Dear Dr. Gott: I read about how much vitamin D to take from your September 30 column. In the information about research on D, you state it is linked to thyroid disorders, hypertension, stroke, diabetes, heart failure and colon cancer, among other things. I have read vitamin D fights off these disorders, not contribute to them. Was this a misprint?

Reply: In essence, yes it was. The article should have indicated, "As research unfolds and theories are validated, deficiency is thought to be linked to thyroid disorders ..." The word "deficiency" did not appear in print. I spoke of insufficient amounts of D at the beginning of the paragraph, but the way the information appeared would lead a person to think just as you did.

Thank you for pointing this out. It's readers like you who keep me on my toes, and I'm grateful you took the time to write.

Dear Dr. Gott: You recently wrote about lichen planus and gold as a risk factor. I've had lichen planus for more than five years, and you are the only reference I've encountered that claims gold could be a problem. I have two gold bridges and two gold caps. Could these be contributing factors?

Reply: This inflammatory condition can affect skin and mucous membranes. When on the skin, it resembles raised, flat bumps or lesions that are itchy and somewhat purple in colour. They can crust or scab, resembling poison ivy or other forms of plant dermatitis. When mucus membranes of the mouth are affected, white patches that resemble lace can appear and be quite painful. Lichen planus occurs when the immune system attacks the cells of the skin or mucus membranes.

As I previously reported, triggers can include allergens, tattoo pigments, specific medications for hypertension, arthritis or heart disease, and the use of nonsteroidal anti-inflammatory drugs such as ibuprofen and naproxen.

One source of information for the gold connection I reported on is Medline Plus, which states that risks include "exposure to medications, dyes and other chemical substances (including gold, antibiotics, arsenic, iodides, chloroquine, quinacrine, quinide, phenothiazines and diuretics)". Furthermore, an October 1, 2010, New York Times article indicated a risk of lichen planus from gold. There have been reports of gold caps causing the breakout, but I cannot find sufficient legitimate documentation to support this. Therefore, I suggest you return to your dentist for his or her opinion.

Dr. Peter H. Gott is a retired physician and the author of several books, including 'Live Longer, Live Better', 'Dr. Gott's No Flour, No Sugar Diet' and 'Dr. Gott's No Flour, No Sugar Cookbook', which are available at most bookstores or online. His website is www.AskDrGottMD.com.