Fats and Oils Fact Sheet
About Fats and Oils
Dietary fat has a bad name and rightly so. It has twice the calories of sugar, and cholesterol clogs our arteries as we age. However, fat is an essential in the body, necessary for storing energy, protecting our organs and insulating the body. Fats also act as chemical messengers and are involved in many other vital roles in the body, including storing and utilising other nutrients such as vitamins D and K.
Fats and Oils and Aging
The body is able to synthesize many of the fats it needs for healthy aging. However, some essential fats must be found from our diet (such as Vitamin F). The most well known of these are the omega-3 and omega-6 polyunsaturated fatty acids.
Omega-3 fatty acids are a precursor of many eicosanoids, which control a number of important pathways relevant to aging, including inflammation, immune function, clotting and cancer growth. There is substantial evidence that a diet high in omega-3 fatty acids can reduce the risk of heart disease and stroke, possibly by lowering blood pressure and cholesterol, stimulating local circulation and preventing clotting. Diets high in omega-3 fats also have beneficial effects on other age-related problems, including cognitive decline, depression, arthritis and varicose veins.
The most nutritionally important omega-3 fatty acids are alpha-linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). It is recommended to eat a gram of EPA and DHA each day from animal fats, or 2-3 g/day of alpha-linolenic acid from plants. This is the equivalent of an oily fish meal two or three times a week. If you can’t keep this up, a number of supplements are available which contain large amounts of omega-3, including fish oils and flaxseed (linseed) oil.
Omega-6 Fatty Acids
Omega-6 fatty acids are essential for making the chemicals that regulate inflammation as we age. However, if our intake ofωomega-6 fatty acids is too high, this excess leads to increased inflammation, clotting and tissue injury. In a healthy diet, these actions are balanced and negated by omega-3 fats because they compete for the same pathways for their metabolism. However, modern diets typically have too muchωomega-6 relative to omega-3, often in an excess of 10 to 1. This imbalance has a number of adverse consequences, including depression, heart attack, stroke, arthritis, osteoporosis, inflammation and some forms of cancer.
The intake of saturated fats from our diets significantly contributes to obesity and heart disease. Saturated fat raises bad (LDL) cholesterol more than dietary cholesterol itself. All natural products have a balance of saturated and unsaturated fats. We should aim to reduce our saturated fat intake to less than 7% of our total calories by limiting our intake of foods high in saturated fat, such as dairy products (especially whole milk, cream cheese and ice cream), coconut, palm oils, meat and eggs. We can also choose products with the lowest content of saturated fat. For example, the meat of grass-fed animals and birds contains much lower levels of saturated fat than conventional bulk (grain) fed stocks. Lean cuts should always be preferred.
Trans fatty acids are not produced naturally and serve no purpose in human metabolism. Most trans fats are deliberately created during the processing of vegetable oils (by hydrogenation) to make them solid at room temperature, to melt on baking (or eating) or more resistant to going off (rancid) compared to animal fats such as butter. Prolonged deep frying can also generate trans fats, which are then transferred to the food.
Trans fats are toxic to a range of important systems, contributing to heart disease, stroke, diabetes, obesity, insulin resistance, prostate cancer and infertility. In fact, on a pound for pound basis, trans fats increase the risk of heart disease more than any other component in our diet. Even a small intake is sufficient to increase our risk of heart disease. There appears to be no safe limit for trans fats.
The only way is to avoid foods containing them, or choose foods in which the processing has specifically prevented their formation. Although all margarine must now be free of trans fats, many common snack foods, rice cakes, chips and biscuits contain significant amounts of trans fats. Just read the nutritional contents label. For a number of reasons, including trans fats, it is best to avoid deep frying at home, even if we regularly change the oil.
Monounsaturated fats (MUFAs) have a number of effects on human health, aging and longevity. A high intake of MUFAs, such as in a Mediterranean diet, can lower blood pressure and cholesterol levels, improve vascular function and reduce our risk of heart disease. The most common MUFA in our diet is oleic acid, found in vegetable and seed oils, nuts, avocado and some meats. Tea oil and olive oil contain more MUFAs than normal canola oils, which in turn have more MUFAs than sunflower, peanut, corn and soybean oils. However, many of these potentially beneficial MUFAs are destroyed by prolonged high temperature cooking or frying. So consider a drizzle on the salad instead.
How Much Fats and Oils Should I Eat?
Within the new draft Australian Dietary Guidelines it is recommended that food high in saturated fat be replaced by polyunsaturated and monounsaturated fats, and that between 28 and 40 grams of ‘good fats’ such as oils and spreads, or from seeds and nuts are incorporated within the daily diet.
Last Reviewed 11/Mar/2014