Gallstones are solid pieces of stone-like material usually made of cholesterol that form in the gall bladder, which is a small organ on the right hand side of the body, below the liver. It stores a green liquid called bile, which is produced by the liver to help the body digest fats. As we eat, bile is released from the gall bladder into the intestines through a thin tube called the bile duct. Gallstones are formed when some of the chemicals stored in the gall bladder harden into a solid mass. They may be as small as a grain of sand or as large as a golf ball. Some people may have one large stone while others may have many small ones. Gallstones are the most common cause of emergency hospital admission for people with abdominal pain. About eight per cent of the adult population has gallstones and 50,000 people a year have an operation to remove their gallbladder (NHS Choices, 2012o).
Gallstones are made up from a mixture of water, cholesterol and other fats, bile salts and the pigment bilirubin. They occur when the composition of the bile is abnormal, the outlet from the gall bladder is blocked (perhaps by infection), or if there is a family history of gallstones. Gallstones can cause inflammation of the gall bladder (cholecystitis), which may then block the bile duct leading to obstructive jaundice. The passage of a gallstone along the bile duct to the duodenum can be extremely painful.
Obesity is a major risk factor for gallstones, especially in women, who are two to three times as likely as men to develop gallstones. Risk also increases with age; people over 40 are at a higher risk. Diet is also a causal factor. A study published in the British Medical Journal in 1985 reported that meat-eaters are twice as likely to develop gallstones as vegetarians (Pixley et al., 1985). Since then the low incidence of gallstones in vegetarians compared to meat-eaters has been reported (Key et al., 1999). Indeed vegetarian diets have been shown to be beneficial for both the prevention and treatment of gallstones (Leitzmann, 2005). The main risk factors appear to be low fibre intake, high saturated fat and cholesterol intake and obesity. An Australian study reported an inverse association between dietary fibre and gallstones (Segasothy and Phillips, 2000). In other words, the more fibre in the diet, the lower the risk of gallstones. Polish researchers examined the diets of patients suffering from gallstones and found that they were characterised by their low fibre diet (Ostrowska et al., 2005). Patients with gallstones ate less wholemeal products, fruit and vegetables and pulses. Furthermore, obese women with gallstones ate significantly more milk, yogurt, meat and meat products.
Due to the role that cholesterol appears to play in the formation of gallstones, the UK government recommends that the following fatty foods with high cholesterol content are avoided: meat pies, sausages and fatty cuts of meat, butter and lard, and cakes and biscuits. They recommend a low-fat, high-fibre diet including plenty of fresh fruit and vegetables (at least five portions a day) and wholegrain foods (NHS Choices, 2012p). They also say that there is evidence that regularly eating nuts (such as peanuts or cashews), can help reduce the risk of developing gallstones. Cutting down your drinking to no more than 3-4 units a day for men and 2-3 units a day for women may also reduce the risk.