Eating your way to a healthy tomorrow
Alexander asks: Proper nutrition is essential for teenage growth, but which nutrients are most easily neglected?
Wynnie says: Adolescence is a time of rapid growth, which has a direct influence on nutritional requirements. Teenagers need additional nutrients; in particular, calories, protein, calcium and iron.
Calories: Adolescents require extra calories to provide energy for growth and increased activity. Boys aged 11 to 18 need between 2,500 and 2,800 calories each day whilst adolescent girls need slightly fewer - 2,200 a day.
Most teens meet their additional energy needs by eating sugary and fatty meals and snacks. It is important instead to choose a variety of healthy foods, such as reduced-fat dairy products, whole grains, fruits, veggies and sources of lean protein.
Protein: Adolescents need between 45 and 60g of protein each day for growth and building muscle. Most teens easily meet this requirement with their intake of beef, pork, chicken, fish, eggs, and dairy products. Vegetarians in particular should remember that alternative sources include legumes, nuts and pulses.
Calcium: This mineral is important for making strong healthy bones and teeth during the teenage years. A lack of calcium in adolescence can lead to low bone density and put teens at an increased risk of developing brittle bone disease (osteoporosis) in later life. We only get one opportunity - between childhood and young adulthood - to build strong, dense bones.
Teens need 1,200mg calcium per day. This can be achieved by eating three or four servings of dairy foods a day, such as reduced-fat milk, cheese and yoghurt, and calcium-fortified breakfast cereals and juices.
Iron: This mineral is needed for growth, brain development, the proper functioning of the immune system and the maintenance of healthy blood. Iron-deficiency anaemia can lead to tiredness, fatigue, dizziness, weakness and headaches, and affect both mental and physical performance.
Teenage boys need 12mg of iron a day, while girls need 15mg - girls' iron stores are depleted every month due to menstruation.
The main sources of iron are red meats such as beef, pork and lamb, and offal. Non-meat sources include whole grains, lentils, nuts, fortified breakfast cereals, green vegetables and dried fruit.
The iron from non-meat sources isn't so easily absorbed; increase absorption by eating them alongside vitamin C-rich food such as green, leafy veggies and citrus fruits. But don't drink them with tea - it contains compounds called tannins which can reduce iron absorption.
How to get the nutrients you need each day
Base meals on starchy carbs: potatoes, and (wherever possible) wholegrain bread, rice, pasta, cereals, noodles and couscous
Eat at least five portions of fruits and veggies.
Three-four portions of dairy, such as milk, yoghurt and cheese.
Two portions of protein-rich foods, such as meat, fish, eggs, beans and pulses.
Go easy on sugar-packed food and drinks.
Go easy on fatty foods.
Drink at least eight glasses of fluids - more if it's hot and humid or if you're exercising. Water is best.
Breakfast: Bread and butter; milk
Lunch: Rice, vegetables with chicken, pork or beef
Dinner: Rice or noodles with vegetables, other Chinese dishes
Exercise: six hours of handball training every week
Wynnie Chan is a British-trained nutritionist. If you've got a question for her or would like to be featured in this column, e-mail firstname.lastname@example.org