chewing the fat on ... fats

For the longest time, fats and oils food groups have been villainized by health professionals and fitness enthusiasts because of its association with weight gain and obesity, and subsequently diseases such as heart attack and high blood cholesterol and diabetes. However in the more recent years, heatlh professionals have started to preach a more holistic approach to nutrition, underlining the importance of including proportionate amount of healthy fats in the meals rather than obliterating it from our foods.

Now the question is: what is healthy and what is not healthy? We are bombarded by words such as cholesterol-free foods, trans-fats, saturated fat, unsaturated fat, poly-monounsaturated fat and all that tongue twisters; what are they actually?

Okay, lets first get to basic, and try to understand the story of fats from the beginning. We'll just discuss the components that are relevant to dietary fats and fats found in our blood, so as not to confuse ourselves even more.

Fat consists of a few groups of chemical compounds in the family of lipids. The main types found in our foods are the glycerides, phospholipids and sterols. More often than not, these groups present together in our food.

For the purpose of this discussion, let's imagine that glyceride is a wooden box, phospholipid is a metal box and sterol is made of plastic. In each of these boxes, there are crayons and coloured pencils. Some of these are short and some are long. 

So far so good with your imagination?

Okay, let's continue. You want to draw a pretty picture using the colours from all the boxes. You must use both the crayons and the coloured pencils, but as much as possible try to use the crayons because the pencils are sharp and may hurt you when you use it. You may use the crayons as much as you like, but don't use a sharpener to sharpen the crayons or else you may hurt yourself too. There are times when you'll need to use a marker pen, and since it is not available in your box, you need to borrow someone else's marker pen for your drawing.

Some of you might get dizzy already, but bear with me while I explain. The crayons are types of unsaturated fatty acids while the pencils are saturated fatty acids. Saturated or unsaturated state of the fatty acids depends on the chemical structure of the acid and has nothing to do with volume or quantity of the fatty acids in the food. Studies have shown association between excessive consumption of saturated fatty acids (or commonly just called saturated fats) with diseases such as high blood cholesterol, heart problems and certain cancers. Note the key-word here being: excessive.

Now back to the colours. While the unsaturated fats being portrayed by crayons, there is a caution for using the sharpener to sharpen the crayons. Now this is where it gets a little bit more tricky. Chemically, the unsaturated fatty acids are divided into the cis- configuration and the trans- configuration. In our crayon analogy, the cis- are the normal crayons, while the trans- are the sharp pointed crayons. 

Comparatively, the trans- configuration is more stable; however, in nature, most of the unsaturated fatty acids exist in the cis- configuration. It is possible to convert the cis- fatty acids into trans- fatty acids (or trans fats) through a process called hydrogenation. This process stabilises oil resulting in higher melting point and ability to stay as semi-solid in normal environmental temperature. This discovery was an important breakthrough with huge economic implications. Vegetable oils can be hygrogenated to become margarine, which is cheaper and lasts longer than animal fats (butter or ghee). The problem: trans- fatty acids may behave like saturated fats, and may be associated with diseases such as high blood cholesterol, heart problems and certain cancers.

Now we come back to the analogy of the containers. The wooden box, the metal box and the plastic box each carries their own mix of crayons and coloured pencils. Just as the glycerides, the phospholipids and the sterols carry their own chains of fatty acids, and it could be a mixture of saturated or unsaturated fatty acids. The crayons and the coloured pencils may be the same, but since the boxes are made of different material, the function could differ from one another.

The glycerides, or specifically triglyceride, is the main currency in conversion of adipose fat into glucose and vice versa in our body. The phospholipids makes up the structure of all our cell membrane while the sterols (or cholesterols) also are essential component of the cell membrane, involved in the production of hormones, bile acids and vitamin D. The glycerides is the commonest form of lipid group found in animal fats and vegetable oils.  Foods that are rich with phospholipids are such as soy, sunflower seeds, chicken egg yolk, cow milk and fish eggs. Major dietary sources of cholesterol include breast-milk, cheese, egg yolks, beef, pork, poultry, fish, and certain crustaceans such as prawns.

Remember the marker pen that you need to borrow from someone else? That's a fatty acid called essential fatty acid (Omega-3 and omega-6), dubbed as "essential" because it cannot be produced by our own body and hence it is essential to get it via dietary source. Essential fatty acids are important in normal body function and health maintenance and not so much in the energy metabolism. Some of the food sources include fish and shellfish, flax seed, hemp seed, soy oil, canola oil, chia seeds, pumpkin seeds, sunflower seeds, leafy vegetables, and walnuts.

Gone are the days of extremely low-fat diets. We realise now that a complete nutrition, and that includes a healthy proportion of fat, is important for maintenance of health and normal body function. That doesn't mean you now can chow down three plates of charkueyteow or snack on fried chicken skin from the pasar malam! According to dietary experts, adults should get 20 to 35 percent of their total daily calories from fats and also try to reduce the intake of saturated and trans fats while replacing those unhealthy fats with beneficial omega-3 fatty acids. 

Eat proportionately, eat healthily!

reference: www.webmd.com