There are two sorts of almonds, the bitter almond and the sweet almond. Bitter almonds are used to make almond oil, which is used in many baking recipes to add an intense almond flavour. Ground, sweet almonds are the basis of sweets such as marzipan, nougat and macaroons. They're especially useful in baking and can be substituted for flour to create a dense, moist texture in cakes and biscuits. For the freshest flavour, grind your own almonds as you need them because they become stale quickly. Sweet almonds also appear in many savoury recipes - from toasted flaked almonds served with trout and brown butter to their role as a thickening agent in romesco sauce. They're often used in Indian cooking to thicken and add texture and flavour to dishes such as chicken korma.

Brazil nuts have an unusually tender, rich and mild flavour. The oil made from brazil nuts has a pleasant nutty flavour and can be used as a high-quality salad oil. Brazil nuts are the seeds of a large tree that grows up to 50 metres (160 feet) tall in the Amazon jungle and their shells are notoriously difficult to crack. Commercial supplies of Brazil nuts are still derived entirely from wild trees though there are concerns that they're being harvested too intensively. They're often used in baking and go well with chocolate, for example in chocolate brownies.

Cashew nuts grow dangling beneath a fleshy stalk known as the cashew pear. The 'pear' can be used for juices, syrups and liqueurs. Cashew nuts are eaten on their own as a snack or as an ingredient in various sweet and savoury dishes. Whole or chopped cashews provide crunch and substance to Asian stir-fries, noodle dishes and curries and they're a good match with chicken.

Coconuts have many roles in the kitchen where their milk, cream, oil and flesh are all in demand for savoury and sweet dishes. Coconut milk and cream is made from squeezing the flesh in water and used often in curries and spicy soups to 'cool' the heat of the dish. It's also delicious in sweets such as coconut rice pudding or coconut ice cream. The dried meat is known as 'copra'. Coconut oil can be made from fresh coconuts, and it is extensively used in making margarine, confectionery and bakery goods, and for frying. Coconut flesh can be used fresh, grated or desiccated in numerous sweet and savoury dishes.

Hazelnuts are globe-shaped or oval, up to two centimetres (nearly one inch) long with a hard brown shell. They grow in most parts of Britain, but cobnuts (a type of wild hazelnut) are particular to Kent. Most of the world's commercially grown hazelnuts come from Turkey. They're used in savoury dishes including soups and sauces, such as romesco sauce. They're excellent in baking and can be ground, like almonds, for use in cakes and biscuits. As with most nuts they have an affinity with chocolate. They're also a key ingredient in praline.

Macadamias are Australian nuts but they're now grown commercially in Hawaii, particularly for the American market, where they're widely used in cookies and ice cream. Macadamias have a taste rather like a very fine hazelnut but their texture is smoother and richer and almost buttery. They're often used with white chocolate and go well with coconut.

Peanuts are actually a member of the pea family and aren't true nuts, as they have to be dug out of the soil to be harvested. Also known as groundnuts, the pods develop after the pollinated flower stalk has grown down into the soil, where the nuts develop. Peanut oil is used extensively in cooking and for making margarine. The nuts themselves are eaten salted and roasted as snacks or made into peanut butter. Whole or chopped peanuts are popular in Asian cusuine and give satay sauce its addictive quality. They're often served as a garnish on noodles and stir-fries. They're also good in baking and can be baked into cookies or pies.

Pecans are native to North America where they're still used in abundance, especially in cakes, pies and cookies. They belong to the same family as the walnut and have the same distinctive texture and 'brain-like' shape, but a slightly sweeter taste. They're perhaps most famous for their role in the all-American pecan-pie, but are equally good in brownies, cookies and cakes.

Pistachios are known as the 'happy nut' in China because of the 'smile' appearance of its open shell. The open shell of the pistachio enables it to be roasted and salted while still in its shell, and that's how they're often sold and eaten. They're also found in many Middle Eastern and Mediterranean pastries such as baklava and Asian sweets such as seera. Pistachios are a good source of calcium, magnesium, phosphorus, potassium, iron, folate and protein.

try Reshma Martin's Pistachio saffron seera

Sweet chestnuts are believed to have originated in Spain and were brought to Britain by the Romans; hence they're also known as Spanish chestnuts. They grow in clusters enclosed in a spiny case. They're delicious eaten on their own, roasted over hot coals, or can be used in all sorts of delicious dishes, including the traditional stuffing for Christmas dinner. Chestnuts have a high starch content so in Europe they're often made into flour and used for cakes and fritters. In France they're preserved in sugar as marrons glaces. Their high level of tannic acid means they shouldn't be eaten raw.

Walnuts have many varieties but the most popular, for its flavour, is the English walnut. They are used in desserts, cakes and confectionery as well as in many savoury dishes such as soups, sauces, stews and salads including the well-known Waldorf salad. They are also pickled for serving with cold meats and cheeses - they go particularly well with blue cheese - or for adding to meaty stews. Walnut oil has a strong nutty flavour which is excellent when used on fish, steaks, pasta or salad. It's not suitable as a cooking oil.

Pine nuts are used a great deal in the Middle East and Mediterranean regions. They have a very delicate taste and texture and are high in protein which makes them especially useful in a vegetarian diet. They can be eaten raw, when they have a soft texture and a sweet buttery flavour and are especially good in salads. They are delicious toasted as this brings out their flavour and adds a little extra crunch. They're probably best known for their use in pesto sauce.

Pumpkin seeds are greenish in colour, and can be eaten raw or cooked both in sweet and savoury dishes. Delicious roasted, or toasted and sprinkled with soya sauce while hot, and served on salads. They're rich in protein, iron, zinc and phosphorus. During the autumn, when pumpkins are in season, you can dry your own seeds for use in various dishes.

Sesame seeds are available in a variety of colours including browns, red, black, yellow and ivory. The darker seeds are said to have the most flavour. The oil is one of the most distinctive, fragrant and flavourful oils you can get, with a slightly sweet nutty flavour (enhanced by toasting). Europe has limited use of sesame seeds in baking, garnishing bread, biscuits and pastries. However, there is much more extensive use elsewhere in Asian, South American and African cooking, where sesame seeds are used in both sweet and savoury dishes. They go particularly well with chicken and other meats, in salads as both garnish and dressing, vegetables and stir-fries as well as adding a distinctive flavour to stir-fried and rice dishes. Ground sesame seeds are used to make tahini, a smooth paste used in Middle Eastern cooking.

Sunflower seeds are one of the most commonly available seeds. The sunflower plant belongs to the daisy family, and probably originated in North America. North American Indians cultivated sunflowers as long as 2,000 years ago. The seeds can be eaten whole, raw or cooked, added to breads and cakes, or sprinkled over salads or breakfast cereals. A good source of potassium and phosphorus, sunflower seeds also contain protein, iron and calcium.

Most nuts can be bought either in the shell or shelled. Whole, flaked and ground nuts are widely available in supermarkets, health food stores and at many street markets. So too are nut butters, which can be added to soups and stews to thicken them. Some nuts are available fresh (or 'green') but most are sold dried. The majority are available year round, but there are some seasonal varieties (chestnuts and cobnuts, for instance). Nut oils are currently extremely popular in cooking; several types of nut are cultivated for their oil including walnuts, hazelnuts, peanuts and almonds.

Nuts do go off, and shouldn't be kept for more than a few weeks or beyond their 'best before' or 'use-by' date. Buy them in small amounts, keep them in airtight containers in a cool, dry place away from the light. Because of their high fat content, nuts and seeds can benefit from storage in the fridge or freezer to help prevent them becoming rancid. Stale nuts will look shrivelled and have a rancid taste (they can also be dangerous to eat as they build up contaminants).

Nut allergy is an increasing problem in the UK, especially among children. Peanuts are the most common cause, but other nuts such as walnuts, hazelnuts, almonds, pecans, brazil nuts, macadamia nuts and cashew nuts, can affect people too. On rare occasions, all these nuts can cause anaphylaxis (a serious and rapid allergic reaction) in people who are sensitive. An immediate injection of adrenaline is a highly effective treatment.

Avoiding nuts is the most obvious thing to do if you're allergic to them, but this is often easier said than done. Since November 2005, food labelling rules require pre-packed food sold in the UK, and the rest of the European Union, to show clearly on the label if it contains nuts (or if one of its ingredients contains them). There could still be foods on the shelves that were produced before this date.

Manufacturers often use warnings such as 'may contain nuts' because they know that minute amounts of certain ingredients, especially nuts, can cause some people to have severe allergic reactions. Even where they make sure that nuts aren't deliberately added to a product, nuts may get into the product for different reasons. For example, the food might be produced on the same line, or in the same factory, as other foods containing nuts. Or the manufacturer may buy ingredients that aren't guaranteed to be nut-free.

Find out more information about nut allergy and how to avoid eating nuts at the

Anaphylaxis Campaign website.

Aflatoxins are toxins formed by moulds growing on various foods including edible nuts, particularly in the tropics and sub-tropics. There's evidence to suggest they may cause liver cancer. Regulations in the UK set limits for aflatoxins, but occasionally tests show these limits have been exceeded (in batches of peanuts, peanut butter and pistachios, for instance). Nevertheless, the levels of toxins found are generally low, and the Food Standards Agency (FSA) advises that there's no need for anyone to avoid eating these products and that nuts contain important nutrients and can be included as part of a healthy, balanced diet.