DEAR DR. ROACH: I am a 76-year-old male who’s thinking of having fetal stem cell therapy for Parkinson’s disease. Please tell me your feelings and offer advice on this subject matter? — S.C.

ANSWER: I am frequently asked about stem cell treatment, and my answer is usually that the theory makes sense and preliminary results are encouraging, but further research is necessary before I (by nature, a conservative physician) feel comfortable advising it for various conditions, including Parkinson’s disease.

However, recent reports from the Centers for Disease Control and Prevention have made me even more concerned — this time, about infection. In December, the Food and Drug Administration issued a warning about stem cell treatment from umbilical cord blood. Twelve patients became ill with infections from E. coli and other fecal bacteria after injection, and the bacteria were found in unopened vials of the stem cells. The FDA plans to increase inspection of stem cell operators. There have been other adverse events reported, such as loss of eyesight (after injections into the eye) and growth of a spinal tumor.

I do not recommend stem cell treatment at this time, apart from its use in combination with chemotherapy for cancer or immune system diseases. More data is needed to prove its effectiveness, and better procedures are necessary to reduce infection risk.

DEAR DR. ROACH: I am an 81-year-old woman, in very good health, with the exception of glaucoma and macular degeneration, both of which are under treatment. So far, I can drive in the daytime and I read the newspaper with the help of a magnifying glass and eyeglasses.

I’ve heard of hypoxia therapy to increase red blood cells and provide general health benefits. Do you know anything about it? I’ve found it easy to do for a brief span of time, a few times a day, or a 20-minute session. Breathing in through the nose, then out through the nose, expelling as much air as possible, and then holding my breath for 12 seconds or so.

Is it considered safe and effective for any health condition, or is it just another health fad? — E.M.

ANSWER: I was unable to find reliable information supporting the use of this type of breathing for any specific condition or to increase either red blood cells or general health benefits. I have two concerns about it:

The first is physiology. It is true that having persistently low oxygen levels will increase erythropoietin, which is a hormone promoting red blood cell production. This is why people who smoke or have chronic lung disease sometimes have higher-than-normal blood counts. However, I doubt that your oxygen level will drop out of normal after 12 seconds of not breathing. Having experimented with a pulse oximeter, which gives immediate results on oxygen level, I know it takes a while — as long as a minute of not breathing — to get the oxygen level to go down. Further, even if your oxygen level does go down, I don’t know if the purported benefit is worth the cost of damage done while having low oxygen.

Secondly, blood cell levels are highly regulated to be optimum in healthy people. Getting more is not necessarily better (athletes who have taken erythropoietin to improve athletic performance have died from stroke due to the blood actually being too thick). If your blood counts are low, it may indicate a serious problem requiring evaluation.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.