Supplement industry is the best scam ever sold to the people. In the US alone there are more than 90,000 of these are sold. The Global Vitamins and Supplements market is anticipated to grow from USD $129.60 billion in 2021 to $196.56 billion in 2028 at a CAGR of 6.13% in the forecast period 2021 -2028.
There's no science behind these supplements and it's not even proved that these
are even safe. Quite obviously some are harmful. Remember the Indian Black Fungus during Covid time - Murcomycosis. I mentioned this before, the stupid Indians went on taking Zincovit like lollies (Zincovit sales went through the roof) - what resulted? The fungus. It had no effect on Covid other than the undesirable Murcomycosis. No where else this was reported.
Also the US studies show that the supplement takers have a higher incidence of prostate cancer. The older women who took supplemental multivitamins over 2 decades died at rates higher than those who didn’t.
However, there are proven benefits in quite a few. For example during pregnancy, the evidence is clear that women who may become pregnant or who are in the first trimester of pregnancy should be advised to consume adequate Folic acid (0.4-0.8 mg/d) to prevent neural tube defects. Folic acid is very important because it can help prevent some major birth defects of the baby’s brain (anencephaly) and spine (spina bifida)
Vitamin D is helpful from infancy, childhood to later in life. Ever since Covid started we have been taking 2000 IU of Vitamin D regularly. Even though how it affects the respiratory diseases is not well understood, it does work. I have written much details on it in earlier Covid time posts, if anyone cares to look or have read them and remember.
Then there's Calcium - even though it's debatable that it could increase the risk for kidney stones and possibly cardiovascular disease, it's needed for preventing Osteoporosis. It helps in the progressive loss of bone mineral density.
Other than that an occasional Magnesium (specially if you are doing sports activites) should be alright. Healthy people on normal diet does not need supplements.
Supplements are a multi-billion dollar industry not because their products are worth their salt, but because their message is intoxicating
. For all those supplement takers - as someone quipped -
Congratulations, you have very expensive pee. 
