October 31, 1997

Students spin new way to gauge nutrition content of breast milk

Students spin new way to gauge nutrition content of breast milk

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Leigh Smith nursing her newborn son, Landreth. (Photo by Donna Jones Bailey.)

When it comes to nutrition, human breast milk is considered optimal.

And nutrition is of the utmost importance when it comes to feeding premature infants in the Neonatal Intensive Care Unit at Vanderbilt University Medical Center.

Measuring the nutrients in human breast milk is another story, however. While a nutritional assessment of infant formula is supplied by the manufacturer, an accurate method for measuring the caloric and nutrition content of human milk ‹ which can vary greatly from person to person ‹ has been lacking.

Until now.

Two second-year Vanderbilt University School of Medicine students, Patricia Chu and Christine Wang, have validated a way to analyze samples of human milk in the NICU, a method which has earned the pair the Young Investigator Award from the National Perinatal Association.

The technique measures the length of the lipid column, called the creamatocrit, which is separated from milk using a standard centrifuge. This creamatocrit varies with the lipid concentration, or energy content, of milk. Assessing creamatocrit was introduced in 1978, but has not been used as routine practice in neonatal intensive care units. The Vanderbilt medical students took the process one step further, validated the technique, and showed that it is accurate and simple to use in the NICU.

The students, who worked on the project under the direction of Dr. Jayant P. Shenai, professor of Pediatrics, will receive the award at the association's annual meeting in Tampa in December. Shenai was the students' mentor in the research, which was part of their Introduction to Biomedical Research class. The project was done during the students' first year of medical school.

Measuring the creamatocrit takes about 15 minutes and allows the calculation of energy content in human milk. For their study of the technique, Chu and Wang analyzed samples of human milk from 19 mothers of premature babies in the NICU. Babies ranged in age from two days to two months. Their gestational age was from 25 to 37 weeks.

A small sample of breast milk was taken, then spun down. The fat, carbohydrates and protein were measured and total energy content was calculated.

"The students proved by doing the creamatocrit, it is possible to know the energy content of milk," Shenai said. "This information is important since the composition of human milk varies quite a bit. It is not easy to know exactly what the energy content is in human milk. We do careful calculations on how much energy a baby is getting and that is hard to do with human milk because it varies so much."

Another important finding of their study is that the test is also accurate on breast milk that has been frozen. Breast milk is commonly pumped and frozen in the NICU for later feedings.

Wang said she is impressed that such a simple test could be so accurate.

"It's an easy and cheap way to measure fat and energy content in breast milk," Wang said. "What's so exciting about this is that it's a technique that is not being currently used in the hospital and it can be done quickly. You don't have to do a bunch of expensive studies on the milk to determine how much fat and energy is there."

Shenai said he is surprised the technique has not become standard.

"It's so practical. It is unbelievable to me that it is not commonly done," he said. "It is unique and has the potential for widespread clinical use."

Wang said she and Chu intended for their Introduction to Biomedical Research project to have clinical applications.

"We wanted to do something with practical significance. This is something that can actually be used in the nursery," she said.

Wang said the analysis is particularly important for infants diagnosed with failure to thrive ‹ those who were not growing as they should.

"It has been assumed that mother's milk has a certain amount of fat, but when some samples are tested, it is actually lower in fat," she said. "By using creamatrocit to analyze the samples, it eliminates guessing."

Also assisting the research were Michael R. Waterman, Ph.D., Natalie Overall Warren Distinguished professor and chair of the Department of Biochemistry, and Larry L. Swift, Ph.D, professor of Pathology. Their laboratories were used in Wang and Chu's research.

Wang said she and Chu will travel to Tampa, Fla., for the presentation.

"It's exciting to think that research we did in a semester could have such a practical application, something that can actually be used in the nursery to benefit the babies in a NICU," Wang said.