I don’t know much but do know it’s best to take D3 with K2, The K2 helps keep the calcium in your bones. D3 without K2 is how you lose the calcium.
I have an elderly friend who’s doctor was surprised to find out she stopped her precipitous bone loss by taking K2 even just 1-2 times/week while taking D3 daily.
You don’t lose the calcium, it clogs up your arteries without the k2. Coronary Artery Calcification.