osteoporosis etc

[Judith Finlay]

I was interested in the post on uptake of calcium and 
vit D and osteoporosis, etc.  I was a graduate student 
in a vitamin D lab.  Milk among other foods contains 
calcium which is important for properbone formation an 
maintainance.  The active form of vit D acts on the 
intestine to increase calcium uptake.  It is not known 
if simply injesting mor calcium will actually increase 
bone strenghth since calcium uptake is highly regulated 
and the blood levels of calcium must remain constant.  
My thesis advisor, Hector DeLuca told me that he feels 
calcium supliments probably won't do any good.  However 
it is known that weight bearing exercise will help 
streghthen bones.  This is probably becasue this causes 
microfractures in the bones.  When the bones are 
subsequenly remodeled by the bone reforming cells this 
makes the bones more strong. So for older women exercise is probably more 
important thant calcium suppliments and most of us are not vitamin D 
deficient.  However ther was one study that showed that highschool girls 
given Ca supplements had a higher bone density when they reached their 
mid 20s.  It is not yet know if these women will be less likely to 
develop osteoporosis.
Judith Finlay
 jet14 at columbia.edu (J Thompson) writes:

>On Feb 16, Kristine <k.vaaler at ic.ac.uk> **my other post had this wrong** wrote:

>>As much as I am aware of, the problem with skimmed milk is that it *does*
>>contain calcium, but not the fat soluble vitamin (cannot remember whether it is
>>A or D) that is required for an efficient absorption of the calcium. 

>Well, if you were to just skim the fat off of milk and drink it, you would
>lose _both_ the vitamin A and the vitamin D which are normally present in
>cow's milk (the vit. D is what you need to best absord calcium). However,
>the USDA thought of that a long time ago, and requires anyone who processes
>skim milk to re-add the A and D which had been lost (you can read the exact
>amount off of any carton of skim milk). Now, to be really nitpicky, by doing
>that, they also add in a tiny amount of fat for the vitamins to float in,
>but 'dietarily' that fat doesn't add up to anything.  

>>It seems there is a good reason that fat is present in milk in the first place.

>While the fat in milk carries the fat-soluble vitamins, it's really there as
>a compact energy source. If you look at the new food labels, sugars and
>proteins both give 4 Cal/gram, while fats give 9. Thus, if you want to give
>a growing baby energy without requiring it to spend even _more_ of it's time
>eating, then it makes sense to load it's food with fat. Once we grow up,
>however, that much energy from fat isn't so good for us (thus the benefit of
>skim or 1% milk).
>                                                    -J

>________________________________________________________________________________
>J Thompson                                                    jet14 at columbia.edu
>        Class of 1997, Columbia University P&S (a.k.a. Columbia Med)

>Avoid strong drink. It can make you shoot at a tax-collector...     and miss!
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