Schizophrenia is a terrible, frightening, fascinating condition. When I first edited the BMJ Group’s patient information about schizophrenia, I was amazed and astonished by some of the things I learned.
The cause of the condition itself is a bit of a mystery. As with many things, it’s likely to be a complex mixture of nature and nurture, genes and environment. But here are some curious facts:
- Schizophrenia is more common among people born in winter or spring
- People who grow up in the city are more prone to schizophrenia than rural types
- The children of immigrants from hot countries to cooler climates are at higher risk of schizophrenia than the general population, and than their parents.
A great deal of ink has been spilt on potential reasons why these factors might affect schizophrenia. One theory that might just explain all three factors is around vitamin D, the ‘sunshine vitamin’.
Although you can get vitamin D from dietary sources, the most common source is by the action of sunlight on your skin. Almost magically, UVB activates chemicals in skin cells to produce vitamin D, which does all sorts of useful things in your body.
The main useful thing we know about is helping the body absorb calcium, hence building healthy bones. But, researchers are beginning to ask, what about the brain?
The theory is that pregnant women who don’t make enough vitamin D (because they’re not getting enough sunshine) will pass the deficiency onto their children, who may be more prone to schizophrenia as a result. It sounds a bit far-fetched. But when researchers checked stored blood samples from newborn babies, they found that babies with low levels of vitamin D in their blood had twice the chance of getting schizophrenia in later life, compared to babies with optimum vitamin D levels.
There are a few problems with the data that means we can’t be completely sure of the results. For one thing, the researchers were unable to account for a surprising increase in schizophrenia rates in the people with the highest levels of vitamin D. Also, research like this can highlight links, but not prove cause and effect.
It’s still an exciting finding. Vitamin D supplements are cheap and readily available. If the researchers are right, as many as 40 percent of cases of schizophrenia could be avoided if all pregnant women took supplements.
Vitamin D is already recommended for pregnant and breastfeeding women. But personally, I’m taking it as yet more proof that a little sun is good for you. Time to head out and enjoy the last of the summer sunshine.