Most people don't give much thought to their gallbladder, a small sac beneath the liver that collects and stores bile – the substance that helps digest fatty foods. After you eat, your gallbladder releases bile into the small intestine to break up fat.
Yet as many as 20 per cent of Canadian women and 10 per cent of men have gallstones by age 60, small pebble-like substances that can trigger abdominal pain, bloating, nausea and vomiting.
While diet doesn't directly cause gallstones, certain foods and eating patterns can increase the risk of developing the condition. Too much animal fat, cholesterol and refined carbohydrates and too little fibre make gallstones more likely. So does carrying excess fat around your midsection.
Yo-yo dieting and losing weight too quickly also have the potential to cause gallstones.
Gallstones form when substances in bile – mainly cholesterol – harden to form crystals. In some cases, gallstones can block the normal flow of bile and cause symptoms following a fatty meal. (The amount of cholesterol in bile is not related to cholesterol in your bloodstream.) Not everyone with gallstones experiences discomfort. Most people don't even know they have them until they're detected by chance during an ultrasound carried out for some other reason. "Silent" gallstones cause no pain and are often left alone.
One in five people with stones, however, experience pain and will require treatment, usually surgery to remove the gallbladder.
People with a family history of the condition as well as those who are overweight and obese are at greater risk for gallstones. Women between the ages of 20 to 60 are three times more likely to develop gallstones than men. (The female hormone estrogen stimulates the liver to remove more cholesterol from the blood which then accumulates in the gallbladder.) Changing your diet won't get rid of gallstones if you already have them. But it could help ease your symptoms if you experience discomfort.
Dietary modifications can also reduce the risk that silent stones will become symptomatic – and help prevent gallstones from forming in the first place.
Reduce saturated fat and cholesterol
Cutting back on saturated (animal) fat and cholesterol can change the composition of bile, making stone formation less likely.
To cut saturated fat choose lean cuts of meat, poultry breast and low-fat dairy products.
There's also some evidence that olive oil – a monounsaturated fat – can reduce the cholesterol content of bile. Other sources of monounsaturated fat include canola oil, peanut oil, avocado, almonds, pistachios, hazelnuts and peanuts.
Choosing animal foods that are low in saturated fat will also reduce your cholesterol intake. Cholesterol-rich foods to avoid or eat sparingly include egg yolks, shrimp and liver.
Fibre in the diet helps guard against gallstones by binding to food cholesterol and bile in the gut, causing their removal from the body.
Insoluble fibre – found in wheat bran, whole wheat bread or pasta, fruit, vegetables, nuts and seeds – is thought to be most protective.
Other fibre-rich foods linked to a lower risk of gallstones include lentils and dried beans (e.g. kidney beans, navy beans, black beans, chickpeas).
Limit processed carbs
A steady intake of added sugars and refined (white) starchy foods can increase the risk of gallstones by increasing the secretion of insulin, the hormone that clears sugar from the blood. Elevated insulin can increase the concentration of cholesterol in the bile.
Limit added sugars to 5 per cent of daily calories – roughly five teaspoons (80 calories worth) a day for women and nine teaspoons (144 calories) for men. (Four grams of sugar is equivalent to one teaspoon worth).
Replace soft drinks, fruit punch, and iced tea with water, low-fat milk, vegetable juice, or unsweetened tea or coffee. Choose breakfast cereals that have no more than 6 grams of sugar per serving. When buying cereal bars and granola bars, choose products with no more than half the total carbohydrate from sugars.
Choose whole grain starchy foods such as brown rice, whole wheat pasta, quinoa, steel-cut and large flake oats and 100 per cent pumpernickel bread. Not only do these foods have more fibre than refined grains, they also stimulate less insulin release.
Maintain a healthy weight
As body mass index increases, so does the risk of developing gallstones, especially if excess weight is carried around the abdomen. Abdominal fat can cause hormonal changes thought to promote gallstone formation.
Weight cycling – the pattern of losing and regaining weight – is also linked to a higher risk of gallstones.
Lose excess weight sensibly
If you plan to lose weight, do so slowly. Shedding weight too quickly (more than 3 pounds a week) increases the risk of gallstones by increasing cholesterol in bile.
Aim to lose one to two pounds a week by following a well-balanced diet. Fasting, very low-fat diets and skipping meals can decrease gallbladder contractions and prevent it from emptying completely.
Meet vitamin C requirements
A low vitamin C intake is associated with a greater risk of gallstones. The nutrient is needed to properly synthesize bile; without it bile becomes cholesterol-rich increasing the likelihood of stone formation.
Include at least two vitamin-C-rich foods in your daily diet: oranges, grapefruit, kiwi, cantaloupe, mango, strawberries, broccoli, Brussels sprouts, cauliflower, red pepper, or tomato juice.
Get enough calcium and magnesium.
Like fibre, these two minerals bind to bile acids in the gut eliminating them from the body.
Calcium-rich foods include milk, yogurt, cheese, fortified plant beverages and juice, baked beans, black beans, soybeans, firm tofu, canned salmon and sardines (with bones), bok choy, broccoli, collard greens, kale, Swiss chard, dried figs and almonds.
Good sources of magnesium include black beans, chickpeas, kidney beans, navy beans, soybeans, firm tofu, spinach, Swiss chard, halibut, almonds, cashews, sunflower seeds, yogurt and wheat germ.
Leslie Beck, a Toronto-based dietitian, is the national director of nutrition for Body Science Centers, medical clinics focusing on healthy aging ( BSC5.com ).