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Fats and Oils

Fats and Oils: Your questions answered

Excerpts from Nicole Senior article in the Healthy Food Guide

Fat is one of the most talked-about nutrients but one of the most misunderstood. Here are some answers to the most commonly asked questions.

1. What are fats?
Fat is one of the major nutrients found in food - called a macronutrient. Protein and carbohydrate are also called macronutrients. Fats are chemically similar substances composed of fatty acids. They include liquid fats (oils) such as olive and sunflower oils; as well as solid fats such as butter, vegetable shortening, ghee and lard.

2. Is a fat-free diet healthy?
No! You need fatty acids to build and maintain cell membranes and to make certain hormones. That's why some fatty acids are called essential fatty acids. It's necessary to include some fat in your diet to ensure you get these essential fatty acids, along with the fat-soluble vitamins A,D,E and K. Fats are also a concentrated form of energy, which is important for growth. So fats are essential, but it's important to choose the right type of fat.

3. How did fat get such a bad reputation?
Saturated fat is the main culprit in raising cholesterol levels and heart disease rates. However, there are other types of fats which are essential for good health.

4. Which fats are the good ones?
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 and  heart health. Polyunsaturated 'good' oils include sunflower, soy bean, walnut and sesame oils. Monounsaturated 'good' oils include avocado, canola, olive, macadamia, rice bran and peanut oils.

5. Why do I love fatty foods so much?
Humans are driven by a powerful survival instinct based on a 'feast or famine' environment;  we're programmed to eat high-energy foods so should food become scarce, we'll have a better chance of surviving. We also tend to eat more fat than is good for us because most of us are used to the flavour of fat. It also gives foods such as biscuits, pastry and deep-fried fish'n'chips a pleasant crunchy texture. Food manufacturers also often add fats to many foods to improve flavour and texture, so we may be eating more fat than we realise.

6. Which fats should I be eating less?
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.

7. Which is healthier: butter or margarine?
Table margarine (Oil spread), is recommended as a healthier choice than butter by the NZ Heart Foundation. It's better because it's made with healthy oils which 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.

8. How much fat should we eat?
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 1ý-2ý tablespoons of healthy oils and oil spreads a day. Saturated fat should make up no more than about 30g in a typical diet.

9. Which is the best oil to use?
Any oil made from vegetables, seeds or fruits is good (see question 4). Coconut and palm oils are the exceptions to this rule - avoid them as they are high in saturated fat.

10. 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.

11. How will I know if oil has gone off?
Oil that has oxidised, or gone rancid, has a characteristic stale, musty smell. Don't use rancid oil. Healthier oils go rancid more easily than unhealthy ones, so use them quickly and store them correctly.

12. How much salad dressing and mayonnaise can I use?
Mayonnaise and salad dressings are usually made with healthy oils but commercial ones can be quite salty. It's best to make your own mayonnaise and use it in moderation.

13. What are omega-3 fatty acids?
Omega-3 fatty acids are essential polyunsaturated fatty acids.
Why we need them: Our bodies can't 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). It's 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.
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.