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Teenage diets, nutrition and health . British Nutrition Foundation. Teenagers (12-18 years). Nutritional requirements Dietary recommendations Macronutrients Micronutrients Energy balance Physical activity Diet and cognitive ability Diet and behaviour Eating disorders
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Teenage diets, nutrition and health British Nutrition Foundation
Teenagers (12-18 years) • Nutritional requirements • Dietary recommendations • Macronutrients • Micronutrients • Energy balance • Physical activity • Diet and cognitive ability • Diet and behaviour • Eating disorders • Summary - key issues
Nutritional requirements • Growth and development are rapid. • Onset of puberty - characterised by a spurt in physical growth (height and weight). • Considerable gain in muscle and bone mass. • Changes in body composition, e.g. increased deposition of fat in girls. • Energy and nutrient requirements at their highest.
A healthy diet is important for teenagers Eating a healthy, balanced diet can: • promote wellbeing by improving mood, energy and self-esteem to help reduce anxiety and stress; • boost concentration and performance; • reduce the risk of ill-health now and in the future, e.g. obesity, heart disease, cancer, and type 2 diabetes; • increase productivity/attainment and reduce days off sick.
Dietary recommendations Teenagers should consume a variety of foods from each of the four main food groups: Bread, rice, potatoes, pasta and other starchy foods (33%) Fruit and vegetables (33%) Meat, fish, eggs, beans and other non-dairy sources of protein (12%) Milk and dairy foods (15%)
Macronutrients - average intakes (Scottish NDNS and Survey of Sugar Intake data)
What about dietary fibre? • NDNS survey found average dietary fibre (NSP) intakes to be low in teenagers: - Boys (11-14 years) 11.6 g/day (15-18 years) 13.3 g/day - Girls (11–14 years) 10.2 g/day (15-18 years) 10.6 g/day • Reference values: - 15 g/day (11-14 years) - 18 g/day (15 years or above)
Micronutrients - percentage of older children and teenagers with intakes below the LRNI Source: National Diet and Nutrition Survey 2003
Micronutrients - percentage of older children and teenagers with intakes below the LRNI Source: National Diet and Nutrition Survey 2003
What about salt? • NDNS survey results - average salt intakes above recommendations in teenagers: - Boys (11-14 years) 6.75 g/day (15-18 years) 8.25 g/day - Girls (11-18 years) 5.75 g/day (excluding salt added in cooking or at the table) • Recommended maximum daily salt intake: - 11 years and over: up to 6 g/day.
Teenagers and iron • Teenagers have increased iron requirements. • Girls need more iron than boys to replace menstrual losses (RNI: boys 11.3 g/day, girls 14.8 g/day). • Low iron intakes (< LRNI) in 44% of girls (11-14 years) and 48% of girls (15-18 years). • 9% of girls (15-18 years) were found to have poor iron status (Hb < 12g/dl). • Lack of iron leads to an increased risk of iron deficiency anaemia and associated health consequences. • Teenagers who follow a vegetarian diet or restrict food intake (e.g. to lose weight) particularly at risk.
Iron absorption • Good sources: meat (especially lean red meat), liver and offal, green leafy vegetables, pulses (beans, lentils), dried fruit, nuts and seeds, bread and fortified breakfast cereals. • Iron from meat sources (haem iron) is readily absorbed by the body. • Vitamin C helps the body to absorb iron from other sources (non-haem iron).
Teenagers and calcium • Teenagers have high calcium requirements. • Around 50% of the adult skeleton is formed during the teenage years (RNI - boys 1000 mg/day, girls 800 mg/day). • Low calcium intakes (< LRNI) found in 24% of 11-14 year-old girls and 19% of 15-18 year-old girls. • A lack of calcium may have consequences for future bone health e.g. increased risk of osteoporosis.
Teenagers and energy balance • Levels of overweight and obesity are increasing: 35% of teenagers (12-15 years) are classified as overweight or obese (Scottish Health Survey 2009). • Teenagers, especially girls, often try to control their weight by adopting very low energy diets or smoking. • Restricted diets may lead to nutrient deficiencies and other health consequences. • Teenagers of unhealthy weight may need guidance on lifestyle changes to help them achieve a healthy weight.
Teenagers – physical activity • Physical activity through life is important for maintaining energy balance and overall health. • At least 60 mins of moderate-intensity physical activity each day is recommended. • Include activities that improve bone health, muscle strength and flexibility at least twice per week. • 68% of boys and 41% of girls (13-15 year-olds) achieve the recommended 60 mins per day (Scottish Health Survey 2005).
Diet and cognitive ability • Food eaten at school can make up a substantial proportion of the diet and have a significant effect on functions such as learning, memory, information processing and mood. • Cognition represents a complex multidimensional set of abilities and cognitive performance is affected by many influencing factors. • Nutritional effects are difficult to measure. Bellisle F (2004) Effects of diet on behaviour and cognition in children Br J Nutr 92 Suppl 2: S227-32. Stevenson J (2006) Dietary influences on cognitive development and behaviour in children Proct Nutr Soc 65(4):361-5.
Glycaemia The brain appears to be sensitive to short-term fluctuations of glucose supply and therefore it might be beneficial to maintain glycaemia at adequate levels to optimise cognition.
Eating breakfast • Starting each day with breakfast will supply energy to the brain & body. • Eating breakfast leads to improved energy and concentration levels throughout the morning. • Breakfast consumption may improve cognitive function related to performance in school. • Other benefits of breakfast include better nutrient intakes and weight control. Hoyland A et al. (2009) A systematic review of the effect of breakfast on the cognitive performance of children and adolescents Nutr Res Rev 22(2): 220-43.
Fluids and hydration • Even mild dehydration (1-2%) can lead to headaches, irritability and loss of concentration. This level is not enough to cause feelings of thirst. • The recommendation is to drink 6-8 glasses/day (1.2 litres) to prevent dehydration. People need to drink more when the weather is hot or when they have been active. • All drinks count in terms of fluid intake but those without sugar are best between meals.
Diet and IQ • Brain health depends on optimal intakes of nutrients from the diet. • Much speculation about the importance of long chain omega-3 fatty acids to behavioural and cognitive development, including IQ. • Supplementation studies show the best outcome observed in children with learning disabilities. • Current recommendation is one portion of oily fish (140g) per week. Willatts P. (2002) Long chain polyunsaturated fatty acids improve cognitive development J Fam Health Care 12(6 suppl):5.
Diet and mood/behaviour • There are a number of foods that have a pharmacological effect in the body which affects mood: * caffeine; * vaso-active amines, such as histamine; * tryptophan and serotonin. • There is evidence to suggest that poor vitamin and mineral status may be associated with poor educational attainment and antisocial behaviour.
Food additives and hyperactivity • The Southampton study suggested that consumption of mixes of certain artificial food colours and the preservative sodium benzoate could be linked to increased hyperactivity in some children. The colours are: sunset yellow FCF (E110) quinoline yellow (E104) carmoisine (E122) allura red (E129) tartrazine (E102) ponceau 4R (E124) • An EU-wide mandatory warning must be put on any food and drink (except drinks with more than 1.2% alcohol) that contains any of the six colours. Bateman B et al. 2007
Eating disorders • Defined as: an eating pattern that becomes harmful to health. • Can affect anyone but most likely young women. • It is estimated that there are 1 million people affected in the UK, with the majority being 12 to 25 year-old women. • Trigger is multi-factorial and often linked to emotions. • New evidence to suggest genetic makeup may have a small impact.
Anorexia Nervosa • Defined as: the refusal to eat enough to maintain a normal body weight. • Sufferers have the impression that they are overweight and often picture themselves as being fat even though they are already underweight. • If it occurs before puberty, anorexia may lead to stunted growth. In teenage girls and young women, menstrual abnormalities may occur including amenorrhoea (the cessation of periods), which can pose a significant risk to bone health. • Other physical symptoms include: constipation, stomach pains; dry, patchy skin; low body temperature and loss of hair.
Anorexia Nervosa Impact on mental health: • intense fear of gaining weight and obsessive interest in what others are eating; • distorted perception of body shape or weight; • denial of the existence of a problem; • changes in personality and mood swings; • becoming aware of an ‘inner voice’ that challenges views on eating and exercise. Impact on behaviour: • rigid or obsessive behaviour with eating, mood swings; • restlessness and hyperactivity; • wearing big baggy clothes; • vomiting.
Bulimia Nervosa • Sufferers are obsessed with the fear of gaining weight and undergo a recurring pattern of binge eating, which is usually followed by self-induced vomiting. • People with bulimia often feel a lack of self-control and have an excessive concern with their body weight and shape. • Sufferers may also use large quantities of laxatives, slimming pills or strenuous exercise to control their weight. • Many bulimics have poor dental health due to regular vomiting; vomit is acidic and can erode teeth in a characteristic way.
Bulimia Nervosa • Impact on mental health • uncontrollable urges to eat vast amounts of food; • an obsession with food, or feeling ‘out of control’ with food; • distorted perception of body weight and shape; • emotional behaviour and mood swings; • anxiety and depression; low self-esteem, shame and guilt; • Impact on behaviour • disappearing to the toilet after meals to vomit food eaten; • excessive use of laxatives, diuretics or enemas; • frequent periods of fasting; • excessive exercise; • secrecy and reluctance to socialise; • shoplifting for food; • abnormal amounts of money spent on food; • food disappearing unexpectedly or being secretly hoarded.
Other eating disorders • Binge Eating Disorder (BED); • complusive overeating; • eating disorders in sport; • ‘Orthorexic’; • ‘Drunkorexic’. Visit www.b-eat.co.uk for further information.
Teenagers - key issues • Nutritional requirements • Dietary recommendations • Macronutrients • Micronutrients • Energy balance • Physical activity • Diet and cognitive ability • Diet and behaviour • Eating disorders
Teenagers - dietary improvements needed More fruit and vegetables, pulses, wholegrain foods. More milk and diary foods. More iron-rich foods. More oily fish. Less foods high in saturated fat and added sugars. Less salt.
For more information visit www.nutrition.org.uk www.foodafactoflife.org.uk