Vitamin D is critical for the immune system and is the most common nutritional deficiency in the world.
For most of the past century it was thought that vitamin D’s primary function was to facilitate calcium absorption and help prevent osteoporosis. However, in the past decade scientists have discovered that all cells in the body have vitamin D receptors and that vitamin D controls and regulates over 2,000 genes. Many of the genes controlled by vitamin D are genes that regulate our immune system. Hence we now realize that vitamin D is one of the most critical nutrients for a strong immune system.
Our primary source of vitamin D is sunlight. When ultraviolet rays from sunlight strike our skin, a chemical reaction occurs which produces vitamin D. However, most people DO NOT get enough direct sunlight to product adequate levels of vitamin D. According to Dr. Michael Holick who is one of the world’s leading vitamin D researchers, “Vitamin D is not only the most common nutritional deficiency in the world, it is also the most common medical condition, affecting over 1 billion people.”
Vitamin D is an important nutritional supplement for all humans. I suggest that adults 5,000 IU/day of vitamin D3. Vitamin D is a fat-soluble nutrient. For optimal absorption, vitamin D should be taken at a
meal that contains some fat which is usually the largest meal of the day.