Do you know if you are vitamin D deficient? Surprisingly, the latest evidence shows that many men and women have insufficient blood levels of this important vitamin. A 2007 study of women in the Northern United States found low vitamin D levels in 54 percent of African American women and 42 percent of white women -- fairly significant numbers.
Vitamin D is mostly known for its role in helping to absorb calcium to build strong bones. This is certainly not its only use, though. Vitamin D deficiency has now been linked to breast cancer, colon cancer, prostate cancer, heart disease, depression, weight gain, and autoimmune disorders. There is still much research that is needed to show cause and effect but there is increasing evidence that supplementing Vitamin D is helpful in some treatments specifically for autoimmune disorders, heart disease, and depression.
This vitamin is so important that our bodies' produce it in our skin from sun exposure. The best source is UVB rays (280-320 mm) through sunlight. A light skinned person with no sun screen can make 20,000 to 30,000 IU of Vitamin D3 in the skin in 30 minutes, and then convert it in the body to its active form. The problem is that sun exposure without using sun screen also increases the risk of skin cancer.
You can also find Vitamin D in foods including fatty fish like salmon, tuna, and sardines. It is also found in egg yolks and fortified foods such as milk, yogurt, orange juice, soy milk and cereals.
Supplements can be necessary if someone is already vitamin D deficient or at risk. The safe upper limit is 2,000 IU per day. The best supplement to take is in the form of Vitamin D3 or cholecalciferol, which is more potent than Vitamin D2. Dosing depends upon if you already have a deficiency and by how much. To find out what your levels are your doctor can provide a simple blood test for 25-hydroxy Vitamin D. It is best to get the facts first instead of self-prescribing supplements without knowing how much you need. Vitamin D is a fat soluble vitamin which means it can be toxic at too high of levels. For a safe, daily amount it is best to take 400 IU of Vitamin D with 500 mg of calcium together twice a day for best absorption.
Individuals who are at the greatest risk are those with limited sun exposure including those who live in northern climates. Women with darker skin colors produce less vitamin D from the sun leaving them at greater risk of deficiency. Vitamin D production also declines with age so it is a good idea to make it a routine to check your 25-hydroxy vitamin D levels at your annual physical.