Understanding cholesterol and triglycerides

The two most important types of fat in your blood are cholesterol and triglycerides. Regular consumption of protective foods will help to keep them at healthy levels.

Your liver, intestines and even your skin create your body's cholesterol. It binds to proteins and is transported around the body in complex molecules called lipoproteins. Amongst other functions, cholesterol helps to build cell membranes, insulate nerve fibres and make hormones, vitamin D and fat-digesting bile acids. There are two types of cholesterol.

• The potentially harmful variety is characterized by low-density lipoproteins (LDL's). Their role is to carry fat from the liver to be used by body cells. LDL's are harmless until they come into contact with unstable molecules in the blood called free radicals, which damage the cholesterol in a process called oxidation. Oxidized LDL's are sucked into the inner linings of artery walls and contribute to the buildup of plaque and inflammation. Excess body fat in the abdominal area, a diet high in saturated fats and lack of activity can all prompt the liver to produce more LDL's.
•  "Good" cholesterol is characterized by high-density lipoproteins (HDL's), which travel around the bloodstream mopping up LDL's and transporting them back to the liver for disposal. They may also act as antioxidants, stopping LDL's from causing damage in artery walls. The higher your level of HDL cholesterol, the closer you are to the "natural" cholesterol balance enjoyed in early hunter–gatherer societies, and the lower your risk of having blocked arteries that could prompt a heart attack or stroke.

• Unsaturated fats — from plants, fish and nuts — can lower LDL and raise HDL levels. Omega-3 fats from oily fish such as salmon, walnuts and canola oil are particularly good at raising HDL levels — as is soluble fibre, found in whole grains, fruit such as grapes, brown rice and lentils.

• Triglycerides are fats that collect excess calories from the food we eat and speed them away to fat cells for storage. Then, when our bodies need extra energy between meals, stored calories are released. If you eat more calories than you burn off through activity, your triglyceride levels will rise.
• Levels tend to be high in obese people and those with diabetes or metabolic syndrome, and are raised by consumption of fatty or sugary foods or excess alcohol.
• High levels of triglycerides are linked to an increased risk of cardiovascular disease, especially in women.