If you're rarely in the sun or a strict vegetarian, you may be at risk for vitamin D deficiency. If you have weak bones or muscle pain, these are signs that you may not be getting enough vitamin D. Vitamin D is naturally produced when the body is exposed to sun, and it also occurs in a few foods like sardines, cod liver oil, and eggs. That's why if you're a strict vegetarian that doesn't eat any animal products, you're more at risk for vitamin D deficiency. Some of the risks of vitamin D deficiency include osteoporosis, depression, some cancers such as prostate and breast cancer, increased risk of cardiovascular disease, as well as severe asthma in children. If you're experiencing any of these symptoms, it's a good idea to try to get more natural sunlight, just make sure you're not getting burnt. You want to be out about five to thirty minutes a week, twice a week. Also if you think you may not be getting enough vitamin D, you may want to consider taking a vitamin D supplement, since few foods contain it.