I had gone through your husband s medical aspects and understood the true concerns. It is a very good thing that you were quite knowledgeable about requirement and dosage. Coming to Vitamin D deficiency, it leads to some symptoms like fatigue, bone pains, delayed wound healing, depression, hair loss etc. When these symptoms are identified, blood tests for vitamin D3 will be sent. If levels are low vitamin D tablets will be prescribed. Hope your husband would have been prescribed in the same way. Normal range of vit -D is 20 ng/mL to 50 ng/mL. So above 30ng/mL is sufficient enough to maintain functioning of body. We have to check levels by blood test. Vitamin-D is a fat soluble vitamin, so it will be accumulated in fat in our body. There is no need of absorption of fat readily, for vit-D. Some amount of fat will be synthesized in our body itself from excess glucose. So no need to worry about absorption of fats. The main thing that you have to consider is dosage of vit-D. If your husband takes more dosage, vitamin-D accumulate and lead to hypervitaminosis D which has many symptoms. One more important thing is, we should not keep on estimating the vitamin levels as it take some time for increasing vitamin levels in body. Coming to treatment part, you can follow as below: 1. vitamin-D supplements 2. exposure to sunlight 3. vitamin-d and calcium rich food Hope you can understand all the aspects and act in a right way to overcome vitamin-D deficiency. No need to worry as this a quite common issue which you can solve very easily.