Fats are one of the macronutrients our body uses to release energy.
Fats are an important part of our diets, playing an essential role in providing energy as well as a number of vitamins which are fat-soluble (vitamins A, D, E, and K) .
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Different Kinds Of Fats
We often distinguish between the "bad" fats: saturated fatty acids (SFA) and trans fatty acids, and the "good" fats: monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA). Trans fats are the only type rarely found naturally, yet they have become common in the food on our shelves.
Solid fats are mainly of animal origin and have the highest amount of SFA. Oils, which are mainly of plant origin have the highest amount of MUFA and PUFA. At room temperature, these are usually in liquid form, except for palm and coconut oils which have higher amount of SFAs.
Saturated fats are mainly found in products of animal origin such as meat and dairy products. They are the main kind of fats in butter, cheese, milk, cream, and meat.
Recent research concluded that a high intake of SFAs contributes to high blood cholesterol and triglycerides. These are thought to be the main reasons for many of today's chronic diseases.
In general, SFAs are not the best type of fats and you should try to limit how much of them you have in your diet. Current recommendations are for SFAs to make up less than 10% of your total daily calories.
Trans fats have been developed by the food industry for the purpose of prolonging shelf-life of products, reducing the cost of production and getting higher product yields. Research has shown that a high intake of trans fats directly raises the risk for many health problems such as obesity, type-2 diabetes, and heart disease. Overconsumption of trans fats can affect brain development in infants and young children and has even been linked to problems like depression.
Some foods that contain trans fats are industrially produced products like margarine, snack foods, fried/fast foods, crisps, sauces, non-dairy creamers, desserts, and salad dressings.
Contrary to SFAs it is believed that MUFAs can actually reduce the risk of heart disease mainly by lowering the blood components that SFAs elevate and by raising the so-called "good" cholesterol – HDL (high-density lipoprotein) – which is thought to be a strong protector of the heart.
Foods containing MUFAs should be used to replace foods high in SFAs and trans-fats in the diet – plant oils (especially olive oil), nuts, nut butters, avocados, olives. The Mediterranean diet is thought to be one of the world's healthiest diets due to the high amount of foods with MUFAs. Certain types of meat such as lamb, beef, turkey, and chicken have a higher amount of MUFAs than SFAs and can also be a part of a balanced diet.
Polyunsaturated Fats (PUFAs)
Similar to MUFAs, PUFAs can also lower the total and LDL cholesterol levels in the blood and therefore reduce the risk of heart disease. They are also essential for the growth and development of certain organs – specifically the brain and eyesight.
PUFAs include linolic acid (LA, omega-6) and α-linolenic acid (ALA, omega-3). It is thought that in the past, the ratio of omega-6s and omega-3s consumed by most people was 1:1 while today's modern diet has ratios of up to 20:1 in favor of omega-6s. This significant shift towards omega-6s may be one of the causes for the higher levels of metabolic diseases such as heart and endocrine diseases, as well as certain psychiatric disorders. The ideal omega-6/omega-3 ratio is thought to be around 2:1 or 3:1.
Omega-3 Fatty Acids
The two most important omega-3 fatty acids are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which are crucial for brain function and development. They can directly be found almost exclusively in fish and seafood. Oily fish are great sources of EPA and DHA – sardines, tuna (excluding tinned tuna), salmon, herring, anchovies, mackerel, cod liver oil, crab, shrimp, oysters.
ALA is the precursor to EPA and DHA and can be found in plant products such as nuts, seeds, oils and green vegetables which the body then converts to EPA and DHA. Unfortunately, conversion is only about 5% for EPA and 1% for DHA which is far too low to obtain sufficient amounts of these omega-3 fatty acids.
It is thought that our high consumption of omega-6 fatty acids compared to omega-3 interferes with the conversion. Meanwhile stressful lives and diets lacking in other vitamins/minerals also contribute to the problem. Ideally, a balanced diet should include oily fish at least 2-3 times a week unless you are supplementing your omega-3s.
Fats In Children's Diets
During the first 6 months of life, fats present in breastmilk/formula are the main source of energy (about 50%). Infants and toddlers generally need more fats than adults as it is such an important contributor to growth and brain development.
Nutritional science today is generally of the opinion that the quality and type of fats is the main factor in increasing or reducing the risks of obesity and other non-communicable diseases later in life, so it's important to try to focus on MUFA and PUFA as well omega-3 fatty acids instead of saturated or trans fats.
The Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) generally recommend that fats make up the following amounts of your daily diet.
|Age||% of total daily calories|
|0 - 4 months||40 - 45%|
|4 - 12 months||35 - 45%|
|1 - 4 years||30 - 40%|
|4 - 15 years||30 - 35%|
|15 - 19 years||30%|
|> 19 years||20 - 30%|
- Avoid: trans fats
- Reduce: saturated fats (meat, cheese and basically most animal products)
- Increase: monounsaturated fats (plant-based oils, nuts, seeds, avocado), polyunsaturated fats (nuts and seeds, plant-based oils, tuna), and omega-3s (oily fish)
- Gallagher ML. The Nutrients and Their Metabolism. In: Mahan LK, Escott-Stump, S. Krause’s Food & Nutrition Therapy. International Edition, 12e. 2008. pg. 39-143.
- Stender S, Dyerberg J. (2004) Influence of transfatty acids on health. Ann Nutr Metab 48:61.
- Kris-Etherton PM, Taylor DS, Yu-Poth S, Huth P, Moriarty K, Fishell V, Hargrove RL, Zhao G, Etherton TD. (2000) Polyunsaturated fatty acids in the food chain in the United States. Am J Clin Nutr. 71:179.
- Abrahamse E, Minekus M, van Aken GA, van deHeijning B, Knol J, Bartke N. et al. (2012) Development of the digestive system: experimental challenges and approaches of infant lipid digestion. Food Dig. 3(1-3):63-77.
- FAO/WHO (2010) Report of an Expert Consultation on fats and fatty acids in human nutrition. FAO Food and Nutrition Paper 91. Rome: FAO; PG. 63 – 77.