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Oils for your diet
By Kylie Andrew (Dietitian)
Fat is important for
many body processes. You need to eat some fat. Fat protects your
organs, keeps you warm and it helps your body absorb and move nutrients
around. It also helps hormone production. However some fats are better
than others and having too much of any type is not a good idea.
Dietary fats are classified by their structure. Different types of fats
react differently inside the body. Saturated fats (found mostly in
animal products) increase blood cholesterol, which is a risk factor in
coronary heart disease. Monounsaturated and polyunsaturated fats tend
to lower blood cholesterol.
Dietary fat can be classified into four groups:
- Saturated
- Monounsaturated
- Polyunsaturated
- Trans fats.
Saturated fats contribute to the risk of heart disease by raising blood cholesterol levels. Monounsaturated and polyunsaturated fats both tend to lower blood cholesterol when they replace saturated fats in the diet, but the polyunsaturated fatty acids have a slightly greater impact than monounsaturated fatty acids.
Trans fatty acids are rare in nature. They are only created in the rumen of cows and sheep, and are only found in small amounts in milk, cheese, beef and lamb. Trans fatty acids are also created during the manufacture of some table margarines and solid spreads used in the food industry. Trans fatty acids are considered to behave like saturated fats in the body; they raise LDL levels and increase the risk of heart disease. Look for margarines that have less than one per cent fatty acids on the label.
Different foods contain different ratios of fatty acids:
- Saturated fats - sources include fatty cuts of meat, full fat milk and cheese, butter, cream, most commercially baked products such as biscuits and pastries, most deep fried fast foods, coconut and palm oil.
- Monounsaturated fats - sources include margarine spreads such as canola or olive oil based choices, oils such as olive, canola and peanut oils, avocado, and nuts such as peanuts, hazelnuts, cashews and almonds.
- Polyunsaturated fats - sources include fish oils, seafood, polyunsaturated margarines, vegetable oils such as safflower, sunflower, corn or soy oils, nuts such as walnuts and brazil nuts, and seeds.
Polyunsaturated fats can be divided into two categories - omega-3 and omega-6:
- Omega-3 fats are found in both plant and marine foods and have been found to reduce the risk of heart disease. Food sources include canola and soy oils and canola based margarines. Marine sources include fish especially oily fish such as Atlantic salmon, mackerel, Southern blue fin tuna, trevally and sardines.
- Omega-6 fats are found primarily in nuts, seeds and plant oils such as corn, soy and safflower.