I have a lot of trouble with my vitamin D levels, I don't go outside very often due to Skin cancer, I try to protect my skin form the UV rays. I can't where sunscreen. At my age vitamin D is even more critical for heart health as well as other health issues and this is very helpful. During my last blood test my vitamin D was even a bit high (a first) so I started taking this every 3 days, and will adjust again if need be after my next blood test