By Dr Harold Gunatillake - Health Writer
Dietary fat or the fat you receive from food is important for your health. It has many different functions in your body.
Some of them are providing long lasting energy, helping feel full after eating, making hormones, forming part of the brain and nervous system, cell membranes for every body cell, carrying vitamins throughout the body, helping to regulate the body temperature and keep it warm and providing two essential fatty acids: linoleic and linolenic acids, which the body itself cannot produce.
Fats are classified as saturated fats and unsaturated fats. The latter could be monounsaturated fats and poly unsaturated fats.
Monounsaturated fats are in high concentrations in olive oil, canola oil, canola margarine, mustard seed oil, avocado and most nuts and their oils: almond, pecans macadamias, cashews, hazelnuts, pumpkin seeds and sesame seeds. Eggs, fish, chicken, pork, beef and lamb contain a small amount.
Unlike dietary saturated fats, monounsaturated fats lower the harmful LDL and raise the good HDL in the blood. Unlike omega 6 type of polyunsaturated fats, they are less prone to oxidation by free radicals, Monounsaturated fats have been shown to improve diabetics' blood glucose levels.
Olive oil is a very special monounsaturated fat. It contains anti-oxidants and other compounds that have been shown to have favourable effects on blood clotting and high blood pressure. Only problem with olive oil is its oleic acid, an important fatty acid in olive oil is fattening.
Unsaturated fats are called good fats since they can improve blood cholesterol levels, ease inflammation, stabilize heart rhythms, and play a number of other beneficial roles.
Poly-unsaturated fats can be divided into two major classes– omega-6 and omega-3 fatty acids: essential fatty acids (EFA). Your body cannot itself produce the EFAs, known as linoleic acid and alpha-linolenic acid, so it receives them from foods.
The main fatty acid in omega-6 is linoleic acid (LA). The modern western diet is abundant in LA– rich poly-unsaturated oils.
They are found in Sun-flower, corn, cotton seed, sesame, soybean, Evening primrose oil, vegetable seed oils, grape-seeds, margarines, breads, cereals, and sunflower seeds.
These poly-unsaturated oils are good for you. Saturated fats cause cancer and heart disease. Today we consume over 30% of our calorie requirement from poly-unsaturated fats. But, We must limits to 2% omega-3 and 2% of omega-6 fatty acids, in a ratio of 1:1. Increased amounts of the omega-6 poly-un-saturates have contributed to too many diseases. Some such diseases are cancer, heart disease, and immune system dysfunction; damage to liver, reproductive organs and lungs: depressed learning ability, and impaired growth.
One reason why poly-unsaturated fats, especially omega 6, cause many health problems are that they tend to become oxidized or rancid when exposed, thus giving out free radicals. We also know that LDL cholesterol (from saturated fats converted in the liver) found in atheromatous plaques are quite innocent, and do not give trouble, until the free radicals acting on them, in the blood makes it unstable and soft. Then the neighbouring immune cells in the blood vessel lining engulf these unstable LDL cholesterol and turns into foam cells. They block the vessels and cause early angina, and heart attacks.
Linoleic acid (LA): The main fatty acid in omega-6 poly-unsaturated fats, LA is an essential fatty acid. It cannot be made in the body that it can receive only from dietary foods.
It is found in sunflower oil, safflower oil, sesame oil, corn oil, cotton seed oil margarines, soy bean oil and others.
Linoleic acid brakes down to arachidonic acid (AA), which gives aggressive omega-6 eicosanoids. These eicosanoids give out: Thromboxane– which promotes blood clotting; Leukotrienes which constricts blood vessels; Prostaglandins which promotes inflammation in the tissues. In 1991, two studies from the USA and Canada showed that linoleic acid (LA) increases the risk of breast tumours. Polyunsaturated fats (omega-6 types) are greatly immuno-suppressive. They prevent the body defensive system from doing its duties to safeguard the body. Thus any system that suppresses the immune system is likely to cause cancer.
Dr R.A. Newsholme of Oxford University, England first suggested that polyunsaturated fats cause cancer was. He said that when our bodies get sufficient nutrition, our diet includes immunosuppressive polyunsaturated fats which make us prone to infection by bacteria and viruses. When we starve, however, our body stores of polyunsaturated fats are depleted. This allows our bodies' immune systems to recover which in turn, allows us to fight existing infection and prevent other infections.
He also said that this effect of polyunsaturated fats in sunflower seeds can treat autoimmune diseases such as multiple sclerosis, and that the same fatty acids could be used to suppress the immune system to prevent rejection of kidney transplants. When kidney transplant patients were fed with polyunsaturated fats in vegetable oils, the incidence of cancer of these patients went up by twenty times.
Omega-3 fatty acids is the other important component of polyunsaturated fats, much has been written and discovered in the recent past. You may call it an "Omega-3 Life Style" as its importance in the longevity process is immeasurable.
In the plant foods Omega-3 fatty acids are usually in the form of the shorter chain alpha-linolenic acid (ALA). Marine Omega-3 in fish is present as longer chain eicosapentaenoic acid, (EPA), and docosahexaenoic acid, (DHA).
A vegetarian diet is a healthy way of eating. However, plant foods commonly eaten by these vegetarians do not contain the long chain omega-3 fatty acids, EPA and DHA. For them, omega-3 eggs (not available in Sri Lanka), provides a good source of both EPA and DHA. Like linoleic acid (LA) in Omega-6 fatty acids, alpha linolenic acid (ALA), is the main fatty acid in omega-3 oils. Like LA, ALA is an essential fatty acid.
It seems that the modern western diet lacks ALA–rich sources such as linseeds, mustard-seed oil, canola oil, wheat-germ oil, soybeans, baked beans, red kidney beans, mushrooms, green beans, spinach, leeks, kale, lettuce, seaweed, mustard, cumin and fenugreek seeds.
Plant foods also have omega 3 fatty acids. They are shorter chain alpha-linolenic acid.
EPA and DHA prevent and treat heart disease, reduce inflammation, and prevent cancer. These oils lower the bad LDL cholesterol, and elevate the good HDL cholesterol, and also help brain growth and development.
Rich sources of omega-3 fatty acids include fish, sea food, Omega-3 eggs, and plants like flax seed, nuts and legumes.
The popular good fish sources of omega-3 include sardines, herrings, mackerel, bluefish, tuna, salmon, pilchard, butterfish and pompano. Organ meats such as brains and bone marrow, lean meat and eggs are other sources. Foods fortified with omega 3such as eggs, milk, yoghurt and bread, as well as fish-oil supplements, is other sources.
You will notice that both omega-6 and omega-3 oils produce eicosanoids, but they have different and opposing effects in our bodies. Eicosanoids produced from omega-6 oils promote blood clotting, inflammation, and constricts blood vessels, whilst the same fatty acids from omega-3 oils reduces blood clotting, inflammatory processes, and dilates blood vessels.
So the value of eating more omega-3 oils, and less of omega-6 oils, in polyunsaturated fats, for health and longevity cannot be neared. 1000mg of omega-3oil is the recommended dose, but one could increase it three times more. It is available in capsule forms, but the 1000mg capsules may have to be obtained from abroad through your friends.
In addition, omega-3 oils create a soothing environment in our body, calms an over-reactive immune system, in addition to the above mentioned functions.
lnuts), salmon, sardines, soy based foods (such as soybeans, soy nuts), Tofu, Tuna
So begin now, and change your body life style. Switch over from sunflower oils to canola oil. Change polyunsaturated margarine to canola margarine. Substitute oily fish three times a week to meat products. Eat nuts, legumes, and other seeds regularly in addition to fresh vegetables and fruits. Walk every day for half an hour. Avoid processed foods when you next visit your super market.
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