Collagen biosynthesis by human pores and skin fibroblasts. III. The results of ascorbic acid on procollagen generation and prolyl hydroxylase activity. Your skin produces vitamin D when exposed to sunlight. Foods like fatty fish, fish oil, and liver also comprise vitamin D — and also specific fortified foods and supplements. https://health-and-wellness92479.iyublog.com/30494040/indicators-on-immune-you-should-know