IN COMMON PARLANCE, ‘fats’ has always been a four-letter word. Whether you are trying to control diabetes, protect your heart or just lose weight, fats have always been the villain. The recognition that dietary fats raise blood cholesterol and consequently risk of heart attack resulted in replacement of fats with refined carbohydrates or simple sugars. Intake of refined carbs makes us feel hungry again, leading to weight gain. Fats, on the other hand, although higher in calories per g, induce satiety for longer periods. The last few years have seen a huge revival of interest in low-carb, high-fat diets for losing weight or managing diabetes.
Fats are required by our body. They are a major source of energy, help us absorb some vitamins (A and D) and are essential for hormone synthesis and building nerve sheaths. Some amount of fats are, thus, desirable. However, not all fats are the same. It is important to understand the distinction between good and bad fats. Although all fats are calorie-rich, providing nine calories per g, there are fundamental differences in their properties and actions on the human body. Monounsaturated and polyunsaturated fats are good; trans and saturated are bad.
Trans fats are the worst. They are a byproduct of hydrogenation that turns healthy oils into solids and prevents them from becoming rancid. Reusing/reheating oils also progressively increases the proportion of trans fats. They are present in virtually every commercial/packaged food like biscuits, cakes, pastries and the everpopular French fries. Eating food rich in trans fats increases the amount of ‘bad’ (LDL) cholesterol and aggravates inflammation and insulin resistance, leading to arterial blockages. Even small amounts of trans fats can harm: every 2 per cent increase in calories due to these doubles the risk of heart attack.
Saturated fats are the other bad type, although this has been debated recently. Red meat and milk products, like butter and cheese, are the main sources. Coconut oil is another rich source, although some diasgree. A diet rich in saturated fats also increases LDL cholesterol. Recent reports have questioned the strength of the association between saturated fats and heart disease, although the jury is still out. Most experts still recommend limiting saturated fats to under 10 per cent of calories a day.
Good fats come mainly from vegetables, nuts, seeds and fish. Healthy fats are liquid at room temperature. There are two broad categories of beneficial fats: monounsaturated and polyunsaturated. Studies in the 1960s revealed that people living in the Mediterranean region enjoyed a low rate of heart disease despite a high-fat (olive oil) diet. Olive oil contains mainly monounsaturated fat. Since then more studies have suggested that Mediterranean diet is the healthiest. Apart from olive oil, monounsaturated fats are found in mustard oil and peanut oil (commonly used in India), canola oil, avocados and most nuts.
Polyunsaturated fats are abundant in liquid oils used for frying. Corn oil, sunflower oil and safflower oil are common examples. Polyunsaturated fats are required for normal body functions and we have to get them from food. There are two main types of polyunsaturated fats: omega-3 and omega-6 fatty acids. Good sources of omega-3 include fatty fish (such as salmon, mackerel and sardines), flaxseeds, walnuts and canola oil. Omega-3 fatty acids help prevent and even treat heart disease and stroke. Omega-6 fatty acids have also been linked to protection against heart disease. Food rich in omega-6 include vegetable oils such as safflower, soyabean, sunflower, walnut and corn. What about desi ghee (clarified butter)? Although it contains more than 60 per cent saturated fats, it also has a favourable ratio of omega-6/omega-3 (1.5:1). In our 15-20 ml daily allocation of visible fats, 5 ml of desi ghee is acceptable, especially for children.
Confused? Advising on fats is walking on a greasy slope! Here goes: fats should not provide more than 30 per cent of total energy; saturated fats, less than 10 per cent; and trans fats, less than 1 per cent. The optimum ratio of omega-6/omega-3 is less than 4—and definitely not over 10. It is more difficult to obtain omega-3 from Indian diets compared with omega-6, so the ratio is often hard to achieve. Clearly, no single oil possesses all the properties we desire. The solution is to use a variety. For frying, oils with high smoke point and neutral flavour like canola, rice bran, sunflower and groundnut are preferable. Mustard oil too, though strongly flavoured, works well for Indian cooking. For sautéing, flavour-rich but low-smoke-point oils like sesame or olive are healthy. And nothing better than olive oil for salad dressing. Examples of combinations shown to be healthy include groundnut/sesame/rice bran/with mustard or canola; sunflower/safflower with olive/groundnut/rice bran.