2. If you work a lot on a computer, you are at high risk of a vitamin D deficiency. You should probably be taking vitamin D supplements; and if you feel tired a lot, and you have a GP, you should consider asking them to test your D levels. In case of deficiency, higher-then-OTC doses are sometimes needed to reset.

In general, taking multivitamins can have many benefits. But be cautious of "B complex" vitamins, which often contain unsafe levels of B6 (one of the rare OTC vitamins you can OD on).