Vitamin D
http://www.100md.com
《新英格兰医药杂志》
Last year, a professor at Boston University who campaigned for exposure to the sun as a source of vitamin D was fired because his department — dermatology — felt that his attitude was irresponsible. If nothing else, the incident shows that the debate over vitamin D is alive and kicking. The role of vitamin D in the prevention of fractures remains controversial, but at the same time, there are signs of its beneficial effects against autoimmune diabetes, psoriasis, multiple sclerosis, and prostate and colorectal cancer. There should thus be a demand for a textbook that summarizes our knowledge about vitamin D.
This two-volume book has 104 chapters, most of them written by acknowledged experts. Most chapters have 10 to 15 pages, uniformly organized into sections and subsections. About every other page has a graph, an illustration, a table, or a photograph, most in black and white. The scope is encyclopedic; chapter topics range from the structure of receptors and enzymes to physiology to clinical and public health issues. Nine chapters deal with cancer, and 10 chapters with the development of vitamin D analogues that are active against specific diseases but do not cause hypercalcemia.
Since I am a consumer, not a producer, of knowledge regarding vitamin D, I thought up some questions about vitamin D and looked for their answers in this book. Is the vitamin D receptor a nuclear receptor? Could it be involved in cholesterol metabolism? A lucid chapter on the vitamin D receptor and bile acids answered both questions in the affirmative. How much vitamin D is there in foods? It took some perseverance to find the answers in a table, but along the way I came across a wealth of information on dietary vitamin D. The authors of various chapters disagree sometimes, but this dissent allows for diverse perspectives. In fact, chapters often contain references to other chapters as sources of alternative views.
One flaw of the book, which is not the fault of the authors of the chapters, was easy to find: vitamin D units are expressed in nanograms per milliliter as well as nanomoles per liter, and in micrograms as well as international units. A true error is the frequent use of milligrams where micrograms are meant. For instance, there is a recommendation for a daily supplement of vitamin D of 100 μg; the text then goes on to say: "Since long-term vitamin D consumption of at least 1000 mg/d would be needed to cause hypercalcemia, there is a large margin of safety with 100 μg (4000 IU)/day." What was meant was 1000 μg per day, not 1000 mg per day. In fact, 1000 mg per day of vitamin D is enough to kill a cow.
Who should buy this book? My impulse is to encourage all large medical, nutrition, and public health libraries to purchase it. But will the book be used? Most scientists and physicians who have questions about vitamin D will turn to PubMed or Google. Even though such searches turn up large amounts of information, much of it is irrelevant and some of it is wrong. In this book, the experts have done the searching, and half an hour's study of its pages will bring the reader closer to the facts than will hours of Web surfing. But finding those facts does require page turning. You need nearly 1 m of desk space to lay down both volumes, and then you need to go through the index — which is provided only in volume 2 — and juggle the two 5-lb tomes while hunting for the right page. My students will not do that; for them, what is not online does not exist. Although this book includes a CD-ROM containing all the images, having the text available electronically would be a treasure. Before a library purchases the print version at the high list price, it should make a realistic appraisal of who is going to take this book off the shelf.
Martijn B. Katan, Ph.D.
Wageningen University
6703 HD Wageningen, the Netherland
swcfs1@wur.nl(Second edition. Edited by)
This two-volume book has 104 chapters, most of them written by acknowledged experts. Most chapters have 10 to 15 pages, uniformly organized into sections and subsections. About every other page has a graph, an illustration, a table, or a photograph, most in black and white. The scope is encyclopedic; chapter topics range from the structure of receptors and enzymes to physiology to clinical and public health issues. Nine chapters deal with cancer, and 10 chapters with the development of vitamin D analogues that are active against specific diseases but do not cause hypercalcemia.
Since I am a consumer, not a producer, of knowledge regarding vitamin D, I thought up some questions about vitamin D and looked for their answers in this book. Is the vitamin D receptor a nuclear receptor? Could it be involved in cholesterol metabolism? A lucid chapter on the vitamin D receptor and bile acids answered both questions in the affirmative. How much vitamin D is there in foods? It took some perseverance to find the answers in a table, but along the way I came across a wealth of information on dietary vitamin D. The authors of various chapters disagree sometimes, but this dissent allows for diverse perspectives. In fact, chapters often contain references to other chapters as sources of alternative views.
One flaw of the book, which is not the fault of the authors of the chapters, was easy to find: vitamin D units are expressed in nanograms per milliliter as well as nanomoles per liter, and in micrograms as well as international units. A true error is the frequent use of milligrams where micrograms are meant. For instance, there is a recommendation for a daily supplement of vitamin D of 100 μg; the text then goes on to say: "Since long-term vitamin D consumption of at least 1000 mg/d would be needed to cause hypercalcemia, there is a large margin of safety with 100 μg (4000 IU)/day." What was meant was 1000 μg per day, not 1000 mg per day. In fact, 1000 mg per day of vitamin D is enough to kill a cow.
Who should buy this book? My impulse is to encourage all large medical, nutrition, and public health libraries to purchase it. But will the book be used? Most scientists and physicians who have questions about vitamin D will turn to PubMed or Google. Even though such searches turn up large amounts of information, much of it is irrelevant and some of it is wrong. In this book, the experts have done the searching, and half an hour's study of its pages will bring the reader closer to the facts than will hours of Web surfing. But finding those facts does require page turning. You need nearly 1 m of desk space to lay down both volumes, and then you need to go through the index — which is provided only in volume 2 — and juggle the two 5-lb tomes while hunting for the right page. My students will not do that; for them, what is not online does not exist. Although this book includes a CD-ROM containing all the images, having the text available electronically would be a treasure. Before a library purchases the print version at the high list price, it should make a realistic appraisal of who is going to take this book off the shelf.
Martijn B. Katan, Ph.D.
Wageningen University
6703 HD Wageningen, the Netherland
swcfs1@wur.nl(Second edition. Edited by)