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NSP, nonstarch polysaccharide.

NSP, nonstarch polysaccharide.

low intakes of some micronutrients in surveys, there is little evidence of widespread clinical deficiencies, or indications that adolescents are failing to achieve appropriate heights and weights. Iron is the exception, where mean intakes are low and clinical markers suggest deficiency in some age groups. There is justifiable concern about the general healthiness of diets eaten by 'at risk' subgroups such as dieters, smokers, strict vegetarians, and adolescents who drink excess amounts of alcohol.

Dietary surveys

Mean daily intakes of energy and selected micronu-trients from a selection of major international surveys of adolescents are presented in Table 3. Caution should be exercised when interpreting data from dietary surveys because under-reporting of energy is widespread in adolescent and adult populations. Selective under-reporting, often focused on energy-dense or high-fat foods, can partially explain low reported intakes of energy and certain micronutrients. It is also complex to make comparisons between the data from different countries given the range of dietary assessment methods used. There is normally a trade-off between sample size and methodology, which sees the larger surveys favoring less precise methods such as 24-h recalls or food frequency questionnaires in order to make data collection more economical. The results of the most recent UK National Diet and Nutrition Survey (NDNS) of 2672 young people aged 418 years (adolescent values given in Table 4) will be discussed in detail as this represents a survey with particularly strong dietary methodology (i.e., 7-day weighed inventory).

Energy and Protein

Despite mean height and weight data, which are consistent with expected results, energy intakes in UK adolescents remain below estimated average requirements (EARs). Mean energy intakes for boys and girls were 77-89% of EARs; a similar finding to that demonstrated by surveys of younger children and adults. Girls aged 15-18 years had the lowest energy intakes as a proportion of EARs and, apart from under-reporting, this could be due to smoking, slimming, or indeed lower than anticipated energy expenditure. It is well documented that physical activity is particularly low in adolescent girls. Indeed, the NDNS reported that 60% of girls (and 40% of boys) failed to perform the recommended amount of 1 h moderate physical activity per day. Popular sources of energy in the UK adolescent diet included cereal products (one third of energy), savory snacks, potatoes, meat/meat products, white bread, milk/dairy products, biscuits/cakes, spreading fats, and confectionery. Soft drinks contributed on average 6% of energy intakes.

Figure 1 gives a comparison of energy intakes across a range of countries; mainly in Europe. The values represent the mean of reported energy intakes for children aged 9-18 years in these countries, with the majority of surveys focusing on intakes of 11-18 year olds. It is interesting that a large number of countries display similar results (around 10 000 kJ day"1), with a handful of countries, namely Germany, Greece, Portugal, Sweden, and the UK displaying intakes closer to 8000 kJ. For these countries, under-reporting, lower energy requirements, or conscious energy restriction prompted by weight concerns could be reasons for the apparent low intakes.

Table 3 Key international surveys of adolescent dietary intakes

Country

Sex (age

Energy

Energy

Protein

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