My 14-year-old daughter has become a vegetarian. How can I make sure she eats healthily?

There are plenty of myths about vegetarianism. One is that it's not possible to have a healthy and nutritious diet without eating meat. This isn't true, but it's also not true that your diet will automatically be healthy if you cut out meat.

A vegetarian diet can be very healthy but, like everyone, vegetarians need to make sure they eat a balanced diet that is:

• based on starchy foods, such as rice, potatoes, pasta and bread (choosing brown or wholegrain varieties where possible)
• rich in fruit and veg (at least five portions a day)
• low in fat and sugar

Vegetarians sometimes don't get enough protein, so your daughter should make sure she eats foods that are good sources of protein every day. These include:

• pulses (such as lentils and beans)
• nuts and seeds
• eggs
• soya products, such as tofu
• milk and dairy products

Vegetarians are sometimes lacking in iron, and this can be a particular problem for teenage girls. Although meat is a very good source of iron, it can also be found in the following foods:

• pulses
• green vegetables, such as watercress, broccoli, spring greens and okra
• bread
• fortified breakfast cereals

It's easier to absorb iron from food if we eat it with foods that contain vitamin C, so it's a good idea to give your daughter some fruit or veg, or a glass of fruit juice, at the same time as an iron-rich meal.

Milk and dairy products are very good sources of calcium, which is important for healthy bones. If your daughter has decided to become a vegan, which means she won't eat any foods of animal origin including eggs and milk, she should have soya, rice or oat drinks fortified with calcium instead.

Some vegetarians, especially vegans, don't get enough vitamin B12. Good non-meat and non-dairy sources of this vitamin include yeast extract, fortified bread and fortified breakfast cereals.

It's OK to have cakes, sweets, biscuits and crisps every now and then, but most of us eat more of these fatty, sugary foods than we should. Many school-age children eat lots of these foods, so a good way to help your daughter to eat more healthily would be to encourage her to eat fruit as a snack, rather than fatty and sugary options.

Are there any vegetarian sources of the omega 3 fatty acids found in fish?

Short chain omega 3 fatty acids are found in certain vegetable oils, such as linseed, flaxseed, walnut and rapeseed, but they aren't the same type of fatty acids found in oily fish.

Oily fish contain the long chain omega 3 fatty acids. The long chain omega 3 fatty acids in fish have been shown to help protect against coronary heart disease.

Although our bodies can use shorter chain omega-3 fatty acids to make long chain ones, this process is very limited and evidence suggests that consuming the short chain omega 3 fatty acids may not have the same benefits as those in oily fish on the risk factors for heart disease.

Marine algae does contain the long chain omega 3 fatty acids. However, the effects of algae on heart disease have not been studied in enough detail to draw conclusions.

If you follow a vegetarian diet you can still look after you heart by eating at least five portions of a variety of fruit and veg every day, trying to cut down on food that is high in saturated fat and watching how much salt you're eating.

How can vegetarians make sure they get enough iron?

It's harder to get enough iron if you don't eat meat or fish, so if you're vegetarian you need to take care to eat plenty of foods that are rich in iron.

Try to eat a good selection of these foods:

• wholemeal bread and wholegrain breakfast cereals
• pulses such as lentils, kidney beans and chickpeas
• green vegetables such as watercress, spring greens, broccoli and okra
• eggs
• dried fruit such as prunes, apricots and figs
• nuts such as peanuts, almonds and brazils

Eating foods containing vitamin C might help us absorb iron from non-meat sources, so it's a good idea to have some fruit or vegetables at the same time as foods that are rich in iron. An easy way to do this is to drink a glass of fruit juice with your toast or cereal in the morning.

Try to avoid drinking tea with meals and for half an hour afterwards because this can reduce the amount of iron we absorb.

And you should avoid adding lots of bran to foods. This can also reduce the amount of iron our bodies absorb.

It's essential to get enough iron to help us stay healthy. Our bodies use iron for a number of important things, including to help make red blood cells, which carry oxygen around the body. If we don't get the iron we need from food, the stores of this mineral in our bodies are gradually reduced. This can lead to iron deficiency and possibly anaemia.

Women who have heavy periods or are pregnant may need extra iron. Talk to your GP if you think you may be low on iron.