Iodine status of breastfed infants and their mothers' breast milk iodine concentration.

Iodine is an essential nutrient for growth and development during infancy. Data on iodine status of exclusively (EBF) and partially breastfed (PBF) infants as well as breast milk iodine concentration (BMIC) are scarce. We aimed to assess (a) infant iodine nutrition at the age of 5.5 months by measuring urinary iodine concentration (UIC) in EBF (n = 32) and PBF (n = 28) infants and (b) mothers' breast milk iodine concentration (n = 57). Sixty mother-infant pairs from three primary health care centres in Reykjavik and vicinities provided urine and breast milk samples for iodine analysis and information on mothers' habitual diet. The mother-infant pairs were participants of the IceAge2 study, which focuses on factors contributing to infant growth and development, including body composition and breast-milk energy content. The median (25th-75th percentiles) UIC was 152 (79-239) µg/L, with no significant difference between EBF and PBF infants. The estimated median iodine intake ranged from 52 to 86 µg/day, based on urinary data (assuming an average urine volume of 300-500 ml/day and UIC from the present study). The median (25th-75th percentiles) BMIC was 84 (48-114) µg/L. It is difficult to conclude whether iodine status is adequate in the present study, as no ranges for median UIC reflecting optimal iodine nutrition exist for infants. However, the results add important information to the relatively sparse literature on UIC, BMIC, and iodine intake of breastfed infants.

Timing of the introduction of complementary foods in infancy: a randomized controlled trial.

OBJECTIVE: To increase knowledge on iron status and growth during the first 6 months of life. We hypothesized that iron status would be better in infants who received complementary foods in addition to breast milk compared with those exclusively breastfed. METHODS: One hundred nineteen healthy term (≥37 weeks) singleton infants were randomly assigned to receive either complementary foods in addition to breast milk from age 4 months (CF) or to exclusive breastfeeding for 6 months (EBF). Dietary data were collected by 3-day weighed food records, and data on iron status and growth were also collected. RESULTS: One hundred infants (84%) completed the trial. Infants in the CF group had higher mean serum ferritin levels at 6 months (P = .02), which remained significant when adjusted for baseline characteristics. No difference was seen between groups in iron deficiency anemia, iron deficiency, or iron depletion. The average daily energy intake from complementary foods of 5-month-olds in the CF group was 36.8 kJ per kg body weight. Infants in both groups grew at the same rate between 4 and 6 months of age. CONCLUSIONS: In a high-income country, adding a small amount of complementary food in addition to breast milk to infants' diets from 4 months of age does not affect growth rate between 4 and 6 months, but has a small and positive effect on iron status at 6 months. The biological importance of this finding remains to be determined.

Optimal duration of exclusive breastfeeding: what is the evidence to support current recommendations?

Before 2001, the World Health Organization (WHO) recommended that infants be exclusively breastfed for 4-6 mo with the introduction of complementary foods (any fluid or food other than breast milk) thereafter. In 2001, after a systematic review and expert consultation, this advice was changed, and exclusive breastfeeding is now recommended for the first 6 mo of life. The systematic review commissioned by the WHO compared infant and maternal outcomes for exclusive breastfeeding for 3-4 mo versus 6 mo. That review concluded that infants exclusively breastfed for 6 mo experienced less morbidity from gastrointestinal infection and showed no deficits in growth but that large randomized trials are required to rule out small adverse effects on growth and the development of iron deficiency in susceptible infants. Others have raised concerns that the evidence is insufficient to confidently recommend exclusive breastfeeding for 6 mo for infants in developed countries, that breast milk may not meet the full energy requirements of the average infant at 6 mo of age, and that estimates of the proportion of exclusively breastfed infants at risk of specific nutritional deficiencies are not available. Additionally, virtually no data are available to form evidence-based recommendations for the introduction of solids in formula-fed infants. Given increasing evidence that early nutrition and growth have effects on both short- and longer-term health, it is vital that this issue be investigated in high-quality randomized studies. Meanwhile, the consequences of the WHO recommendation should be monitored in different settings to assess compliance and record and act on adverse events. The policy should then be reviewed in the context of new data to formulate evidence-based recommendations.