FOODS AND NUTRITION are essential for maintaining good health and in preventing diseases. Although food occupies the first position in the hierarchical needs of man, ignorance of many basic facts relating to foods and nutrition is still widespread. Good nutrition is a function of both economics and education. Economics, because money is required to buy food, and education, because that helps buy the right food!
After the two macro nutrients we saw in the previous issues, viz., Carbohydrates and proteins, now we will see some important aspects of the third macronutrients……
Lipids/fats are compounds that are insoluble in water but are soluble in organic solvents such as ether and chloroform. Lipids that are important to our discussion include fats and oils (triglycerides or triacylglycerol’s), fatty acids, phospholipids, and cholesterol. Fats are an essential part of our body, accounting for a sixth of our body weight. The cells and tissues of our body have fat as an integral part of them. The vital organs (brain, heart, liver) are protected by a sheath of fat and water, which holds them in place and prevents injury. The nerves are also protected by fat. A layer of fat beneath the skin acts as an insulation against cold. The fat around the joints acts as a lubricant and allows smooth and easy movements. Thus fat is a crucial part of the body composition.
Coming to food….
Fats are an integral part of our diet, whether we are on a fat free diet or a normal diet. Food fats include solid fats, liquid oils and related compounds such as fat-soluble vitamins and cholesterol. Fats are enjoyed in the diet due to its flavor, palatability, texture, and aroma. Fats also carry the fat-soluble vitamins A, D, E, and K. Sources of fats and oils may be animal, vegetable, or marine which may be manufactured by industrial processing. Fats appear solid at room temperature, whereas oils are liquid at room temperature.
In the middle of last century, fats were expensive and a meal containing large amounts of fat was called a ‘rich meal’. Persons consuming such meals were thought to be healthy. But with the improvement in the methods of production and their availability, there has been an indiscriminate increase in fat intake in the overall society leading to overweight and obesity, which has turned out to be a major cause of concern in the urban population . The weight increase in an individual, discourages movement, increases pressure on circulation, respiration and on the skeletal frame. Hence it is recognized as a risk factor for several chronic ailments. It is easier to control visible fats in the diet than that which is hidden. For example, one can monitor use of butter, ghee and oil used directly. Invisible fats include the cream in the milk and dahi ,nuts used in preparation ,egg yolk, oil used in seasoning vegetables, dal and salads etc. Even toned milk contains 3 per cent fat. Invisible fat contributes to about 10 or more per cent of total energy in the diet.
Uses of fat in the diet:
Fats are energy giving foods and they give 9 Kcal/g which is the same as carbohydrates.
Fats serve as a vehicle for fat-soluble vitamins like vitamins A, D, E and K and carotenes and thereby promote their absorption.
They are also sources of essential polyunsaturated fatty acids. It is necessary to have adequate and good quality fat in the diet with sufficient polyunsaturated fatty acids in proper proportions for meeting the requirements of essential fatty acids.
The type and quantity of fat in the daily diet influences the level of cholesterol and triglycerides in the blood.
Diets should include adequate amounts of fat particularly in the case of infants and children, to provide concentrated energy since their energy needs per kg body weight is about twice that of adults.
Adults need to be cautioned to restrict intake of saturated fat (butter, ghee and hydrogenated fats) and cholesterol (red meat, eggs, organ meat). Excess of these substances could lead to obesity, diabetes, cardiovascular disease.
Sources of Fat:
It is at the sources of fat that every one is a little concerned. Fat sources are broadly classified as
- Plant Sources
- Animal Sources
Nuts and oilseeds are the sources of plant fats. We have the groundnut oil, sesame oil, sunflower seed oil, mustard oil and so on. Each of these sources vary in their composition and hence it their properties as well. As with their properties, so is their taste in the food in which they are used.
Animal sources of fat are butter, ghee, cod liver oil, and the likes. Also fat from lamb and chicken are also a source of fat for the body.
Recommended Daily intake of fats:
For a normal healthy adult, fat intake can be up to 20 – 35% of the total calorie intake. A normal healthy adult with less physical activity will require about 1800 to 2000 Kcal of energy per day of which 40 to 65 g of fat intake is the recommended intake.
However, to generalize at 40g/day is not the point but what fats to be taken and what to be avoided or taken in less quantities should be an important aspect of our diet.
In the coming issues we will see the different types of fats and their effect on our body!
……….. to be continued……
Article writer Dr Manomani Seenivasan
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