(Reblogged from Deakin Nutrition)
Coconut oil. Coconut water. The world it seems has gone coconuts for coconuts. To see if coconuts live up to the superfood hype surrounding them, or are just the latest fad food du jour, Master of Human Nutrition student Melissa Ferguson digs deeper.
I first became interested in coconut oil when I used it to make a butter-free shortbread for my dairy intolerant son. An internet search for more coconut oil recipes unearthed a testimonial by supermodel Miranda Kerr who credits her clear skin and shiny hair to ingesting several spoonfuls a day. Other health claims and applications ranged from the potential ability to cure Alzheimer’s disease, its use as a balm for dry skin, and its ability to protect against coronary artery disease (CAD). It all sounded too good to be true. So I went in search of ‘The Facts’, focussing on its role in CAD.
So what did you find?
Coconut oil is almost 90% saturated fat. In general, saturated fats increase serum cholesterol, which is a leading risk factor for CAD (the narrowing or blockage of the coronary arteries by a process called atherosclerosis). Other fats, such as polyunsaturated fats (including linseed or flax oil) and mono-unsaturated fats (including olive and canola oil), are protective against CAD.
Not all saturated fats are the same in their effects on cholesterol. Myristic, lauric and palmitic saturated fatty acids are known to raise total serum cholesterol while stearic acid has a neutral effect. Coconut oil contains approximately 40- 50% lauric acid, 20% myristic acid, 9% palmitic acid and 3% stearic acid. As can be predicted by its composition, coconut oil has been shown in several studies to raise total serum cholesterol.
So coconut oil is bad for our arteries because it raises total serum cholesterol?
It’s complicated. There are two types of serum cholesterol that comprise total cholesterol. HDL-cholesterol is known as ‘good’ cholesterol as it lowers atherosclerotic effects (possibly by carrying cholesterol away from the arteries to be processed and removed from the body by the liver). While LDL-cholesterol, the ‘bad’ cholesterol, can undergo a chemical process called oxidation which causes cells lining the arteries to deposit the cholesterol on the artery walls.
In limited studies, coconut oil has been shown to raise HDL cholesterol more than it raises LDL cholesterol, which results in a lower ratio of LDL to HDL (which your GP will tell you is a good thing). This effect is thought to be due to its unusually high percentage of lauric acid.
So coconut oil is good for our arteries because it raises the ‘good’ cholesterol?
This is what advocates of coconut oil claim. They also point out that studies on coconut oil in the past used coconut oil that was partially hydrogenated (and thus containing nasty trans fats). Also the processing of coconut oil affects the antioxidants present. There are more antioxidants in the expeller-pressed virgin coconut oil on the market these days, which may contribute to beneficial health effects.
Studies have also shown that, when compared to butter, coconut oil has less of a total cholesterol raising effect. However, the studies showing an increase in HDL are small and short in duration. Further data confirming this effect would probably make everyone a little more comfortable with the idea. Other studies have also shown that there are two types of HDL: one which is protective against CAD and another which is ‘non-functional’ and offers no protection. No one seems quite sure yet which HDL coconut oil is increasing when you eat coconut oil.
So coconut oil could possibly still be bad for our arteries then?
Well, for me, the jury is still out. A recent (2013) review on dietary fats and health has suggested that the already complex relationship between saturated fats, polyunsaturated fats, cholesterol and CAD is even more complex than previously thought. The interplay of other dietary and genetic factors could have more bearing on CAD than simply the quantities and types of saturated fats consumed.
You seem a bit clueless. What do the experts say?
The bottom line for most at the moment is that coconut oil contains saturated fats, which raise serum cholesterol, which is a risk factor for CAD. Moderation in the use of coconut oil is advised and health experts warn against replacing components of the diet (such as polyunsaturated fats or carbohydrates) with coconut oil. However, coconut oil may be a good choice for the replacement of other saturated fats, such as butter or hydrogenated vegetable fats (sources of trans fats).
Give us your conclusion then
I’m sure this is not the end for the coconut oil debate and I eagerly await further evidence. Further examination of the roles of dietary fats and serum cholesterol in CAD will make the picture clearer. For now though, I’ll continue to occasionally make coconut shortbread for my son. I may even rub some coconut oil into dry skin, but, at the risk of not becoming an international supermodel, I won’t be eating teaspoons of coconut oil each day.
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