Suppléments de vitamine D et prévention des fractures

Suppléments de vitamine D et prévention des fractures

Dr. Adrian Lau, Dr. Rowena Ridout, Dr. Claudia Gagnon, Dr. Zahra Bardai, Dr. Emma Billington and Dr. Wendy Ward.

Recommendations from Osteoporosis Canada Rapid Response Team.

LeBoff and colleagues (1) recently published the results of an ancillary study of the Vitamin D and Omega-3 Trial (VITAL), concluding that Vitamin D3 supplementation of 2000 IU daily did not result in a significantly lower risk of fractures than placebo among generally healthy midlife and older adults.

In an editorial in response to these results, Cummings and Rosen (2) suggest that “providers should stop screening for 25-hydroxyvitamin D levels or recommending vitamin D supplements, and people should stop taking vitamin D supplements to prevent major diseases or extend life”.

These articles have raised concerns in the osteoporosis community, amongst health care professionals, patients, and caregivers.  Should patients with osteoporosis or previous fragility fractures continue their vitamin D3 supplementation?  Should their vitamin D levels be checked?

An individual’s medical risk of conditions in which vitamin D monitoring and supplementation may be of benefit should be carefully evaluated.

It is important to note that the participants in this study were representative of the general American population and thus results and recommendations may or may not be applicable to patients with osteoporosis, previous fractures, or those at risk of severe vitamin D deficiency.  At baseline, only about 10% of the study participants had previous fragility fractures, and less than 5% were on osteoporosis medications.    

About 42% of participants were already on vitamin D supplementation prior to the initiation of the study.  If participants were randomized to the placebo group (as opposed to the vitamin D 2000 IU group), they were allowed to continue their vitamin D supplementation, up to 800 IU daily.  Of note, the baseline 25-hydroxyvitamin D level of participants was 30 ng/ml, or 75 nmol/L, which is in target as per our current guidelines.  While vitamin D was not shown to prevent fractures in this study group, this effect of vitamin D supplementation cannot be generalized to patients with osteoporosis given their higher risk of fractures.

What should we do about Vitamin D testing?

The screening of 25-hydroxyvitamin D levels in the general population is currently not recommended (3).  However, there may be specific situations where vitamin D testing may be of clinical use.  These include patients with co-morbidities which affect vitamin D absorption and metabolism, where testing may help identify significantly low 25-hydroxyvitamin D levels, and facilitate correct dosing of vitamin D supplementation.  These co-morbidities include malabsorptive disease, renal disease, living in institutionalized settings, and taking certain medications which may affect vitamin D metabolism.  Screening lab tests may also be useful prior to the initiation of anti-resorptive agents for osteoporosis, as low 25-hydroxyvitamin D levels may be a risk factor for hypocalcemia.

What should we do about Vitamin D supplementation?

We encourage our patients with osteoporosis to continue with their current vitamin D supplementation, as per the current Osteoporosis Canada Guidelines (4), and according to their personal clinical needs.  As few foods contain vitamin D, Health Canada recommends that all Canadians over age 50 take 400 IU of vitamin D per day (5).  Also, most pharmacotherapy trials provided participants with a minimum of 400 IU of vitamin D per day.  Patients should discuss their vitamin D requirements with their health care professionals before making any changes to their routines.

References

  1. LeBoff MS, Chou SH, Ratliff KA, Cook NR, Khurana B, Kim E, Cawthon PM, Bauer DC, Black D, Gallagher JC, Lee I, Buring JE, Manson JE.  Supplemental Vitamin D and Incident Fractures in Midlife and Older Adults.  New England Journal of Medicine. 2022;387(4):299-309.
  2. Cummings SR and Rosen C. VITAL Findings — A Decisive Verdict on Vitamin D Supplementation.  New England Journal of Medicine.  2022;387(4):368-370.
  3. Lindblad AJ, Garrison S, McCormack J.  Testing vitamin D levels.  Canadian Family Physician. 2014;60(4):351.
  4. Papaioannou A, Morin S, Cheung AM, Atkinson S, Brown JP, Feldman S, David A. Hanley DA, Hodsman A, Jamal SA, Kaiser SM, Kvern B, Siminoski D, Leslie WD.  2010 clinical practice guidelines for the diagnosis and management of osteoporosis in Canada: summary.  CMAJ.  2010;182(17):1864-1873.
  5. https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/vitamins-minerals/vitamin-calcium-updated-dietary-reference-intakes-nutrition.html

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