Generally speaking, the medical industry discourages the use of supplements and recommends getting micronutrients through a balanced diet. But they do support taking a supplement to offset a dietary deficiency.

For myself, I track everything I put in my mouth with an IPhone app that then reports back to me on a daily, weekly and monthly basis which nutrients and how much of each I have received through my diet. Through that, I have been able to figure out which nutrients I am deficient in and which supplements I need to take.

For instance, right now I am often running just a tad bit below the recommended intake of protein. I MAY start taking a protein supplement -- or may adjust my diet. I haven't decided yet. Another example is Vitamin D: My intake is usually only about a third of the recommendation for that vitamin and, when I had my vitamin D tested it was right at the very bottom of the 'normal' range. I now take a vitamin D supplement each morning.

One exception though: if you take a statin, CoQ10 is often recommended. That enzyme is used by the mitochondria to generate energy (ATP) for the muscles -- but all statins block that along with blocking LDL production.