Last week I went to the doctor for my annual physical. I had never been to this doctor before. My old doctor, I was told, was out of the office on an extended medical leave. That in itself was a little upsetting, since the doctor is supposed to cure you, not get sick himself.
I asked several people what was wrong, but everyone claimed they didn't know. I don't count my doctor as a friend. But he's the same age as I am, I've been going to him for about 15 years, and he asks me about my kids and tells me about his vacations, and I feel I know him well enough to at least extend my regards. Would it be appropriate to send him a get well card in care of the medical center?
Anyway, my new doctor seemed okay, and I liked him right away because he told me I was healthy and my EKG looked good. But I do have a history of cancer in my family. My mother developed breast cancer in her late 50s and finally succumbed to the disease at age 89. My dad got cancer when he was 90, and died at age 91. I have a sister who had breast cancer, although it was years ago and she seems to be doing fine now.
The doctor asked about my smoking history, and my drinking, and my exercise and diet. Then he said he wanted to do a test for vitamin D in my blood.
He told me there have been studies suggesting that vitamin D has a preventive effect in the development of cancer. He was careful to say that the research was preliminary and inconclusive. But he advised me to drink skim milk fortified with vitamin D, as well as orange juice with calcium and vitamin D. And I should try to get outside to the sun for half hour a day, especially in the winter. Then, he told me, if I tested low for vitamin D, he might prescribe a supplement for me.
I hadn't heard about any anti-cancer effects of vitamin D, so after I got home from my appointment I did a little research.
The American Cancer Society has a report on the topic, pointing out that very few foods naturally contain Vitamin D, so some people may not get enough from their everyday diet. There's vitamin D in some fish like salmon, tuna and sardines, as well as in beef liver and cod liver oil. Milk and orange juice are often fortified with calcium and vitamin D. And you make your own vitamin D from sunlight.
According to the National Cancer Institute, vitamin D's potential anti-cancer qualities were first identified when doctors noticed that groups of people from southern latitudes were showing lower rates of cancer than people in more northern climes. And so researchers started doing some tests. In mice, vitamin D exhibited several activities that might prevent or slow the development of cancer, including decreasing cancer cell growth and reducing blood vessel formation in tumors.
A survey in the 1990s of more than 3,000 humans, mostly men, showed that those with the highest vitamin D intake were less likely to have advanced cancer than those with low intake. A study published in 2007 of 1,179 women over age 55 showed that those who took calcium and vitamin D, or who otherwise had high levels of vitamin D, had significantly less risk for all types of cancer combined.
Some other studies failed to produce these results, and one even associated an increased risk of pancreatic cancer with high levels of vitamin D, especially among smokers. But a researcher who collected and analyzed a series of studies seemed to confirm the protective effects of vitamin D, in particular for colon and rectal cancer.
So, like my doctor said, the studies are suggestive, but not conclusive. The American Cancer Society does say that people over age 50 whose skin does not make as much vitamin D, and people who live in northern areas with limited sun exposure, and adults with darker skin, may be at risk of vitamin D deficiency. These people might consider a supplement -- although all the experts say it's better if you can get your vitamin D in foods rather than pills.
So for most of us, I guess we should just eat some fish, drink our milk, and quaff some orange juice fortified with calcium and vitamin D. As for me, I actually like salmon and tuna, but I'm not going to order up sardines any time soon. And I drink my share of milk -- I can deal with 1%, but cannot stomach skim milk, so I hope that little bit of fat isn't going to pose other problems that I'm trying to stave off by drinking milk in the first place.
And, I'm sorry to say, apparently the milk products in ice cream are not fortified with vitamin D, so going out for ice cream doesn't count.