This may seem like a flippant or blasphemous answer. But I’d say none.
There are three ways in which you could imagine that vitamins or supplements might be useful.
First, if you are genuinely lacking in something. But with our plentiful and varied western diet, that's incredibly unlikely.
To be truly vitamin or mineral deficient, you’d have to be diseased (for example, suffering from malabsorption), alcoholic or following a really weird dietary regime. All these scenarios are highly unlikely for the average Mansized reader.
Second, if they in some way protected you from disease. True, barely a day goes by that you don’t hear we should eat more of A, B or C to prevent disease X, cancer Y or event Z. But the fact is that these stories are nearly always based on minor research which is of quirky interest only.
They are given far more prominence than they deserve because there are pages of newsprint and hours of airtime to fill. If your diet was dictated by the miracle food or supplement of the day then you’d end up sick - simply because your head would be spinning.
Bear in mind that we already have a long lifespan. The chances that using this vitamin or that supplement will make a significant difference – over and above a standard healthy diet – are minimal.
Third, if they help you sculpt the body beautiful. I’m no sports physiologist but I suspect the evidence for any genuine benefit is, at best, flimsy. Besides, I’d argue that artificially augmenting what you can achieve with a sensible diet and exercise regime is a dodgy road to go down.
Still not convinced? Just ask yourself what’s more plausible. Either vitamins or supplements have a genuine and significant impact, achieving effects that can’t be attained through a healthy lifestyle. Or they provide a ‘feel good factor’ to help us as we strive for health, boosted energy levels or longevity, a placebo effect that vitamin and supplement manufacturers are very happy to exploit.
As far as I’m concerned, it’s a no brainer, though that may be because I’m lacking omega 3 oils.
