Steroids
Steroids are naturally made by our bodies in small amounts. They help to control many functions. But steroids can also be made artificially and used as drugs to treat different diseases, including cancer. Steroids used to treat cancer are usually a type called corticosteroids. These are man made versions of the hormones produced by the adrenal glands just above the kidneys.
Corticosteroids include:
- prednisolone
- methylprednisolone
- dexamethasone
steroids help control many body functions including:
- how your body uses food to produce energy (metabolism)
- keeping the balance of salt and water in your body
- regulating blood pressure
- reducing allergies and inflammation
- controlling mood and behavior
Cholesterol
Cholesterol is a waxy, fat-like substance that occurs naturally in the body. It plays a vital role in how every cell works and every single cell needs and contains cholesterol. The body also turns it into vitamin D and a variety of hormones and it is also the raw material for bile acids which the body produces to aid digestion of fat.
However, the type and level of cholesterol in the body is important for health and too high a cholesterol level increases the risk of heart disease. Although genetic factors play an important role in determining a person’s cholesterol level it is also influenced strongly by diet and while cholesterol level is regarded as a major risk factor for coronary artery disease, it is regarded as a “modifiable” risk factor. It can be modified by diet and the type and quantity of foods we eat can make a big difference and this provides an opportunity to develop specific foods which can help lower cholesterol levels. Cholesterol can enter the body in the foods we eat or can be produced in the body by the liver.
Dietary cholesterol accounts for around 25–40% of the daily turnover of cholesterol whereas production in the body accounts for 60–75%.
The liver is the “control centre” for the body’s cholesterol transport system. Cholesterol is transported around the body in the form of lipoproteins. There are two main types of lipoproteins involved in cholesterol transport and these are called LDL cholesterol (low density lipoprotein) and HDL cholesterol (high density lipoprotein).
The liver may transport cholesterol through the bloodstream to supply cells of the body via LDL cholesterol or cholesterol can be transported from the body’s cells back through the bloodstream, via HDL cholesterol. If there is a shortfall of cholesterol the liver can make some more. If there is an excess, the liver may send cholesterol back down to the gut, via the bile.
If LDL cholesterol is too high, too much cholesterol arrives at the artery walls and if there is not enough HDL cholesterol to carry away excess cholesterol, then cholesterol starts to build up on the artery walls. Eventually the lining of the arteries starts to become overloaded with cholesterol and the artery walls thicken and become less flexible and coronary artery disease is underway.
LDL cholesterol is therefore often called “bad” cholesterol and HDL cholesterol is called “good” cholesterol because of their relative roles. Usually when cholesterol is described as “high” it is the LDL cholesterol which is of main concern whereas the key concern with HDL cholesterol is whether it is too low.
Dietary Cholesterol
All dietary cholesterol is derived from animal products. The major sources of cholesterol in the diet are egg yolks, products containing milk fat, animal fats, and animal meats. Many studies have shown that high intakes of cholesterol will increase the serum cholesterol concentration. Most of this increase occurs in the LDL cholesterol fraction. When cholesterol is ingested, it is incorporated into chylomicrons and makes its way to the liver with chylomicron remnants. There it raises hepatic cholesterol content and suppresses LDL receptor expression. The result is a rise in serum LDL cholesterol concentrations. Excess cholesterol entering the liver is removed from the liver either by direct secretion into bile or by conversion into bile acids; also, dietary cholesterol suppresses hepatic cholesterol synthesis. There is considerable variability in each of these steps in hepatic cholesterol metabolism; for this reason the quantitative effects of dietary cholesterol on serum LDL cholesterol levels vary from one person to another. For every 200 mg of cholesterol per day in the diet, serum LDL cholesterol is increased on average by about 6 mg dl−1.