Cholesterol

Cholesterol is a fatty molecule found in our bodies and in our food. Now generally associated with an unhealthy diet, it first came under suspicion in the twentieth century when we discovered it in the plaques that can block people’s arteries, leading to heart attacks. It was also found suspended in our blood, higher levels of which correlate with a greater risk of heart disease. So by the 1960s the advice was to eat less cholesterol-laden foods, such as red meat, eggs and butter.

But the real picture is more complex. As well as being present in plaques, cholesterol is also a vital molecule in cell membranes, and a precursor to some hormones. If we don’t get enough cholesterol in our food, our liver manufactures it. The current thinking is that in fact, the amount of cholesterol in our blood is mainly affected not by our dietary cholesterol but by dietary saturated fat. Saturated fat is also mainly found in animal products, but there are some foods, such as eggs and shellfish, that are high in cholesterol but not saturated fat, so it is now seen as OK to eat those.

More controversially, some doctors are questioning even the advice to avoid saturated fat. This is because people’s cholesterol levels do not soar if they adopt low-carbohydrate diets – shunning sugar and starchy foods such as bread and pasta, which tends to mean eating more saturated fat by default. Several national diabetes bodies now recommend low-carbing as one way of losing weight and managing diabetes symptoms.

We can also lower our risk of heart disease by taking medicines that lower blood cholesterol levels, called statins. Many trials have shown that people who take statins after surviving a heart attack are less at risk of having a second one. But these drugs are also controversial, as they are increasingly recommended for people who do not have any signs of heart disease but are statistically at risk because of their age or other factors, such as being overweight. Statins seem to cause some people side-effects like muscle pain and fatigue, and some question if this is worth the small risk reduction they bring for this lower-risk group. In the UK, about 140 people need to take a statin for five years for one of them to avoid a heart attack or stroke. Clare Wilson