Popular wisdom and well meaning advice recommends that people with the digestive system problem of diverticular disease should avoid small, sharp and hard foods such as nuts, seeds and corn for the risk of inflaming the condition. Research studies now say otherwise, and these foods shouldn't be excluded from the diet, except for when experiencing painful flare ups of the disease.
Diverticular disease is a common disorder of the digestive system with estimates that one-third of people will develop this condition by the age of 60. Many people have small defects in the muscle of the wall lining the large intestine which can allow small pockets or pouches (called diverticula) to form. The condition of having diverticula is called diverticulosis.
Symptoms of diverticular disease can include pain in the lower left abdomen, constipation and diarrhoea, flatulence, bloating and small amounts of blood in the stool.
What causes diverticular disease isn’t known, though not eating enough fibre is thought to be one factor. A low fibre diet possibly leads to increased pressure inside the bowel, especially during the straining motion of passing a ‘difficult stool’, with diverticula caused by this pressure then forming on the walls of the bowel.
Common advice given to people with diverticular disease is to avoid small, sharp and hard foods such as nuts, seeds and corn because of the risk of undigested remnants of these foods lodging in the diverticula pockets and causing diverticulitis. Yet clinical evidence to support these dietary restrictions is poor.
Cutting back on foods that are high in fibre means missing out on important parts of a healthy diet. Because the foods recommended to be excluded can also have fibre-like effects and contain important nutrients, they could also potentially help to prevent diverticular disease, rather than exacerbate it.
Despite widespread views on the topic, there is actually little published research looking at nuts, seeds and corn and diverticular complications. That is until now.
Getting to the bottom of it
A large study  involving over 47 000 men who were all part of the long running Health Professionals Follow-up Study has looked for links between diet and diverticular disease. The study tracked the health (biennially) and diet (4 yearly) of health professionals from the United States over 18 years. None of the men had diverticular disease at the start of the study. Men who subsequently developed diverticular disease were invited to take part in additional diet and lifestyle questionnaires.
Going against conventional wisdom, the researchers found no link between nut, seed, popcorn, and corn consumption and the risk of either developing diverticulosis or progressing to the inflammatory condition of diverticulitis. There was in fact evidence that men who ate the most nuts or popcorn were less likely to develop diverticulitis compared to men who ate the least amount of these foods and this was after allowing for known or potential risk factors such as age, weight and a low-fibre diet.
What it all means
Until evidence arises finding a link between certain foods increasing the risk of diverticular disease, the general recommendation is that people should not unnecessarily avoid foods that are an important part of a healthy diet. For people who find that eating certain foods can cause a flare up of their diverticular disease then the advice is still to avoid those foods
Confused about the mixed soup of nutrition messages being stirred through the media? Tim maintains an active nutrition blog at www.thinkingnutrition.com.au  where you'll find the latest nutrition research and controversies discussed in straight forward language, distilling out what you need to know for your better health.