Daily vitamin C has limited value; benefits of fish oil controversial

Dear Dr. Roach: I read your recent column on vitamin C. I am 88 years old, and my family and I have taken supplemental vitamins most of our lives. Five years ago, I was diagnosed with prostate cancer and survived it with radiation treatments and a change of diet. I had taken a handful of vitamins every day for years, including 400 IU of vitamin E. My doctors told me that my prostate cancer probably was caused by taking too much vitamin E.

My sister took a handful of vitamins every day and recently died from liver cancer. I believe her liver cancer was caused from vitamin toxicity, too, but the family is not talking about it, so I don’t know for sure. I have stopped taking vitamins altogether and instead rely on a healthier diet, but am considering going back to taking a low-dose multivitamin or just vitamin C and a heart-healthy fish oil. What is your opinion? E.O. A large randomized, controlled trial published in 2011 showed that 200 IU daily of vitamin E by itself increased the risk of prostate cancer. There were about two extra cases of prostate cancer per year found per 1,000 men taking the vitamin E (9.3 cancers per 1,000 men per year on placebo, 10.9 cancers per 1,000 men per year of men taking vitamin E). The risk is low, but since there has been no significant benefit from vitamin E shown, it is not recommended.

The evidence on liver cancer is more reassuring. A study from China did not show an increase in risk of liver cancer among vitamin users. People with large intake of vitamin E, either from diet or from supplements, had a small decrease in risk of liver cancer.

A new study published in May provided more evidence that a daily vitamin supplement or a daily vitamin C has limited value. Fish oil (omega-3) remains controversial, with a new study due to be released soon. As yet, the evidence is not compelling that it reduces heart disease risk the way that eating two or more servings of fatty fish a week does.

Dear Dr. Roach: I have some questions about blood types. Is Type O universal for donations?

If a person who is A-positive has a child with a person who is B-positive, what blood type would their child have? L.M.E.

Blood types follow classical genetics. Each person has, at most, two proteins, A and B, on their red blood cells, one from each parent. However, Type O means there is no A nor B proteins on the red cells.

If a person is Type A, for example, you can’t tell just from a person’s blood type if he or she has an A from each parent (we call that an AA genotype) or just from one (an AO genotype). All Type O people are genotype OO.

Similarly, the D antigen (formerly called Rh factor) also has two copies, and if both are positive (a positive/positive genotype) or only one is (a positive/negative genotype), the person is positive.

So, in your example, if the Apositive parent had an AO genotype and a positive/negative genotype, and the B-positive parent had a BO and positive/negative genotype, their child could have literally any possible combination: A-positive, A-negative, Bpositive, B-negative, AB-positive, AB-negative, O-positive or O-negative.

You can’t get a blood transfusion from a person who has a protein you don’t, so the only person who can donate universally is Onegative, but that person absolutely needs an O-negative donor.

Someone who is AB-positive can receive blood from anybody, but can donate only to another AB-positive recipient.