<s>[INST] I spend time in the sun. Do I have to worry about vitamin D? [/INST] There are a number of good reasons to supplement vitamin D. If you are using sunscreen, it screens out the UV rays that convert precursors of vitamin D to vitamin D in your skin. People with darker skin do not process vitamin D as well as those with lighter skin. People, especially older adults, are not generally out in the sun on a regular basis. 

In northern latitudes for much of the year, vitamin D is screened out by the atmosphere due to the low angle of the sun. And as we get older, our skin does not process vitamin D as well as it does when we are younger. The skin also becomes less efficient at producing the vitamin from sunlight as we age. Vitamin D is being shown to have a beneficial effect on many body functions and is safe at the recommended 25 –50 mcg (1,000–2,000 IUs) per day and not expensive to supplement. Source: American Bone Health. Link: https://americanbonehealth.org/frequently-asked-questions/. Field: Rheumatology. Disease: Ostoeporosis </s>