A school canteen 'healthy' snack under the policy limit
A secondary school canteen sells a 40 g 'oat and honey' cereal bar and a 330 mL carton of fruit juice as a 'healthy break'. The bar label gives, per bar: energy 780 kJ, protein 4.2 g, carbohydrate 28 g (of which sugars 14 g), fat 6.1 g (of which saturates 3.0 g), fibre 1.8 g, salt 0.25 g. The juice carton gives 540 kJ and 30 g sugars. A typical student eats both at the 20-minute break. The school food policy says a snack should provide no more than 15% of an 8,400 kJ daily energy intake and no more than 10 g of free sugars per portion. The canteen manager says the bar is healthy because it contains oats and honey, and that fruit juice is 'natural' so its sugar does not count. The student council wants a cheap change that students will accept.
1. Calculate the energy and sugar provided by the pair, compare with the policy, and judge the manager's claim.
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Energy: 780 + 540 = 1,320 kJ. As a fraction of 8,400 kJ, 1,320 ÷ 8,400 = 0.157, or 15.7%, which is above the 15% policy limit. Sugars: 14 g in the bar + 30 g in the juice = 44 g. Even the bar alone provides 14 g, above the 10 g free-sugar limit. The manager's claim is not supported. Honey is a free sugar under the policy, and juice sugars are also treated as free sugars because the fruit's cell structure has been broken down; 'natural' does not mean the body handles them differently in this context. The 1.8 g fibre is a small amount and does not cancel the sugar. The pair is therefore a high-sugar snack, and the 'healthy' label is misleading. A better claim would be based on the whole break, not on the presence of oats.
2. Design a four-week trial to test whether replacing the juice with water and the bar with a lower-sugar alternative reduces students' total free-sugar intake at break. Name the variables and one ethical issue.
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Independent variable: the break snack offered (current bar plus juice versus lower-sugar bar plus water). Dependent variable: total free sugars consumed at break, estimated from sales minus plate waste, or from a short self-report checked against packaging. Controlled variables: price, display position, break length, day of week, year group, and the wording of the canteen sign. I would run two weeks of each condition, or alternate classes, and compare average sugar per student. Ethical issues include informed consent, not singling out students by weight, allergen labelling, and ensuring the alternative is still enough food. I would also record how many students refuse the new snack, because a trial that reduces sales may not reduce intake if students buy elsewhere. The trial tests the change, not just the label.
3. The cheaper alternative is a 30 g nut-and-dried-fruit bar with 520 kJ and 7 g sugars, costing €0.55 versus €0.45. Evaluate this swap, including at least two factors other than sugar.
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The nut-and-dried-fruit bar meets the sugar limit (7 g) and has lower energy (520 kJ), so on the policy numbers it is better. But nuts are a major allergen; the school may have a nut-free policy, and a 30 g bar may be too small for hungry students. Dried fruit is sticky and can still count as free sugar, so the 7 g needs checking. Cost rises by €0.10 per bar, which matters over a term. Fibre and protein may improve satiety, and the lower energy may help, but student acceptance is uncertain. I would trial it with clear allergen labels and keep a nut-free alternative. The swap is reasonable only if the school can manage the allergy risk and if students do not compensate by buying more. Otherwise, water plus the existing bar may be the cheaper first step, even though it does not fix the sugar problem.