15 minutes of bathing sunscreen-free arms and legs in the sun a few times a week generates plenty of the sunshine vitamin.
Fatty fish such as wild-caught salmon, mackerel, tuna and sardines; eggs; and fortified milk, orange juice and cereal are all good sources.
In addition to sun exposure and food, Vitamin D supplements (800 to 2,000 IU a day) should bring your levels up to par. Take the supplement with your largest meal of the day. This simple step can boost the level of vitamin D in the blood by more than 50 percent, according to a study from the Cleveland Clinic.