Vitamin D is believed essential to maintaining calcium and phosphorus balance in the body. It may keep bones healthy, protect against high blood pressure and guard against osteoporosis. Vitamin D is sometimes found in eggs and fortified milk. Individuals may also absorb Vitamin D through 10 minutes of daily sunlight. It comes in supplemental form as well as in multivitamins. Too much vitamin D may result in dry mouth, nausea, vomiting, headache, kidney disease and artery hardening.