Vitamin D can be made by our bodies from sunlight; most people can synthesize sufficient amounts if you’re in the sun between 10am and 3pm, at least twice a week, for about 5–30 minutes (and with your face, arms, legs, or back exposed without sunscreen). Of course, you should also choose foods that are naturally rich in vitamin D or fortified with vitamin D (like milk). Most Americans do not have adequate vitamin D levels.
Boosts immune system
Foods (1 serving provides at least 20% of the Daily Value)
Seafood: the best sources are cod liver oil, swordfish, salmon, tuna, and sardines
Dairy: Milk, yogurt, Swiss cheese, and margarine
Eggs (though you would need at least 10 eggs per day to provide sufficient quantities – which I do not recommend!)
Plant Sources – there are no natural plant sources that provide 20% of the DV
Fortified breakfast cereals
Fortified orange juice
Fortified soy products
If you don’t get any (aka deficiency), you might develop…rickets, osteomalacia, osteoporosis, greater risk of cancer, diabetes, and hypertension
If you get too much (aka toxicity), the risks include… kidney damage, growth retardation, hardening of soft tissues
Enhances absorption…calcium, vitamins A and C, phosphorous, oral contraceptives
Inhibits absorption…mineral oil, steroid hormones (like prednisone), and alcohol
There are 2 types of vitamin D supplements on the market (in the form of D2 and D3); right now there is no superior supplement, though I’d lean toward D3
There is consensus that the daily recommended intake (600 IUs for adults) is not enough for most Americans but the amount needed is still up for debate. The point however is that, as of now, we’re not getting enough.