Not only is this vitamin crucial for healthy bones and strong muscles; it has also been linked to reduced levels of depression and possibly improved immunity and may help lower your chance of heart attack.
How much you need: Ages 18-50: 5 micrograms (mcg)/day; ages 51-70: 10 mcg/day; ages 71+: 15 mcg/day
Where to get it: Fortified milk, fatty fish (salmon, tuna). Also formed naturally as a result of exposure to sunlight.