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Eating more whole fruits each day reduces the risk of diverticulitis, as does eating apples, pears and prunes.Eddie Keogh/Reuters

If you’re at risk for developing diverticulitis, you’ve probably been told to eat lots of fibre. Since the 1990s, research has suggested that doing so can prevent the painful digestive disease, particularly in men.

But a study published online last month in the American Journal of Gastroenterology has found that a high-fibre diet guards against diverticulitis in women, too. Getting extra fibre from grains and fruits, such as apples, pears and prunes, may be especially protective.

What is diverticulitis?

Diverticulitis occurs when small balloon-like pouches or sacs in the wall of the large intestine, called diverticula, become infected or inflamed. Symptoms range from mild to severe and can include abdominal tenderness and pain, fever, nausea, vomiting and constipation.

Most diverticulitis is treated with antibiotics, but 25 per cent of cases can lead to complications that require surgery.

The presence of diverticula in the colon is called diverticulosis, which is usually discovered by chance during a routine colonoscopy.

The biggest risk factor for diverticulosis is aging, which weakens muscles in the wall of the large intestine. A low-fibre diet, obesity, a sedentary lifestyle and a high intake of red meat are also thought to contribute.

Diverticulitis is more common in men under 50, while women over 50 experience it more often than men.

Apples have 4.4 grams of fibre per one medium.Eddie Keogh/Reuters

The latest findings

For the current study, researchers from Harvard Medical School in Boston followed 50,019 women for 24 years; participants were healthy and aged 43 to 70 years at the outset. Their diets were assessed by questionnaire every four years.

Compared with women whose daily diets contained the least amount of total fibre (13 g), those who consumed the most (27 g) were 14 per cent less likely to develop diverticulitis requiring antibiotics or hospitalization.

When the researchers examined sources of fibre, they found that fibre from cereal grains and fruits, but not vegetables, were protective.

Women who ate the most fruit fibre (7.7 g per day) had a 17 per cent lower risk of diverticulitis than their peers who consumed only 1.4 g. Eating the most cereal fibre (9.8 g versus 2.9 g a day) was tied to a 10-per-cent lower risk of diverticulitis.

The results also showed that eating more whole fruits each day reduced the risk, as did eating apples, pears and prunes.

It’s thought that fibre may guard against diverticulitis by preventing constipation and the pressure it exerts on the colon wall. Fibre also nourishes beneficial gut bacteria which, in turn, can help keep chronic inflammation at bay.

Eating more fibre from fruit and cereal grains has also been associated with lower levels of circulating estrogen, a hormone that may influence the risk of diverticulitis in women.

The study wasn’t a randomized controlled trial and therefore can’t prove that a high-fibre diet prevents diverticulitis. Still, its long-term follow-up and detailed and repeated collection of diet and lifestyle information are strengths.

How much fibre?

The new findings suggest that a woman can lower her risk of developing diverticulitis by consuming 27 g of fibre a day.

Current fibre recommendations for adults, established by the U.S. based Institute of Medicine, are 25 g per day for women to age 50 and 21 g for older women. Men, ages 19 to 50, require 38 g of fibre each day; older men need 30 g.

I recommend that adults aim for 30 g of total fibre each day, twice as much as the average Canadian consumes. It’s a target that’s also been tied to a lower risk of Type 2 diabetes, heart attack, stroke and colorectal cancer.

Eat fruits, vegetables and whole grains every day. Include beans and lentils in your diet, too.

To increase your intake of fruit fibre, choose apples (4.4 g per one medium), apricots (3 g per four), avocado (4.3 g per one-quarter), blackberries (4 g per half-cup), pears (5.5 g per one medium), prunes (2.5 g per four) and raspberries (4 g per half-cup).

Higher-fibre cereal grains (amounts per half-cup) incude bulgur (4 g), farro (6 g), freekeh (5 g), black rice (2 g), whole wheat pasta (2.5 g) and 100-per-cent bran cereals (12 g). Choose 100-per-cent whole-grain bread with at least 3 g fibre a slice.

It’s important to note that during a flareup of diverticulitis, a low-fibre diet is to be followed as the bowel heals.

Leslie Beck, a Toronto-based private-practice dietitian, is Director of Food and Nutrition at Medcan.

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