Currently, five different growth charts are available in the UK (see Further reading for more information). The UK-WHO ‘0–4 years’ is the growth chart most commonly used to monitor growth in healthy infants and young children. In addition to this, a Neonatal and Infant Close Monitoring chart (NICM) has been designed to monitor growth in very preterm infants and those whose growth may be affected by early health problems or chronic disease. This chart has low lines to monitor unusually short or underweight children and provides assistance with correction for gestational age. Two different charts are now available for school-aged children: the ‘2–18’ chart, whose features include guidance on monitoring puberty, BMI and an adult height predictor; and the new Childhood and Puberty Close Monitoring chart (CPCM). This chart is for use in school-aged children with growth or nutritional problems and can be used until the age of 20. Separate charts are also available for children with Down’s syndrome.

In May 2009, the new UK-WHO growth charts replaced the British 1990 (UK90) charts for children aged 0–4 years. These new charts combine data from the British 1990 reference at birth with data from the WHO Multicentre Growth Reference Study (MGRS; see Further reading) from 2 weeks to 4 years. The MGRS was conducted to provide data on the way that infants should grow (a standard) rather than how they do grow (a reference). It is conceptually different from older growth references and is based on the premise that babies of all ethnicities grow similarly and to the same extent when receiving optimal nutrition – breastfeeding – and with no environmental constraints on growth. Therefore, the WHO MGRS collected anthropometric data from term infants exclusively breastfed for at least the first 4 months of life from the most advantageous backgrounds in six countries of differing ethnicity. By contrast, older growth charts (references) were based on data from a mixture of formula-fed and breastfed babies from a range of socio-economic backgrounds, generally in a single country or area.

Key differences between the new UK-WHO chart and the old UK90 chart are:

Nutritional programming

The concept that there are sensitive periods in early life when insults or stimuli may have long-term or even lifetime effects has been defined as ‘programming’. Evidence that nutrition could act as a programming agent was shown in a variety of animal species by McCance and Widdowson. For example, in the early 1960s, they showed that malnutrition during an early ‘critical period’ in rats permanently impaired their growth. In this experiment, rat pups that were malnourished during the suckling period by putting them in large litters showed later growth deficits which were not reversible even with an unrestricted food supply after weaning; whereas a similar period of malnutrition later in the growth period produced only a temporary effect on weight gain, which was rapidly reversed when adequate food was supplied. Since then, animal studies in a wide range of species, including non-human primates, have shown that nutrition during critical periods in early life can programme outcomes such as changes in metabolism, endocrine function, gut function, size, body fatness, blood pressure, insulin resistance, blood lipids, learning, behaviour and longevity. Over the past few years, findings from randomized intervention studies in human infants with later follow-up have confirmed that health outcomes in human infants, as in other species, can be programmed by early diet. Early diet has been shown to have long-term effects on blood pressure, insulin resistance, blood lipids, obesity risk, bone health, atopy, cognitive function and brain structure. The size of the effect on some outcomes is large enough to be of public health significance; for example, in the case of cardiovascular risk factors (blood pressure, blood lipids, insulin resistance), the programming effects of early nutrition are greater than non-pharmacological interventions in adult life, such as exercise and weight loss. The implication of these findings is that it is no longer sufficient to think about nutrition only in terms of short-term adequacy or outcomes; potential effects on later health must also be considered.

Nutrient requirements for healthy infants and children

Recommendations for nutrient intakes in the UK are provided as Dietary Reference Values (DRVs) for boys and girls (0–3, 4–6, 7–9, 10–12 months, 1–3 years, 4–6 years, 7–10 years), and for males and females (11–14 years, 15–18 years, 19–50 years, 50+ years). There are separate recommendations for pregnant and breastfeeding women.

In North America, recommendations for the intake of specific nutrients are provided in the Dietary Reference Intakes (DRIs; see Further reading for more information), a set of recommendations intended to provide guidance for evaluating nutrient intakes and planning diets for both individuals and population groups. Recommendations are provided for the following life stage groups: Infancy (first 6 months, second 6 months), Toddlers (1–3 years), Early childhood (4–8 years), Puberty/adolescence (9–13 and 14–18 years), Young adult/middle age (19–30 and 31–50 years), Adulthood and older age (51–70 and 70+ years), and pregnancy and lactation.

The DRVs and DRIs consist of different estimates, summarized and defined in Table 13.2 and Figure 13.2. They share a number of common features, which are important to consider when interpreting and using the recommendations:

The recommendations for energy intake in infants and children (see Further reading) require special consideration. EAR values are provided, since an RDA/RNI (representing the mean + 2SDs) would provide excess energy for the majority of the population. Historically, recommendations were based on observed energy intakes in different populations, but this approach has obvious flaws for populations experiencing increasing rates of overweight and obesity. The development and refinement of the doubly-labelled water technique, which uses stable isotopes to measure total energy expenditure (TEE) non-invasively in free-living subjects, has allowed the development of recommendations based on energy expenditure. New EARs for energy intakes were produced in 2011.

The main components of TEE are the basal metabolic rate (BMR), which makes up 40–70%, and physical activity, which makes up 25–50% in the majority of individuals and is the most variable component of energy expenditure. Infants and children have an additional energy requirement for new tissue deposition. The energy costs for growth make up about 35% of the total energy requirement during the first three months of life, about 17.5% in the next three months and reduce further over the next six months to only 3% at 12 months. Energy for growth falls to less than 2% of daily requirements in the second year, remains between 1 and 2% until mid-adolescence, and gradually disappears by 20 years of age.

Breast milk composition

The composition of breast milk has long been used as the basis for determining infant nutrient requirements during the first 6 months of life, and as a basis for regulations on the permitted composition of breast milk substitutes (infant formulas). Whilst this makes sense theoretically, in practice there are a number of problems associated with this approach, summarized in Table 13.3. Recognizing these problems, in recent years, there has been a greater focus on trying to achieve the performance (health and developmental outcomes) of breastfed infants rather than simply trying to mimic the composition of breast milk, which is in many ways impossible.