A healthy diet and lifestyle is key to avoiding most health problems. But with gallstones, thought to affect as many as one in six people, with famous sufferers including the likes of Eric Clapton and the Dalai Lama, it's not quite that simple.

While eating healthily, keeping your weight down, exercising regularly and not smoking are indeed vital tenets for avoiding the - sometimes excruciatingly painful - condition, some lifestyle factors which may seem healthy, like low-fat diets and losing weight quickly, plus not drinking alcohol, can actually make gallstones more likely.

BILE HIGH CLUB

One of the most common medical and surgical conditions, it's believed they occur due to chemical imbalances in bile stored in the gallbladder; this leads to tiny crystals developing, which can grow into gallstones, ranging from many as small as grains of sand, to one the size of a pebble.

The stones can sometimes cause extreme pain, often described as being worse than childbirth. However, only one in five people with gallstones experience this agony - the remaining four out of five carriers don't even know they've got them, although they sometimes find out during routine screenings.

GP Dr Sarah Brewer, whose book Overcoming Gallstones has just been published, points out that 70% of gallstones are made from cholesterol, and a diet high in saturated fat and pre-formed cholesterol increases the amount of the substance being pumped by the liver into bile, making it more likely gallstones will form.

However, she warns that "the opposite is also true". A diet that's unusually low in fat can promote gallstones, as the gallbladder mainly contracts in response to dietary fats, so it empties less frequently if a low-fat diet is followed, or if dieters eat less regularly than normal. Bile can pool in the gallbladder, giving gallstones more chance to form.

Dr Brewer references a study of almost 90,000 nurses, which found that losing 4kg-10kg in weight over a two year period increased the risk of gallstones by 44%, and those who lost more than 10kg were almost twice as likely to develop them, with a 94% increased risk.

WHAT'S YOUR TIPPLE?

Avoiding gallstones may even be aided by a moderate intake of alcohol.

Dr Brewer says: "Alcohol acts as a solvent, helping to stop the components of gallstones precipitating out of the solution in stored bile. This is probably the main way in which a moderate intake of alcohol reduces gallstone formation - but please don't use this as an excuse to increase your intake!

"And you may think you're doing good by trying to lose weight, cutting back on fats and being really strict on your diet, but your gallbladder can become underactive, the bile in it sludges, and you're more likely to develop stones.

"But other than that, it's all the usual messages - eat lots of fruit and vegetables, high fibre, nuts. You can take steps to reduce the risk, and even if you do develop gallstones, not everybody has symptoms."

Those who do get symptoms will often suffer with biliary colic, from gallstones causing gallbladder and bile duct spasms. The pain usually begins suddenly across the upper abdomen - often after a fatty meal - and may spread to the upper back. Some people feel sick or vomit, and may need to do a huge burp!

If the gallstone is too big to pass further into the bile duct, it may settle back into the gallbladder, but symptoms can recur.

COMPLEX CAUSES

While cholesterol levels in the gallbladder is a factor, one in five gallstones are made of bilirubin (a waste product produced when red blood cells are broken down).

And some risk factors are unavoidable. The chance of developing the condition also increases with age, females are more prone to them than men (because of the effects of the female hormones oestrogen and progesterone), certain medical conditions like cystic fibrosis or sickle cell disease can also play a part, and a family history of gallstones may lead to an increased risk.

Also, despite the links with losing weight too quickly and low-fat eating, traditionally 'unhealthy' lifestyle factors certainly play a part too, and gallstones can be linked to things like obesity, poor diet, smoking and lack of exercise, which may cause 'silent gallstones' to form with no symptoms - although that's not to say they won't cause symptoms in the future.

LIFESTYLE CHANGES

Where lifestyle factors are a probably cause, the good news is, there's lots you can do to help.

"These people are the ones who can do lots about their diet and lifestyle to ensure they don't develop more gallstones," advises Dr Brewer, who's also a registered nutritionist.

She says plant sterols, fibre and vitamin C can all help prevent the condition, and a diet rich in monounsaturated fats from foods like olive, Macadamia nut and avocado oils can also be beneficial, as can omega-3 polyunsaturated fats, like those found in flaxseed, walnut and fish oils.

In addition, Dr Brewer says a number of nutritional and herbal supplements, like vitamin C, magnesium and lecithin, may help to reduce stone formation or enlargement.

"If you eat the right food and take the right supplements, and avoid things that are going to make gallstones worse, then you can live with them quite happily - and many people do, without even knowing they've got them."

SERIOUS TURN

Sometimes, but thankfully rarely, serious problems can develop if the stones cause a severe blockage, or move into another part of the digestive system.

In some cases, a bile duct can become permanently blocked, which can lead to a build-up of bile inside the gallbladder causing infection and inflammation (acute cholecystitis). Symptoms include upper abdomen pain, fever and a rapid heartbeat, and a round one in seven people with acute cholecystitis will also get jaundice - yellowing of the skin and eyes - dark brown urine and itching.

Acute pancreatitis may also develop, when a gallstone moves out of the gallbladder and blocks the opening of the pancreas, causing it to become inflamed and painful.

TREATMENT OPTIONS

Sometimes, a stone passes from the bile duct on its own, so treatment - aside possibly from pain relief - won't be needed. However, if it doesn't, it needs to be removed.

Generally though, t here are three options for gallstones: conservative care, where patients manage symptoms through nutritional and lifestyle changes; medication such as painkillers and antispasmodic drugs, or sometimes even drugs to dissolve the stones or reduce their size; or surgery to remove the gallbladder.

This is one of the most common operations performed by the NHS - there are more than 60,000 gallbladder removals every year in the UK, but whether this happens or not depends on the severity and frequency of symptoms, and a patient's general health.

"If your gallstones were diagnosed by chance, and have never caused symptoms, you may wish to avoid surgery. In this case, nutritional and lifestyle approaches help between 85% and 90% of people to have no further problems."

She says keyhole surgery to remove the gallbladder is relatively safe, although some people suffer from painful adhesions afterwards. And without a gallbladder, bile to help digest food isn't produced in appropriate quantities, so people may experience stomach pain after a big meal, for instance. Taking digestive enzymes, or even eating globe artichoke, which can hugely increase bile output, can help.

"I think a lot of people would prefer to avoid surgery if they can, but the ideal is not to have an episode in the first place, by maintaining a healthy diet and lifestyle," Brewer stresses.

:: Overcoming Gallstones by Dr Sarah Brewer is published by Medilance, priced £4.99. Available now