Claire Turnbull: The Truth About Fats - 16 August
Claire Turnbull, Healthy Food Guide Nutritionist - The Truth about fats
Fat is one of the most talked-about nutrients but one of the most misunderstood. Healthy Food Guide Nutritionist Claire Turnbull is here to answer the common questions and help you to make healthier choices.
1. What are fats?
- Fat is a macronutrient found in food, along with protein and carbohydrate.
- Fats are chemically similar substances composed of fatty acids. They include liquid oils such as olive oil, as well as solid fats such as butter, vegetable shortening, ghee and lard.
- We tend to eat more fat than is good for us because fat is full of flavour and gives foods such as biscuits, pastry and deep-fried fishnchips a pleasant crunchy texture.
- Food manufacturers also often add fats to many foods to improve flavour and texture, so you may be eating more fat than you realise.
2. Is a fat-free diet
No! Its necessary to include some fat in our diet because fats provide essential fatty acids, fat-soluble vitamins and a concentrated form of energy. We need fatty acids to build and maintain cell membranes and to make certain hormones. So fats are essential, but its important to choose the right type of fat.
3. How much fat should we
Between 30-35% of our daily kilojoule intake from fat is usual. In a typical diet of 8700kJ, this is between 50-80g fat each day. Fat is already present in some foods, so a healthy amount to use is between 1½-2½ tablespoons of healthy oils and oil spreads a day. You may need a little less or a little more, depending on your energy needs. Saturated fat should make up no more than 10% of your daily kilojoule intake, or no more than about 30g in a typical diet.
4. Which fats are the good
Fats are classified as saturated or unsaturated, depending on their chemical structure. Unsaturated (good) fats include polyunsaturated and monounsaturated types, which are better for you because they help maintain healthy cholesterol levels. Polyunsaturated good oils include sunflower, safflower, soy bean, walnut and sesame oils. Monounsaturated good oils include avocado, canola, olive, macadamia, rice bran and peanut oils. Extra-virgin olive oil comes from the first mechanical pressing of olives and is rich in antioxidants. The alternative, refined oil, is produced when the pulp is further processed to extract every last drop of oil.
5. Are all oils good?
Any oil made from vegetables, seeds or fruits is good. Coconut and palm oils are the exceptions to this rule avoid them as they are high in saturated fat. Oil reacts to air, light and heat, so it needs to be stored in a cool dark place not next to the stove. Buying oil in tins will help protect it from light. If you buy olive oil in a bottle, store it in the cupboard. Oil is best used within three to four months of opening, so buy it in smaller quantities to keep it fresh. Reheating will cause oils to oxidise and degrade, but some do this more slowly. Polyunsaturated oils are the most readily oxidised, but mono-unsaturated oils such as olive oil are more stable and can be re-used. Be sure to strain out any bits of food left in the oil, store in a sealed jar after cooling, and only re-use the oil a few times.
6. Can I cook with
extra-virgin olive oil?
Yes. But other oils, such as rice bran oil, have a higher smoke point, which means these oils tolerate high temperatures better than extra-virgin olive oil. Extra-virgin olive oil also costs more.
7. What are omega-3 fatty
Why we need them: Omega-3 fatty acids are essential polyunsaturated fatty acids. Our bodies cant make them so we need to get them from our diet. Omega-3 refers to both short-chain fatty acids (plant foods) and long-chain fatty acids (animal foods). Its best to eat a mix of both.
Where to find them: Plant foods such as canola and soy bean oils, flaxseeds and walnuts are the best sources of omega-3 short-chain fatty acids. The richest source of long-chain fatty acids is oily seafood (especially mackerel, sardines and salmon), eggs, brains, liver, kidneys, and lean red meat (especially pasture-fed beef and lamb). Fish-oil capsules can help boost your omega-3 intake.
What they do: Omega-3 fats, and especially the long-chain fats, are linked to better heart and mental health, a reduced risk of inflammatory diseases, and brain development in children.
8. Which fats should I be
Saturated fats are found in fatty meat, butter, cream, full-fat milk and dairy foods, processed foods containing palm oil, and many deep-fried takeaway foods. Chocolate and coconut products like Kremelta and coconut cream are also rich in saturated fat.
9. What are trans
Trans fats are a particular type of bad fat that should be limited because they adversely affect cholesterol levels. They are naturally present in low levels in butter and meat fat, but they are produced in higher amounts when liquid oils are partially hydrogenated to make them solid. They are often used commercially to make pastry, biscuits and cakes. Commercial deep-frying oils can contain trans fats, although one prominent fast-food chain has already switched to a low-trans frying oil. Eating a diet low in saturated fats will help you eat less trans fats as well.
10. Whats with this whole debate of butter or
Table margarine (more accurately termed oil spread in New Zealand), is recommended as a healthier choice than butter by the New Zealand Heart Foundation. Oil spread is better because it is made with healthy oils and therefore contains much less saturated fat than butter. Contrary to popular belief, oil spreads are not a major source of trans fats. Check the nutrition information panel and choose spreads with less than 15g saturated fat per 100g.