Was sitting down to breakfast from a "certain fast food chain" when this idea about good fats and bad fats struck. Singaporeans love to eat and what better way to kick start this blog than with food!Even my 6 year old son has become health conscious from the adverts he sees on TV. He tells me - we can still eat from this "certain fast food chain" because if you order the stuff with a "red pea" it is healthy. So why all this campaigning to consumers to convince us that fast food is healthy? Also, have you noticed that the latest buzz word with food operations is that their food contain "no trans fats"? So...are good fats and bad fats just a fad?
Two starting points to answer this question:
1) What are fats?
2) Why are fats bad for health?
1) What are fats?
Fats come under a group of biochemical macromolecules called "lipids". Where lipids are a large and diverse group of molecules characterised by their insolubility in water. Other lipid molecules include steroids, of which, cholesterol and sex hormones are well known compounds. So, fats and cholesterol are not the same compound but they are both lipids. Infact, the scientific name for fats is "triglycerides".
Our bodies utilise lipids for various functions such as energy, as components of our cells, to protect our nerves and many more. How are these lipids transported to the sites where it is needed by our bodies? It has to be transported via the blood stream. But remember...lipids are insoluble in water and our blood is aqueous in nature. So, how are lipids transported in the blood? The answer is using specialised lipid packing molecules called "lipoproteins". These are the LDL and HDL molecules that you so often hear about when one goes for a cholesterol test.
Low Density Lipoproteins (LDL) are considered "bad cholesterol". Actually, they aren't strictly speaking cholesterol molecules but cholesterol PACKING molecules. LDL is considered bad because these molecules circulate in the blood stream and having too much of these could result in lipids being deposited in one's arteries (more about this later).
High Density Lipoproteins (HDL) are considered "good cholesterol". Again, these aren't strictly speaking cholesterol molecules but cholesterol PACKING molecules. HDL differs from LDL in its function. HDL transports lipids away from the body to the liver for excretion. In other words, HDL removes any potentially damaging lipids from the body and, thus, is "good".
So why am I going on about LDL and HDL molecules? This is because these molecules hold the answer to my second question.
2) Why are fats bad for health?
Everyone has heard this - watch your diet if you do not want heart disease. What is the scientific basis for this saying?
As mentioned above, too much LDL circulating in the blood stream could result in lipids being deposited onto arteries (blood vessels). The consequence of this, is that the arteries become increasingly narrow and eventually totally blocked - a condition known as "artherosclerosis". When this occurs, no blood will be able to flow through the blocked artery which then leads to strokes and heart attacks.
For good health, a person needs to maintain high levels of HDL (to remove potentially damaging lipids) and low levels of LDL (to minimize the amount of circulating lipids in the body).
Fats become damaging when they alter this HDL/LDL profile in the body. Trans fats are especially damaging because they raise levels of bad LDL and lower levels of good HDL! It has been suggested that this negative effect may be so because trans fats are not naturally occurring and hence the body has not been designed to metabolise these type of fats. Trans fats are produced by heating liquid vegetable oils in the presence of hydrogen. This occurs during food processing as with potato chip snacks, french fries and onion rings, just to name a few. The findings of the effects of trans fats in the 1990s have been so pertinant to health that as of January 1, 2006, trans fats must be listed on food labels in the US.
For more about the effects of consuming different types of fats please refer to the following link:
http://www.hsph.harvard.edu/nutritionsource/fats.html
In closing, until some other scientific finding proves otherwise, it is not so much the amount of fat we eat but the type of fat we eat. To this end, good fats and bad fats are not just a fad but a fact (well, at least for now)!
Tried to embed this but couldn't. Do check out this YouTube video about "Understanding Cholesterol".
http://www.youtube.com/watch?v=hjv5OnbcjE8
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