Cholesterol

Main functions of cholesterol

• The major function of cholesterol is to sense the changes in the level of fluidity in the membrane and maintain the appropriate balance. The need to maintain the fluidity level is so significant that each cell in the membrane can naturally synthesize its own cholesterol.
• Membranes are built by fatty acids, the intake of which varies from day to day. If we consume unsaturated fats the membranes become more fluid, while saturated fats harden membranes. Cholesterol from our cells is required to maintain this day to day change in fluidity levels, by hardening membranes when loose and increasing fluidity when the membranes are stiff.
• Cholesterol is required to manufacture steroid hormone. The female hormone estrogen and the progesterone and male hormone testosterone are developed and maintained by cholesterol to allow difference in the genders.
• The adrenal corticosteroid is made by our body from cholesterol. Aldosterone, one of the hormones manufactured, regulates the balance of water through our kidneys and also helps to increase the retention of sodium in the renal tubules. Cortisone helps in the synthesis of glucose which is necessary to boost the energy for fighting or fleeing in stressful circumstances. This hormone also suppresses inflammation.
• Synthetically made steroids like anabolic steroid, which is a male steroid hormone, are used by the athletes. These artificially manufactured steroids have many side effects like damage to the brain, liver, kidney, ligament, and joint. They can cause cancer too. In women steroids cause bone growth, muscle growth, growth in facial hair or deeper masculine voices.
• Vitamin D is made from cholesterol and which regulates metabolism of two minerals calcium and phosphorous.
• Cholesterol along with bile acids performs the vital function of digesting and absorbing oils, fats, and fat soluble vitamins from food. Bile acids are derived from cholesterol and when cholesterol is not needed as bile acids it is discarded by the body.
• Cholesterol protects our skin against the ravages of weather and prevents dehydration, cracking and general wear and tear, as cholesterol is secreted into our skin through glands. As a covering over our skin, cholesterol prevents the skin from getting infected by foreign organisms and also helps in the healing process of skin tissues.
• Cholesterol might do the trick for you when minerals and vitamins in the body are in short supply by acting as an antioxidant. Both lipoproteins LDL as well as HDL contain large amounts of oxidized cholesterol which pep us up when antioxidants are not available from food. Antioxidants like vitamins B3, C, E, carotene and elements like zinc, copper, sulphur and selenium help to lower cholesterol levels. People who have high serum levels are treated with a combination of chromium with niacin (vitamin B3) molecules to lower cholesterol with a 50% success rate. Chromium however is not an antioxidant.

Main sources of cholesterol

Cholesterol from the body

As mentioned cholesterol can be manufactured in the body or obtained from food intake. Cholesterol is absolutely necessary for many of our body functions. Cholesterol is definitely required for maintaining the fluid content in the membranes. As an illustration let us take the example of alcohol. Alcohol when drunk dissolves in the body and the membranes become more fluid than required. As a result cells in the membrane build more cholesterol so as to bring the membrane back to normalcy. Slowly the alcohol wears off, naturally the fluid in the membrane will decrease, hardening it and so some cholesterol membrane is removed in order to maintain the fluidity level required in the membrane.
This extra cholesterol takes a piggy ride on the back of essential fatty acids ( EFA) and together they move to the liver through the bloodstream and here it is changed to bile acids, provided that vitamins and minerals needed for the transformation are available.
The liver in turn deposits the bile acids into the intestines where it helps to digest fat. The bile acids then find their way out of our body along with solid waste. It is necessary therefore to eat a diet rich in fiber for regular bowel movement or else the bile acids in the intestines will be reabsorbed and recycled into the body instead of getting removed.
Besides cells, other organs that make their own cholesterol in order to efficiently carry out those functions that require cholesterol use are liver, intestines, adrenal glands and sex glands. The placenta makes cholesterol during pregnancy, as it requires it to make progesterone which in turn is essential for the continuity of the pregnancy.

The process of making cholesterol

Cholesterol is made through a complicated process of hooking together fifteen of the two- carbon acetates to make a chain of thirty carbons. Other steps follow in which different enzyme catalysts are involved in a cyclic of changes which results in removing the three extra carbons so that the 27-carbon cholesterol molecule can be formed. What is important in this whole process is to be able to find the source from which the 2-carbon acetates can be procured.
When mitochondria is required to produce energy, cells break down fatty acids, amino acids, sugars and starches, at each step 2-carbon acetates are clipped off to make them available for the thirty carbon chain. Another source of acetates is alcohol.

Cholesterol from proteins and essential fatty acids

Our body does not burn proteins in order to make energy. It conserves proteins so that it can use them for making enzymes and for building other structures. Only in extreme cases like fasting or due to some diseases and when extra protein has been consumed, does the body use its protein stock.
Similarly essential fatty acids are also conserved for some vital functions. So the main sources of acetate from fats is derived from saturated and monounsaturated fats.
Cholesterol is also increased from foods that are rich in refined carbohydrates. Acetates are easily available when people eat too many processed foods, raising cholesterol levels due to high calorie intake.
Stress too can produce cholesterol from where acetates could be available.

Cholesterol from food sources

Most food from animal sources like, eggs meat, fish, shellfish and dairy sources, has high cholesterol content. An egg, � pound of liver has about 250 mg of cholesterol. Fish and shellfish have less and plants are cholesterol free. Increased levels of cholesterol from foods, decreases the production of cholesterol in the body. This is true for 70% of the population in affluent countries. The remaining 30%, who may not be able to have a feedback, it is advisable that they limit cholesterol intake. However, the feedback system which triggers cholesterol production in the body when required may go wrong when certain drugs cause an increase in cholesterol. Also toxic molecules in the environment, food, water may result in faulty feedback.

Elimination of cholesterol

Cholesterol is made in the body but it can be broken down unlike sugar, amino acids, fatty acids or nucleic acids. These sugars and acids do not only break down but can be converted to water, ammonia, and carbon dioxide. The only way cholesterol can be removed is through passing stool when it is deposited in the intestines in the form of cholesterol molecules and bile acid. Dietary fiber is essential to the removal of cholesterol from the body.

Atherosclerosis

Atherosclerotic deposits consist of fats, proteins, cholesterol and minerals. People who suffer from atherosclerotic deposits suffer from narrow arteries and a slow blood flow. In addition saturated fatty acids make blood platelets sticky and clot formation could increase. A person with both these problems could find an artery completely blocked, which could result in the cells dying in the affected area, as nutrients and oxygen to that part of the body could be completely cut off.

Narrow or blocked arteries in various parts of the body can be fatal and will result in the following problems.

• In case the artery supplying blood to the brain is blocked it will result in a stroke which could be fatal.
• When arteries in the chest narrow down it causes angina pain after fat-heavy meals or on exertion as it thickens the blood and so supply of oxygen is reduced.
• If a clot blocks an artery in the lungs it will cause pulmonary embolism.
• A blocked artery in the heart will cause a heart attack.
• Blocked artery in the legs will cause circulation problems which could lead to gangrene.
• Deafness and blindness can ensue from blocked arteries to the ear and eyes.
• Atherosclerotic deposits also lead to high blood pressure because the arteries are hardened and no longer resilient to the heartbeat.
• The heart and kidneys have to work harder and so water retention could result in kidney and heart failure.

North Americans, Europeans and other affluent nations have at least two thirds of the population that is prone to atherosclerotic deposits.