Fats get a lot of bad publicity. While some are potentially detrimental to health, there are others without which the human body cannot survive. As with vitamins, minerals and amino acids, essential fatty acids help to form our basic physiological structure.
Fats – also known as lipids – are the richest dietary source of energy and play an important role in numerous physiological functions. In standard Western diets, however, the ‘good’ fats are usually overwhelmed by their ‘bad’ counterparts. To redress this imbalance it is necessary to understand ‘good’ fat structure and functions and increase the intake of them in order to promote optimal health.
Chemical Composition
Fats are comprised of building blocks called fatty acids which consist of carbon atoms linked together by chemical bonds to form chains. At one end of a carbon chain is a cluster of carbon and hydrogen atoms called a methyl group. At the other end is a cluster of carbon, oxygen and hydrogen atoms called a carboxyl group.
Different fatty acids are made up of carbon chains of different lengths. Short-chain fatty acids have fewer than six carbons, whereas long-chain fatty acids have 12 or more. The chemical bonds between carbon atoms can be either single or double bonds. Single bonds have more hydrogen molecules around them than double bonds.
Fatty acids are categorised as saturated or unsaturated, as determined by their chemical bonds. These differ markedly, not only in chemical structure but also in dietary sources and health effects. For example, saturated fatty acids are mainly of animal origin, solid at room temperature and tend to raise blood cholesterol. Unsaturated fatty acids are derived from both plant and some animal sources (such as fish), are liquid at room temperature and help to reduce blood cholesterol.
Unsaturated fatty acids can be further subdivided into monounsaturated, polyunsaturated, cis and trans-fatty acids. Cis and trans contain fatty acid double bonds. In cis hydrogen is arranged on the same side of a double bond while in trans hydrogen on the opposite side of a double bond. In nature, most unsaturated fatty acids are cis. A small percentage of trans fatty acids also occur in nature as the result of fermentation in grazing animals and can be found in meat and dairy products. However trans double bonds are also formed during the hydrogenation of oils. This is a manufacturing procedure in which solid fats (like margarine) are artificially produced by heating liquid vegetable oils in the presence of hydrogen. Trans fatty acids are associated with various health disorders.
Monounsaturated fats contain one double bond and the resultant carbon chain has one empty site where a hydrogen atom can be added. Polyunsaturated fats contain two or more double bonds and consequently two or more sites are available for additional hydrogen atoms.
The Good Fats
Essential fatty acids (EFAs) are vital for health maintenance. They are polyunsaturated fats and fall into two main families, omega-3 (n-3) and omega-6 (n-6), which means they contain more than one cis double bond. In all omega-3 fatty acids the first double bond is located between the third and fourth carbon atom when counting from the methyl end of the fatty acid chain (n-3). The first double bond in omega-6 fatty acids is located between the sixth and seventh carbon atom (n-6).
Although humans and other mammals can synthesise saturated fatty acids and some monounsaturated fatty acids from carbon groups in carbohydrates and proteins, they lack the enzymes necessary to insert a cis double bond at the n-6 or n-3 position of a fatty acid. Consequently, omega-6 and omega-3 fatty acids must be obtained through food. The body requires EFAs for the normal functioning of every cell, tissue, gland and organ.
EFAs support the cardiovascular, reproductive, immune and nervous systems. The human body needs EFAs to manufacture and repair cell membranes, enabling the cells to obtain optimum nutrition and expel harmful waste products. As structural components of membranes, they form a barrier that keeps foreign molecules, viruses, fungi and bacteria outside the cells, while keeping proteins, enzymes, genetic material and organelles inside. They also ensure that hormone producing glands remain active and help produce joint lubricants, transport cholesterol and prevent the development of allergies. A primary function of EFAs is the production of prostaglandins which regulate body functions such as heart rate, blood pressure, blood clotting, fertility, conception and nerve transmission, as well as the functions of the kidneys and gastrointestinal tract and production of other hormones. Prostaglandins also play a role in immune function by regulating inflammation and encouraging the body to fight infection. EFAs are necessary for proper growth in children, particularly for neural development and maturation of sensory systems. Foetuses and breast-fed infants require an adequate supply of EFAs through the mother’s dietary intake.
OMEGA–3 (LINOLENIC ACID)
Alpha Linolenic Acid (ALA) is the principal omega-3 fatty acid. It can be converted in the body with the help of nutrient-dependent enzymes into eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and GLA, which is synthesised from linoleic (omega-6) acid, are later converted into hormone-like compounds known as eicosanoids. The latter aid in many bodily processes, including vital organ function and intracellular activity. Omega-3s are used in the formation of cell walls, making them supple and flexible, and improving circulation and oxygen uptake with proper red blood cell flexibility and function. All omega-3 fats are indispensable for human health.
Omega-3s are found primarily in flaxseed oil (which has the highest linolenic content of any food), flaxseeds, flaxseed meal, hempseed oil, hempseeds, walnuts, pumpkin seeds, Brazil nuts, sesame seeds, avocados, some dark leafy green vegetables (kale, spinach, purslane, mustard greens, collards, etc.), canola oil (cold-pressed and unrefined), soybean oil, wheat germ oil, salmon, mackerel, sardines, anchovies, albacore tuna and others. Certain algae are also rich in DHA.
Health Benefits
Omega-3s promote the growth of healthy cell membranes, aid cardiovascular health, have anti-inflammatory properties, improve blood flow by reducing platelet aggregation and are necessary for foetal brain and eye development.
Deficiency Signs
Omega-3 is the essential nutrient most often lacking in Western diets, so many people in those countries suffer from omega-3 deficiency. This may be linked to decreased memory and mental abilities, dry/itchy skin, low energy, weakness, impaired vision, poor motor coordination, tingling sensations in the nerves and limbs, high serum triglycerides and ‘bad’ cholesterol, hypertension, diminished immune function, depression, difficulty in losing weight, poor coordination, constipation, oedema, joint pains, digestive problems, acne, weight gain, inflammatory diseases, allergies, auto-immune conditions, irregular heartbeat, learning disorders, menopausal discomfort, cancer, itchiness on the front of the lower legs and growth retardation among infants, children and pregnant women.
OMEGA–6 (LINOLEIC ACID)
Linoleic Acid is the primary omega-6 fatty acid. This is converted in the body to gamma linolenic acid (GLA) which is later synthesised, with the help of the enzyme elongase, into dihomo-gamma-linolenic acid (DGLA) and then further converted into arachidonic acid (AA) with the help of delta 5 desaturase. AA, which is also derived from meat and dairy products, is required by the body in small amounts only, as high levels convert into pro-inflammatory prostaglandins which contribute to poor health. Some omega-6s improve diabetic neuropathy, rheumatoid arthritis, PMS, skin disorders and can aid in cancer treatment.
Omega-6 is found in flaxseed oil, flaxseeds, flaxseed meal, hempseed oil, hempseeds, grape-seed oil, pumpkin seeds, pine nuts, pistachio nuts, sunflower seeds (raw), olive oil, olives, borage oil, evening primrose oil, blackcurrant seed oil, chestnut oil and chicken, among many others. Corn, safflower, sunflower, soybean and cottonseed oils are also sources of linoleic acid, but many are refined and may therefore be nutrient-deficient. Borage oil and evening primrose oil are the richest sources of GLA.
Although most people in Western countries ingest an excess of linoleic acid, it is often not converted to GLA because of metabolic problems caused by diets rich in sugar, alcohol and trans fats from processed foods, as well as smoking, pollution, stress, ageing, viral infections and other illnesses such as diabetes.
Health Benefits
Omega-6 oils manufacture series 1 prostaglandins that reduce inflammation and pain, improve nerve and immune function, regulate platelet aggregation, relax blood vessels, lower blood pressure and cholesterol levels and limit artherosclerosis. Series 1 prostaglandins are involved in the control of hormone production and nerve functions and can help manage PMS, fibrocystic breast problems and menorrhagia.
Deficiency Signs
Many degenerative symptoms may be linked to an omega-6 deficiency, including kidney, liver and brain degeneration, attention deficit disorder, depression, poor wound healing, sterility, miscarriage, arthritis-like conditions, heartbeat abnormalities, hypertension, PMS, cyclical breast pain, dry eyes, inflammatory health disorders, difficulty in losing weight, blood sugar irregularities, low energy, dry skin and hair loss.
The Right Ratio
ALA is deficient in the diets of most people in affluent societies. Due to processing damage, shelf-life considerations and changes in food choices, the average intake of omega-3 has decreased dramatically over the years. It is estimated that the ratio of omega-6 to omega-3 fatty acids in the diet of early humans was 1:1, but in today’s typical Western diet is about 20:1 due to increased use of vegetable oils rich in LA and the consumption of trans-fats in the form of hydrogenated oils. It is said that between 90 and 95 percent of the modern population gets less omega-3 than is necessary to maintain good health. A large body of scientific research suggests that increasing the relative abundance of dietary omega-3 fatty acids may have a number of health benefits.
EFAs are only advantageous to health when consumed in the correct proportions to one another. Because of imbalances in Western diets, significantly more omega-3 should be consumed – approximately 1 part of omega-6 to 3.5 parts of omega-3.
However, too much omega-3 (for example, flax and flax oil as the only dietary source of EFAs) can lead to an omega-6 deficiency and thereby work against the health of cells, tissues, glands and organs. Thus the ratio of omega-3 to omega-6 is a highly important consideration. And because GLA converts to AA, excessive omega-6 intake can lead to pro-inflammatory conditions and omega-3 deficiency.
In Addition
There are two more omega oils to take into account – Omega-7 (palmitoleic acid) and Omega-9 (olaic acid) – but these are considered non-essential as the body is able to manufacture them. The former is a monounsaturated fatty acid which occurs naturally in skin and sebum but tends to diminish with age. Diet-wise, it is mainly found in animal fats, particularly fish and marine mammals, and also in tropical oils such as macadamia nut, sesame seed and sea buckthorn. Omega-7 has become very popular due to its purported anti-ageing and skin-healing benefits. Omega-9 is found in abundance in olive oil but can also be sourced from almonds, avocados and peanut oils. It is thought to be particularly supportive to cardiovascular health.
Supplementary Matters
There are a wide variety of essential fatty acid supplements on the market. Fish oil supplements are very popular as they provide both EPA and DHA. Be sure to favour supplements made by reputable companies which certify that their products are free of contaminants and heavy metals such as mercury, lead and cadmium. Be aware that pyrrolizidine alkaloids, which are potentially hepatotoxic and carcinogenic compounds, are found in various parts of the borage plant. People who take borage oil supplements should use products that are certified free of pyrrolizidine alkaloids. EFAs are very sensitive to light and heat, so flaxseed oil, fish and krill oils should always be refrigerated.
Dosage Directions
Adults should not take more than 3g daily of omega-3 fatty acids from capsules without the supervision of a healthcare provider. There is no established dose for children. Omega-3 fatty acids are used in some infant formulas. Fish oil capsules should not be used in children except under the direction of a healthcare provider.
Precautions
Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable healthcare provider. Omega-3 fatty acids should be used cautiously by people who bruise easily, have a bleeding disorder or take blood-thinning medications, because high doses may increase the risk of bleeding. Fish oil can cause gas, bloating, belching and diarrhoea. People with diabetes or schizophrenia may lack the ability to convert alpha-linolenic acid (LNA) to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the forms more readily used in the body. People with type 2 diabetes may experience increases in fasting blood sugar levels while taking fish oil supplements and should use these only under the supervision of a healthcare provider.
Suzanne Ellis
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