Most people don't know they have it until it's diagnosed during a routine screening colonoscopy. Yet diverticulosis, a condition in which small sacs, called diverticula, form in the colon, affects about half of people over the age of 60. And almost everyone over 80 has it.
Diverticula usually don't cause problems, but in up to 25 per cent of people with the condition the sacs can become inflamed or infected and cause diverticulitis, whose symptoms include sudden abdominal pain, tenderness, fever, nausea, cramps and constipation. It is estimated that the risk of diverticulitis increases tenfold by the age of 55 and by a factor of 40 at the age of 75.
Doctors aren't sure what causes diverticulosis. With age, the outer walls of the intestine become thickened and less elastic, narrowing the passageway through the colon and making it more difficult to move waste through. Increased pressure from constipation can cause naturally weak places in the colon wall to give way and form marble-sized pouches.
However, altering your diet can help to control diverticulosis and reduce the likelihood of diverticulitis. Too little fibre, not enough water, a steady surplus of calories and physical inactivity can lead to digestive difficulties.
If you have diverticulosis, no doubt you've been told to avoid eating nuts, seeds, corn and popcorn, foods that could lodge in small intestinal pouches and cause them to become inflamed or infected. Yet there's little evidence to support the link between these foods and diverticulitis.
In fact, a 2008 U.S. study followed 47,228 healthy men, aged 40 to 75, for 18 years and found the opposite was true. Men who ate the most nuts - at least twice a week - were 20 per cent less likely to develop diverticulitis than their peers who ate the least. Those who ate popcorn at least twice weekly had a 28-per-cent reduced risk. The researchers speculated that fibre and anti-inflammatory nutrients in these foods protected against the complications of diverticulosis.
Even so, many people who have experienced a painful attack of diverticulitis don't want to take a chance and prefer to avoid nuts, seeds, popcorn and fruits and vegetables with seeds such as strawberries, figs, grapes and cucumbers.
Although it is difficult to predict who will suffer complications, the following strategies can help to prevent diverticulitis:
It is well accepted that a high-fibre diet guards against many digestive disorders, including diverticulitis. Foods such as wheat bran, whole grains and vegetables contain mainly insoluble fibre, the type that prevents constipation. Insoluble fibre retains a large amount of water in the intestinal tract, increasing stool bulk, promoting regularity and reducing pressure in the colon.
The average Canadian consumes 11 to 17 grams of fibre each day - half the recommended amount. Women aged 19 to 50 are advised to get 25 grams of fibre each day; men require 38 grams. As we get older and our calorie requirements decrease, we need less fibre. After 50, women should aim for 21 grams, men 30 grams.
To increase fibre, eat seven or more servings of fruits and vegetables each day. Higher-fibre choices include apples, oranges, grapefruit, figs, pears, prunes, broccoli, Brussels sprouts, carrots, cauliflower and green peas.
Choose a breakfast cereal with at least five grams of fibre per serving. Mix in half a cup (125 millilitres) of 100-per-cent bran cereal to boost fibre further. Add raw wheat bran or ground flaxseed to muffin and pancake batters, casseroles, yogurt and smoothies.
Choose a bread that is made from whole grains and offers at least two to three grams of fibre per slice. Eat whole brown rice, barley, bulgur, quinoa and whole-wheat pasta more often.
Eat beans and lentils - add white kidney beans to pasta sauce, black beans to tacos, chickpeas to salads and lentils to soup. Reach for higher-fibre snacks such as dried apricots, dates, almonds, raw vegetables and fruit.
Some people may find that bulk-forming supplements, such as psyllium husk powder or Metamucil, help to prevent constipation.
Fibre works only if you drink enough water; otherwise, it can be constipating. Women should drink nine cups (2.2. litres) of water or fluids daily to help fibre promote regularity; men need 13 cups (three litres). Water, juice, milk, soups, coffee, tea and herbal tea all contribute to your daily water requirements.
Manage your weight
A handful of studies have linked obesity, especially abdominal obesity, with a greater risk of diverticulitis. The same study of more than 47,000 men that found no link between nuts and diverticulitis determined that men with a body mass index (BMI) of 30 or greater were 78 per cent more likely to develop diverticulitis than were normal weight men. What's more, having a waistline greater than 40 inches increased the odds of diverticulitis by 56 per cent.
Obesity is thought to contribute to diverticulitis by promoting inflammation and altering bacteria in the intestinal tract.
BMI is calculated by dividing your weight in kilograms by the square of your height in metres. For adults, a body mass index (BMI) of 18.5 to 24.9 is considered healthy; 25 or more signals overweight; 30 or more indicates obesity.
Regular physical activity helps to stimulate regular bowel contractions, promotes regularity and reduces pressure in the colon. Aim for 30 minutes of moderate physical activity each day.
If you have a persistent change in bowel habits, or experience symptoms that may be related to diverticulitis, be sure to consult your doctor.
Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is lesliebeck.com.