Vitamin A was discovered in 1913 — almost a century ago — and researchers have yet to know everything about it, Dr. A. Catharine Ross tells friends who ask why she has been studying the same topic for about 26 years.

"I tell them there are easily 200 people worldwide who are researching vitamin A, and no one has exhausted the topic yet," the Penn State nutrition scientist recently said.

Ross and a team of student researchers, including five undergraduates, are among those discovering more about the function of the vitamin in the body. Proper eye, skin and immune system health depend on adequate supplies of vitamin A in the body.

Once the vitamin is ingested as food, the body changes it into an acid that actually acts as a hormone, Ross said. She and her team have identified two enzymes involved in the storage of vitamin A in the eyes, reproductive organs and the liver. Ross studies how the body maintains the vitamin.

"I would say our overall thrust is that regulation," Ross said.

April 1, Ross will be the recipient of the Osborne and Mendel Award of the American Society for Nutritional Sciences because of the contributions she has made to the understanding of the how the body metabolizes the vitamin.

"I'm really honored, just because the people who have received it in the past are really respected scientists," said Ross, adding the award is peer-reviewed. "It's nice to be in that line of scientists."

Graduate students Chris Cifelli and Yuanping Wang said they are proud to take "a very tiny" bit of credit for Ross' award-winning research.

The Friday before spring break, as most students packed their bags to leave town, Wang and Cifelli continued research in a South Henderson laboratory, amid the fluorescent lights and surrounded by monitors and beakers.

"Most of the work is right here in our lab," said Ross, who seemed at home with the students in the crowded room. Despite the tight quarters — with chemicals and stacks of papers lining the counters and several machines humming — the laboratory is a controlled environment.

In fact, the laboratory where the team keeps mice and rats used for research is off limits to guests. Here the animals' lighting, temperature and diets are controlled to insure proper research.

Wang and Cifelli were involved when the team cloned genes for an enzyme critical to the storage of vitamin A from mice and rats. Cloning the enzyme lecithin: retinol acyltransferase was one the team's biggest accomplishments, said Ross, adding that senior research associate Reza Zolfaghari was a major contributor to that project.

Prior to cloning the enzyme, researchers knew what the it did — store vitamin A — but not its mechanisms, Ross said.

"Finding the regulation of this enzyme was one of those 'ah-ha' moments," Ross said. "I think that we've provided some insight to what kind of systems are affected by vitamin A."

As the team moves on to study human liver cell lines and biopsy tissues, they hope to discover the level of vitamin A necessary for proper human and animal health.

"We make animals a model for vitamin A-deficient children," Ross said.

Their research confirms that the vitamin is vital to an embryo and throughout the rest of life, Ross said.

Sources of the vitamin include animals and plants, especially those like carrots that have a lot of beta-carotene. Babies get their supply from breast milk.

Despite its availability, an inadequate vitamin A supply is the No. 1 cause of blindness in the world. "It's not hard to obtain, that's one of the ironies," Ross said.

One of her research goals is to find ways to teach the public about the vitamin's importance. "The real solution is going to have to be education," she said, with Wang and Cifelli nodding in support. "We're not the educators per se, but we talk to those who are."

Although the students learn from being members of the research team, they also make important contributions, Ross said. The student researchers collaborate to identify the regulating genes and the proper balance of the vitamin.

"If something works, you go from there," Cifelli said of the students' research technique. "If it doesn't, you go back and try again."

The researchers work on specific projects and then meet as a group every other work to update each other.

"And in between we have one or two classes daily," Cifelli said. "It's up to us to plan it and make it go."

If the students are like Ross, they could spend the rest of their careers studying the vitamin. As a graduate student at Cornell University, Ross used vitamin A to track the body's cholesterol level.

"One thing leads to another, you have to make decisions, and I decided to study vitamin A," she said.