Seeds, nuts and their oils are perhaps the most important sources of healthy fats. They also provide useful amounts of some vitamins and minerals, and are easily incorporated into many meals. The omega-3 and omega-6 fatty acids they contain are not only healthy, but are essential to a balanced diet. Fish is another nutritious food that provides healthy polyunsaturated fats. Foods containing healthy fats should be included in a balanced diet in preference to foods such as meat and dairy products, which can be high in saturated animal fats.
Seeds and their oils
As well as being high in unsaturated fats, which can help to lower blood cholesterol levels, seeds are an excellent source of protein, and a good source of vitamin E, most B vitamins, iron, zinc, selenium and dietary fibre. Seeds make nutritious snacks and add a nutty flavour to soups, salads, casseroles and breakfast cereals. They are best eaten raw because their essential oils are damaged by cooking. Seed oils can be used in salad dressings – again, choose cold-pressed seed oils because their essential oils have not been damaged by heat processing. Seeds are, however, high in calories – about 100 calories per tablespoon. Eating one to two tablespoons of seeds or cold-pressed seed oil each day provides an appropriate intake of essential fats without contributing too many calories.
Also known as linseeds, flax-seeds and their oil are used for the many health benefits associated with the omega-3 fatty acids they contain. Cold-pressed flax oil is a particularly rich source of omega-3 fatty acids. Cooking destroys these essential fats, so use the oil raw in salad dressings.
A good source of linoleic acid, pumpkin seeds also contain iron, which is important for healthy blood; magnesium, which is important for maintaining healthy body cells; and zinc for a strong immune system. They are rich in protein and can be sprinkled over meals to add flavour and texture, or eaten as a snack.
Rich in linoleic acid, vitamin E, zinc and calcium, sesame seeds are used in Middle Eastern cuisine to make the sweetmeat, halva and the spread, tahini. They can also be added to baked goods. Sesame oil is extracted from the seeds and adds a nutty flavour to many exotic dishes.
The seeds of the sun-flower plant are a rich source of omega-6 fatty acids and vitamin E. They also provide iron and protein. The seeds are used to make sunflower oil and polyunsaturated margarines. They can be added to salads and baked goods or eaten as a snack.
These seeds, which come from the marijuana plant, are a useful source of both omega-3 and omega-6 fatty acids. Although it is illegal to grow the plant in many countries because of its use as a narcotic drug, the seeds and fibre do not cause the narcotic high and can therefore be legally sold. Hemp is becoming increasingly popular, both in terms oi the nutritional value of the seeds and the use of the fibre to make textiles. The seeds can be ground in a coffee grinder and added to breakfast cereals, and the oil can be used in salad dressings.
Nuts and their oils
Like seeds, nuts are an important source of unsaturated fats – brazil nuts, walnuts, hazelnuts and pecans, for example, provide around 4-10g (1/10 – 1/3 oz) of linoleic acid per 28g (1 oz). Nuts are rich in vitamin E and contain useful amounts of B vitamins and some minerals; they also provide moderate quality proteins, which can be improved in combination with grains and pulses. Nuts have been found to reduce the levels of cholesterol in the blood, thereby reducing the risk of coronary disease and heart attack – a US study found that substituting saturated fats with a small serving of walnuts, as part of a low-fat diet, lowered blood cholesterol. Nuts make nutritious snacks, so long as they are eaten in their natural state and not in the form of processed products containing added salt and saturated fat. Nuts can also be added to salads, pasta dishes, rice dishes,yoghurt, baked goods and breakfast cereals; their oils can be used in salad dressings. They are best eaten raw because their essential oils are damaged by cooking.
The nutritional value and fat content of fish varies according to species. In general, most varieties provide protein, a number of minerals and B vitamins. White fish, such as cod, plaice, haddock and whiting, store their fat reserves in the liver; their flesh therefore contains very little fat. Oily fish, such as salmon, sardines, mackerel and tuna, have a moderate-to-high fat content in the form of beneficial polyunsaturated fatty acids from the omega-3 family. The consumption of these fats is associated with a reduced risk of heart disease, stroke and various cancers. The health benefits are increased if total consumption of saturated fats in the diet is also reduced – eating fish several times a week in place of red meat can help an individual to reduce her intake of saturated fats, provided that healthy cooking methods, such as grilling, steaming and poaching, are used. These cooking methods preserve the essential oils contained in the fish and avoid the need for extra fat.
Eggs and dairy products
Although eggs, milk and the dairy products made from it (including cheese, fromage frais and yoghurt), provide the body with high quality protein, as well as important vitamins and minerals, these foods can also be high in saturated animal fat. Whole milk, for example, contains approximately 4 per cent fat; Parmesan cheese contains about 35 per cent fat; and cream may contain as much as 48 per cent fat. An individual whose diet includes a large proportion of full-fat dairy foods therefore risks developing the health problems associated with a high intake of saturated fats: obesity, increased blood cholesterol levels and an increased risk of developing heart disease and some cancers. To balance fat intake, choose lower-fat dairy products – skimmed or semi-skimmed milk, low-fat yoghurts, low-fat fromage frais (instead of cream) and reduced-fat cheeses. These products retain most of the nutrients of full-fat varieties, but contain much less fat. Dairy alternatives made from plant or vegetable sources can be a low-fat option. Tofu, for example, is a dairy alter-native made from soya beans. It is nutritious, cholesterol-free, contains unsaturated fatty acids and has many uses.
However, other products made from plant or vegetable sources may not be as healthy as they appear. Many vegetable oils and margarines contain seemingly healthy mono-unsaturated and polyunsaturated fatty acids. However, when these fatty acids are processed (by hydrogenation) to make solid products, such as margarine, the unsaturated fats are actually converted into saturated fats and the health benefits are lost. When selecting products labelled ‘low fat’, check any nutrient tables printed on the items to ensure that they really are low in fat, and that the fats they contain have not been hydrogenated.
Meat and poultry
Although meat is a good general source of protein, iron, zinc and B vitamins, it can also contain a high percentage of saturated fats. A number of health problems have been associated with the saturated fat content of a high meat diet; these include high levels of blood cholesterol and an increased risk of obesity, heart disease and certain cancers, such as cancer of the colon.
The fat content of a cut of meat depends on the animal that it comes from. Red meats, such as beef and lamb, can contain high levels of saturated fat, whereas white meats and poultry, such as pork, veal, chicken and turkey, contain lower levels of mainly unsaturated fat (fatty birds, such as duck and goose, contain more fat). Most of the fat in poultry is found in the skin, which is easily removed. Processed meats, such as bacon, ham, salami, sausages and burgers, contain particularly high levels of saturated fat- up to 80 per cent of their total calories may come from fat. Lower-fat alternatives may be available, but because these products usually contain high levels of additives, they are best avoided or eaten only occasionally.
A moderate amount of red meat and poultry may be eaten as part of a balanced diet.