The Effect of Consumption of Animal Milk Compared to Infant Formula for Non-Breastfed/Mixed-Fed Infants 6–11 Months of Age: A Systematic Review and Meta-Analysis

Abstract

Many infants do not receive breastmilk for the recommended 2-year duration. Instead, alternative milk beverages are often used, including infant formula and raw animal milk products. The purpose of this systematic review was to summarize the effect of animal milk consumption, compared to infant formula, on health outcomes in non-breastfed or mixed-fed infants aged 6–11 months. We searched multiple databases and followed Cochrane guidelines for conducting the review. The primary outcomes were anemia, gastrointestinal blood loss, weight-for-age, length-for-age, and weight-for-length. Nine studies were included: four randomized controlled trials (RCT) and five cohort studies. All studies, except one, were conducted in high income countries. There was a low certainty of evidence that cow’s milk increased the risk of anemia compared to formula milk (Cohort studies RR: 2.26, 95% CI: 1.15, 4.43, RCTs: RR: 4.03, 95% CI: 1.68, 9.65) and gastrointestinal blood loss (Cohort study RR: 1.52, 95% CI: 0.73, 3.16, RCTs: RR: 3.14, 95% CI: 0.98, 10.04). Additionally, there was low certainty evidence that animal milk consumption may not have a differential effect on weight and length-for-age compared to formula milk. Overall, the evidence was of low certainty and no solid conclusions can be drawn from this data. Further studies are needed from low- and middle-income countries to assess optimal milk type in non-breastfed infants aged 6–11 months.

Anemia among Syrian Refugee Children Aged 6 to 23 Months Living in Greater Beirut, Lebanon, including the Voices of Mothers’ and Local Healthcare Staff: A Mixed-Methods Study

“…All children aged 6 to 23 months that did not consume cow’s milk on the previous day had lower odds of suffering from mild anemia. Cow’s milk consumption in infancy, especially the second part of infancy from 6 months to 1 year, has been associated with anemia in numerous studies due to different mechanisms such as that cow’s milk consumption decreases non-heme iron absorption in the gut and can cause intestinal bleeding in the infant [ 94 , 95 , 96 , 97 , 98 , 99 , 100 ]. Less than half of the children aged 6 to 17 months consumed non-dairy animal-source foods on the day prior to the survey, hence the children’s diet has more characteristics of a vegetarian diet.…”

Dietary Strategies for Complementary Feeding between 6 and 24 Months of Age: The Evidence

“…To update the WHO's guidance on consumption of alternative milk beverages, a systematic review assessed the effects of the consumption of animal milk compared to infant formula in non-breastfed or mixed breastfed infants aged 6-11 months [14]. See S1.1.-S1.5.…”

“…Recent evidence continues to suggest increased risk of iron deficiency anemia from consumption of cow's milk during infancy. Meta-analyses found that consumption of cow's milk between 6-11 months of age in apparently healthy non-breastfed infants, compared to consumption of infant formula, seemed to increase the risk of anemia during infancy by two to four times (Figure 2) [14]. In addition, when considering duration of cow's milk consumption, for each additional month of cow's milk feeding, the risk of anemia increased by 23% (p < 0.001).…”

“…However, these studies were not included in every anemiarelated outcome, thus, there is not enough evidence to determine whether additional supplementation or fortification of cow's milk could potentially avert the risk of anemia. The proposed mechanisms that may cause cow's milk to increase the risk of anemia include: the decreased amount of iron found in cow's milk, decreased bioavailability of iron, and increased blood loss from the gastrointestinal tract [11,14].…”

“…This review will focus on a subset of topics related to adequate intake of breastmilk and breastmilk-substitutes, solids, and micronutrients during CF and how they influence the growth, morbidity, mortality, and developmental outcomes of the child. Although these elements have been reviewed separately in various recent reviews [14][15][16][17][18], there is a need to consider the evidence in its totality, and to include additional recent information on small-quantity lipid-based nutrient supplements (SQ-LNS) and fortified foods [19]. This review will therefore aim to cover the evidence related to the following dietary components and interventions: (1) continued breastmilk feeding during the CF period; (2) animal milk and infant formula feeding;…”