The importance of vitamin D for calcium utilisation in the body

 In January  I wrote about the benefits of combined calcium and vitamin D supplements for fracture prevention.  Many adults, particularly women, are interested in eating for bone strength and prevention of osteoporosis (or brittle bones).

Many people still assume that a higher calcium intake is key for osteoporosis prevention.  As you can see from the posts linked above there are many nutrients that interact to protect our bones.  Calcium is, indeed, very important for bones however, recent evidence (1) seems to suggest that increasing calcium intakes may not help bone strength if the body is deficient in vitamin D, or body levels are insufficient.  This is a worrying concern since, as you will know from my past posts on vitamin D, most people in the UK have insufficient levels of this crucial vitamin.

This recent study (1) explored the importance of dietary calcium intake and blood serum vitamin D status with regards to bone mineral density in about 5000 women and men.  The researchers found that among men and women vitamin D status seemed to be the dominant predictor of bone mineral density relative to calcium intake.  The study highlights the importance of vitamin D and its ability to help the body utilise calcium efficiently, thus helping to explain why increasing calcium intakes alone is not always a successful way of dealing with osteoporosis prevention. 

Calcium is vital for bone mass, but nutrient interactions do need to be taken into account.  “The study supports the idea that correcting inadequate blood levels of vitamin D is more important than increasing dietary calcium intake beyond 566 mg a day among women and 626 mg a day among men for better bone mineral density” (2).  It seems that only women with the very lowest vitamin D levels seemed to benefit from higher calcium intakes.

Again, this adds to the evidence for the importance of vitamin D, to recap: most people in the UK do not get enough vitamin D and have insufficient/deficient levels in their blood.  There is no current consensus about the amount of daily vitamin D intake necessary to maintain blood levels at around 40-50 nmol/l (which is currently seen as optimal by many medical practitioners).  Most adult (age 18 and over) individuals in the UK would probably require a supplement of around 2000iu vitamin D daily.  It is always a good idea to check with a medical doctor prior to starting any supplement regimen.  Higher doses, up to 5000iu daily, may well be useful but I would not recommend such a regimen unless under the supervision of a medical doctor who can monitor blood levels regularly.  When looking for vitamin D supplements two forms are generally available.   Cholecalciferol, known as vitamin D3, and ergocalciferol or vitamin D2. Cholecalciferol is generally taken to be the more potent, easily absorbed and preferred form of vitamin D.

Related posts:

1. Combined vitamin D and calcium supplements for fracture prevention
2. Can calcium aid weight loss?
3. Does calcium play a role in cancer prevention?
4. Calcium and Vitamin D may reduce abdominal fat
5. D is for December – the importance of vitamin D is again highlighted by scientists