Adolescence is a critical time of physical, psychological and social development, and thus, optimal nutritional intakes are required during this life stage. Despite this, adolescence is recognised as a period of nutritional vulnerability, with many reportedly failing to meet current dietary guidelines. The school-setting presents a favourable environment to intervene and promote positive dietary behaviours and is also inclusive regardless of socio-economic status. However, a lack of consensus exists on how best to utilise schools to facilitate improvements in dietary behaviours among this age group. Whilst previous research has focused on identifying the factors motivating dietary choices within the school-setting, less is known on the optimum strategies to enhance these dietary choices which could positively contribute to the design of future interventions. It is reported that adolescents have good nutritional knowledge, although this does not appear to be a central consideration when making their dietary choices. Alternative factors at the individual (taste, visual appeal, familiarity, food quality, price, portion size, value for money, time/ convenience), social (peer influence), physical (product placement) and macro environment (food availability) levels have been frequently cited as important influences on adolescents' dietary choices in school. Although school-based interventions have shown potential in achieving positive dietary change among adolescents, more research is needed to determine the most effective methods in improving dietary behaviours in schools. This review summarises the key factors which influence adolescents' school-based dietary choices and the effectiveness of previously conducted interventions, identifying promising components for consideration when developing future dietary interventions within the school-setting.

The purpose of the present experiments was to extend previous data on the strategy used by adult rats to select feed appropriately when faced with diets devoid of protein or an essential amino acid (EAA), and to compare this strategy with that used when facing vitamin (thiamin) deficiency. Rats fed on either balanced or deficient (EAA or protein) diets were offered a choice between a novel deficient and a familiar (deficient or corrected) diet and their choice was monitored. It was shown that protein- and EAA-deficient rats acquired an aversion for their corresponding familiar devoid diet, which by itself promoted a neophilia for the novel diet. This neophilia was not non-specific because protein-deficient rats facing a choice between a protein-devoid and an EAA-devoid diet did exhibit neophilia but only in the short term (less than 5h), and then switched to a preference for the familiar protein-devoid diet. These results show that, in contrast to the case of vitamin deficiency, the protein- or EAA-devoid diet-induced neophilia can be rapidly reversed if the novel feed happens to be more deleterious than the familiar, inappropriate one. This behaviour suggests the existence of sensitive mechanisms able to reveal within a short time the EAA inadequacy of the ingested feed and to adapt the choice for the most appropriate feeds more promptly than in the face of thiamin deficiency. Thus it appears that balancing EAA is more urgent than balancing thiamin.

The purpose of the present study was to assess whether rats are capable of selecting the right proportions of two diets that are individually inappropriate in terms of essential amino acid composition to satisfy their amino acid requirements. Rats were offered a choice of one protein-free regimen and another devoid of only one essential amino acid (either threonine or isoleucine) set up in such a way as to provide amino acid balance if they were consumed in 1/3 and 2/3 proportions respectively. Preliminary experiments had established that all our diets were aversive by themselves except for the 60 g casein/kg diet. Rats did reach almost the necessary proportion with, according to published standards (National Research Council, 1978), some excess in isoleucine intake. In addition, given access to two aversive diets that were each nutritionally inadequate, rats showed no aversion and gained body weight when they had the opportunity to consume both of them. Beyond the capacity that rats have of rebalancing their micronutrient intake, the present experiment brings out the idea that the imbalance-induced aversion: preference ratio may be completely upset when this omnivore has access to more than one feed.