How common is vitamin D deficiency?

Mihaela B. Taylor, MD
Rheumatology
Vitamin D deficiency is common, and experts believe the incidence of vitamin D deficiency may be increasing. During winter months in the northern hemisphere, vitamin D deficiency can affect up to 50% of the population. Standardized, normal vitamin D levels are hard to define because they can vary from person to person. A person's level can be determined through a blood test, and doctors have certain guidelines to follow to determine if someone is deficient in vitamin D.
Neal Spruce
Neal Spruce on behalf of dotFIT
Fitness
Yes and no. It depends on what levels are deemed most healthy, which unfortunately is not agreed upon among researches and experts. There are currently two opposing views  -- adequate levels versus suggested optimal levels based on strong recent evidence. Although the Institute of Medicine (IOM) recently tripled the Vitamin D recommendation (from 200 IUs to 600 IUs for most adults), they also believe that most Americans blood levels are safely above the 20 ng/ml (nanograms per milliliter) level that is deemed adequate. With the IOM acknowledging research showing that most American diets fall far short of even the old lower recommendation of 200 IUs, they concluded that most people must be making up the dietary shortfall through sunlight and/or supplements. This explains why the answer to this question is “no” --  most people do not have blood levels of vitamin D below the adequate level of 20ng/ml because they get to this level from supplements and/or sunshine since it’s obvious that their diet is insufficient.

On the other hand, most top Vitamin D researchers still think both the vitamin D blood level cut off and new dietary recommendations are still too low. Many recent studies have linked significantly higher blood levels of Vitamin D to a reduced risk of many chronic diseases including heart disease, hypertension, cancers, diabetes, infections and falls. Therefore, most Vitamin D experts recommend blood levels of vitamin D (25-hydroxyvitamin D [25OHD]) to be no less than 30 ng/ml. This may require a daily intake of at least 1000 IUs of Vitamin D. The strength of evidence for increased blood levels of vitamin D has lead many physicians to order blood tests for their patients costing between $100 and $200. The blood levels of 25OHD deemed normal by the National Institute of Health (NIH) as posted on their MedlinePlus website is a range between 30 and 74ng/ml. This is where the Vitamin D experts would like to see blood levels since these levels appear to decrease the risk of disease. In order to reach these levels most people would need to supplement the diet since sunshine is not considered a safe or reliable therapy.

This is why the answer to this question is ultimately “yes” -- the suggested “better than adequate” blood level would be at least 30 ng/ml and most Americans fall short, meaning they should supplement the diet if they want to hedge their bets against certain common diseases.
F. Michael Gloth, III
Geriatric Medicine
Vitamin D deficiency is relatively common. It appears to be a problem for more than three-quarters of people over 70 and more than half of middle-aged adults, depending on the season and latitude. This makes vitamin D one of the most important vitamin supplements.
Fit at Fifty and Beyond: A Balanced Exercise and Nutrition Program (A DiaMedica Guide to Optimum Wellness)

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Fit at Fifty and Beyond: A Balanced Exercise and Nutrition Program (A DiaMedica Guide to Optimum Wellness)

As people reach their fifties, the body’s metabolism slows. Without a change in eating or exercise habits, it’s common to put on weight and become less able to perform routine physical...
Vitamin D deficiency is fairly common in the United States. About two-thirds of Americans have sufficient blood levels of vitamin D, according to recent statistics from the U.S. Centers for Disease Control and Prevention (CDC). "Sufficient" means the levels of a form of vitamin D called 25-hydroxyvitamin D, or 25OHD, are between 50 and 125 nanomoles per liter (nmol/L). About one-quarter of Americans are at risk for vitamin D inadequacy, with 25OHD blood levels of 30 to 49 nmol/L. About 8% of Americans are at risk for vitamin D deficiency because their blood levels measure below 30 nmol/L. For more information about vitamin D, talk to your doctor.
Dr. Rovenia Brock, PhD
Nutrition & Dietetics
Although rare, recent evidence has indicated a re-emergence of vitamin D deficient rickets. There is also an alarming prevalence of vitamin D insufficiency in the U.S. population, including those with darker skin pigmentation, the elderly, and people living in geographical areas with limited sunlight or heavy pollution.
Dr. Michael Roizen, MD
Internal Medicine
Most American adults do not get enough vitamin D. Estimates are that 30 to 40 percent of adults are deficient in vitamin D. In three studies of elderly people who live north of Raleigh-Durham, North Carolina, as many as 65, 87, and 89 percent were deficient in vitamin D.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.