Drinking Milk and Health Problems Uncovering some facts about vitamin D

Vitamin D2 should no longer be considered appropriate for supplementation or fortification of foods.

What D does not stand for is debate: there should be none whatsoever about the importance of vitamin D. Once thought to be simply a safeguard against childhood rickets, it is now acknowledged that vitamin D is essential to general health.¹ Of course, vitamin D is well known to maintain serum calcium concentrations within the normal range, but its importance extends well beyond bone metabolism. It has been shown to interact with nuclear receptors present in a variety of cells, such as those of the small intestines, colon, bone, activated T and B lymphocytes, beta-islet cells in the pancreas, and most organs.¹ Thus, vitamin D deficiency not only increases the risk of osteomalacia, osteoporosis and hip fractures, it has been implicated in conditions ranging from hypertension to cancer.¹

Vitamin D intake recommendations currently range from 200 IU/day for adults up to age 50 up to 600 IU/day for those over age 70, but these amounts are actually considered by many experts to be too low.^2,3 Moreover, the recommendations do not distinguish between the two supplemental forms of vitamin D: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).^2,4 The former is a synthetic plant-derived form whereas the latter is a natural animal-derived type that forms in response to sunshine exposure. Synthetic vitamin D3 is similarly manufactured via the production of 7-dehydrocholesterol from cholesterol.³ Until recently, the two types were considered equal but studies now indicate that vitamin D3 is at least twice as effective at raising blood hydroxyvitamin D concentrations.^1,2,4,5 The most plausible explanation is that vitamin D3 binds more effectively to the body’s receptors.³ Studies have consistently shown preservation of bone density and fewer fractures in older adults who adhered to a protocol of daily doses from 400 to 800 IU of vitamin D3. The same cannot be said for vitamin D2.⁴ In addition to unequal bioavailability, vitamin D2 is also considerably less stable than D3, particularly upon exposure of its crystalline powder to varying temperatures, humidity, and even storage.⁴

Health Canada is considering adding soy beverage to the Milk Products food group. It is therefore worth noting that while milk is fortified with vitamin D3, most fortified soy beverages contain vitamin D2,⁵ most likely to appeal to the small portion of vegans in the Canadian population who repudiate the consumption of animal products.

References:
1. Anthony M. 2005. Nutrition beyond the trends: D is for denial. FoodProcessing.com.

2. Armas LG et al. 2004. Vitamin D2 is much less effective than vitamin D3 in humans. J Clin Endocrinol Metab 89:5387-5391.

3. Vieth R. 2006. What is the optimal vitamin D status for health? Prog Biophys Mol Biol 92:26-32.

4. Houghton LA and Vieth R. 2006. The case against ergocalciferol (vitamin D2) as a vitamin supplement. Am J Clin Nutr 84:694-697.

5. Trang HM et al. 1998. Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2. Am J Clin Nutr 68:854-858.

6. Corporate data on file.