 He was extremely low in vitamin D. Vitamin D can cause high cholesterol, high blood pressure, ED, and it can contribute toward digestion problems. Vitamin D is easy to fix. $40 a year will buy him 5,000 urinary units a day. That's easy. That's easy. But you have no idea. Even if you got a tan, you can be low in vitamin D. If you're a dark-skinned person, you're low in vitamin D. The only way to know how you're doing is to test your vitamin D.