The supplements-aren't-necessary-advice is often the lawerly "you don't need supplements if you're not malnourished" or "if you're getting a balanced diet."

Left unsaid is my takeaway: modern agriculture has damaged our food supply to the point where a nourishing and balanced diet isn't readily available in the produce section of your local supermarket. If you're eating stunted frankenfood, you need to supplement, because you're malnourished from eating an unbalanced diet.

Costco multivitamins cost 2 cents per pill. I don't think saving money is a good reason to try to get all your minerals from whole foods.

I did a blind trial on myself by getting liquid multivitamin (bargain large European superstore brand, powdered), and creating a sequence of vitamin or placebo based on a pseudorandom hash function to take every day with breakfast in drink. The sequence is prepared a month ahead so I don't know on any specific day what I'm getting.

I also record my mood and excercise at some time most days with a survey.

After 2 years, I saw a significant decrease in general happiness on days I took the multivitamin, and a lesser (not p<0.01) effect the following day. I was less likely to leave the house, and less likely to plan a social activity on those days.

I've now stopped taking the multivitamin for that reason.

I'd still like to know if I have stumbled on a p<0.01 fluke, or if I'm unique somehow, if the multivitamins have a negative short term but positive long term effect, if these particular multivitamins are harming me somehow, or if all multivitamins have this issue.

Life isn't long enough for me to find out, but if anyone else is happy to take on a bigger trial, results could be interesting.

I am also worried they put toxic doses of vitamins and minerals. My hair supplement used to contain 10000 micrograms of biotin and caused acne. Other supplements put 100 micrograms. Melatonin doses also vary too wildly, like 4x. They seem to be concerned about bragging rights at our expense.

Agreed the standard dose is probably 300mcg, but there’s a reason it doesn’t get sold at that amount. There’s communities that track what the right amount is for them and take that, see https://trackmystack.com