Fats: understanding the good from bad

Variations of saturated and unsaturated fats are found naturally in our body tissue and serve vital roles for living organisms. These include insulating body organs, energy storage, maintaining body temperature, maintaining healthy skin and hair as well as promoting healthy cell function. Fat has often been associated with a negative connotation however consumption of essential fats (fats that cannot be produced in the body) must be incorporated into a healthy balanced diet. There are three main types of fats found in foods: saturated, monounsaturated and polyunsaturated. If consumed appropriately and in moderation, the positive benefits of fat in the diet will be obtained. Total fat intake should not exceed 30% of your daily caloric needs and should be 90% unsaturated fats, ideally predominant in omega-3 fatty acids.
Unsaturated fats
These are fats have low melting points and are often found as a liquid at room temperature and increase fluidity of cell membranes in the body. They are known to be the most heart healthy fats and have a range of benefits. Due to the chemical composition, they are prone to peroxidation and are easily destroyed by increased temperature, light and air exposure. There are two types: mono-unsaturated fats and polyunsaturated fats. Most oils are blends of various unsaturated fats however some have a predominance of either mono or poly-unsaturated fatty acids.
Mono-unsaturated fats have a slightly higher melting point than polyunsaturated fats, they include oleic acid. They have the ability to lower LDL cholesterol and are attributed to promote cardiovascular health, they are found in high amounts in olives and avocadoes. Other sources include almonds, peanut oil, macadamia oil, grapeseed oil, sesame oil, camellia tea oil, canola oil and wheatgerm oil.
Poly-unsaturated fats have more of a profound effect on the body, they consist primarily of two types – omega-3 (linolenic) and omega-6 (linoleic). They are highly susceptible to damage through processing methods, this must be considered when looking at the therapeutic quality of various polyunsaturated oils. Polyunsaturated fatty acids form a part of every cell membrane in the body which is why adequate consumption can improve a broad range of conditions.
Omega-3 fatty acids found in the most bioavailable form in oily fish, algae, krill and other seafood and to a less bioavailable form: flaxseed, walnut and chia seeds. These fats, just like omega-6 are essential to human health as they cannot be produced by the body and must be obtain from exogenous sources. Once converted to their active forms in the body (EPA and DHA), they are attributed to protect against cardiovascular disease and stroke due to lowering LDL and increasing HDL cholesterol, managing blood triglyceride levels, reducing circulatory viscosity to reduce blood pressure, promote brain health, improve immune function as well as being anti-inflammatory.
Conditions that have been associated with beneficial effects from omega-3 consumption include arthritis, cardiovascular disease, high cholesterol, high blood pressure, acne, hormonal imbalances, depression and anxiety.  Recommended daily consumption of these fats are 3-6g or 0.4-1% of total energy intake.
Omega-6 fatty acids are predominant in the western diet, however ensuring adequate consumption of omega-3 fatty acids are crucial, with the optimal ratio of omega-6 to omega-3 being 4 to 1. Sources of omega-6 fatty acids include palm oil, soybean oil, sunflower oil, evening primrose oil, avocado, borage oil and poultry. Current recommendations suggest around 4-10% of total energy intake of omega-6 fatty acids.
Saturated fats
They are commonly referred to as the ‘bad’ fats however there are various subgroups of saturated fats that must be looked into as this is often a misconception. Long-chain saturated fats are found predominantly in fatty meats and animal products. These are usually responsible for raising blood cholesterol and increasing the risk of atherogenesis and heart disease. However, short-chain saturated fats (butyric acid, lauric acid, propionic acid, valeric acid and caproic acid) found in such foods as coconut oil and butter possess numerous beneficial health benefits such as positive influences on insulin sensitivity and glucose absorption, provide nourishment to intestinal cells, promotes beneficial cholesterol ratio, stimulates immune system as well as being anti-inflammatory. Short chain fatty acids are also produced by colonic bacteria by fermentation of soluble dietary fibres found in foods such as fruit (especially apples and prunes), oats, chia, legumes and root vegetables. 
Saturated fat intake should be limited to less than 7% of total caloric intake, and replaced with beneficial unsaturated fatty acids where possible.  
Foods containing saturated fat include butter, cream, cheese, ice cream, lard/shortening, red meat (fat portion) and poultry skin.
Trans fats
An unsaturated fat in which the consumption has been linked to cardiovascular disease particularly due to raising LDL (‘bad’) cholesterol while lowering HDL (‘good’) cholesterol. Other conditions which it may be a contributing factor include Alzheimer’s disease, cancer, diabetes, liver dysfunction, infertility and obesity. This type of fat is commonly found in processed foods due to the effect of partial hydrogenation, causing a change in chemical structure. They are best AVOIDED as they are non-essential for human consumption and have no known benefit to human health. Current recommendations suggest trans fats must be <1% of total dietary energy intake.   
Foods high in trans fatty acids include fast food (due to the high amount in deep fryer shortening of restaurants), baking shortenings, commercially baked products such as biscuits, cakes, donuts and margarine.     

How to manage fat in your diet
  • Limit your total fat intake to the recommended amount; women often require more due to hormonal needs, too much fat will contribute to weight gain.
  • Adopt appropriate food preparation methods – be familiar with which oils should be used raw and which can be good for cooking. Coconut oil is the ideal cooking oil as it is able to withstand high temperatures unlike others. Oils that should ideally be consumed raw are flaxseed, extra-virgin olive oil, sesame, sunflower, safflower, almond and other nut oils.
  • Liquid fats are extremely delicate and must be stored in an appropriate area such as the refrigerator in order to retain their goodness, store at cool temperatures away from direct light and air as they are susceptible to rancidity.
  • Nut oils are very versatile as they can be added to smoothies, yoghurt or cereal dishes, drizzled over steamed vegetables or in salad dressings. Remember to ensure they are not exposed to high temperatures.
  • Purchasing good quality oils are important, organic is preferable due to many pesticides being fat soluble and look for oils stored in amber coloured bottles that are non-genetically modified.
  • Deep sea fish are a great source of omega-3 fatty acids, species with the highest amount include mackerel, herrings, silver warehou, sardines and Atlantic salmon. Choosing smaller fish will limit toxin and mercury consumption.
  • Fish should be lightly steamed or grilled to ensure it is not overcooked as this will destroy the omega-3 fats. Try sashimi instead – a Japanese style of good quality raw fish a squeeze of lemon juice.
  •   A small handful of raw mixed nuts (6-8 nuts) are a good source of unsaturated fatty acids as well as protein, vitamins and minerals. However, ensure nuts are unroasted and unsalted and as fresh as possible out of the shell.
  •  When supplementing fats in the diet, high dietary antioxidants are crucial to prevent lipid peroxidation, a chemical reaction which can be detrimental to body tissues. Food sources of antioxidants include raw cacao powder, green tea, purple coloured fruit and vegetables such as blueberries, prunes, red cabbage, raddichio, beetroot, grapes and plums.
  • Following an extremely low fat diet is not recommended as it can lead to a range of health conditions. Having a small amount of good quality fats is beneficial for health and adding it to meals improves satiety and can lower the glycaemic index of the meal.
  • Different stages of life will vary in their needs of essential fatty acids, for example children and pregnant women have a higher demand.