How much evidence is there regarding the effectiveness of dietary supplements and additional vitamins?

I have just done a RealAge questionnaire, and, congratulate me, I am 78, but one of the rejuvenating issues they raise is taking supplements. Other people I know, those killjoy scientists, affirm that the impact is negligible. Anecdotes and websites, please.

The evidence is they are of no benefits, why not believe people who have data like scientists? Do you just want someone with no real knowledge to say ' yes they will make you live for ever'?

Excess vitamins for example, above RDA are not only useless but toxic!

Vitamin C in doses of 500mgs or more may be carcinogenic, other excess water soluble vitamins are peed out unchanged.

Fat soluble vitamins accumulate, Vitamin D is toxic to the kidney and Vitamin A to the eyes.

i am 29 yrs old and take a multivtamin on a daily basis along with some other minerals. i think the vitamins help me with my skin, hair, nails and over all wellness.

if you are having a normal varied diet then you should not need them.
If you think you are lacking in something always buy the most expensive you can afford.
saw this on UK TV years ago.

If i don't take certain supplements I have problems like painful periods and sore joints. I use good quality ones. As I am a cynic and a skeptic by nature I can honestly say this is not psychological. if i forget to take them away with me or sometihng i will notice a physical difference. I notice a benefit from cod liver oil, zinc, b vitamins, magnesium and calcium, also spirulina. I can say nothing else really gives me any difference that I can see. It's true that often there is a placebo effect from certain things in life, but it is also true that science cannot determine what works for a certain individual by doing a few widely based general tests and basing their evidence on this alone. There is more we don't know than we do and we need to stop listening to what we're told, because it all conflicts anyway, and find out what's right for us as individuals.

there is little proven evidence to say taking extra vitamins is worth while as the body just excretes the unused ones anyway, there are meant to be enough vitamins and minerals in your daily diet, recomendations for extra vit are mainly pregnant and elderly people

surprisingly few relevant ethical studies of the benefits of vitamins for general comsumption have been done -those that have tend to be biased, from Drug companies. I have given trauma and surgical patients a geberal cheap prescribed vitamin tablet to aid healing, but they are not prescribed. A good varied diet is more beneficial