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Vitamin D during adolescence crucial for bone geometry, according to new research

Posted on: August 6, 2013   by  Vitamin D Council


A new look at an old randomized controlled trial has found that vitamin D supplementation during adolescence positively affects bone geometry of the femoral neck.

The randomized control trial took place in Beirut in 2001 and 2002. One hundred sixty seven girls (mean age 13.1 years) and 171 boys (mean age 12.7 years) were randomly assigned to receive either a weekly placebo pill or a weekly vitamin D pill of 1,400 IU or 14,000 IU for one year.

Initially, researchers were interested if vitamin D influenced bone mass density. They found that it did, for both the low dose and high dose groups, but only in the girls.

However, no one to date had looked at whether the vitamin D supplementation affected the geometry and structure of bone.

Bone mass accrual during adolescence is important. In general, the more mass accrued during this development stage in life, the more likely you are to have healthy bones later in life. The development of good bone geometry, in addition to development of good bone mass density, is essential in bone mass accrual.

In this analysis, researchers found that once again, vitamin D supplementation affected the girls but not the boys.

For girls, vitamin D supplementation reduced the buckling ratio at the narrow neck of the femur. It also improved the cross sectional area of the intertrochanteric and outer diameter of the shaft. There was no statistically observed benefit in those who took the 14,000 IU of vitamin D compared to those who took the 1,400 IU; both vitamin D groups fared equally well compared to the placebo group.

The researchers concluded,

“To our knowledge this (study) is the first to demonstrate a measurable positive effect of vitamin D supplementation on bone geometry in girls but not boys, during a critical time of growth and peak bone mass accrual… If confirmed and sustained into adulthood, these observed changes would be anticipated to translate into a reduced risk of hip fractures in elderly years.”


Al-Shaar L et al. Effect of vitamin D replacement on hip structural geometry in adolescents: A randomized controlled trial. Bone, 2013.

7 Responses to Vitamin D during adolescence crucial for bone geometry, according to new research

  1. John

    Boys probably need more vitamin D.

  2. Rita and Misty

    Greetings John!

    And why would you assume that boys probably need more vitamin D?

    It appears from the article above that this isn’t the case….

    Your thoughts?

    Rita 🙂

  3. Brant Cebulla

    I think the boys’ vitamin D levels were higher at baseline. So one explanation could be that too many of the boys were already above the vitamin D threshold for bone health, though the researchers don’t know for sure.

  4. Estelle Carenza

    I agree with Brant. He may be correct in his theory of thinking that the boys had/have a higher baseline. The study took place in Beirut. The mean age of the girls in the study was 13.1. I believe that girls soaked up the vitamin D supplement more than the boys because at that age they would have been covered from head to to in a burka! Therefore, they were not exposed to natural vitamin D–the glorious sun!

  5. IAW

    Another thing to probably blame on lack of Vitamin D!
    The epidemiology of slipped capital femoral epiphysis: an update. (2006)
    “The relative incidence of SCFE was 3.94 times higher in black children and 2.53 times higher in Hispanic children than in white children. The incidence rate was significantly higher in boys.”

  6. Rita and Misty


    I owe you an apology. I misunderstood your comment.

    After contemplating your statement today, I realize you are saying that boys needs a higher dose of D3, or a 25(OH)D level to see any impact on bone geometry.

    I think this is correct. And I am musing that this would be because of how our hormones cascade.

    I am not a physician nor am I a scientific researcher, so I just might have the hormonal cascade a bit incorrect.

    I apologize. Those with more knowledge, please do correct me.

    But, I am thinking that Vitamin D as a pro-hormone, impacts cholesterol, which in turn cascades to testosterone, which then cascades to estrogen.

    I think it is estrogen which has a healthy impact upon bones? Although, I think I read somewhere that testosterone is also required for bone health, even in females….

    Regardless, let me continue:

    Since girls require significantly less testosterone than boys, vitamin d at a lower dose and/or lower 25(OH)D level, perhaps will have a more significant impact on bone health and geometry.

    Since boys need vitamin d for significant amounts of testosterone, they do perhaps required much more vitamin d to have a positive effect upon their estrogen levels for good bone health.

    Again, these are my musings.

    I would truly appreciate hearing from those with more knowledge.


  7. Rita and Misty

    Estelle~~Greetings and salutations!!

    If I may quote from your above comment: “I believe that girls soaked up the vitamin D supplement more than the boys because at that age they would have been covered from head to to in a burka! Therefore, they were not exposed to natural vitamin D–the glorious sun.”

    Agreed, and so true, about vitamin D–and the glorious sun!

    Also agreed, with you (and Brant) that the boys had a higher baseline 25(OH)D level. I understand that the burka is a meaningful and religious tradition, but no doubt the women do suffer from low vitamin d blood levels due to it.



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