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Is there a safe upper limit of vitamin D?

Kathleen Blanchard's picture
Research pinpoints safe upper limit of vitamin D for heart health

When it comes to vitamin D, more is not always better when it comes to heart health. But until know no one knew how much of the hormone we need for a healthy cardiovascular system.

Too much vitamin D can lead to coronary events. How much vitamin D the heart needs is discovered for the first time. Too much might mean higher risk of heart disease.

Range of vitamin D for heart health

The findings that are due to be published in The Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM) highlights too much vitamin D has no benefits for cardiovascular health and could contribute to coronary artery events.

Yosef Dror, PhD, of Hebrew University in Rehovot, Israel, and lead author of the new study found more than 60 percent of the population tested had low vitamin D levels, and 50 percent were severely deficient in the vitamin; linked to a 1.5 fold increase of heart related events including death.

Vitamin D levels above 36 ng/mL, found in 3 percent of those tested, was associated with a 1.13 times higher risk of coronary morbidity or death.

Dror, who studied vitamin D levels of 422,000 people aged 45 years or older, who had their vitamin D levels tested, found the safe range of vitamin D levels with related to heart disease is between 20 to 36 ng/mL. Levels above or below the range increased coronary mortality and rate of heart disease significantly.

Research has shown vitamin D deficiency or insufficiency is widespread.
How much vitamin D is optimal has been the subject of much debate. This is the first time researchers have been able to quantify a save upper limit.

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How much vitamin D is needed for optimal health has been the subject of much debate that is likely to continue.

Some experts believe we all need more vitamin D, while others believe most of us have adequate levels.

One of the problems in getting enough vitamin D is that it is not naturally found in food. Fish is a good source of the vitamin, but look or wild-caught. Farm raises fish tends to have lower levels of the hormone.

Ocean salmon and mackerel are good choices, vitamin D expert Chantal Mathieu, MD, from Catholic University, Leuven, Belgium said in a Medscape report.

Meanwhile, Mark Cooper, MD, from University Hospital, Birmingham, United Kingdom says only high risk groups should take vitamin D supplements, because of the chances of harm from levels that are too high.

Vitamin D deficiency is defined as level less than 20 ng/mL (

What do we know about vitamin D levels?

  • The newest study suggests heart risks with too much vitamin D.
  • Too much vitamin D during pregnancy might contribute to childhood food allergies
  • One study suggested upper normal limits of vitamin D changes genes to fight disease (but not higher than recommended)
  • Multiple studies show deficiency of the vitamin can lead to poor health
  • One of the best ways to get your vitamin D is from sunshine

Rather than recommending supplementation for everyone, which might raise the risk of heart disease, Dror suggests people with low vitamin D taking supplements should be monitored closely so they don’t shift to high vitamin D status.

doi: 10.1210/jc.2013-1185
The Journal of Clinical Endocrinology & Metabolism March 26, 2013 jc.2013-1185