It is well established that diet can play an important role in preventing heart disease. Controlling cholesterol is the key, since high cholesterol levels are a cause of atherosclerosis, which in turn leads to heart disease. The Mediterranean diet provides a good model diet for preventing heart disease.
As the body ages, the arteries (blood vessels) thicken and become furred up, a process known as atherosclerosis. This thickening is associated with a cholesterol-rich fatty deposit called atheroma that forms a plaque on the walls of the arteries. A pronounced blockage in the arteries that supply the heart with oxygen can result in angina, a condition that is experienced as chest pain on exertion or under stress. Atherosclerosis can also lead to thrombosis, which occurs when the plaque causes the narrowing of a blood vessel; a blood clot then forms, and the flow of blood is blocked.
Men are prone to atherosclerosis when they reach their 50s and women become vulnerable after the menopause. Some people inherit a tendency towards high blood cholesterol levels, but many others have an increased risk as a result of poor diet, obesity and smoking.
There are two kinds of cholesterol: blood cholesterol, which is manufactured by the body, and dietary cholesterol, found in food. Excesses of blood cholesterol are linked with the development of atherosclerosis, particularly in people who smoke and have high blood pressure. Contrary to popular belief, the amount of cholesterol in the blood does not reflect the amount in the diet. It is saturated fats, rather than high-cholesterol foods, that increase the risk of heart disease. Trans fats are also blamed for an increase in blood cholesterol; these are found in the ‘hydrogenated’ vegetable oils that are used in many spreads, biscuits and cakes.
The reduction of saturated fats in the diet is therefore the most important way to lower blood cholesterol levels. Saturated fats are found in full-fat dairy products such as hard cheese, butter and cream; in fatty meats such as mince and sausages; and in pastries and pies that are made with butter. As a sensible precaution, people with heart problems or a history of heart disease are also advised to limit their dietary cholesterol, found mostly in eggs, offal, shrimps and prawns, which are also high in saturated fat.
Foods that are rich in soluble fibre, such as fresh and dried fruit, vegetables, whole grains, oats and pulses (beans, peas and lentils) may help to lower blood cholesterol levels. Garlic is also said to be good for combating cholesterol; the active ingredient is a pungent substance called allicin, which is released when a fresh clove of garlic is cut or crushed. Studies indicate that one clove of garlic should be consumed daily in order to have the desired effect.
Another important dietary measure in combating heart disease is increasing fruit and vegetable consumption. These supply the body with precious antioxidant nutrients, including vitamins C, E and beta-carotene, which help to prevent cholesterol from accumulating in the arteries; these nutrients also protect the body from degenerative diseases.
The unsaturated fats found in oily fish, nuts (especially walnuts and almonds), seeds and olive oil may also be useful. Research has shown that eating fresh oily fish twice a week can cut the risk of a heart attack by almost one-third. This is because oily fish contains omega-3 fatty acids, which the body converts into hormone-like substances called prostaglandins. These substances help to prevent thickening of the arteries; they also make blood platelets less ‘sticky’, preventing blood clots.
Alcohol and heart disease
Although excessive alcohol consumption should be avoided, it is now generally believed that moderate drinking, in the form of one or two units of red wine a day, may help to protect the heart, preventing heart attacks in men over 40 and post-menopausal women. This level of consumption increases the amount of ‘good’ HDL cholesterol in the body, the kind that helps to remove fatty deposits from the arteries. There is also a reduction in the blood’s tendency to clot. Red wine has the added advantage that it contains more antioxidants than other alcoholic drinks.