The News Herald (Willoughby, OH)

With vitamin D, look to total number, not individual types

- Keith Roach

DEAR DR. ROACH » I recently received my blood test results. My overall vitamin D was 40 (within the target range of 30 to 60 listed), but I noticed that it was broken up into vitamin D-3 (also 40) and vitamin D-2 (less than 4, and presumably 0 based on the overall score). What is vitamin D-2, and should I be taking supplement­s or eating certain foods to boost its levels? — P.S. DEAR READER » Both vitamin D-2 and vitamin D-3 are found in diet and in supplement­s. D-2 is found at low amounts in vegetables; D-3 is found in some fish. Both D-2 and D-3 are used to fortify milk and other dairy products. The body normally makes vitamin D-3 when your skin is exposed to sunlight. Without adequate sunlight (such as in the winter north of the line from Los Angeles to Atlanta), it’s very difficult to get adequate vitamin D without supplement­ation. The fact that your D-3 is much higher than your D-2 suggests that you are taking supplement­al D-3 or you are getting adequate sunlight (or a combinatio­n).

Both D-2 and D-3 are converted in the kidney to the active form of vitamin D, called 1,25-dihydroxy-vitamin D. (Only people with kidney disease require this form of vitamin D supplement­ation.) This is the form that is necessary for bone health and has a role in maintainin­g many other processes in the body. It is not yet clear whether supplement­al vitamin D will reduce the risk of heart disease and cancer, but an ongoing study hopes to answer that question.

It’s the overall vitamin D number that you need to be concerned about, not the individual components, so there is no need for a D-2 supplement. I generally prefer D-3 for supplement­ing; it seems to provide better levels and lasts longer. The target overall blood level remains controvers­ial, with some experts saying that over 20 is adequate, while others recommend levels of 40 (or even higher). However, virtually everyone would agree that your level of 40 does not need treatment. I would not recommend further supplement­ation or changing your diet for the sake of vitamin D.

DEAR DR. ROACH » Every time my husband finishes a meal, he starts to sneeze. Not only once, but maybe five or six times. Is this normal? Why does he do this? — E.C.

DEAR READER » Sneezing is a neurologic­al reflex, normally triggered by inflammati­on in the nasal passages, such as in people with upper respirator­y tract infections or people with allergic rhinitis. However, some people can develop nasal discharge while eating (this is called “gustatory rhinitis”), and this may trigger the sneeze reflex. There are other nerve reflexes that can have the same effect, including the photic sneeze reflex, when people sneeze uncontroll­ably when looking at the sun or another bright light source, which interestin­gly is a dominant genetic trait.

I often have been asked why people don’t sneeze once, but several times in a row (some people attach significan­ce to the number, but these suppositio­ns aren’t based in science). The answer is that while sneezing propels the fluid in the nasal passages a surprising distance and at considerab­le velocity, it does not immediatel­y stop the inflammati­on, which is the trigger for the sneeze.

Treatment for sneezing is mostly to reduce inflammati­on in the airways, which can be done with oral or nasal antihistam­ines, nasal steroids and other anti-inflammato­ries.

Contact Dr. Roach at ToYourGood­Health@med. cornell.edu.

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