It looks like caffeine might inhibit vitamin D absorbtion @ppeatfruit - I found this article www.livestrong.com/article/464884-does-caffeine-affect-the-absorption-of-vitamins-or-minerals/ which cites a recent study.
@PartTimeDomesticGoddess I don't mind at all - it was Thriva that I used. I was impressed with how quickly you get the results, and they're interpreted by a medically qualified person so you get both the raw data and the interpretation, and then some context about what it all means.
You might be able to get a deal if you sign up, do the health questionnaire, but don't order a test for a couple of days. Their marketing team is pretty proactive. I found this out because i baulked at paying the full price, which would have been around £80 for a full blood work up - which I wanted for my first time: cholesterol, blood glucose, thyroid function, inflammatory markers, liver function, the whole enchilada. Before I knew it there was a friendly email in my inbox with a half price coupon code. If you do go with Thriva make sure you cancel after you get the results, unless you want a new test sent out every 3 months. You can then re-activate whenever you want to do your next test.
You can mix and match what you want tested- so this time it was just Vitamin D, B12 (they did B9 as well), iron, and it was £30, with another coupon code I found somewhere.
It was a worthwhile expense for me I think. I didn't feel it was right to go to go to my GP, because essentially I feel fit and healthy. There's quite a lot of anti-vegan stuff in the press (and people like my parents and in-laws lap it all up) so it's good to be reassured!