Recovery 2.3 and vitamin D

The knee is feeling somewhat better today although yesterday I had  few jarring pains from it when I caught my foot on uneven pavement. I am aware of the patellar tendon but that's not painful, just niggly.

This morning I completed a 1000m swim  trying got be a bit more relaxed with my stroke and also not to pause so long at each end of a length. This approach was successful as my average pace improved to 3:41min/100m which is as good as I've done for many months. A relaxed stroke may mean scruffy but what use is tidiness if it doesn't yield forward motion?

I've had a letter about my recent hospital review which included the advice, in response to various blood analyses, to take a vitamin D supplement. The comment is unsupported by a rationale and not helped by the fact that I've been taking a multivitamin with 100% RDA for a few years. The current tablets are supposedly 200% RDA. I suppose a question is whether the RDA is enough for me?

This industry briefing is quite a nice overview of vitamin D stating that the EU RDA is 5micrograms/day (1microgram is 40 International Units) with a long term safe limit of 50micrograms/day. Notably the US raised its advised intake to 15micrograms/day in 2010 on the recommendation of an expert panel and publications, although cynics might see the hand of the supplement industry behind this as they underwrite some of the principal researchers. In terms of my ongoing medication, despite internet chatter it seems likely that Omeprazole does not disturb vitamin D although there are weak links with osteoporosis. So I can't lay the blame there.

Generally vitamin D₂ and D₃ are considered equivalent but recent research is casting doubt on that. Oversimplification of vitamin metabolism and the role of bioassays is commonplace and has been especially clear in the case of B₁₂ where certain forms that are active in bacteria or inactive in humans. Nonetheless, D₂ is biologically active in primates, probably just less so. I have ordered some of this lichen-derived D₃:

Image from Cytoplan of 62.5 microgram tablets

...and the science seems valid.