What is the question?

• The question is: What is the relationship between types and amounts of complementary foods and beverages and micronutrient status?

What is the answer to the question?

• Strong evidence suggests that consuming complementary foods and beverages that contain substantial amounts of iron, such as meats or iron-fortified cereal, helps maintain adequate iron status or prevent iron deficiency during the first year of life among infants with insufficient iron stores or breastfed infants who are not receiving adequate iron from another source. However, the benefit of these types of complementary foods and beverages for infants with sufficient iron stores, such as those consuming iron-fortified infant formula, is less evident. 
• There is not enough evidence to determine the relationship between other types/amounts of complementary foods and beverages containing lesser amounts of iron, such as fruits and vegetables, and iron status.
• Limited evidence suggests that consuming complementary foods and beverages that contain substantial amounts of zinc, such as meats or cereals fortified with zinc, supports zinc status during the first year of life, particularly among breastfed infants who are not receiving adequate zinc from another source. However, the benefit of these types of complementary foods for infants consuming fortified infant formula is less evident.  
• Moderate evidence suggests that consuming complementary foods and beverages with differing fatty acid profiles, particularly long-chain polyunsaturated fatty acids, can influence fatty acid status.
• During the second year of life, good sources of micronutrients are still needed, but there is limited evidence to indicate which types and amounts of complementary foods and beverages are associated with adequate micronutrient status.
• There is not enough evidence to determine the relationship between types and amounts of complementary foods and beverages and vitamin B12, vitamin D, or folate status.

Why was this question asked? 

• This important public health question was identified and prioritized as part of the U.S. Department of Agriculture and Department of Health and Human Services Pregnancy and Birth to 24 Months Project.

How was this question answered? 

• A team of Nutrition Evidence Systematic Review staff conducted a systematic review in collaboration with a group of experts called a Technical Expert Collaborative

What is the population of interest? 

• Generally healthy infants and toddlers who were fed complementary foods and beverages from ages 0-24 months and had micronutrient status examined through 24 months of age

What evidence was found? 

• This review includes 31 studies.
• These studies compared different types or amounts of complementary foods and beverages and micronutrient status.
• Complementary foods and beverages are foods and beverages other than human milk or infant formula provided to an infant or young child.
• Studies need to consider other factors that could impact this relationship.

How up-to-date is this systematic review? 

• This review includes literature from 01/1980 to 07/2016.

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 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 types and amounts of complementary foods and beverages and micronutrient status?

Conclusion Statement and Grade

• Strong evidence suggests that consuming complementary foods and beverages that contain substantial amounts of iron, such as meats or iron-fortified cereal, helps maintain adequate iron status or prevent iron deficiency during the first year of life among infants with insufficient iron stores or breastfed infants who are not receiving adequate iron from another source. However, the benefit of these types of complementary foods and beverages for infants with sufficient iron stores, such as those consuming iron-fortified infant formula, is less evident. 
• There is not enough evidence to determine the relationship between other types/amounts of complementary foods and beverages containing lesser amounts of iron, such as fruits and vegetables, and iron status.
• Limited evidence suggests that consuming complementary foods and beverages that contain substantial amounts of zinc, such as meats or cereals fortified with zinc, supports zinc status during the first year of life, particularly among breastfed infants who are not receiving adequate zinc from another source. However, the benefit of these types of complementary foods for infants consuming fortified infant formula is less evident.  
• Moderate evidence suggests that consuming complementary foods and beverages with differing fatty acid profiles, particularly long-chain polyunsaturated fatty acids, can influence fatty acid status.
• During the second year of life, good sources of micronutrients are still needed, but there is limited evidence to indicate which types and amounts of complementary foods and beverages are associated with adequate micronutrient status.
• There is not enough evidence to determine the relationship between types and amounts of complementary foods and beverages and vitamin B12, vitamin D, or folate status.
  
  Grade: Strong – Iron status; Moderate – Fatty Acid status; Limited – Zinc status; Grade Not Assignable – Vitamin B12 status, Vitamin D status, Folate status

Methods 

• The systematic review was conducted by a team of staff from the Nutrition Evidence Systematic Review 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 types and amounts of complementary foods and beverages (CFB) consumed and micronutrient status. CFB were defined as foods and beverages other than human milk or infant formula provided to an infant or young child. Micronutrient status outcomes included iron, zinc, vitamin B12, folate, vitamin D, and/or folate status. 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, risks of bias were assessed, and both were checked for accuracy. 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.

Summary of Evidence 

• Thirty-one studies published between 01/1980 and 07/2016 met the inclusion criteria for this systematic review.
  • Most studies examined the relationship between types and/or amounts of CFB and iron status, and the CFB examined were largely limited to Fe-fortified cereals and meats.   
  • Several studies examined zinc and fatty acid status and few studies examined vitamin D, vitamin B12, and folate. 
• One randomized controlled trial, conducted in both breastfed (BF) and formula fed (FF) infants, showed that consuming meats or Fe- and/or Zn-fortified cereals as CFB generally protected against Fe deficiency anemia and supported Zn status in the first year of life, though evidence is more limited in the second year of life.
  • Among BF infants, meat and Fe- and Zn-fortified cereals supported iron and zinc status in later infancy. Meat provided a valuable source of trace minerals for BF infants who may not have been fed Fe- and Zn-fortified products; in fact, the frequency of meat consumption was associated with iron status in the first and second years of life. 
  • In infants/toddlers whose diets already contained other bioavailable Fe and Zn sources (i.e. infant formulas and cereal fortified with iron and/or zinc), meat offered little additional benefit for Fe or Zn status, though it is an important source of bioavailable Fe and Zn.
• Dietary sources of fatty acids, particularly LC-PUFA, in CFB (i.e., oils, fish, meats, and eggs) influenced the plasma fatty acid profile of infants and toddlers. 
• A limitation of some of the studies included in this systematic review was lack of accounting for whether infants were fed breast milk and/or infant formula, and other aspects of the overall diet, including consumption of fortified products and bioavailability of nutrients consumed. Another limitation is a lack of studies that examined vitamin D, vitamin B12, and folate.