Good and bad dietary fats
 

by Dr. Nimal Ratnayake, Ph.D., Head, Metabolism Section, Nutrition Research Division, Health Canada, Ottawa, Ontario, Canada

Fats and oils are needed in the diet to supply energy or calories. Sugars (also known as carbohydrates) and proteins in our diet also supply energy, but on a gram to gram basis, fats and oils provide more energy than carbohydrates and proteins.

One gram of fat provides nine calories of energy whereas carbohydrates and proteins provide only four calories. Simply put, fat represents a convenient energy rich food source, the consumption of which reduces the volume of food required.

However, most consumers are addicted to over eating fatty foods because of their superior taste, which contributes towards excess of energy intake and if this pattern continues on a regular basis leads to overweight and obesity, which may pave the way for diabetes, hypertension and cardiovascular diseases.

This article provides some background information on dietary fats, their role on health and disease, and some tips to consumers for selecting good, "healthy fats" for cooking, food preparations and deep frying.

Fat and fatty acids

A number of foods contribute to the total amount of fat in the diet. For instance, fat is naturally present in many foods such as meat, fish, milk, nuts, seeds and pulp of certain fruits, in particular avocados and olives.

A significant amount of fat in the diet however comes from oils and fats that are added to foods. Examples of fat added to foods in Western countries include: most salad dressings and sauces, mayonnaise, gravies, shortening, lard (pork fat), butter and margarine.

These fats are added typically during preparation or cooking, such as oil used for deep-frying of various foods. Coconut oil is the primary fat in the Sri Lankan diet and its main sources are coconut milk (pol-kiri ), coconut salad (pol-sambol ) and foods fried in coconut oil.

Coconut milk is used by almost all the Sri Lankan house holders for the preparation of their daily foods, especially various types of curries and milk rice (kiri bath). For Sri Lankans a meal is not complete without rice and a curry prepared with pol-kiri.

One dietary message for consumers has not changed in decades. Eat less fat. This advice aims particularly at adults to reduce their risk of overweight, obesity, cardiovascular disease and diabetes. In recent years, a new message about fat has emerged that the type of fat in the diet is important.

Fats are made up of smaller units called fatty acids. There are at least seven hundred different fatty acids occurring in nature, but only twenty or so are quantitatively important in the human diet, which are divided into three broad classes; saturated, monounsaturated and polyunsaturated fatty acids.

All natural food fats contain all the three classes of fatty acids but at different proportions. Over 90% of the fatty acid content of coconut oil is saturated fat and therefore coconut oil is classified as a saturated fat.

In fact, coconut oil has the highest amount of saturated fat of any dietary fat. Other oils or foods that contain a high proportion of saturated fat are palm kernel oil, butter, whole milk cream, cheese and various other dairy products and eggs.

Although fat present in beef, pork, chicken and in other meats, would be considered by many people as being saturated fat, over 40% of the fatty acid is monounsaturated and 10% is polyunsaturated. Foods high in monounsaturated fatty acids include canola oil, olive oil, high oleic safflower oil, high oleic sunflower oil, peanuts, peanut oil and avocados.

The polyunsaturated fatty acid class includes two sub-families; the n-6 family (also known as omega-6) and n-3 family (also known as omega-3 family). There are several n-6 and n-3 fatty acids in our diet. The parent fatty acid of the n-6 family is called linoleic acid and that of the n-3 family is linolenic acid.

Healthy skin

These two polyunsaturated fatty acids are considered as essential fatty acids because our bodies cannot make them and we have to obtain them from foods. Essential fatty acids are needed for the growth and development of brain and the central nervous system and keeping our skin healthy.

A lack of either of the two essential fatty acids will result in symptoms of deficiency that includes scaly skin, dermatitis and poor mental and cognitive development. In addition, the essential fats, in particular the n-3 fats protect against heart attacks and strokes.

People who eat diets rich in n-3 fatty acids have a lower risk of heart disease and cardiac deaths than people with low intakes of n-3 fats. Foods rich in n-6 polyunsaturated fatty acids include nuts, seeds and vegetable oils such as sunflower, safflower, corn and soybean oils.

Major food sources of n-3 fatty acids include plant seed oils such as flaxseed, canola and soybean oils and fatty fish such as mackerel, herring, sardines, smelts, and salmon. Fish oils extracted from fatty acid such as salmon are a very convenient source of n-3 fatty acids.

Deficiencies of essential fatty acids are non-existent in Canada, the United States and in many industrialized nations. The Sri Lankan diet is marginally deficient in essential fatty acids due to the widespread use of coconut oil as the primary source of dietary fat. Coconut oil contains very little linoleic acid (2% of total fat) and no linolenic acid.

In addition to saturated, monounsaturated and polyunsaturated fatty acids, another class of fatty acids called trans fatty acids are present in human diets. Small amounts of trans fatty acids are naturally present in cows' milk and other dairy products and meat from ruminant animals.

However, most of the trans fat in our diet originates from processed foods, such as hard margarines, cakes, biscuits and crackers prepared using partially hydrogenated vegetable oils. Partial hydrogenation converts liquid oils rich in polyunsaturated fatty acids into solid fats. This process results in the conversion of the naturally occurring monounstaurated and polyunsaturated fatty acids to trans fatty acids.

Continued next week

Acute diarrhoea

Here are certain hygienic measures which will help you to avoid getting diarrhoea and which should specially be followed during a trip or if you live in a country in which hygienic conditions leave much to be desired.

. wash your hands frequently.

See that children and house staff observe this rule.

. don't drink tap water. Drink only boiled and filtered water or bottled water. Never add ice cubes.

. avoid raw foods and salads, and only eat fruits which have to be peeled.

. eat meat and vegetables which have been well cooked and are served hot.

. avoid seafood and shellfish.

Treatment

When faced with a case of diarrhoea, first observe the degree of hydration of the patient, especially in the case of a child or an old person. A thirsty, irritable or sleepy child passing little urine dark in colour and with a swiftly beating pulse will have moderate dehydration and quick action must be taken.

Vomiting and high fever contribute to accelerating dehydration even it at first sight the case does not seem serious.

One can search for the cause of the diarrhoea once rehydration has been begun. This can be carried out by giving the patient sufficient liquid to compensate losses. The patient should be given drinking water, rice starch, slightly sweetened lemonade, light sugared tea, Coca-cola or other mineral waters such as Soda. If the loss of liquid is really high or if the diarrhoea continues, certain oral rehydration solutions on the market (such as REHIDRIN) should be given to the patient.

If the diarrhoea ceases or becomes less frequent, it is not necessary to give anti-diarrhoea medicines such as IMODIUM which do not prevent a recurrence of the ailment. Intestinal disinfectants such as ERCEFURIL or BEDELIX may prove useful in certain cases.

If the illness persists more than 24 to 48 hours with no improvement, with high fever or if the stools contain blood or pus, one must have them analyzed. It will also be necessary to follow adequate antibiotic treatment (BACTRIM AUGMENTIN, or others if necessary).

Travellers' diarrhoea

Nearly half the travellers coming into a tropical zone fall victim to acute diarrhoea which may vary in intensity at the beginning of their stay. The diarrhoea begins suddenly with frequent watery stools showing no trace of blood.

This is preceded by intense abdominal pains. Nausea and vomiting with a temperature of around 38C accompany the diarrhoea. Usually the patient recovers in 2 to 4 days. If the stools become bloody, temperature rises, or if the diarrhoea continues, one must consider that it is not tourist's diarrhoea.

Treatment is symptomatic: bed rest, diet with plenty of liquids. This must soon be replaced by light meals with a rice, coconut, apple or banana base, or crackers. Fruits, fibrous vegetables, whole grain and sometimes milk products must be avoided.

Anti-diarrhoea medication such as IMODIUM may be used, but intestinal disinfectants such as ERCEFURIL or INTETRIX must be avoided. If it is hot, one must watch out for dehydration, and the patient should take small quantities of drinking water frequently, slightly sweetened lemonade or the oral rehydration solutions previously mentioned.

What is diarrhoea:

Diarrhoea caused by a virus: slight fever, soft stools without any particular characteristics. This is the most common type. Usually rehydration and a suitable diet puts an end to this type of illness.

Diarrhoea caused by a bacteria which invades the intestinal mucus: stools may be glaireous, bloody or stink, with a general alteration in the condition of the patient and high fever. Rehydration and individual treatment of each case is necessary.

Enterotoxigenic diarrhoea: no fever, watery, extremely abundant stools due to the secretion of E. Coli enterotoxin and more rarely of vibriocholera. Rehydration and treatment are carried out under normal conditions during an epidemy.

Diarrhoea caused by a parasite: passing of stools is generally preceded by severe pain and cramp in the intestines. One must search for an amoebae or other type of parasite and carry out specific treatment.

Bonjour

How parents can deal with....

An overdependent, clinging child

Dependent behaviour involves the seeking of excessive help, affection or attention from another.

The overdependent child shows many signs of immaturity such as whining, crying and dependency behaviours. He also lacks initiative and demands that parents do things for him that he could do for himself.

Reasons why

1. Child is rewarded for his dependency behaviour, that is, he gets his own way.

2. Parents give in to whining child out of unconscious guilt like being away from the child too much.

3. Parents are permissive in their discipline. They have difficulty in setting limits.

4. Child wants to gain attention or power over parents.

5. Child is self-centred as he sees others only in terms of how they can be of use to him.

6. Child feels deprived or neglected.

How to prevent

1. Involve your child in decision making. In his daily activities allow him to choose what food to eat, clothes to wear and games to play.

2. Provide early support by being responsive to your child's physical and emotional needs.

3. Give immediate and friendly attention to any request your child makes. If "no" is the difinite answer, state it firmly and explain the reason.

4. Practice being away from your child for short periods of time from an early age.

5. Tell your child what both of you would be doing in your absence.

6. Before any separation, reassure your child that you will be coming back.

7. Provide activities that your child only gets to do when you are away or busy.

What to do

1. Be firm that your child comply to reasonable demands.

2. Encourage your child to adopt independent behaviour by correction. Identify unacceptable behaviour like "You just interrupted me". State your feelings about the behaviour such as "I feel like leaving the room when you cry" and point out an acceptable alternative like "When you talk to me without whining I'll listen to what you have to say".

3. Ignore your child's request for help. You can acknowledge your child's request with a phrase of encouragement such as "I'm sure you can do that."

4. Praise or reward your child for independent behaviour like playing on his own. You can also reward him for reduction in dependent behaviour; for example, you can state "If you whine less than five times today, you can go to the playground."

5. Use time-out to discourage dependent behaviours such as whining, crying or interrupting; for example, when your child starts to whine you can state "Jane, go to your room until you are ready to talk clearly without whining."

6. Set aside a "special time" daily for your child to give him positive undivided attention.

7. Encourage your child to engage in independent behaviour on a regular basis such as playing on his own.

8. Use a timer to gradually increase the time whereby your child has to play by himself.

What not to do

1. Procrastinate or be vague in response to child's request.

2. Pamper or doing things for your child that he is able to do for himself.

3. Punish child for clinging.

4. Dominate your child by imposing many rules and by nagging.

Source: Handlling Common Problems of Children