Check the nutrition label on just about any packaged food, and you’ll see how much carbohydrate or salt, or how many calories, are lurking inside waiting for you. But that label won’t give you the whole nutritional picture. How much magnesium does your bag of chips contain? Or iodine, or copper?
These elements are all on the list of human micronutrients: nutrients that help maintain many of the critical biochemical processes within our cells. And while we only need them in very small amounts, micronutrient deficiencies can be devastating, even fatal.
Most of us get the micronutrients we need from our diet (chips aside), but for children whose digestive tracts can’t process regular food – such as those with intestinal disorders like short bowel syndrome (SBS) – getting the right amount of micronutrients is a different story. These children often often have to get all their nutrition intravenously through a process called parenteral nutrition (PN).
Since dieticians can tailor the nutrients given to a child on PN, you’d think that it would be easy to get the right amount of micronutrients, like copper, into the mix. But that isn’t necessarily so.
“We do have standards for dietary copper intake, and they are for the most part based on adults who get their copper from what they eat,” according to Danielle Arsenault, a nurse practitioner in Children’s Center for Advanced Intestinal Rehabilitation (CAIR). “But we have questions about how well this carries over to infants on PN. We don’t really know specifically what dose is the right one for these children.”
Too little copper can lead to anemia, poor growth, even bone problems. With the support of a Patient Services Research Grant, Arsenault is conducting a comprehensive study of infants on PN aimed at detecting copper deficiency, better defining optimal copper dosing, catching low copper levels more effectively, and identifying factors specific to short bowel syndrome that put children at risk of copper deficiency.
“There’s a school of thought that limiting copper is good for the liver in children on PN,” Arsenault says. “So in situations when we are facing liver dysfunction, we often give only half of what’s currently considered the standard copper dose. But are we giving too little?”
To find out, Arsenault and her team – including her mentor, Christopher Duggan, the medical director of CAIR, and Megan Brenn, a dietician who has worked closely with infants on PN – will enroll 30 infants seen for intestinal failure or short bowel syndrome, all on PN. Over the course of a year, they will track a range of biochemical measures – including serum copper, ceruloplasmin (a blood protein that binds to copper much like iron binds to transferrin) and liver function markers – and match the results to traits like growth, bone strength and structure (weak bones can be a sign of copper deficiency) and clinical factors that can affect copper levels in the blood, like inflammation or transfusion.
Arsenault also hopes to validate what she hopes will be a more sensitive marker of copper levels in the blood. “We think that the body works very hard to maintain a certain level of copper in the bloodstream, especially if you are deficient,” Arsenault says. “So serum copper and ceruloplasmin may actually not be the most accurate way to see if we are providing enough copper to meet a child’s needs.” Her study will compare serum copper and ceruloplasmin levels with those of a protein called copper chaperone for superoxide dismutase (CCS), which animal studies suggest could give a more comprehensive view of the body’s copper status.
Altogether, Arsenault’s work should help build a more refined understanding of how much copper is right for children on PN. “We at times use information that’s been handed down to us as a guide in setting up micronutritional regimens for these children, but there’s a need for strong science behind it,” she says. “It’s good for us to step back and see why we do what we do and try to improve on it in a systematic way.”
[Ed. Note: This is the sixth and last in a series about Children’s Hospital Boston staff who received Patient Services Research Grants in 2011. This grant program engages the professional staff in the Department of Patient Services in high-quality pediatric research with the ultimate goal of improving child health.]