Teenage diets and health

Healthy eating for teenagers

During puberty, young people grow and develop rapidly. At this stage, a number of physiological, physical and behavioural changes occur. Adolescents require an increased amount of nutrients for these physical changes.  Research also shows that this age group intake of saturated fat added sugar and salt are above recommended guidelines.  Teenage girls in particular do not consume sufficient vitamin A, iron, calcium, zinc and iodine.  It is recommended that young people should do at least 60 minutes of activity of moderate intensity every day. Only 14% of boys and 8% of girls aged 13-15 years are meeting these guidelines.

Teenagers  have a high calorie demand to fuel their growth spurts, this is why they seem to always be eating.

  • Boys require an average of 2,800 calories per day.
  • Girls require an average of 2,200 calories per day.

Whilst the demand for most nutrients is similar to other age groups, there are some nutrients that adolescents need more of to meet the period of increased growth, for example calcium.  Requirements for many other vitamins and minerals are higher compared to the needs of younger children.

This demand differs between boys and girls: for example boys need more protein than girls as they are generally larger and have a great lean body mass.

A restricted diet especially one that excludes whole food groups, can lead to nutrient deficiencies and problems in later life.

Encouraging a healthy lifestyle is of prime importance during adolescent years. Therefore, maintenance of good habits throughout adolescence is likely to benefit health throughout adulthood and into old age.

Main nutrients of concern in a teenage diet include:-

Iron

Iron requirements increase during adolescence to help with growth and muscle development. Iron is needed within the body to carry oxygen to the cells, if Iron intake is low the body depletes the stores of iron in the bone marrow, spleen and liver which may result in anemia, iron deficiency has also been linked to immune system functioning which increases susceptibility to disease.

Those on low calorie diets are at risk of iron deficiencies.

After menstruation begins, girls need more iron than boys to replace menstrual losses.

Iron absorption

Iron from meat sources, e.g. liver and red meat, is more readily absorbed by the human body compared with iron found in other non-meat sources, such as dark green leafy vegetables (e.g. watercress, broccoli), nuts, wholegrains (e.g. wholegrain breakfast cereals), beans and dried fruits (e.g. apricots, try to obtain organic since the bright orange ones are treated with sulphur a common allergen).

Since the 1950s in the UK, all wheat flours (other than wholemeal) have been fortified with iron by law.  Many breakfast cereals are also fortified with iron on a voluntary basis and can also contribute to iron intake.

Vitamin C helps the body absorb non-ahem iron (non animal source); therefore drinking a glass of fruit juice or eating vitamin C-rich fruit and vegetables (such as tomatoes) at mealtimes can help the absorption of iron from non-meat sources. On the other hand, tea and coffee can reduce the amount of non-haem iron the body absorbs, so they should not be consumed with meals.

Unless you have a diagnosed iron deficiency it is not recommended to take an iron supplement unless its part of a multi-vitamin. 

Calcium

The rapid increase in bone mass in young people means that they require more calcium during their teenage years and if this is not provided, future bone health may be compromised. At ages 11-18 years, the UK reference nutrient intake for boys is  1000 mg per day and for girls the figure is 800 mg per day. In the US they believe 1300mg is more appropriate.

8oz Yoghurt – 415mg

3oz Sardines with bones – 325g

Cheddar Cheese – 1.5oz – 307g

8oz Milk – 299g

8oz Calcium fortified soy milk – 299g

6oz Calcium fortified orange juice – 261g

3oz pink salmon with bones – 181g

Slice of white bread – 77g

Slice wholewheat bread – 30g

Calcium may be lost from the body via sweat, and urine

A poor diet may deplete the body of calcium, diets high in sodium increases urinary calcium excretion.

Caffeine intake can modestly increase calcium excretion, one cup of regular brewed coffee cause a loss of 2-3mg, so one cup of coffee per day has no negative effects on bone health but it may effect those that drink higher amounts.

Physical Activity

Physical activity throughout the life course is important for health. During adolescent physical activity can be particularly beneficial in terms of social interaction and wellbeing, self-esteem and confidence, and maintaining energy balance. Maintaining physical activity throughout the adolescent years also means that the risk of chronic diseases in later life can be reduced. High impact physical activity during the pubertal years is particularly important because it can help to increase bone mass, which has long-lasting effects on bone health.

The daily 60 minutes can be achieved through short bursts of physical activity, as well as longer training sessions such as organised sports and exercise classes.  Moderate exercise can also include walking to school, walking the dog, or cycling which are easier to fit into a day than organized activities.

At least three days a week, activities that improve bone health and muscle strength should be included, for example gymnastics, dance tennis or weight (resistance) training.

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