High Cholesterol.

Cholesterol is a fat-like substance essential to the human body. It’s used to build cell walls, hormones, bile and vitamin D.

Cholesterol is carried in the blood by proteins called LDL and HDL, levels of which can be measured in a blood test along with triglyceride (TG - a type of fat).

Certain levels of LDL, HDL and TG are associated with increased risk of heart disease (e.g. heart attacks). This is known as dyslipidaemia - commonly known as “high cholesterol”.

LDL

Traditionally, doctors have used LDL levels to help predict heart disease risk. However, the LDL level alone, is not well correlated with risk. Many people with normal or low LDL levels still develop heart disease, and many people with high levels do not.

LDL comes in different sizes - it can be large and fluffy (imagine a beach ball), or small and dense (like a golf ball). We now know that LDL size, is more important than the total LDL number.

Imagine your blood vessels like a fast flowing river and throw in both types of balls. The large fluffy beach balls will be carried along by the water (the blood), whereas the small, dense golf balls are more likely to sink to the bottom (the blood vessel wall). Here, cholesterol can build up in plaques, leading to narrowing and hardening of arteries. Having more small and dense LDL, is therefore associated with a higher risk of heart disease.

LDL size can be accurately estimated by calculating the ratio of TG to HDL. This ratio is much more accurate at predicting heart disease risk than total LDL level alone.

HDL

HDL has long been known as the “good” cholesterol, protective from heart disease. It helps to carry cholesterol away from blood vessels back to the liver, so higher levels are good.

Triglycerides (TG)

TGs are associated with higher risk of heart disease, so it’s important to keep levels low. TG level is strongly influenced by diet.

The impact of diet

Although baseline levels of some cholesterol levels (e.g. LDL and HDL) are strongly influenced by genetics, the most important factor is nutrition, and whether the food we eat is increasing levels of a hormone, called insulin.

Insulin released every time blood sugar levels increase. If we regularly eat foods that spike blood sugar, insulin levels stay high, leading to chronic diseases.

Chronic high insulin causes:

• reduced protective HDL

• significantly increased trigylycerides

• more small dense (golf ball) LDLs.

It also increases blood pressure, another important risk factor for heart disease.

Cholesterol in food.

In the past, people with high cholesterol levels were advised to avoid foods that contain it. We now know that dietary cholesterol has very little (if any) effect on blood cholesterol levels.

The liver produces most of the cholesterol in blood. If you eat less, your liver simply makes more. Studies also suggest that the cholesterol we eat, is not linked to heart attacks or strokes.

Many foods high in cholesterol are among the healthiest and most nutritious. Rather than avoiding these, it’s more important to keep insulin low, by avoiding foods which cause blood sugar spikes.