A few years ago a Specialist suggested I take Calcium Supplements because I am Dairy Intolerant (altho' can eat cheese and yoghurt). A couple years ago my GP decreased it to 1/2 tab daily because there are studies coming out which shows that quite a few people are at risk of heart disease with the supplements. He said to keep it at 1/2 until more extensive reports come out. I now have a different GP because the first left the practice - his recommendation is the same.
Below are a couple of links that you MAY find useful regarding the supplements: www.health.harvard.edu/blog/link-between-c
I have also read that it is better when we use supplements to only have about 300mg at a time because the body has difficulty in absorbing more than at a time, altho' strangely it doesn't seem to be affected the same way when it comes from food.
The other thing is, be careful not to take too much calcium - hubby has had some very large kidney stones (just on an INCH in diameter IN his kidney - he has had 3 procedures for them and is now on permanent medication to restrict the formation. He was a very big diary/cheese consumer, and even now has quite a bit but no where near as much as he used to.
Vitamin D can be obtained from going outside in the daylight, or sitting by a window with the curtains open.
Below is a link re Vit.D with food sources: ods.od.nih.gov/factsheets/VitaminD-HealthP
My Dietitian told me that altho' you can have blood tests done to see if you are deficient, they are often inaccurate results. She also suggested that I ask the Dr for a script for one. She said that the OTC ones here in NZ are not therapeutic - something to do with the source they are manufactured from. I don't know if that applies to other countries.