Instead of anticipating the painful prick of a needle when you’re being tested for nutritional deficiencies, in the future you might just need your tears.
Researchers from Michigan Technological University teamed up with UP Health System – Portage in Michigan to determine whether vitamins can be found in tears. The study suggests that tears could be an alternate source of diagnostic fluid for testing children for nutritional deficiencies.
“We hypothesized that nutrients are transferred to the living cells of your cornea through your tears,” Khaksari said. “We would like to translate the information we have for blood to tears. In this paper, we did show that there are correlations between vitamin concentrations in tears and blood – so it’s possible.”
The researchers fielded samples of both blood and tears from 15 families, each with a four-month-old infant. Samples taken from a parent and a child were then compared between blood and tears, infants and their parents, and against self-reported dietary intakes.
Vitamin B1, B2, B3, B5, B9 and E were all detected in both the tears and blood, but vitamin A was only found in blood samples. Adrienne Minerick, the dean of Research and Innovation and professor of Chemical Engineering at Michigan Tech, said the study was only the beginning.
“This project was the first step that proved vitamins are detectable in tears, that they do correlate with blood levels,” Minerick said. “Next we want to engineer a portable, lab-on-a-chip device relying on a minimally invasive sample from tears to assess nutrition.”
Until then, the information from this study suggests strong links between the content of tears versus blood. The infants who participated in the study had higher concentrations of water-soluble vitamins than their parents, while fat-soluble vitamins were generally higher in parents.
Fat-soluble vitamin A was higher in concentrations in the parents, but fat-soluble vitamin E concentrations were lower in tears than in blood for both parents and infants. The study said “strong positive correlations” were found between tears and blood for vitamin E in both parents and infants, and vitamin B2 for parents.
There were also correlations between infants and parents for vitamins B1, B2, B3 and E in tears, while vitamins B2, A and E were more detectable in blood. The authors noted that the correlations were stronger between parents and breast-fed infants, but there was no significant difference between breast- and bottle-fed infants.
The ‘lab-on-a-chip’ device would only need to pick up a few microliters of fluid for testing, and researchers are hoping to create an inexpensive solution in the form of strips or other devices.
“Our goal was to seek the viability of establishing measurable vitamin concentrations in tears for nutritional assessments,” Khaksari said. “Your body cannot manufacture vitamins, and vitamins reflect available food sources in your body. That’s what makes them good indicators of nutritional health.”