Jeannine Baumgartner, Ph.D. in Nutrition; Centre of Excellence for Nutrition, North-West University (Potchefstroom Campus), Potchefstroom, South Africa
Reprinted with permission from Nursing Update
Fats form an essential part of a child's diet, however, it is not solely the amount of fat that requires attention, equally or even more important is the quality (type) of fat a child consumes.
Traditionally, fats have been considered mainly as a source of energy, and got a bad reputation for causing obesity and coronary heart disease.Even though energy supplied from fat is necessary for a child's normal growth and physical activity, fats are more than just a convenient source of energy.Dietary fats carry fat-soluble vitamins (e.g. vitamins A, D, E and K) from the food into the body, and some specific dietary fats are of critical importance fora child's physical healthas well as the developmentand function of the brain and eyes1.
Most dietary fats and oils contain a mixture of three types of fatty acids: saturated, monounsaturated and polyunsaturated fatty acids. Fats high in saturated fatty acids, such as animal fat (e.g. visible fat on meat, butter,dairy cream) and certain plant oils (e.g. coconut oil, palm oil, palm kernel oil), are often referred to as 'hard' fats, because they are solid at room temperature. Saturated fatty acids are present in all dietary fats and oils in different quantities. Humans have no nutritional need for saturated fats because the human body can produce them. Furthermore, a high dietary intake of saturated fats might increase the risk for cardiovascular disease2. Monounsaturated fatty acids found in olive oil, canola oil, avocado, nuts and meat can also be produced by the human body. Nevertheless, they are usually regarded as 'healthy' fats as several studies have found beneficial effects of dietary monounsaturated fats on blood lipids when replacing saturated fats. Polyunsaturated fatty acids can be categorized into two families, the omega-3 and the omega-6 fatty acids (also known as n-3 and n-6 fatty acids). The parent fatty acids of these families, alpha-linolenic acid (omega-3 family) and linoleic acid (omega-6 family) cannot be made by the human body and must be provided by the diet. Therefore, they are called "essential" fatty acids. Dietary sources of alpha-linolenicacid include green leafy vegetables, flaxseed oil, canola oil, soybean oil and walnuts. Linoleic acid is present in many vegetable oils, and found in high quantities in safflower oil, sunflower oil, poppy seed oil, grape seed oil and maize oil.The essential parent fatty acids alpha-linolenic acid and linoleic acid can be converted by the body into longer chain versions, such as eicosapentaenoic acid (EPA, omega-3 family), docosahexaenoic acid (DHA, omega-3 family) and arachidonic acid (ARA, omega-6 family). However, it was shown that this conversion is not very efficient in humans3. EPA and DHA are found mainly in (fatty) fish (e.g. pilchards, mackerel, salmon, sardines, snoek), while ARA can be found in all types of meat, eggs and dairy products including milk, cream, butter, cheese and yoghurt. Omega-6 fatty acidsare less likely to be lacking from a child's diet, thus more attention is required to increase the dietary intake of omega-3 fatty acids, particularly of EPA and DHA.
When ignoring its water content, the human brain consists of 60% fat. DHA and ARA are the most abundant types of fat found in this crucial organ. DHA and ARA are needed to maintain the brain's structure and function. Thus, it comes to no surprise that a good supply of these fatty acids during early life is essential, as the brain is developing and maturing until young adulthood. There is growing evidence that cognitive performance (such as learning, memory and problem-solving) and behaviour in children can be enhanced by the provision of omega-3 fatty acids through breast milk and omega-3 fatty acid-rich foods during early life4, 5. In fact, breast milk provides all the essential fatty acids, as well their longer chain products ARA and DHA6, and is considered to be the optimal method for infant feeding. However, the concentration of these important fatty acids in breast milk is influenced by the mother's diet. Thus, it is important that breast-feeding mothers consume a diet rich in omega-3 and omega-6 fatty acids. Once the transition to solid foods occurs, the omega-3 fatty acid intake, particularly of DHA,usually drops dramatically7. This is of concern, considering that several studies have shownthat children withlow dietary DHA intake performed worse in tasks thatmeasure brain development4.
The eye is another important organ that is dependent on omega-3 fatty acids. 30-50% of the retina of the eye (the part that receives light signals) is made from the omega-3 fatty acid DHA. Several studies have shown that infants who were breast-fed or received formula supplemented with DHA and ARA had better clearness of vision than infants that received formula without added DHA and ARA8.
Besides its critical role in visual and brain development, omega-3 fatty acids may also be useful in supporting the child's immune system and heart health9. Omega-3 fatty acids, especially EPA, have anti-inflammatory properties10. Recent studies suggest that the provision of EPA and DHA to infants, toddlers and children reduces the incidence and the duration of illness11-13, and protects them against allergies and eczema14. Unfavorable blood lipids and high blood pressure are now also observed in young children15.It has been suggested that early intake of DHA and ARA may reduce the risk for cardiovascular disease later in life16.
According tothe latest available information on the food intake of South African children, the averageamount of fat consumed is not exceeding the recommended 30–35% of energy for children older than 6 months of age17, 18. However, the quality (type) of fat in the diet of South African children requires attention19.The three most popular food groups that supply fats consumed by South African children 1–5 and 6–9 years are milk, meat and vegetable fats and oils20. Full cream milk is the major food item consumed by both age categories, followed by brick margarine and chicken meat. Also, salty snacks, confectionary products (e.g. cookies, cakes and tart), and non-dairy creamers are among the top ten food items that contribute to fat intake in South African children, most of which contain high amounts of saturated fatty acids and often also contain trans fats. Trans fats have many health risks and are produced during manufacturing when liquid oils are converted to more solid oils (e.g brick margarines, shortenings). Furthermore, South African children are increasingly exposed to fast foods21, which are generally high in total fat and saturated fatty acids.
In order to improve the quality of fat intake in South African children, processed foods (e.g. polony, viennas, pies, etc.) and fast foods should be avoided or eaten infrequently. Soft tub margarines that contain polyunsaturated fatty acids, preferentially high in omega-3 fatty acids, and that are labeled as "trans fat free" should be chosen overhard brick margarines and butter.Vegetable oils rich in polyunsaturated fatty acidsrather than hard fats should be chosen for food preparation. However, not all oilsshould be used for frying and deep frying of foods, because they can produce compounds detrimental to health when heated to high temperatures.Most suitable for frying are canola oil, olive oil (but avoid Extra Virgin) and sunflower oil. Furthermore, frying oils should be replaced after each use. Nevertheless, the amount of fried foods in a child's diet should be limited. In order to increase the intake of EPA and DHA, it is advised that children eat two portions of fatty fish per week. Therefore, it is recommended to introduce fish early in the diet of children to ensure that fish is consumed on a regular basis throughout life.
In summary, fat plays an important role in a child's diet. Fat is not only a source of energy but is crucial for the development of the brain and eye, as well as a healthy heart and immune system. Therefore, not only the amount but also the type of fat in a child's diet is critical19.
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