Vitamin D levels can be painlessly measured in the hair
Our bodies need vitamin D, but many peoples' indoor lifestyles keep them from getting enough via sunlight exposure. So, how can someone find out just how high their D levels are? Well, blood sampling works, although levels can now also be determined simply by analyzing one of the person's hairs.
While blood analysis does provide an accurate indication of vitamin D levels, obtaining samples is painful to the patient, and it must be conducted by trained professionals under hygienic conditions. Additionally, it only provides a reading of what the level was at the time the sample was taken – if doctors want to monitor how a patient's levels fluctuate over a period of weeks or months, they have to take multiple samples throughout that time period.
The hair-analysis method, which is being developed at Trinity College Dublin, isn't subject to these limitations.
Led by the college's Assoc. Prof. Lina Zgaga, a research team started by obtaining hairs from the scalps and beards of three of the scientists. Those hairs were subsequently cut into 1-cm (0.4-inch) lengths, then weighed, washed and dried. Next, a "steroid hormones extraction procedure" was used to extract the prehormone 25-hydroxyvitamin D, which had been naturally deposited in the hairs. That chemical is produced in the liver by the hydroxylation of vitamin D, and is a reliable indicator of vitamin D levels in the body.
When compared to the results of blood tests taken from the same people, the hairs were found to provide an accurate indication of the scientists' current vitamin D levels. What's more, however, by analyzing samples taken from different points along a hair's length, it was possible to see what those levels had been at different times in the semi-recent past – essentially, since the scientists last got a haircut.
It is now hoped that once further research has been conducted, the hair-testing method could be used not only on present-day patients, but also to assess the changing vitamin D levels in the remains of ancient peoples at archeological sites.
"The idea is that vitamin D is being deposited continuously in the hair as it grows; more might be deposited at times when vitamin D concentration in the blood is high, and less when it's low," says Zgaga. "Therefore, tests based on the hair sample might be able to give doctors a measure of vitamin D status over time – if the hair is long enough, this even might be over a few years."
A paper on the research was published this week in the journal Nutrients.