This blog is in response to Dr Briffa's post here. as I keep having problems commenting on his blogs.

While 44ng/ml is sufficient to not only maximize uptake of calcium (>32ng/ml) and ensure maximum bone mineral density (>42ng/ml), pregnant and nursing mothers should be aware that in order to maximize the amount of vitamin D3 in human breast milk 6400iu/daily was found to be necessary to raise (>58ng/ml) at latitude 32.
This is detailed in the Taylor, Wagner and Hollis paper.
Vitamin D supplementation during lactation to support infant and mother.
Although 4000iu/daily met the mothers daily needs in full it left babies being born with lower 25(OH)D status than required for optimum calcium absorption

They also found DAILY use of supplements was required by pregnant and nursing mothers to ensure an even daily Vitamin D3 supply to the foetus & baby.
It makes virtually no measurable difference for everyone else if you supplement daily or weekly.

While Dr Briffa will not be lactating he may be interested seeing in the
Grassrootshealth chart showing disease incidence by 25(OH)D status.
this may encourage him to go just another 10ng/ml higher and a bit nearer to the natural level at which human breast milk flows replete with D3.

Although 5000iu cholecalciferol capsules are now available online in the UK may I remind readers these are cheaper from USA discount providers like IHERB providing you don't order more than £18 in any single order as you then have to pay VAT on import + £8 Post Office handling fee.
WAB666 Introductory discount code WAB666.

These recent papers make me think the recent move to encourage mothers to take the "official" prenatal Vitamins available will do little or nothing to reduce MS or other disease incidence.

Developmental vitamin D deficiency causes abnormal brain development

Vitamin D, a neuro-immunomodulator: Implications for neurodegenerative and autoimmune diseases

If we are going to ensure babies come into the world vitamin D replete then we have to ensure vitamin D is getting to the foetus and via breast milk to the baby. As Dr Briffa has discover getting anywhere near 55ng/ml requires a lot more vitamin D3 than is "officially" regarded as sufficient.