I am one of those blonde (now grey) blue eyed people who are allergic to sunlight. It is manageable and since a teenager I have coped . When I was over 60 I was given Vitamin D in the winter and since being diagnosed with Osteoporosis I have had it all year round in a monthly dose of 80,000 UZ2ml ampule. I suddenly got a very high Vit D blood test and have been pulled off the supplement. I have to return to the doctor in a month with a new set of blood tests. Excess Vitamin D can cause severe side effects. If you are taking Vitamin D, have a good diet and going out in the sun etc, you need regular blood tests to ensure you are not overdoing it. I knew that if you were over 65 you should not take additional Vitamin B12.
I am still on Vitamin D3 with Calcium which is totally different. I also take vitamin K2.