Scurvy disorders, unusual eating habits, alcoholism, and old people who live alone. Other risk factors include intestinal malabsorption and dialysis. Humans and certain other animals require vitamin C in their diets to make the building blocks for collagen. Diagnosis typically is based on physical signs, X-rays, and improvement after treatment. Treatment is with vitamin C supplements taken by mouth. Improvement often begins in a few days with complete recovery in a few weeks. Sources of vitamin C in the diet include citrus fruit and a number of vegetables such as tomatoes and potatoes. Cooking often decreases vitamin C in foods. Scurvy
Vitamin A deficiency reference point for the extent of deficiency (with mortality increasing with severity of the eye disease). In a longitudinal study of preschool Indonesian children, susceptibility to disease increased nine times when severe VAD was present. The reason for the increased infection rate in vitamin A deficient populations is the T-killer cells require retinoids to proliferate correctly. Retinoic acid binds the promoter region of specific genes, so activates the transcription process and cell replication. A vitamin A-deficient diet will have a very limited surplus of retinol, so cell proliferation and replication will be suppressed, contributing to a reduced number of T-cells