Fat is an essential part of our diet and supports many metabolic processes. Fats play a role in:
- Hormone production, where fats are used as precursors
- The control of and reduction of inflammation
- The essential absorption of fat soluble vitamins (A,D, E, K)
- The formation of a protective sheath that surrounds nerves
- Cell membrane permeability
To achieve optimal health and weight control it is essential to include some fat in the diet, although the focus needs to be on the type and quantity of the fats that are included.
What are the different types of Fats?
The fats in our diet originate from either plants i.e. oils or from animals i.e. butter. Fats are classified into fatty acid categories according to the largest amount of a certain fatty acid present in the food product. Recent evidence is beginning to show that variations in the structure of the fatty acids – particularly the length of the chains – result in different physiological functions in the body.
Fat with a high percentage of saturated fatty acids are mostly hard at room temperature and are commonly from animal origin. Although there are plant oils that are classified as saturated fats, such as coconut and palm kernel oils. Saturated fat can potentially increase LDL cholesterol levels and recent evidence indicates that the shorter the saturated fatty acid chain length, the greater the increase on LDL cholesterol. However, numerous impacts on health outcomes have been noted depending on the specific chain length of the saturated fatty acid. Various genetic adaptations will also impact how individuals react to saturated fats, highlighting the necessity for personalized nutrition interventions. Current dietary guidelines recommend limiting saturated fat to less than 10% of total energy and giving preference to monounsatured fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs).
Examples of Saturated fats: are visible fats on meats, chicken skin, butter, ghee, cream, and certain plant fats such as coconut oil, palm kernel oil, cocoa butter, and coconut.
Fats with a high percentage of unsaturated fatty acids are divided into two groups namely, monounsaturated fats and polyunsaturated fats. Monounsaturated fats help to reduce Total and LDL cholesterol and may increase HDL cholesterol which is cardio-protective. Monounsaturated fats also increase insulin functioning in the body by optimising cell membrane structure and may reduce inflammation. The monounsaturated fats should be given preference in the diet over the other types of fat, due to their beneficial health effects.
Examples of Mono unsaturated fats: are avocado pear, avocado oil, olives, olive oil (the richest dietary source), canola oil, peanut butter, peanut oil, and nuts such as almonds, cashews, hazel, macadamia, peanuts, pecans and pistachio nuts, and canola and olive oil margarine.
Examples of Poly unsaturated fats: are sunflower seed oil, soy bean oil, cottonseed oil, corn oil, sesame seed oil, walnut oil, safflower oil, walnuts, pinenuts, brazil nuts, sunflower seeds, linseeds as well as products made from these oils e.g. soft tub margarines and salad dressings.
Essential Fatty Acids
There are two essential fatty acids that fall into the polyunsaturated group. The body cannot manufacture these fatty acids, and it is therefore essential to get them from food. These fatty acids are called omega 3 (alpha linolenic acid) and omega 6 (linoleic acid).
Omega-3 Fatty Acids
Eicosapentaenoic acid (EPA) and Docosapentaenoic acid (DHA) are two of the metabolites of essential long-chain fatty acids in the Omega-3 family. They function as bioactive molecules that are involved with many physiologic activities in the body. These include inflammation modulation, cell growth, muscle contraction and constriction and dilation of veins. EPA and DHA end stage metabolites have anti-inflammatory properties which have beneficial health effects.
Sources of Omega-3 Fatty Acids: are linseed, chia seeds, flaxseeds, rapeseed (canola), soybean, hemp seed as well as green leaves. Fish oils from deep cold water fish such as salmon, sardines, tuna, mackerel, herring and trout are rich sources of EPA and DHA.
It is important to note that plant sources of Omega-3 fatty acids contain mainly Alpha-linolenic acid (ALA) which only converts to EPA at a rate of 5-10% and to DHA at a rate of <1%. Considering it is the EPA and DHA that provide the anti-inflammatory benefits of omega-3 fatty acids, it is far more beneficial and important to include daily sources of foods rich in these metabolites. The fatty fish mentioned above contain much higher amounts of EPA and DHA and therefore it is imperative that these sources are included in the diet.
Omega-6 Fatty Acids
Arachidonic acid (ARA) is a metabolite of the essential long-chain fatty acids in the Omega-6 family. ARA is also involved in metabolic pathways such as gene expression and immune modulation pathways. The results of biological pathways that include ARA have small anti-inflammatory effects but mostly, promote inflammation.
Sources of Omega-6 Fatty Acids: are a variety of vegetable oils and seeds such as sunflower, cottonseed and Soya bean. Meat, poultry and eggs are rich sources of ARA.
Hydrogenated fats otherwise known as trans fats are fats which have undergone a chemical process called hydrogenation. During this process the fatty acids change their chemical structure and where oils are normally liquid at room temperature, they become more solid such as in hard margarines.
Examples of Hydrogenated fats: are hard margarines, confectionary and bakery items such as pies, pastries, biscuits and salty crackers. Hydrogenated fats are also used by the fast food industry for all deep-frying such as potato chips.
Yours in Health