Senior Health

11/15/2022 | By Howard LeWine, M.D.

A reader wonders if vitamin D testing is worthwhile or if perhaps the value of D has been overblown. Dr. Howard Lewine of Harvard College addresses the value of the vitamin and who benefits from testing.


It seems like the health benefits of vitamin D may have been overblown. Should anyone get a vitamin D testing to check their blood level? If yes, who?


The importance of sufficient vitamin D for bone health has a long history. In the past few decades, several studies have suggested that vitamin D might have other health benefits as well.

For instance, observational studies have found an association between low levels of vitamin D and heart disease, diabetes, and certain cancers. While people with these diseases may be more likely to have lower levels in their blood if given a vitamin D test, no studies have shown that insufficient vitamin D actually causes the diseases.

Even the benefit of vitamin D to prevent bone fractures has now been questioned based on results of a clinical trial looking at vitamin D supplementation in a general population. So, what does all of this mean regarding routine testing for vitamin D deficiency?

vitamin D supplement, image by Megaflopp. Is vitamin D testing worthwhile? Dr. Howard Lewine of Harvard College addresses the value of vitamin D and who benefits from testing.

The position of the U.S. Preventive Services Task Force (USPSTF) has not changed. According to the USPSTF, the evidence is insufficient to recommend routinely screening asymptomatic people for vitamin D deficiency.

Their main reasoning was that there is no consensus regarding the optimal level needed to keep bones healthy. For instance, traditional guidelines state that vitamin D levels should be at least 20 nanograms per milliliter (ng/mL). (A blood test measures a form of the vitamin known as 25-hydroxyvitamin D.) But some experts say this amount is too low and the level should be 30 ng/mL or higher.

Who might benefit from vitamin B testing?

Most experts acknowledge that true vitamin D deficiency is below 12 ng/ml, but this is quite uncommon. People who might have a level this low and need regular vitamin D testing include those who have a gastrointestinal condition like celiac disease that decreases the ability to absorb vitamin D; are malnourished; or regularly take medication that interferes with vitamin D activity, such as an oral corticosteroid (such as prednisone) or certain anticonvulsants.

In addition, both women and men who have thin bones (either osteopenia or osteoporosis) or fragility fractures (broken bones that occur from minimal trauma) should get at least a one-time vitamin D testing.

Related: Maintaining bone health – risk factors and supplements

How do I get enough vitamin D?

The good news is that getting enough vitamin D is easy for most people. Men ages 50 to 71 should get 600 international units (IU) per day, and men older than this should get 800 IU. Sunshine is the easiest way to get enough vitamin D – five to 30 minutes of sun exposure without sunscreen, twice a week, often can supply what the body needs.

Good food sources of vitamin D are swordfish, salmon, and tuna, and vitamin D-fortified orange juice and milk. For men who think they don’t get enough of vitamin D, a daily 1,000 IU vitamin D3 supplement is quite safe.

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Howard LeWine, M.D.

Howard LeWine, M.D., is an internist at Brigham and Women’s Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit