A stroke occurs when blood circulation to the brain fails. Brain cells can die as a result of the decreased blood flow and subsequent lack of oxygen. There are two broad categories of stroke: those caused by a blocked blood flow (the most common kind of stroke, known as an ischaemic stroke); and those due to bleeding (known as a haemorrhagic stroke).
Strokes can occur in all age groups, in both sexes, and in all races in every country. It can even strike a fetus still in the womb. Often, it is a secondary problem to other diseases such as diabetes and heart disorders. The good news is that you can halve your chances of having a second stroke by reducing your risk factors.
* Fruit and vegetables can reduce stroke risk considerably (Int J Epidemiol, 1997; 26: 1-13). Vegetables provide the best protection, perhaps because of their high fibre content (known to lower blood pressure). Fruit and vegetables also contain carotenoids and vitamin C as well as other beneficial substances, such as tannins, phytic acid, flavonoids and phytoestrogens, all of which can lower cholesterol.
* Exercise. Sedentary individuals have almost double the risk of stroke of active ones (Am J Epidemiol, 1996; 143: 860-9). Vigorous exercise early in life protects against stroke later on, irrespective of other 'risk' factors such as social class, smoking, alcohol consumption, family history, hypertension or diet. Continued vigorous exercise later in life helps reduce the risk still further. Regular exercise can also speed recovery from stroke (Stroke, 1998; 29: 2049-54, 2055-60).
* Wholegrains. Women who eat more than one wholegrain food per day can cut their risk of ischaemic stroke by 35 per cent over those who eat no wholegrains (JAMA, 2000; 284: 1534-40).
* Cigarette smoking can promote the build-up of fat in the carotid, the main neck artery supplying blood to the brain. A block in this artery is the leading cause of ischaemic stroke. Nicotine also raises blood pressure, and cigarette smoke makes your blood thicker and more likely to clot. By quitting at any age, you also reduce your risk of lung disease, heart disease and a number of cancers, including lung cancer.
* High blood pressure and heart disorders. Heart disorders such as coronary artery disease, valve defects, irregular heart beat and enlargement of one of the heart's chambers can cause blood clots that may break loose and block vessels in or leading to the brain. The most common cause of high blood pressure is atherosclerosis, due to fatty deposits in the arteries. Reducing your risk of atherosclerosis will also reduce your risk of stroke. This includes maintaining a proper weight, reducing stress, changing your diet, lowering salt intake, and taking regular exercise and relaxation.
* Antioxidants. Stroke victims with a high level of vitamin A in the blood recover more quickly and are less likely to die than those with lower levels (Lancet, 1992; 339: 1562-5). Supplementing with vitamins such as A, C and E may help reduce oxidative damage and, in elderly people, higher levels of vitamin C can protect against stroke (BMJ, 1995; 310: 1563-4).
* Diabetes causes destructive changes in the blood vessels throughout the body, including the brain. Also, if blood-glucose levels are high at the time of a stroke, the brain damage is usually more severe and extensive than when blood glucose is well controlled. Treating diabetes can delay the onset of complications that increase the risk of stroke.
* B vitamins - specifically folic acid, B6 and B12 - help break down homocysteine which, in excess, can damage blood vessels, laying the foundation for cholesterol deposits. Homocysteine levels go up when people consume too much methionine, particularly found in meat so, in addition to supplementation, consider getting your protein from sources other than meat.
* Obesity increases stroke risk by as much as twofold. Excess weight strains the entire circulation and predisposes to other stroke risk factors such as high blood pressure, diabetes, high cholesterol and obstructive sleep apnoea (where the sufferer temporarily stops breathing). Do what you can to maintain a sensible weight.
* Walnuts can help reduce the risk of stroke (JAMA, 1995; 273: 1563) and, along with soya or canola oil, provide essential omega-6 alpha-linolenic acid (ALA). In one study, for every 0.13 per cent increase in ALA in the blood, the risk of stroke dropped 37 per cent. It may be that ALA reduces the formation of blood clots. Other good sources include other nuts, seeds and fatty fish (Stroke, 2002; 33: 2086-93).
* HRT. Although prescribed to some as a stroke preventative, we now know that HRT increases your risk of stroke - by 41 per cent in the first five years. The risk of blood clots is twice that of women not taking HRT (JAMA, 2002; 288: 321-33, 366-8).
* Brush your teeth. Good evidence links oral health and heart health. Researchers have found that those with severe gum disease have a twofold risk of stroke as a result of clogged arteries (Arch Intern Med, 2000; 160: 2749-55).