Some are happy, most are sad and others are just a result of chopping onions. Yes, tears. Psychiatrists could probably spend hours telling you what your tears mean for your mental health. But the little watery droplets are usually seen as fruitless for physical information. However, a team of scientists at Michigan Technological University may have changed that. Read on to see how tears can be used for medical testing.

Despite the perception of tears as empty and invaluable, they might contain important nutritional information. At present, the only way to access patients nutritional information, like vitamin levels, is through invasive (and expensive) blood tests. And it was this that led the team at Michigan Tech to their main question are there links between tear content and nutritional values in blood?

"We hypothesized that nutrients are transferred to the living cells of your cornea through your tears," explains Michigan Tech research specialist Maryam Khaksari. "We would like to translate the information we have for blood to tears. The link is certainly possible, with previous studies finding people with vitamin deficiencies blink more than those without.

To test the link, they focussed on three vitamins A, B and E. After taking samples of the tears and blood from 15 babies aged four-months as well as their parents, they used liquid chromatography and mass spectrometry to assess the content of the samples. Improved analytical development for this method is explored in the article, Capillary Flow LC-MS Unites Sensitivity and Throughput.

Overall, the results showed that levels of fat-soluble vitamins were higher in parents, while water-soluble vitamins were seen more in babies. There was a connection between the vitamin levels in parents and babies, with a correlation between vitamins B and E also shown by the results.

However, whats more significant is the promise this research shows in using tears for vitamin research. In this paper, we did show that there are correlations between vitamin concentrations in tears and bloodso it's possible," says Khaksari. The next step is to develop a device capable of performing these tests.

This project was the first step that proved vitamins are detectable in tears, that they do correlate with blood levels. Next we want to engineer a portable, lab-on-a-chip device relying on a minimally invasive sample from tears to assess nutrition, said Adrienne Minerick, professor of chemical engineering at Michigan Tech.

Looks like our parents were wrong when they said crying wont help.

Excerpt from:
What Do Your Tears Say About Your Health? - Chromatography Today