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Zinc status of breastfed and formula-fed infants of different gestational ages
P Hemalatha1, P Bhaskaram, P A Kumar
1National Institute of Nutrition, Indian Council of Medical Research, Hyderabad, India.
Insights
Routine zinc supplements may not be necessary for infants. Zinc levels naturally decline and recover with proper weaning, suggesting timely food diversification is key for infant zinc status.
Area of Science:
- Pediatric Nutrition
- Human Physiology
- Nutritional Biochemistry
Background:
- Infant zinc status is crucial for development.
- Breast milk zinc content varies with lactation stage.
- Formula-fed infants may have different zinc profiles.
Purpose of the Study:
- To assess infant zinc status from birth to 12 months.
- To correlate infant zinc levels with maternal milk zinc.
- To determine the need for routine infant zinc supplementation.
Main Methods:
- Longitudinal study of 186 term and preterm infants.
- Measurement of leukocyte and plasma zinc levels.
- Analysis of zinc in breast milk and infant formula.
Main Results:
- Breastfed infants showed declining zinc levels by 4-6 months, recovering post-weaning.
- Preterm infants had higher birth leukocyte zinc than term infants.
- Formula-fed infants had lower leukocyte zinc at 3 months but improved after weaning.
Conclusions:
- Transient low zinc levels in early infancy may be reversed by appropriate weaning.
- Focus on timely food supplements rather than single-nutrient zinc supplements is recommended.
- Further investigation into the functional significance of transient low zinc values is warranted.
Abstract:
Zinc status in 186 full term and preterm infants was determined at birth, and 3, 6, 9, and 12 months of age along with determination of zinc levels in breast or formula milk to find out if routine zinc supplements are needed during infancy. The leukocyte and plasma zinc levels in all breastfed infants were high at birth and gradually declined reaching lowest values by 4-6 months of age, and improved to normal levels by 9 months following weaning. The preterm infants however, had significantly (P < 0.05) higher leukocyte zinc (213.6 +/- 46.91 micrograms/10(10) cells) at birth compared to term infants. Colostrum of all the mothers had higher zinc concentrations which declined to significantly lower levels in breastmilk by 4-6 months of lactation, corresponding to the age when the breastfed infants had lower zinc levels. The improvement of the levels to normal after weaning suggests that the fall in zinc status during early infancy could be a transient phenomenon which could be reversed by proper weaning, thus strengthening the plea for timely food supplements rather than the need for single nutrient supplements. Formula-fed full term infants had significantly lower leukocyte zinc levels (49.3 +/- 2.59 micrograms/10(10) cells) at 3 months of age compared to breastfed infants of the same age (92.8 +/- 14.04 micrograms/10(10) cells). Even these infants improved their zinc status after weaning on par with breastfed infants. The functional significance of their transient, but low zinc values during early infancy needs to be investigated.