The Health, Nutrition and Wellness site
16 Apr
Cholesterol, that’s the bad stuff right? Not all true actually, our bodies need some cholesterol to function normally and some is produced by the body itself. Let’s take a look at how cholesterol functions in the body:
Cholesterol, a steroid lipid(fancy word for a fat) made up of carbon and hydrogen and a precursor of many steroids synthesized in the body (eg. Progesterone, bile acids) is transported in blood via something called the cholesterol transport system. This is done on little ‘vehicles’ called lipoproteins, fatty substances carried in an envelope of proteins and lecithin-like substances, of which there are various forms. These are: Chylomicrons, Very-Low-Density-Lipoprotein [VLDL], Low-Density-Lipoprotein [LDL] and High-Density-Lipoprotein [HDL].
Cholesterol taken in by dietary means (all those weekend fry-ups) and cholesterol in bile is carried from the intestines to the liver by the chylomicrons. These are lipoproteins which contain mainly triglycerides which are molecules of fat or oil. Lipoproteins are particles which are constructed so they have charged hydrophilic( water-loving) protein groups aimed at the outside (to make them able to travel in the water-rich environment of the body), with their hydrophobic (water-fearing) cholesterol and triglycerides on the inside ( away from the watery environment). When the triglyceride is removed from the chylomicron, one is left with a chylomicron remnant. This chylomicron remnant can then be metabolized by the liver or be used to make LDL. Cholesterol is then secreted by the liver in VLDL (Cholesterol is one of its main components). The VLDL is transported via the blood to the tissues, where it is converted to LDL in the adipose (fatty) tissue. The Low-Density-Lipoprotein (LDL) then carries the cholesterol to the receptor sites on the cells of many different body tissues and releases the cholesterol when it is taken up by the cell receptors. High-Density-Lipoprotein (also manufactured by the liver) then ‘picks up’ the released cholesterol and transports it back to the liver. In the liver the returned cholesterol is converted into bile. Bile acids is the last step in the body’s breakdown of cholesterol as the body is not able to break down cholesterols’ steroid nucleus.
Reducing overall cholesterol levels is simply a matter of increasing the levels of HDL (which removes cholesterol from the tissues and takes it to the liver to be excreted or recycled) and decreasing the levels of LDL (which takes cholesterol to receptor sites on cells). There are various ways of doing this:
Take a look at your diet. Increasing the intake of dietary fibre can decrease cholesterol levels as the fibre binds to the bile acids and so keeps the cholesterol in them from being reabsorbed by the body. Fibre can be found in legumes(chickpeas, butter beans), fruits such as apples and also in vegetables.
Monounsaturates , a type of fatty acid, found in olive oil (omega 6 fatty acids), avocado oil and peanut oil can help to raise HDL levels and lower LDL levels while the polyunsaturated fatty acids found in evening primrose oil can lower LDL levels but will lower HDL levels as well.
Omega-3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), both found in fish oils also contribute to higher levels of HDL and lower levels of LDL.
Lifestyle habits such as smoking lead to low levels of HDL so giving up smoking would significantly help to raise levels of HDL. Another risk factor for low levels of HDL is obesity, thus following a regular exercise program and having a healthy diet would assist in raising these levels.
Another way to keep LDL levels healthy is to ensure you are getting enough Vitamin C and chromium in your diet as a deficiency in either of these can contribute to raised levels of LDL. Avoiding excess intake of copper, iron and sodium (watch your salt intake) can also help as too much of any of these can contribute to raised LDL levels. Moderate alcohol consumption (no more than two drinks(units) a day) can also help to raise HDL levels.
Eating too much animal protein can raise LDL levels whilst eating vegetable protein like pulses can help lower LDL levels, thus a higher proportion of vegetable protein as opposed to animal protein is recommended in the diet. Try replacing one meat meal a week with a good vegetable protein like soy in the form of tofu or soya sausages or even a glass or two of soya milk.
Keeping HDL levels high and LDL levels low is very much a case of living sensibly: doing enough exercise, not eating too much animal protein, whilst eating plenty of vegetable protein, fruits and vegetables (for the fibre, vitamins and minerals) and ensuring you get a good intake of EFAs (essential fatty acids) from fish and vegetable oils.
Cholesterol is a necessary substance in our body and as with all things, a little forethought can go a far way in keeping it at levels optimum for good health.
Sources: Fats that Heal, Fats that Kill – Udo Erasmus