December 25, 2023 TOPICS

[Ambitious Graduate Students] Working to develop bone-strengthening foods—Leveraging the functionality of retired egg-laying hens —

Tamao Nishiura, 2nd-year doctoral program student, Graduate School of Gastronomy Management

When the number of eggs produced by an egg-laying hen declines, it becomes an adult chicken and is used to make chicken carcasses for soup broth or ground chicken meat. These adult chickens have what is called medullary bone, a calcium-rich bone layer that researchers expect can improve bone strength and bone metabolism.

Tamao Nishiura, a second-year doctoral student in the Graduate School of Gastronomy Management at Ritsumeikan University, is working on research to elucidate the benefits of this material and to create products that people can eat to strengthen their bones.

Nishiura joined the doctoral program while working as a researcher for a company. We sat down with her to ask about her research on medullary bone and what she finds appealing about this research that keeps her busy every day.

New potential that lies within 100 million hens

The annual per capita egg consumption of Japanese people is about 340 eggs, the second highest in the world and considerably higher than that of most other countries (according to a survey by the International Egg Commission in 2022). To meet this demand, there are approximately 140 million egg-laying hens in Japan.

The egg-laying efficiency of hens declines about two years after they hatch, and after they become adult chickens, they are used as the raw materials for a variety of processed foods. In processing these chickens, the bodies, bones and all, are crushed with a screw-like machine to separate the bones from the ground meat, but this ground meat still contains some of the components derived from the bones (hereinafter, " whole ground adult chicken mince "). Nishiura works for a major meat products company that also produces meatballs and chicken patties made from adult chickens. As an in-house researcher, it is her job to study the functionality of whole ground adult chicken mince.

Adult chickens have a special material called medullary bone that is only found in female birds. It differs from bone marrow, the blood-producing tissue, and is responsible for storing calcium. At their peak, hens lay eggs almost every day that are encased in shells containing about 2.3 g of calcium, so their bodies must supply a large amount of calcium in a short period of time. This is why researchers think medullary bone plays an important role in the mechanism that enables this short egg-laying period. We believe we can find functionality in whole ground adult chicken mince, which contains these kinds of bone-derived materials.”

When eggshell formation begins in the hen's body, medullary bone is resolved and calcium is released into the bloodstream and supplied to the eggshell. After the eggshell is formed, the hen's body starts to actively form bone, and the calcium that is ingested by way of feed is once again used to form medullary bone where calcium is stored.

In particular, researchers hold expectations that medullary bone, a tissue thought to be deeply involved in calcium metabolism, is a component that influences both bone strength and bone metabolism.

“Humans also keep their bones healthy with a cycle of bone building and resorption. My hypothesis is that whole ground adult chicken mince contains components derived from medullary bone, which could have a positive effect on human bones, and I am conducting research to develop products that can contribute even more to people's health.”

Nishiura is currently researching the functional evaluation of how components derived from adult chicken bones contributed to the improvement of bone metabolism. To evaluate this functionality, she tested and verified whether bone strength and bone metabolism improved when whole ground adult chicken mince was administered to mice.

A “clear difference” revealed from experiments with mice

Nishiura prepared two types of mice: wild-type mice, which are commonly used in experiments, and VDRKO mice, a special type of mouse in which systemic vitamin D receptors do not function and calcium absorption from the intestinal tract is significantly reduced. For four weeks, she fed each group of mice with regular feed or with pellets replacing 25% of the weight with powdered whole ground adult chicken mince.

The VDRKO mice that consumed the feed that did not contain whole ground adult chicken mince had significantly lower serum calcium levels as well as brittle bones. On the other hand, the VDRKO mice fed pellets containing whole ground adult chicken mince had higher serum calcium levels and stronger bones, and Nishiura found that their bone strength and bone metabolism had risen to the same level as healthy wild-type mice.

“I was happy to get the expected results on the functionality of whole ground adult chicken mince, and I was surprised that the difference was so clear, as you can see from the graph below. I believe this is the first step toward clarifying this functionality in greater detail in the future.”

Although Nishiura achieved amazing results, she had to face many hardships before achieving the desire results. The breeding and crossbreeding of the mice did not proceed as planned, and she struggled to collect data to improve the accuracy of the experimental results, so it was not a straightforward process.

“Considering that the slightest deviation can affect the experimental results, we must proceed with as much care as possible. We have to measure the weight and feed intake of the mice, measure the mineral concentration of their feces and blood, measure the strength of the bones removed from the dissected mice, and analyze bone density using micro-CT scans taken at a collaborating research institute. I believe that by steadily building on this kind of meticulous work, I can get closer to the truth.”

Nishiura was nominated to present her research at a panel entitled "Empowering Tomorrow's Nutrition Leaders: The Young Scholars Forum on Innovative Nutrition and Health Research" at the Asian Congress of Nutrition held in Chengdu, China. She received a great response, which suggests just how important her achievement is, even in the eyes of experts.

Nishiura is now moving on to the next phase of her research, which incorporates cell tests, in order to clarify the mechanism by which whole ground adult chicken mince exhibits functionality and to identify the functional components contained in the adult chicken.

A busy schedule: Two days a week at her company and three days a week doing research. And presenting at conferences

Nishiura enrolled in the Graduate School of Gastronomy Management after contacting Professor Ritsuko Masuyama when she was looking for a professor to collaborate on research on the functionality of whole ground adult chicken mince as a corporate researcher. As they proceeded with their joint research, they discovered the potential benefits of whole ground adult chicken mince, and Nishiura says this made her want to get more deeply involved in the research.

“I earned a master's degree in agronomy, but did not plan to continue on to the doctoral program in that field. However, in the course of my joint research with Professor Masuyama, I came to realize that I wanted to conduct experiments by myself, using the latest instruments. I also liked that I could discuss my research with other graduate students, so I decided to enroll in the Graduate School of Gastronomy Management because I wanted to do serious research in the doctoral program.”

Nishiura has a busy schedule, working two days a week at her company and attending graduate school for the remaining three days. Because her schedule tends to fill up quickly, she makes sure to report, communicate, and consult with her colleagues at work, other members of the graduate school, and her chief and professor, and she tries to work efficiently and steadily on both her work and her experiments.

In addition to conducting research, another important responsibility of graduate students is to disseminate their findings. Since enrolling in the graduate school, Nishiura has given many conference presentations. Having overcome many major obstacles, we could sense from her facial expression that Nishiura is leading a fulfilling life as a doctoral student.

Aiming to contribute to society with foods that maintain bone health

Since her current research differs from what she studied in her undergraduate and master's programs, Nishiura has to develop her knowledge from scratch, but she says this exposure to new knowledge is what makes the program so rewarding.

“The doctoral program is ull of learning about fields of specialization. Besides that, I’ve also had the opportunity to be exposed to social science disciplines such as economics and psychology, which I have found to be very refreshing. In addition to students who run experiments, I also have classmates who are tackling research questions using methods such as interview surveys and collecting data from the literature. It is very interesting to learn about a wide variety of research fields.”

As she works to elucidate the mechanisms underlying the functionality of whole ground adult chicken mince, Nishiura's ultimate goal is commercialization.

One of the great strengths of a working doctoral student like myself is the ease with which new findings from the research can be encouraged to be considered as new products for the company. The results we have uncovered yield added value that cannot be found in other products, and can be used widely for the benefit of society. Although this is a lofty goal, I will continue to steadily build on my research with an eye toward commercialization.”

In Japan, where the birthrate is declining and the population is aging, maintaining bone health is a major issue. With the potential to extend people's healthy life expectancy, all eyes will remain on Nishiura and her research.

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