and physical positions within each food. If not for the exact correctness then you would not have a green kiwi fruit.

He’s right. There are tens of thousands of substances, one might say nutrients, in foods. We pull out 20 or so, purify them, and swallow them in concentrations we’d never experience in nature – outside of the food matrix our bodies evolved to recognize them in, and absorb them from. What happens when we do that? He gives the example of one nutrient, beta carotene:

Beta-carotene is one of about 50 similar naturally occurring active substances in our diet classified as carotenoids. They are all especially abundant in yellow and orange fruits and vegetables. After nutrients enter cells they float around in the cell’s fluids (cytoplasm) until they attach themselves to the cellular machinery through a specific receptor, like a key fits into a lock. Beta-carotene and all of the other biologically active carotenoids must attach to these specific carotenoid receptors before they can function.

When a cell is flooded with one kind of carotenoid, in this case beta-carotene after vitamin supplementation, then there is an overwhelming competition for the carotenoid receptor sites. The other 50 functional carotenoids are displaced by the beta-carotene from their cellular connections.

He says we risk imbalances when we take supplements. He’s not wrong:

• Too much zinc can reduce magnesium and copper absorption.
• Too much iron can reduce zinc absorption.
• Too much calcium can reduce magnesium absorption.
• Too much vitamin E or vitamin A can interfere with activity of vitamin K.

And on…

I think there are a few supplements that some people can benefit from. But the whole supplement business is mostly about making money. It’s a scam.