Quite a few NYT readers sent in comments on the article, mentioning a variety of other recent findings about the “sunshine Vitamin” (many of which we’ve already cited on this blog). We do know that a federal panel is reviewing recommendations on daily intake of Vitamin D, and is expected to issue new guidelines in the next year or so. But we hadn’t heard, as one NYT reader pointed out, that, as of recent years, the general practice in Canada is to recommend up to 2000IU of Vitamin D3/day for children to support and promote good health. Here’s an extract from the Canadian Paediatric Society’s 2007 position statement on Vitamin D supplementation (yes, all of those numbers in parenthese refer to scientific journal articles):

The emphasis is no longer solely on preventing rickets,
which requires only a relatively small amount of vitamin D
supplementation. The focus is now also on the prevention
of associated childhood and adult diseases. New findings
suggest that adequate vitamin D status in mothers during
pregnancy and in their infants may have lifetime implications.
These findings modify our knowledge and understanding of
vitamin D metabolism, our basis for diagnosis of vitamin D
deficiency and our recommendations for supplementation.

It is now clear that vitamin D is involved in the regulation
of cell growth, immunity and cell metabolism. Vitamin D
receptors are found in most tissues and cells in the body (7).
The interaction of 1,25(OH)2D with these receptors may
result in a variety of biological responses influencing disease
processes (8). Vitamin D deficiency has been linked to
osteoporosis (9); asthma (10); autoimmune diseases such as
rheumatoid arthritis, multiple sclerosis (11) and inflammatory
bowel diseases (12); diabetes (13); disturbed muscle function
(14); resistance to tuberculosis (15); and the pathogenesis of
specific types of cancer (16,17) (evidence level III).

Maternal vitamin D status during gestation and lactation
may influence the health status of the child later in life.
Bone density in nine-year-old children (evidence level II-3)
(9), the severity of asthma in three-year-old children (10)
(evidence level II-2) and the susceptibility to type 1 diabetes
(11) (evidence level II-2) have been linked to low
vitamin D status during fetal life. Intervention trials have
demonstrated that supplementation with vitamin D or its
metabolites may improve blood glucose levels in diabetics
and decrease symptoms of rheumatoid arthritis and multiple
sclerosis (11,13) (evidence level III).

Read the full text at:

http://www.cps.ca/ENGLISH/statements/II/VitaminD.pdf

See also the NYBC entries:

Vitamin D3 2500IU

Vitamin D3 1000IU

Vitamin D3 400IU

The second paragraph quoted below (from the same 2008 article in Virology) reports rather dramatic evidence that African-Americans, who are especially prone to Vitamin D deficiency, might very substantially decrease their susceptibility to colds and flu by supplementing with 2000IU daily during winter months.

Vitamin D, innate immunity, and influenza

Hope-Simpson’s model theorized that an unidentified “seasonal stimulus,” inextricably bound to solar radiation, substantially controlled the seasonality of influenza. Recent evidence suggests the “seasonal stimulus” may be seasonal impairments of the antimicrobial peptide (AMPs) systems crucial to innate immunity, impairments caused by dramatic seasonal fluctuations in 25-hydroxy-vitamin D [25(OH)D] levels. The evidence that vitamin D has profound effects on innate immunity is rapidly growing.
…
In fact, Aloia and Li-Ng presented evidence of a dramatic vitamin D preventative effect from a randomized controlled trial (RCT). In a post-hoc analysis of the side effect questions of their original three-year RCT, they discovered 104 post-menopausal African American women given vitamin D were three times less likely to report cold and flu symptoms than 104 placebo controls. A low dose (800 IU/day) not only reduced reported incidence, it abolished the seasonality of reported colds and flu. A higher dose (2000 IU/day), given during the last year of their trial, virtually eradicated all reports of colds or flu. Recent discoveries about vitamin D’s mechanism of action in combating infections led Science News to suggest that vitamin D is the “antibiotic vitamin” due primarily to its robust effects on innate immunity.

References:

Cannell, John J, Michael Zasloff, Cedric F Garland, Robert Scragg and Edward Giovannucci. On the epidemiology of influenza. Virology Journal 2008, 5:29. We accessed this 11/10/2009 at http://www.virologyj.com/content/5/1/29.

Aloia J F, Li-Ng M: Epidemic influenza and vitamin D. Epidemiol Infect 2007; 135: 1095–1096.

See the NYBC entry Vitamin D3 2500IU for additional information. This format of D3 is a convenient way to supplement at approximately the levels discussed by Cannell and others. (NYBC also stocks D3 1000IU and D3 400IU formats.)