Supplemental Vitamin D Does Not Prevent Bone Fractures in Healthy Adults

Vitamin D supplements are widely recommended to keep bones healthy, as it helps to absorb calcium and phosphorus. However, the new study shows that vitamin D supplementation does not decrease the risk of bone fractures in healthy midlife or older adults.

The new study on how vitamin D supplements affect bone health, published in the peer-reviewed The New England Journal of Medicine and led by investigators from Brigham and Women’s Hospital, involved 25,871 participants. They were midlife or older adults and not selected for vitamin D deficiency, low bone mass, or osteoporosis.

Researchers tracked participants over a five-year period and found that supplemental vitamin D3 (2000 IU/day) did not significantly lower the risk of fractures among generally healthy midlife and older adults.

Dangers of the vitamin D overdose

The journal BMJ Case Reports recently described a case of vitamin D intoxication in a middle-aged man who was taking 150,000 IU of vitamin D per day while the recommended dose is 400-800 IU/day. As a result, the man experienced various symptoms, including recurrent vomiting, nausea, and abdominal pain, for nearly three months and was hospitalized.

In 2019, a study led by the University of Calgary revealed that vitamin D supplementation at doses higher than those recommended by Health Canada or Osteoporosis Canada (400 to 2,000 IU/day) was not associated with an increase in bone density or bone strength.

Instead, researchers detected a dose-related decrease in bone density, with the largest decrease occurring in the group, taking 10,000 IU/day.

Crucial to active immune defenses

While more than 40% of the US population is vitamin D deficient, many studies show the importance of the vitamin to human health.

A research team led by Northwestern University conducted a statistical analysis of data from hospitals and clinics across ten countries in 2020. They found out that patients from countries with high COVID-19 mortality rates, such as Italy, Spain, and the UK, had lower levels of vitamin D compared to patients in countries that were not as severely affected.

A study from the University of South Australia found that low vitamin D levels were associated with an increased risk of dementia and stroke. Researchers concluded that in some populations, as much as 17% of dementia cases might be prevented by increasing everyone to normal levels of vitamin D.

In 2010, researchers at the University of Copenhagen discovered that vitamin D is crucial to activating our immune defenses. According to researchers, without sufficient intake of the vitamin, T cells will not be able to react to and fight off serious, life-threatening infections in the body.

What is the best source of vitamin D?

Vitamin D3 can be produced when skin is exposed to sunlight and can also be found in certain foods. The best sources of the vitamin, according to the T.H. School of Public Health at Harvard University, are:

  • Cod liver oil
  • Salmon
  • Swordfish
  • Tuna fish
  • Orange juice fortified with vitamin D
  • Dairy and plant milks fortified with vitamin D
  • Sardines
  • Beef liver
  • Egg yolk
  • Fortified cereals


1. The New England Journal of Medicine. Supplemental Vitamin D and Incident Fractures in Midlife and Older Adults.

2. University of South Australia. Vitamin D deficiency leads to dementia.

3. University of Copenhagen. Vitamin D crucial to activating immune defenses.

4. Northwestern University. Vitamin D appears to play role in COVID-19 mortality rates.

5. University of Calgary. Vitamin D: How much is too much of a good thing?

6. BMJ Journals. Vitamin D intoxication and severe hypercalcaemia complicating nutritional supplements misuse.

7. Harvard T.H. School of Public Health. Vitamin D.

8. Cleveland Clinic Mercy Hospital. 42% Percent of Americans Are Vitamin D Deficient. Are You Among Them?

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