CHOLESTEROL, DIET AND EXERCISE
Cholesterol is a waxy, fat like substance found in all animal products (i.e., meats, dairy products and eggs). The body can make cholesterol in the liver and it can absorb cholesterol from the diet. Cholesterol is essential to the body and is used to build cell membranes, produce hormones and form bile acids which are necessary for the digestion of fats.
However, when blood levels are too high some of the excess is deposited in the artery walls, increasing the risk for heart disease.
Cholesterol is a fat-soluble substance that is carried in the blood by transporters called lipoproteins. Lipoproteins are an essential part of the complex system that exchanges lipids between the liver, the intestine, and peripheral tissues. Lipoproteins are classified as high density, low density, or very low density, so named by the amount of protein present in relation to fat.
High-Density Lipoprotein (HDL)
HDL-cholesterol, sometimes called the ‘good’ cholesterol, is responsible for the transport of cholesterol from the blood and artery walls to the liver where it is converted to bile to be used for digestion or disposed of by the body. In essence it ‘mops up’ the bad cholesterol. This process is helpful in preventing or reversing heart disease. If levels of HDL are too low the risk of heart disease increases.
The role of LDLs, sometimes called the ‘bad’ cholesterol, is to transport cholesterol to various body cells and deposit any excess in the artery walls. These deposits restrict blood flow, thereby increasing the risk of heart disease.
Very low density lipoproteins (VLDL)
Similar to LDL cholesterol as it contains mostly fat and little protein.
Another type of fat that is carried in the blood by LDLs. Any excess consumption of sugar, alcohol or calories are converted and stored in fat cells throughout the body.
A high total cholesterol level is a risk factor for future health problems. Even if your total levels are within recommended levels, the ratio of HDL to LDL levels is also important. A high level of HDL cholesterol and low level of LDL (a low TC to HDL ratio) is optimum.
Factors affecting cholesterol levels
* Diet - Saturated, trans fats and cholesterol in your diet increases cholesterol levels.
* Weight – If you are overweight you are likely to have an undesirable ratio of LDL cholesterol and triglycerides, to HDLs.
* Exercise - Regular exercise can lower LDL cholesterol and raise HDL cholesterol.
* Diabetes - Poorly controlled diabetes increases cholesterol levels.
* Smoking - Acrolein, a chemical found in cigarettes stops HDLs from transporting LDLs to the liver.
* Age and Gender - Cholesterol levels rise as we hit middle age. This is especially true for post-menopausal women.
* Genetics - Your genes can influence the amount of cholesterol the body makes.
Problems associated with elevated cholesterol levels
Coronary Heart Disease (CHD) and Cholesterol
CHD is the main risk associated with high cholesterol. If cholesterol levels are too high it will build up in the walls of the arteries. Over time, this will lead to a hardening of the arteries (atherosclerosis). The arteries will subsequently narrow, slowing blood flow to the heart leading to angina or if the vessel becomes completely blocked; a heart attack.
Stroke and Cholesterol
Atherosclerosis can block normal blood flow to the brain and cause a stroke.
High Blood Pressure and Cholesterol
Hypertension is linked to high cholesterol. Hardened and narrowed arteries cause the heart to work much harder to pump blood resulting in increased blood pressure.
Diabetes and Cholesterol
Diabetes can negatively alter the balance between HDL and LDL cholesterol levels. Diabetics are likely to have LDL particles that stick to arteries and damage blood vessel walls more easily. Glucose attaches to lipoproteins and remains in the bloodstream longer, potentially leading to plaque forming on the artery walls.
Peripheral Vascular Disease and Cholesterol
The fatty deposits along the arterial walls can affect blood circulation, predominately in arteries leading to the legs and feet.
The role of diet and exercise in reducing and preventing high cholesterol levels
A number of foods contain dietary cholesterol including prawns, kidneys and eggs. However, saturated fat has a far greater impact in the amount of cholesterol present in your blood. The most effective way to reduce blood levels is to limit the amount of saturated fat in your diet and increase your fibre (whole grains, beans, lentils) fruit and vegetables.
Replacing saturated fats with unsaturated by eating at least two portions fish, one of which should ideally be oily fish high in omega 3s (helping reduce your LDL levels), and including nuts and seeds is a great way towards a healthy diet. It’s also important for everyone to avoid artificial transfats where possible. These are found in processed foods as hydrogenated fats.
Cooking processes also affect the amount of saturated fat in the diet. Opt for steaming, poaching, boiling and grilling where possible.
It is recommended to limit your average daily cholesterol intake to less than 300 milligrams. For those with heart disease, this limit is lower at 200 milligrams per day.
The role exercise plays in reducing cholesterol levels is to significantly reduce triglycerides and activate a number of metabolic processes within the muscles and liver that convert LDL to HDL cholesterol. A reduction in triglycerides decreases the number of particles that promote the growth of fatty deposits on artery walls. Even moderate exercise can raise your levels of the ‘good’ HDL cholesterol.
The response in change of HDL levels is dependent of the duration, intensity and frequency of exercise and will vary between individuals. However, the volume required is similar to that for weight loss, which is why fat weight loss (not muscle) is linked to a positive rise in good cholesterol and an overall reduction in total cholesterol. Combining exercise with dietary changes will give you the double whammy of also reducing levels of LDL cholesterol.
Recommended blood levels
Cholesterol is measured in millimoles (mmol) per litre (L) of blood. The NHS guidelines for healthy adults are:
Total cholesterol 5.0 mmol/l or lower.
LDL 3mmol/L or lower
HDL above 1 mmol/l
Triglycerides below 1.7 mmol/l
The ratio of total cholesterol to HDL - total cholesterol divided by HDL - should ideally be below 4. These figures will be lower for those with high risk factors.
If you're new to exercise and have elevated cholesterol levels consult your GP before beginning an exercise programme.
If you'd like more advice on how you can lower your cholesterol with diet and exercise contact Hillcliff Personal Training today to see how we can help.