Title: What age for weaning?

Key words: weaning, formula milk, breast milk, solid food, development

Date: July 2000

Category: 11. Life Changes

Type: Article

Author: Dr Van Rhijn

What age for weaning?

The scientific basis for the age of introduction of complementary feeding in infants

Introduction

The process of expanding the diet with foods and drinks other than breast milk (formula) is referred to as weaning (as defined by the Department of Health [DoH])1. Various reports from different groups concluded that 84%2, 94%3 and 97 %4 of infants had begun the weaning process by 4 months. The mothers had therefore ignored the guidelines from the COMA Working Group which recommend delaying weaning until after this period. What is the scientific basis for this recommendation?

Increasing Requirements

Numerous factors determine the age of weaning, including volume, energy, nutrient composition of milk, infant growth velocity, size and gender. The rapidly developing infant has increasing nutritional and energetic demands, which eventually cannot be met by fluids alone5. Additional dietary sources of energy, protein, vitamins A & D, absorbable iron and zinc are usually needed by the age of six months6. Inappropriate timing or composition of introduced foods may adversely interfere with the child’s development7. However, a mixed diet should be offered by the age of 6 months.

In fact, solids given with breast milk can actually reduce the absorption of nutrients in the milk. Formula fed infants and boys appear to require more energy, and may have different weaning needs8. Late weaning of babies is associated with compromised nutritional status, especially iron and vitamin D deficiency. This may lead to failure to thrive and a delay in psychomotor development 9. Preterm infants, however, also have special nutritional needs due to their low body stores of fat, minerals and vitamins10. They grow better on an enriched preterm formula11, with higher IQ scores at 8 years of age12.

Physiological Maturity

There are various reasons why it is undesirable to introduce solids before the age of four months.

The neuromuscular co-ordination needed to maintain a suitable posture for swallowing solid foods, along with the ability to bite and chew, needs to be developed first. The secretion of digestive enzymes and gastric acid, as well as the absorptive capacity of the small and large bowel may not be adequately developed. Kidney function may not be sufficiently mature to deal with the greater concentrations of solutes. There is greater vulnerability to allergic sensitisation. Studies showed that early introduction of solid foods (before 15 weeks) was significantly associated with obesity, respiratory illness and persistent cough13, and an increased probability of wheezing14. The latter is probably secondary to an infection rather than due to allergy15. Late weaning, on the other hand, results in a missed opportunity to acquire feeding skills during the developmental stages and possible refusal to accept lumpy foods.

Conclusion

Numerous individual and cultural factors determine the age of weaning16, but the timing remains critical for maintaining health. For the majority of full-term infants, with normal requirements, it is recommended that solid food should be introduced between the ages of 4 and 6 months, a mixed diet added by 6 months or at a weight of at least 5Kg. Formula fed infants may require weaning somewhat earlier than their breast-fed counterparts.

 

References
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  2. Mills, A. & Tyler, H. Food and nutrient intakes of British infants aged 6 – 12 months. MAFF. London: HMSO. 1992
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  4. British Nutrition Foundation. Nutrition in Infancy. British Nutrition Foundation Briefing Paper. 1997; 28 – 38.
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