Background:
Complementary feeding is the process that starts when human milk or infant formula is complemented by other foods and beverages, beginning during infancy and typically continuing to 24 months of age.
This systematic review was conducted by the Nutrition Evidence Systematic Review (NESR) team as part of the U.S. Department of Agriculture and Department of Health and Human Services Pregnancy and Birth to 24 Months Project.
The goal of this systematic review was to answer the following research question: What is the relationship between timing of introduction of complementary foods and beverages and bone health?
Conclusion Statement and Grades:
Insufficient evidence is available to draw conclusions about the relationship between the timing of introduction of complementary foods and beverages and bone health. Grade: [Grade Not Assignable]
Methods:
This systematic review was conducted by a team of staff from NESR in collaboration with a Technical Expert Collaborative.
A literature search was conducted using 4 databases (CINAHL, Cochrane, Embase, and PubMed) to identify articles published from January 1980 to July 2016 that examined the age when complementary foods and beverages (CFB) were first introduced and bone health. CFB were defined as foods and beverages other than human milk or infant formula provided to an infant or young child. Bone health outcomes included bone, biomarkers of bone metabolism, and incidence and prevalence of osteoporosis, osteopenia, rickets, and fracture. A manual search was done to identify articles that may not have been included in the electronic databases searched. Articles were screened in a dual manner, independently by 2 NESR analysts, to determine which articles met predetermined criteria for inclusion.
Data from each included article were extracted, risk of bias was assessed. The body of evidence was qualitatively synthesized, a conclusion statement was developed and the strength of the evidence (grade) was assessed using pre-established criteria including evaluation of the internal validity/risk of bias, adequacy, consistency, impact, and generalizability of available evidence. Research recommendations were identified.
Summary of Evidence:
Three studies met the inclusion criteria for this systematic review, one randomized controlled trial, one prospective cohort study, and one case-control study.
The randomized controlled trial included a small sample of infants fed only vitamin D fortified infant formula, and did not follow infants long enough to assess the impact of timing of introduction to CFB and bone health, as outcomes were assessed when infants were 26 weeks (wk) of age.
The observational studies did not measure and/or account for a number confounding factors that could have impacted the relationship between timing of CFB introduction and bone health later in childhood.
The ability to draw conclusions about the relationship between the timing of CFB introduction and bone health is limited by an overall lack of research, as well as heterogeneity in the three studies included in this systematic review with regards to methodology, subject populations, and results.