There are numerous vitamin supplements available and our needs differ as individuals, so it's difficult to prescribe just one. While there are some common deficiencies in the general population (magnesium, zinc, D3, etc.), your best bet may be to try a higher-potency multi-vitamin/mineral supplement to augment your current diet. Multi-vitamins cover a wide variety of nutrients and would be beneficial to almost anyone.
Note that no single multi-vitamin supplement will make up for a poor diet, so make sure you are eating plenty of vegetables, fruits, and other whole (non-processed) foods.
Good multi-vitamin supplements usually come in multiple doses, requiring you to take several tablets or capsules over the course of the day. Take them with meals to ensure proper absorption of the nutrients.
For more information on multi-vitamins, please consult our
http://www.wyldeabouthealth.com/healthnotes/us/assets/feature/multivitamins_12615_1/~default" target="_blank">Health Notes.