Cholesterol has endured a poor reputation for being the instigator of the condition known as atherosclerosis, the hardening and narrowing of artery walls over time that can lead to Cardiovascular Disease (CVD). Some people believe that reducing dietary cholesterol will reduce our blood cholesterol levels and therefore reduce our risk of CVD by slowing down or preventing the build up of plaque in our arteries... These are the people that are still asking their doctors and dietitians if eggs are okay, as well as the doctors and dietitians themselves who are promoting that they aren't! But is dietary cholesterol really the problem?
Consider this - the total amount of cholesterol we have in our bodies at any one time is about 140 grams, and this far exceeds the amount anyone could eat in one day. On average, only 1 gram of cholesterol enters the body from the diet, and only half a gram of this is actually absorbed into the blood. Even if you happened to decrease your dietary cholesterol, by eating less red meat for example, your body has an amazing capacity to make up for any shortfall. Think of strict vegans or vegetarians who eat hardly any cholesterol, how are their bodies getting it? The human body is a very efficient cholesterol making machine, and the fact of the matter is that the problem of ‘high blood cholesterol’ does not lie in the amount of cholesterol we get through our diet!
It must be recognised that cholesterol is an integral part of our system’s structure and function. For example, cholesterol is important for regulating membrane fluidity of every cell in our body. Cell membranes are made from saturated and unsaturated fatty acids, and form compartments which not only need to be strong, they need to be flexible. The fluidity of these compartments is essential for processes including the transport of proteins. There is a delicate level of selection involved to ensure that the right proteins are going into the right cells so that they can carry out their designated functions. Membranes formed with unsaturated fatty acids can be too flexible (allowing any protein under the sun to flow through it), while those formed with saturated fatty acids can be too rigid (freezing proteins in their place and inhibiting transport). A role of cholesterol is to “fine tune” both extremes by either fixing membranes that are too fluid, or by introducing flexibility into those that aren’t fluid enough. Without cholesterol, the transport of particular proteins in and out of cells would be highly inefficient, or even impossible. Is a lower level of cholesterol in the blood really better?
Now that you have an insight into the function of cholesterol in the body; do you think cholesterol itself is responsible for "clogging" our arteries? Could it be that something else is causing the damage and cholesterol is simply found at the scene of the crime? There are multiple theories as to what causes the narrowing of artery walls, and the Cholesterol-Heart-Hypothesis is just one.
It’s important to be aware that the actual mechanism behind what causes atherosclerosis is still heavily debated. There is growing evidence to suggest that inflammation caused by a state of excess insulin in the body or the consumption of oxidised fats might warrant greater consideration. What we can all agree on, however, is that cholesterol is an essential component of our advanced biological systems. By choosing real foods that are minimally processed, low in sugar and rich in natural fats and high-quality protein, including a wide range of vegetables, you are taking a giant leap toward improving and optimising your health, longevity and well-being.
Information sourced from G. Denyer, Human Biochemistry 2014 lecture series, University of Sydney.