Vitamin C the scorbutic diet was fed. Men in both studies on a diet devoid, or nearly devoid, of vitamin C had blood levels of vitamin C too low to be accurately measured when they developed signs of scurvy and, in the Iowa study, at this time were estimated (by labeled vitamin C dilution) to have a body pool of less than 300 mg, with daily turnover of only 2.5 mg/day, implying an instantaneous half-life of 83 days by this time (elimination constant of 4 months). Vitamin C has a definitive role in treating scurvy, which is a disease caused by vitamin
Vitamin D deficiency Vitamin D deficiency Vitamin D deficiency, or hypovitaminosis D, most commonly results from inadequate sunlight exposure (in particular sunlight with adequate ultraviolet B rays). Vitamin D deficiency can also be caused by inadequate nutritional intake of vitamin D, disorders limiting vitamin D absorption, and conditions impairing vitamin D conversion into active metabolites—including certain liver, kidney, and hereditary disorders. Deficiency impairs bone mineralization, leading to bone softening diseases such as rickets in children. It can also worsen osteomalacia and osteoporosis in adults, leading to an increased risk of bone fractures. Muscle weakness is also a common symptom of vitamin D deficiency,