If you can give Mr. Bowles a little grace on not being the most polished writer, you’ll find this book very informative. I enjoyed it for its content. He is passionate about his findings, as he should be. 3 weeks ago I receive an alarmingly low D3 report from my doctor. He casually told me to take a supplement and get some sun. Because of this, I did not immediately know how dire I was, but there were these symptoms. I felt horrible!!!!! Every joint in my body hurt, hips, shoulders (especially my right one), wrist, knees, and ankles. I felt like my body was betraying me. I have always been athletic, full of energy and a go-getter, until recently. Nevertheless, I went on a search, found Jeff’s book, started myself on 5,000 ius. My first day I noticed I could get out of bed without wincing. 2nd day, my gym work out was less painful. By the 3rd day, I started telling others and I upped my dosage to 10,000ius. Week 3, I just began 20,000ius and feel terrific. I can’t wait to see and fell my results. I am not sure what my optimal daily intake should be, but I will have my D3 levels checked again in two months. One last thing, my hair was falling out in lumps and clumps. I thought I would go bald. I felt discouraged, especially bc all other tests said I was perfectly healthy. The hair falling out has ceased, completely. Thank you Mr. Bowles!!!! Keep researching!!!!