title: Opportunities and challenges in conducting systematic reviews to support the development of nutrient reference values: vitamin A as an example.
abstract: Nutrient reference values have significant public health and policy implications. Given the importance of defining reliable nutrient reference values, there is a need for an explicit, objective, and transparent process to set these values. The Tufts Medical Center Evidence-based Practice Center assembled a group of nutrition experts from academic institutions and federal government agencies, led participants in discussions, conducted exercises in formulating questions and evidence review criteria that would be amenable to systematic reviews of the scientific literature, performed a literature search on the questions to identify potentially relevant publications, and identified challenges and limitations of applying this method to support the development of nutrient reference values using vitamin A as an example. The workgroup concluded that the systematic review approach could be productively used to inform the development of reference values. Challenges identified in this exercise include prioritizing and defining research questions when the volume of literature is large, relying on intermediate (surrogate) outcomes when few or no studies directly linking nutrient intake with clinical outcomes are available, and determining reliable nutrient biomarkers. Ultimately, an objective, unbiased systematic review of a defined question could be useful, not only in helping to set nutrient reference values, but also for increasing the transparency of the decision making process.
authors.affiliation: Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Russell
authors.forename: Mei
authors.initials: M
authors.lastname: Chung
authors.forename: Ethan M
authors.initials: EM
authors.lastname: Balk
authors.forename: Stephanie
authors.initials: S
authors.lastname: Atkinson
authors.forename: Edward L
authors.initials: EL
authors.lastname: Giovannucci
authors.forename: Stanley
authors.initials: S
authors.lastname: Ip
authors.forename: Alice H
authors.initials: AH
authors.lastname: Lichtenstein
authors.forename: Susan Taylor
authors.initials: ST
authors.lastname: Mayne
authors.forename: Gowri
authors.initials: G
authors.lastname: Raman
authors.forename: A Catharine
authors.initials: AC
authors.lastname: Ross
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Trikalinos
authors.forename: Keith P
authors.initials: KP
authors.lastname: West
authors.forename: Joseph
authors.initials: J
authors.lastname: Lau
mesh_terms: D006801:Humans; D018673:Nutrition Policy; D012196:Review Literature as Topic; D014801:Vitamin A / Q000008:administration & dosage*
chemical_list: D014801:Vitamin A