Linseed is the small, reddish-brown or golden-yellow seed of the common flax plant, linum usitatissimum, the same plant that's used to grow the fibre from which linen has been made for thousands of years. Some flax plants produce more seeds than others, and these have carefully been chosen as a crop plant. It's equally correct to call the same small seeds linseed or flaxseed.
Traditionally pressed to make linseed oil, the seeds have long been used medicinally to help with constipation, but are packed with many other health benefits. They are more likely to be recommended as a vegetarian source of an important omega-3 fatty acid usually found in fish oils, but the accessibility of this ingredient can be affected by association with other constituents, and it’s best to take specialist dietary advice if this is important.
Linseeds add marked dietary fibre to your diet, and thus should first be added in modest amounts and always with increased liquid intake.
Culinary grade linseed or flaxseed oil has a rich, buttery taste and is useful to add richness to bland dishes; it can be used as a milder laxative than the seeds.
Whole and crushed seeds are widely available in speciality stores and online. The oils are less common but can be found online.
Choose the best
Avoid dull colour or dustiness – really old linseeds will smell slightly off if their oils have oxidised. The ground or crushed seeds will deteriorate much faster than whole ones.
Culinary grade linseed or flaxseed oil should come in small containers that exclude the light: coloured glass or metal are suitable.
Buy small amounts of the seeds and keep in a cool, dark place. Linseed and flaxseed oil are very prone to rancidity, and must be bought only in small amounts. Keep cool and away from sunlight. A bitter aftertaste is a sure sign that the oil is past its best.
Whole or ground linseeds do not need to be cooked and can be added to almost any dish, including breads, biscuits and cakes, cooked or uncooked snack bars, muesli mixes and porridges, and even to curries and vegetable stews. Beware of their high-fibre content and use sparingly – a light scattering will do until you know how your body reacts to them.
Linseed and flaxseed oils should never be used for cooking as they have a very low flash point and can easily burst into flame. Use these as a condiment on starchy foods or bland dairy products. Otherwise, mix with other oils in dressings for salads and vegetables.
Linseeds are also a great binder, and work really well as an egg replacer in lots of recipes. Add 1 tbsp milled linseed to 2 tbsp water and leave to absorb and become 'gloopy' before adding to cakes, biscuits and stuffings to bind ingredients together as an egg would.