Are you getting enough Vitamin D?
Vitamin D is a fat-soluble vitamin essential for the absorption of calcium by the body. Along with phosphate, it regulates bone mineralization and modulates the immune system.
The recommended daily dietary intake of vitamin D is 600 IU per day. This is primarily achieved through vitamins or supplemented foods. Most of the circulating vitamin D in our bodies is actually synthesized by the action of sunlight on the skin. First, vitamin D is converted to 25-hydroxyvitamin D (calcidiol) by the liver. Next, it is converted to 1,25 dihydroxyvitamin D (or calcitriol, the physiologically active form of the vitamin) in the kidneys.
How can I know my vitamin D status?
Serum (blood) vitamin D levels (25-hydroxyvitamin D) are the most accurate indicator of physiological levels since calcitriol concentrations fluctuate greatly with hormonal signals. Individuals with levels less than 30nmol/L (<12ng/mL) are considered at risk for vitamin D deficiency. Levels at or above 50nmol/L (12-20ng/mL) are recommended for optimal health.
- over 60 (the skin does not produce vitamin D as efficiently as before)
- with darker complexion
- who live in northern latitudes or
- obese persons (BMI >30)
are at greater risk for vitamin D deficiency.
Which foods are good sources of vitamin D?
Few foods contain vitamin D. However, fortified foods are readily available including vitamin D added orange juice, milk and ready to eat cereals. Egg yolks and sardines are good natural sources.
Unfortunately, even with fortified foods, many Americans are still deficient in Vitamin D. According to the Centers for Disease Control, roughly a quarter of the population has insufficient levels of Vitamin D. This may be due in part to the fact that food manufacturers supplement with vitamin D2. The latest research has determined that vitamin D3 is more effective than vitamin D2 in raising physiological levels of vitamin D.