By HANS DUVEFELT
People here in northern Maine, as in my native Sweden, don’t get a whole lot of natural sunlight a good part of the year. As a kid, I had to swallow a daily spoonful of cod liver oil to get the extra vitamin D my mother and many others believed we all needed. Some years later, that fell out of fashion as it turned out that too much vitamin A, also found in that particular dubious marine delicacy, could be harmful.
This is how it goes in medicine: Things that sound like a good idea often turn out to be not so good, or even downright bad for you.
Other vitamins, like B12, can also cause harm: Excess vitamin B12 can cause nerve damage, just as deficiency can.
Both B12 and D can be measured with simple blood tests, but the insurance industry doesn’t pay for screening. That is because it hasn’t been proven that testing asymptomatic people brings any benefit. In the case of B12, it is well established that deficiency can cause anemia and neuropathy, for example. But here is no clear evidence what the consequences are of vitamin D “deficiency”. A statistically abnormal result is not yet known to definitely cause a disease or clinical risk, in spite of all the research so far, but we’re staying tuned.Continue reading…