Can fats be healthy? The answer is “yes”. Fats are one of three vital nutrients which are used as an energy source by our body. Fat-soluble vitamins like vitamin A, D, E, and K can be absorbed by the body only in the presence of fats. Fats act as energy reserve and allow us to withstand long hours of starvation. It is also an important component of the cell membrane.
Removing fats totally from our diet is never advisable. The choice of fats has to be made wisely. The total fat intake consists of saturated, monounsaturated and polyunsaturated fats together. Research has proved that intake of mono and polyunsaturated fats helps to reduce the levels of blood cholesterol.
Difference between Saturated and Unsaturated Fats
Structurally, a saturated fat is fully saturated with hydrogen atoms and none of the carbon atoms are linked with double bonds. Saturated fats are solids at room temperature and are usually found in animal products. Some of the most prevalent sources of these chemically least active fats are dairy products, meats, pork etc. Processed foods like chips, pastries, ice-creams etc also show a very high concentration of saturated fats. These fats are not friendly to heart, as they increase the concentration of low density lipoproteins (bad cholesterol) in the blood leading to heart diseases.
Unsaturated fats, on the other hand, have one or more double bonds between their carbon atoms. Unsaturated fats are liquid at room temperature and hence are also known as oils. Fats which have single double bond between the carbon atoms are termed as monounsaturated fats, for example, 18-carbon oleic acid. Fats which have more than one double bond between their carbon atoms are known are polyunsaturated fats, for example, linoleic, linolenic and arachidonic acids. Prevalent sources of unsaturated fats are vegetable oils extracted from sunflower, safflower, soy bean, cotton seed, corn etc. Apart from these whole grain cereals, fish oil and oils extracted from nuts and olives are also rich in unsaturated fats. These fats are considered to be healthy and friendly to heart, as they increase the concentration of high density lipoproteins (good cholesterol) in the blood.
Why are unsaturated fats considered to be good for health?
Unsaturated fats increase the levels of high density lipoproteins which prevent the accumulation of bad cholesterol on the walls of the arteries. HDL carries LDL to the liver where it gets broken down and released.
Essential Fatty Acids
Fats which cannot be synthesized by the body and which have to be acquired through diet are termed as essential fatty acids. They are long chain polyunsaturated fatty acids, categorized into two families: Omega-3 and Omega-6 fatty acids.
Omega-3 and Omega-6 fatty acids are also known as n-3 and n-6 fatty acids. The counting of the carbon atoms begins from the methyl end of the fatty acids. In Omega-3 and Omega-6 fatty acids, the first double bond is positioned at third and sixth positions respectively.
Essential fatty acids perform some vital functions in our body like:
Manufacture and repair of cell membranes
Production of prostaglandins, which in turn regulate heart rate, blood pressure, maintenance of fertility and conception etc.
Encouraging the body to fight against infections
Maintenance of proper growth in children
Sources of Omega-3 Fatty Acids
There are three nutritionally significant omega-3 fatty acids which are extracted from different sources.
Alpha Linolenic Acid (ALA) obtained from plants
Eicosapentaenoic acid (EPA)
Docosahexaenoic acid (DHA)
Out of the three, the later two are found in animals. ALA later gets metabolized to EPA and DHA. Recommended dietary intake of omega-3 fatty acids is suggested to be 1 – 2 g per day.
Plants sources of ALA:
Flaxseeds – They are known as alsi in Hindi, Aviselu in Telugu, and Agasi in Kannada. The oil extracted from these seeds is the richest source of ALA.
Canola – The name canola comes from Canadian oil and is extracted from the seeds of a genetically engineered plant developed in Canada from the Rapeseed plant. The Rapeseed plant belongs to the mustard family. This is a cheaper alternative for ALA.
Soy beans – The oil extracted from these seeds also contains ALA but in a lesser concentration when compared to omega-6 fatty acids.
Perilla – This is an annual herb which belongs to the mint family.
Chia – It is a flowering plant native to central and southern Mexico and belongs to the mint family. Its seeds are used for extraction of oils. These seeds can also be taken raw. The sprouts of these seeds are very nutritious and taken as salads along with sandwiches. Soaked chia seeds can be used in porridges and puddings.
Hemp – Hemp is a common name used for Cannabis plant. These seeds can be consumed raw as sprouts or can be converted into milk similar to soy milk. This can be used to prepare hemp tofu or a non dairy ice-cream.
Walnuts – They can be directly consumed as they are rich source of omega-3 fatty acids. Walnuts are high in calories too. So moderation in consumption is advised.
Animal sources of ALA:
Few varieties of cold water fish have been found to be rich in ALA. They are Salmon, sardines, herring, mackerel etc. So the fish oils extracted from these sources can form an important component of our diet.
The thylakoid membranes of green plants with broad leaves also have a high proportion of ALA. Hence animals which consume these plants are also a good source of ALA.
Sources of Omega-6 Fatty Acids
Nutritionally significant omega-6 fatty acids are Linoleic acid and Arachidonic acid. They are also known as polyunsaturated fatty acids or PUFAs. The Linoleic acid gets converted to gamma-linolenic acid (GLA) within our body. They act as precursors for prostaglandins and are vital for healthy brain functioning.
A large number of vegetable oils have been found to be rich in omega-6 fatty acids and few of them are:
Cotton seed oil
Evening primrose oil
Note: Although these oils are rich in essential fatty acids it is advised to avoid the consumption of refined and hydrogenated versions of these oils as they are injurious to health.
Some other plant sources which are rich in omega-6 fatty acids are:
Other poultry products like chicken.
The Ratio of Omega-6 to Omega-3
Clinical studies have shown that maintenance of n-6 / n-3 ratio within the range of 1:1 to 1:4 is very essential for healthy heart condition and prevents inflammation which leads to type-2 diabetes. A large variety of diseases like cancer, arthritis, obesity, asthma, depression, are also associated with the imbalance in the ratio of n-6 / n-3. Although both are essential fats and have to be obtained from our diet, a search for healthier source of omega-6 fatty acids having a considerable amount of omega-3 fatty acid is advisable.
An individual’s intake is expected to be higher in omega-3 fatty acids. This was possible in olden days when the availability of processed foods was less and people used to feed more on fresh vegetables and whole grains. Poultry animals and cattle used to graze on naturally available fresh grass and green leaves which are a rich source of omega-3 fatty acids. We used to get them naturally from animal products like meat, eggs, and milk. The modern man depends more on fast foods and almost every cereal, seed or grains of pulses are processed in many steps. At each step, food item becomes easier for consumption but at the cost of loss of certain vital nutrients. The food processing techniques increase the concentration of omega-6 fatty acids in the foods. The deep fried items like chips etc are prepared using vegetable oils. Hence it is advisable to take natural foods in the raw form.
Selection Criteria for Intake of Fats:
Avoid saturated fats as far as possible
Choice of an apt polyunsaturated fat is a wise decision to be taken
Try to take foods rich in omega-3 fatty acids like whole-grains, fresh fruits and vegetables.
Non-vegetarians can supplement their diet with fish.
Try to minimize the intake of processed and fast foods.
Anna Purna Edara is currently a freelancer working on home-based jobs. She has about 2 and a half years of experience in the annotation of Biological databases in various organizations. She is a Post Graduate in Biochemistry and hold a PG Diploma in Bio-informatics. Visit her website at http://purnasrinivas.webs.com