Dietary fats and oils, health benefits and dietary recommendations
Fats are one of the three macronutrients that nourish the body. The other two are carbohydrates and protein. Fats and oils are very important to the overall functioning of the human body. They play such roles as energy production, protection against various diseases, heat regulation etc.
They are esters of three fatty acid chains bonded to an alcohol known as glycerol. Fats are also known as triglycerides and they consist of long chains of carbon atoms. In the carbon chains of the fatty acids, there are either single bonds (-C-C-C-) or a combination of single and double bonds (-C-C=C-C). Fats that have only single bonds are said to be saturated and this kind is found mostly in animal fats. The ones that have one or more double bonds are unsaturated fats found commonly in plants and fish. When there is only one double bond, the fatty acid is known as monounsaturated fatty acid. Where there is more than one double bond, it is referred to as polyunsaturated fatty acid.
The double bond of the unsaturated fat can be broken into two and each half of the bond made to take up an hydrogen atom. When this happens, all the bonds become single and the fat is said to be saturated. This is achieved by heating liquid vegetable oil to very high temperatures and pumping hydrogen atoms into it. The heat breaks the double bonds and hydrogen atoms pumped in get attached to the single bonds created. This process is known as hydrogenation. The saturated fat thus produced, known as trans-fat and like all single bonded saturated fats, is solid at room temperature. Not only that, it has an extended shelf life, which is the intention of the manufacturer in the first place. However, saturated fats are dangerous to the consumer.
Types of fats
From the above description, four types of fats can be identified and they are:
monounsaturated fats, polyunsaturated fats, trans fat and saturated fat.
Unsaturated (good) fat
Unsaturated fats are either monounsaturated or polyunsaturated. The monounsaturated have only one double bond in the fatty acid chain, while the polyunsaturated has more than one double bond.
Sources of monounsaturated fatty acids: almonds, hazelnuts, macadamia nuts, peanuts, pecans, cashew nuts, avocados and olives.
Sources of polyunsaturated fatty acids: walnuts (roasted), pumpkin seeds, sesame seeds, flaxseed, sunflower seed. Polyunsaturated fats are predominantly found in fresh cold water fish such as salmon, tuna, herring, sardines, mackerel and trout. Omega 3 is the best known example of a polyunsaturated fat. There are three types that have been extensively studied which also play important roles in the health of human beings.
1. Eicosapentaenoic acid – EPA
2. Docosahexaenoic acid – DHA
These two are commonly found in cold water fish as listed above. Oysters also have some omega 3. Plant sources particularly rich in omega 3 are flaxseed, Brussels sprouts, walnut, spinach and parsley.
3. Alpha-linolenic acid – ALA is the third type of omega 3 fatty acid. Common sources of ALA are flaxseed, walnut and canola oil.
Alpha-linolenic acid (ALA) is also converted to EPA and DHA in the body.
Saturated and trans fat
Saturated fats are fats that have single bonds connecting all the carbon atoms. In this kind of fat, there are no double bonds. The carbon atoms are bonded to other carbon atoms or hydrogen atoms by single bonds. The fat molecule is said to be saturated with hydrogen atoms. Saturated fats are characteristically solid at room temperature. Commonly, the word fat is used for fats that are solid at room temperature, while oils are reserved for fats that are liquid at room temperature. Most animal fats are solid at room temperature (they are saturated) and fats sourced from plants and fish oils are more often than not, liquid and these are the monounsaturated and polyunsaturated fats. However, these all constitute the class of food referred to as lipids.
Sources of saturated fats
As I have mentioned earlier, saturated fatty acids are mainly from animal sources and this makes them solid fats at room temperature.
The sources of saturated fatty acids include: Fatty portions of red meat, pork, chicken and turkey eaten with the skin, butter, dairy products such as whole milk, cheese, cream and fried and baked foods. Some prepared foods, for example, sausage, pizza and desserts are also high in saturated fatty acids. Researchers have found out that these products may be liable to increase the blood level of cholesterol. Other sources are certain oils from plants like palm oil, kernel oil and coconut oil. These do not contain cholesterol.
The double bond in the unsaturated fatty acid can be broken into two halves and each half can become attached to hydrogen atoms making all the bonds single and saturated. This is achieved by heating liquid vegetable oils to very high temperatures and pumping hydrogen into it. The heat breaks the double bond making it available for hydrogen atoms to be attached to each single bond created.
We shall continue with trans fats in next Thursday’s edition of the Guardian Newspapers.
*Pastor Dr Paul Nanna is a Medical Doctor and a Pastor in the Redeemed Christian Church of GOD. Telephone: +2348033018181. Email address: email@example.com. Blog: nutritionandhealthmanagers.com. Twitter Handle: @paulnanna.
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