4. Vitamin D
Why You Need It: Vitamin D is a fat-soluble nutrient that’s important in bone building and has been linked with lower incidences of cancers and lower rates of immune-related conditions, such as type 1 diabetes and multiple sclerosis. The primary way we get vitamin D is by making it ourselves—UV rays from the sun help us to produce it. In the wintertime, in northern latitudes, many people start to run out of their internal vitamin D stores.
How to Get It: Soak up some sun (ultraviolet, or UV, rays cause skin cells to produce vitamin D). Eat vitamin-D-fortified foods, such as milk, soymilk and cereals. Vitamin D is also found naturally in a few foods: fatty fish, such as salmon, mackerel and sardines, and in egg yolks. If you live in the northern part of the United States, spend lots of time indoors and/or slather on the sunscreen anytime you’re outside, you may not be getting enough. Some studies suggest that as many as 7 out of 10 Americans are deficient in vitamin D. To be absolutely sure you’re covering your needs for this nutrient, consider a vitamin D supplement (for folks ages 1 to 70, the recommended amount is 600 International Units).
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