Vitamin D and Calcium

What’s the real deal with vitamin D and calcium?  Lately, there’s been a lot of talk about vitamin D and calcium and sometimes the information about how much to take, the potential health benefits or the risks has been confusing.

First, a bit about the basics of these two substances. Vitamin D is fat-soluble vitamin that is necessary for making and maintaining healthy bones. Deficiency causes rickets in children and a condition of weak, brittle bones in adults. Vitamin D promotes the absorption of calcium from the intestines, reduces inflammation and is important in the function of the immune system. It is found in foods such as fortified dairy products, fatty fish (like mackerel, cod liver oil, sardines and salmon), and less so in eggs and certain mushrooms. Importantly, Vitamin D is also manufactured in the body by a chemical reaction involving the effect of sunlight on the skin.

Calcium is a mineral that works with Vitamin D to help maintain strong bones and is also necessary for muscle and blood vessel contraction and for proper function of the nervous system. It’s found in high concentration in milk, cheese, as well as in leafy greens, fortified juices and also in some medicines (like antacids).

People at risk for Vitamin D and calcium deficiencies include: those with darker skin (less UV radiation absorption), those who avoid sunlight exposure, persons with certain types of gastric bypass surgery or malabsorption, individuals on certain types of medications (e.g. anti-seizure drugs), and those who avoid dairy products due to a milk allergy or lactose intolerance.

In 2010, the prestigious Institute of Medicine asked a panel of scientists and experts to review over 1,000 studies containing scientific data related to calcium and Vitamin D. The panel came up with new recommendations for the necessary amounts of Vitamin D and calcium and concluded that:

  1. Though a lot has been reported in the media about potential evidence of health benefits, studies to date support a role for Vitamin D and calcium only in bone health.
  2. The majority of people in Canada and the United States are getting enough calcium and Vitamin D, (and in fact taking too much of either could potentially be harmful).

But, this is not the end of the story on Vitamin D as studies are underway to find out more about the effects of Vitamin D on calcium and health.  But for now at least, we have an authoritative comment from the Institute of Medicine as a place to start.


Dietary Supplement Fact Sheet: Calcium, Office of Dietary Supplements, National Institutes of Health, 2011 (Accessed July 19th, 2011 at

Dietary Supplement Fact Sheet: Vitamin D, Office of Dietary Supplements, National Institutes of Health, 2011 (Accessed July 19th, 2011 at

2010; pages 1-2. Dietary Reference Intakes for Calcium and Vitamin D, IOM of the Natl Academies:


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