What is vitamin D? Vitamin D is a “fat soluble” vitamin that works with other vitamins, minerals and hormones to maintain normal blood levels of calcium and phosphorous. It increases the absorption of calcium from the intestines, promotes retention of calcium by the kidneys, and slows down the secretion of parathyroid hormone by the parathyroid glands.
How much vitamin D do I need? The recommended daily intake of vitamin D varies according to age. A daily intake of at least 400-800 International Units (IU) is suggested for all adults. Some individuals may need more than this. If there is uncertainty that you are getting enough vitamin D, it may be helpful to measure the level of 25-hydroxyvitamin D in the blood. Many experts recommend that the blood level be kept in the range of about 30-57 ng/ml. This is the “desirable” level, which is higher than the “normal” or “average” level that is often given on laboratory report forms.
What happens if I don’t get enough vitamin D? Vitamin D deficiency can impair calcium metabolism enough to cause osteoporosis, osteomalacia, or rickets, depending on age and the severity of deficiency. A condition called “secondary hyperparathyroidism,” which increases the rate of bone metabolism and causes loss of bone, often occurs. Vitamin D deficiency may also result in reduced muscle strength, increased risk of falling, and possibly increased risk of some types of cancer, such as colon cancer.
How common is Vitamin D deficiency? Unfortunately, vitamin D deficiency is common. It can occur in anyone, but those most likely to have it are the elderly; anyone with an intestinal malabsorption problem; anyone taking anticonvulsant medication; anyone who gets little exposure to the sun due to being indoors, using protective clothing or sunblock; those living in Northern latitudes; and those who never take vitamin supplements. Even in sunny New Mexico, vitamin D deficiency can occur.
Can I get too much Vitamin D? Yes, you can get too much, but vitamin D toxicity is a very rare condition that is an insignificant in comparison to vitamin D deficiency.
How do I get Vitamin D? In children, exposure to the sun with normal outdoor activities is usually sufficient. There are few natural food sources with a significant amount of vitamin D- primarily fish oils, such as cod liver oil, and oily saltwater fish, such as cod, mackerel and sardines packed in oil. All adults should consider taking a daily multivitamin containing vitamin D. Some individuals may need additional over the counter vitamin D supplements or a high dose of vitamin D available only by prescription.