Why Test for Vitamin D?
Long-recognized for its value in maintaining bone strength and promoting calcium absorption, vitamin D has exploded onto center stage as possibly the most important vitamin humans can take to reduce their risks of cancer, heart disease, immune deficiency and overall mortality.
Scientists are now redefining blood levels of vitamin D that are considered optimal. Indeed, the term “vitamin D insufficiency” is now used to describe vitamin D levels that are above the bare minimums needed for bone health … but below the middle of the so-called optimal range. A whopping 42–57% of Americans are vitamin D insufficient by these newer, more rigorous criteria, and nutritionists now strongly recommend monitoring levels of vitamin D in the blood.
Life Extension® recommends that a healthy serum level of vitamin D (25-hydroxyvitamin D) is 50–80 ng/mL based upon current research, with the most recent research suggesting that maintaining levels in the upper one-third of the range is optimal.
Vitamin D levels do not always correspond to ingested doses of vitamin D supplements or to sunlight exposure. Factors like body mass affect how much supplemental vitamin D is needed to achieve optimal ranges. Those who take at least 5,000 IU a day of supplemental vitamin D (up to 7,000 IU a day during cold and flu season) are probably in favorable ranges. To make sure you are taking enough vitamin D, a blood test can provide a definitive answer.
Also, because vitamin D deficiency occurs most commonly during the winter months when the majority of Americans do not receive adequate sunlight, spring is the ideal time to check your vitamin D status.