It's incredible how many Americans have Vitamin D deficiencies. Unless you eat a lot of oily fish, the only place in your diet you can get it is from fortified milk. Old folks drink VERY little milk. And nowadays, everybody who ventures out in the sun besides life guards and professional tanners, slathers on the sunscreen. So there goes our other source of Vitamin D. The American Endocrine Society recommends 4000-5000 iu per day for teens and up. The FDA still recommend 600 iu per day because of a math error they made about 40 years ago!. And that's what they teach docs in med school. So "Ask your doctor" is usually a path to deficiency. At least in America, most docs will run a Vitamin D level on you, if you insist. In the UK, it's so ingrained the National Health refuses to even run Vitamin D levels on anybody.

We're flying electric helicopters on Mars yet you can't turn on your clothes dryer in Texas. That's because scientists are in charge of Mars, and Republicans are in charge of Texas.