Here is an excerpt from an article on Vitamin D3 added to milk. Muslims that dont eat pig might find it interesting.
How is vitamin D produced commercially for food supplementation?
When the critical importance to human health of a regular dietary access to vitamin D3 was understood (in the 1930’s), milk suppliers realized it would be advantageous to their customers’ health to market milk which had been supplemented with vitamin D3. Thus there developed in the 1940’s, and continues to the present, a large business of industrial production of vitamin D3 used for the supplementation of foods for human consumption: milk (both homogenized and evaporated), some margarine and breads. Since the 1960’s vitamin D3 has been used also for the supplementation of farm animal and poultry food. …The commercial production of vitamin D3 is completely dependent on the availability of either 7-dehydrocholesterol or cholesterol. 7- Dehydrocholesterol can be obtained via organic solvent extraction of animal skins (cow, pig or sheep) followed by an extensive purification. Cholesterol typically is extracted from the lanolin of sheep wool and after thorough purification and crystallization can be converted via a laborious chemical synthesis into 7-dehydrocholesterol. It should be appreciated that once chemically pure, crystalline 7-dehydrocholesterol has been obtained, it is impossible to use any chemical or biological tests or procedures to determine the original source (sheep lanolin, pig skin, cow skin, etc.) of the cholesterol or 7-dehydrocholesterol.
Next the crystalline 7-dehydrocholesterol is dissolved in an organic solvent and irradiated with ultraviolet light to carry out the transformation (similar to that which occurs in human and animal skin) to produce vitamin D3…
The major producers of vitamin D3 used for milk and other food supplementation are the companies F. Hoffman La Roche, Ltd (Switzerland) and BASF (Germany).
What is the source of vitamin D in milk?
Milk from all lactating animals, including humans, contains vitamin D3 that has been produced photochemically from 7-dehydrocholesterol present in the skin. In cow’s milk it has been determined that the concentration of vitamin D3 in milk provided by the cow is roughly 35-70 International Units per quart as determined via biological assay (12) and approximately 5080 International Units as determined by modern chemical mass spectrometric procedures (13). However these are rather low levels of vitamin D3 from the perspective of providing the 200-400 IU per day as recommended by the Food and Nutrition Board of the Institute of Medicine (9). Accordingly, as discussed above, the business practice of supplementing cows milk with chemically synthesized vitamin D3 was initiated. At the present time almost all milk sold commercially in the United States has 400 IU of chemically synthesized vitamin D3 added per quart. **Any vendor of milk for human consumption containing added vitamin D3 is required by the US Food and Drug Administration (FDA) to include a notice on the milk carton label. Usually this label states “400 IU of added vitamin D3”. However it is not required by law to indicate either the manufacturer of the added vitamin D3 or the sources of the cholesterol and 7-dehydrocholesterol used for its production. **
**It is a fact that most milk sold in the US will contain vitamin D3 with two origins. (a) That vitamin D3 made by the cow using sunlight to irradiate 7- dehydrocholesterol present in her skin. (b) That vitamin D3 made by a chemical process and then added to the cow milk as a nutritional supplement. It is simply not possible to distinguish the origins of the two vitamin D3 preparations by any biological or chemical procedure, because they are the same molecular structure. Further, there is no legal requirement for the manufacturer of the vitamin D3 formulated for human food supplementation to specify the animal sources of the precursor molecules that were employed in the synthesis of the D vitamin. **If a “food product” is construed to include a chemically pure substance that is the same in all animal species, then those individuals with strict religious reasons for avoiding food products from a particular species have, in the instance of milk and vitamin D3, a dilemma.
For the whole article complete with references and the email of the author (so u can get in touch with them if you want) click http://www.notmilk.com/vitamind.html
