I know I should eat more fish because it’s healthy – does scampi count as a healthy choice?

Scampi can be a healthy choice. It’s a good source (and so are other shellfish) of nutrients such as calcium, iodine, selenium, and protein so you can easily include it as part of a healthy diet.

Scampi is actually a small lobster, sometimes known as ‘langoustine’ or ‘Norway lobster’.

The dish most of us know as scampi are langoustine tails, which are either baked in breadcrumbs or deep-fried in batter. This can make scampi quite high in fat and salt, a 150g portion of scampi baked in breadcrumbs gives you about 20.4g of fat and about 2.5g of salt (over a third of your maximum recommended salt intake of 6g a day), so it’s best to have scampi only occasionally.

Amounts of fat and salt can vary quite a lot depending on the recipe or brand so when you’re eating at home, if you want to choose the healthier option it’s important to check labels so you can compare similar products.

Another way to make scampi even healthier is to make your own at home, and if it’s hard to come by where you live, you could always make something similar using a different type of shellfish or fish.

You can make scampi healthier by baking instead of frying, using just a small teaspoon of an unsaturated oil such as olive, sunflower or rapeseed, and using breadcrumbs instead of batter.

You can also keep your salt intake down by avoiding adding salt to your breadcrumb mixture. Try serving with a big crunchy salad and a baked potato.

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

Some 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 fish.

The omega 3 fatty acids in fish have been shown to help protect against coronary heart disease.

But evidence suggests that the type of fatty acids found in vegetable sources may not have the same benefits as those in fish.

I've heard that pregnant and breastfeeding women should avoid some types of fish. Why is this?

You can eat most types of fish when you're pregnant or breastfeeding. Eating fish is good for your health and the development of your baby. But you should avoid some types of fish and limit the amount you eat of some other types.

When you're pregnant or planning to get pregnant, you shouldn't eat shark, swordfish or marlin. You should also limit the amount of tuna you eat to no more than two tuna steaks (weighing about 140g when cooked, or 170g raw) or four medium-size cans of tuna a week (with a drained weight of about 140g per can).

This is because these fish contain more mercury than other types of fish. The amount of mercury we get from food isn't harmful for most people, but if you take in high levels of mercury when you're pregnant this could affect your baby's developing nervous system. When you're breastfeeding you don't need to avoid shark, swordfish or marlin, or limit the amount of tinned tuna you eat.

When you're pregnant, you should generally avoid having more than two portions of oily fish a week, such as salmon, trout, mackerel and herring, because it can contain pollutants such as dioxins and PCBs (polychlorinated biphenyls).

Remember that fresh tuna is an oily fish, so if you eat two fresh tuna steaks in one week, you shouldn't eat any other oily fish that week. Tinned tuna doesn't count as oily fish, so you can eat this on top of the maximum of two portions of oily fish (as long as it's not fresh tuna or swordfish). But remember not to eat more than four medium-sized cans of tinned tuna a week when you're pregnant or trying to get pregnant.

There is no need to limit the amount of white fish you eat when you're trying for a baby or pregnant, apart from shark and marlin. When you’re breastfeeding, the recommendations are the same as those for all adults, you should eat no more than one portion of shark or marlin a week.

I read about salmon being fed something to make their flesh redder. What is it and is it safe?

To increase the intensity of colour in fish, the additive canthaxanthin (E161g) is added to fish feed intended for farmed salmon and trout.

Canthaxanthin occurs naturally and belongs to a group of substances called carotenoids. These substances are related to beta carotene, the red/orange pigment present in carrots; and beta carotene itself is related to vitamin A. Canthaxanthin can be used in feed for trout, salmon and poultry (to enhance the colour of egg yolks).

In 1999, the UK's Food Advisory Committee and Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment, looked at the use of canthaxanthin in feed and agreed that this use of the substance did not give rise to any food safety concerns.

At its December 2001 meeting, the European Commission's Standing Committee on Food considered whether ingredients used in animal feed to colour the final product should be indicated on food labels. Most Member States, including the UK, supported the view that this should be required and the Commission has agreed to set up an expert group to discuss the issues in more detail.

New rules introduced across Europe on 1 January 2002 require certain fish and fish products, including salmon, to be labelled with information about the production method (e.g. whether the fish has been caught at sea or in inland waters, or farmed) and the catch area.

How much protein do I need each day?

Protein is essential for growth and repair of the body, and 15% of the calories we eat each day should come from protein. If you're eating a balanced diet you're probably getting enough protein.

Men need about 44 to 55g a day and women need about 36 to 45g protein each day.

Children also need plenty of protein to help them grow and how much will depend on what they weigh. As a general guide:

• children aged 4 to 6 need about 15 to 20g protein each day
• children aged 7 to 10 need about 23 to 28g protein each day

Most adults and children in the UK have more protein than they need.

The following foods are all good sources of protein:

• poultry (an average portion of roast chicken breast contains 27g protein)
• lean meat (an average portion of bolognese sauce contains 28g protein)
• fish (a small can of tuna and an average portion of poached cod fillet each contain 24g protein)
• cheese (an average cheese sandwich on white bread contains about 17g protein)
• eggs (an average-size boiled hens' egg contains about 6g protein)
• milk (a 150ml glass of semi-skimmed milk provides about 5g protein)
• pulses (three tablespoons of boiled red lentils contains about 9g protein)
• tofu (100g tofu contains about 23.5g protein)
• bread (a slice of wholemeal bread contains about 3g protein)

Don't forget that you need a healthy balanced diet including:

• meals based on starchy foods, such as bread, rice, pasta and potatoes – these types of foods should make up about a third of the food you eat
• lots of fruit and vegetables, also making up about a third of your diet – aim for at least five portions of a variety of fruit and veg each day
• some meat, fish, eggs or pulses
• some milk and dairy products, such as yoghurt and cheese, choosing lower-fat varieties when you can

It can be harder for vegetarians, and especially vegans, to get enough protein. So if you're vegetarian, try to eat a mixture of foods that are rich in protein every day, and vary the types you choose. For example, you could eat:

• pulses, such as lentils, beans and chickpeas
• nuts and seeds
• eggs
• soya products, such as tofu, miso and soya drinks
• mycoprotein, sold as Quorn^TM
• wheat proteins, such as cereals, bread, rice and maize
• milk and dairy products

Why should women limit the amount of oily fish they eat now, if they think they might have a baby one day?

Oily fish, such as salmon, trout, mackerel, herring, eel and whitebait, can contain pollutants called dioxins and PCBs (polychlorinated biphenyls). These can build up in our bodies over a long period of time.

Women shouldn't have more than two portions of oily fish a week, if they think they might have a baby one day. This is to help prevent high levels of dioxins and PCBs building up in their bodies because these could interfere with the development of the baby if they get pregnant in the future. If a woman changes her diet when she gets pregnant, or when she starts trying for a baby, this won't change the levels of dioxins and PCBs that are already in her body.

Fish is an excellent source of protein and it contains essential vitamins and minerals, so it is still important for women to eat plenty of fish, as long as they don't eat too much oily fish.

Women who aren't going to have children can eat up to four portions of oily fish a week. Men and boys can also have up to four portions. A portion is 140g.

Recent surveys have shown that some other fish and crab may also have similar levels of dioxins and PCBs as oily fish. These fish are: sea bream, turbot, halibut, dog fish or huss, and sea bass.

Anyone who regularly eats a lot of fish should consider choosing a wider variety – eating less crab and these five species, and more that have lower levels of pollutants, such as red snapper, haddock, coley or hake.

Are tinned sardines and pilchards high in omega 3 fatty acids, and do pilchards contain more than sardines?

Sardines and pilchards are both oily fish, so they are good sources of omega 3 fatty acids, which can help to prevent heart disease.

Pilchards and sardines are both small fish in the herring family. Since they are essentially the same fish, they have a similar omega 3 content.

The canning process doesn't reduce the amount of omega 3 in sardines or pilchards, so both canned and fresh sardines and pilchards count as oily fish. Canned tuna doesn't count as oily fish because most of its oils are lost during the canning process. This is because tuna is cooked before it’s canned and most of the oil is lost during the cooking process. In contrast, oily fish such as salmon and sardines are cooked whole in the can and, as a result omega 3 levels are not affected.

Some brands of sardines and pilchards say on the can that they contain omega 3 fatty acids. But all canned sardines and pilchards will contain omega 3, whether or not it says so on the can.

A snack of sardines or pilchards on toast is a quick and easy way to fit in a serving of oily fish.

We should all eat at least two portions of fish a week, including one portion of oily fish. Girls and women who might have a baby one day, and women who are pregnant or breastfeeding, shouldn't eat more than two portions of oily fish a week. Other women, boys and men can eat up to four portions a week.

Do canned fish, such as tuna and salmon, count as oily fish?

Salmon, sardines, mackerel, trout and pilchards all count as oily fish when they're canned and when they're fresh. This is because the canning process doesn't significantly reduce the fat content of the fish.

Fresh tuna is an oily fish, high in fatty acids. But when it's canned, these fatty acids are reduced to levels similar to white fish. This is because tuna is cooked before it’s canned and most of the oil is lost during this process. So, although canned tuna is a healthy choice for most people, it doesn't count as oily fish.

We should all eat at least two portions of fish a week, including one portion of oily fish. A portion is 140g. Girls and women who might have a baby one day, and women who are pregnant or breastfeeding, shouldn't eat more than two portions of oily fish a week. Other women, boys and men can eat up to four portions a week.

People can eat as much tinned tuna as they like, except women who are pregnant or are planning to get pregnant in the next year. These women should eat no more than four medium-size cans of tuna a week (with a drained weight of about 140g per can), or two fresh tuna steaks (weighing about 140g when cooked, or 170g raw).

If fish has been farmed, does it have to say so on the label?

The label on pre-packed fish must show how it has been produced, for example, 'farmed', 'cultivated' , 'caught' or 'caught in fresh water'. The label must also state:

• the name of the fish (according to rules about what species can be sold under certain names)
• the catch area, for example, 'north-west Atlantic'

The label doesn't have to show the production method if it's obvious from the name and the catch area that the fish was caught at sea, for example, 'Atlantic salmon'.

When fish is sold loose at a fish counter, the same rules apply. The information will generally be displayed on a sign next to the fish.

Are kippers oily fish?

Kippers are herrings that have been split, gutted, salted and smoked. And because herrings are oily fish, kippers are too.

Kippers are smoked in a kiln at a temperature low enough to avoid cooking the flesh (below 33°C). So, always cook kippers until they are steaming hot before you eat them.

We should all be aiming to eat at least two servings of fish a week, including one serving of oily fish such as herrings, sardines, mackerel, trout and salmon (fresh or canned). Fish is an excellent source of protein and it contains essential vitamins and minerals. Oily fish are rich in omega 3 fatty acids, which can help prevent heart disease.

Traditionally kippers are served, either baked or grilled, for breakfast. But you could also try eating them with bread and a green salad for lunch or dinner.

Can you refreeze prawns that have been defrosted?

It's better to avoid defrosting and refreezing prawns. When you defrost food, there's a chance that any harmful germs in it will grow and make you ill.

Prawns tend to go off quickly and don't last very long once they're defrosted. This is why it's important to follow any defrosting or storage instructions on the label.

When you buy prawns from a supermarket or fishmonger, they might have been frozen before, even if they aren't frozen when you buy them. Check the label or ask the person serving you, if you're not sure. You shouldn't freeze prawns that have already been defrosted.

You should defrost prawns in a sealed container at the bottom of the fridge. This is to stop any liquid that might come out of them spreading germs onto other food. Once they are defrosted you should use the prawns within two days. When you cook or reheat prawns, always make sure they're steaming hot all the way through.

Can oysters cause food poisoning?

Oysters are nutritious – they contain minerals such as calcium and iron, and vitamins – and they're low in cholesterol too. Of course, they're also famed for their supposed aphrodisiac properties, which could be why a lot of oysters are eaten around Valentine's Day.

But eating raw oysters could cause food poisoning or hepatitis. This is because oysters filter large volumes of water to get their food and any bacteria and viruses that may be in the water could build up in the oysters.

If you're worried, you could cook your oysters – they will still taste delicious. There's also no reason to think that cooking will reduce any aphrodisiac properties!

If you want to eat oysters safely, follow these tips:

• Choosing – Fresh oysters should have tightly closed shells. Don't choose any oysters if the shell is open and it doesn't close when you tap it.
• Chilling – Oysters can be kept in the fridge for up to one week. Always throw away any oysters if their shells aren't tightly closed because this means they're already dead or dying. Store them with the 'cupped' side of the shell down and the flatter side up. Put them on a plate and cover with a clean damp cloth – never keep them in water. When you're ready to use them, first rinse them in cold water.
• Freezing – You can keep oysters in a freezer for up to three months. Because freezing kills them, once you've thawed them they will be easier to open than fresh ones. Before freezing, wash them well, scrub the hinge end and throw away any that aren't tightly closed, then freeze. Eat them as soon as possible after you've thawed and cooked them.
• Cooking – If you choose to cook your oysters there are several ways to do this, but one of the simplest is grilling. Heat the grill for ten minutes. Check that the oysters are still tightly closed then carefully open and lay them in their half shells, open side up, on top of a piece of foil. Dot a little butter or olive oil on them and grill for two minutes.

Will eating fish with worms in it make me ill?

When fish is cooked thoroughly, so it's steaming hot all the way through, any worms in the fish will be killed and it will be fine to eat. Eating fish containing a dead worm shouldn't do you any harm. Eating fish containing live worms can cause inflammation in the stomach or the gut and make you ill.

Freezing raw fish also kills any worms. If a shop or restaurant buys fish to be eaten raw or almost raw, for example, sushi or raw herring, it must have been frozen at minus 20°C for at least 24 hours.