Advances in Diverticular Disease and Diet
New evidence is shedding light on the ways diet influences diverticular disease and is reinforcing some of the Gastrointestinal Society’s long-held positions, such as how nuts and seeds are safe to eat. This article will focus on the latest research and how that influences recommendations on what you can do to help reduce the risks of diverticular disease through food and lifestyle changes.
Diverticular disease and diverticulosis are interchangeable terms meaning the presence of small out-pouches (diverticula) in the large intestine (colon). It occurs in about 5% of the Western adult population who are younger than forty years of age, but it rises sharply to occur in at least 50% of those who are older than 60 years of age. It’s a disease most prevalent in the elderly, with the prevalence approaching 65% in those 85 years of age and older, and the majority not experiencing any symptoms or complications.1 Diverticulitis occurs when these pouches become inflamed or infected, which causes symptoms such as nausea, vomiting, abdominal pain, and bleeding. Why does this happen? Scientists suggest that it is likely due to several factors, including genetics, the environment, and more recently, inflammation and the intestinal microbiome.2,3
The traditionally accepted theory that a low fibre diet causes diverticulosis comes from a paper published in 1971 by Painter and Burkitt in the British Medical Journal.4 They hypothesized that the reason why diverticulosis was so common in the West was that the typical Western diet was much lower in fibre when compared to countries in Africa, where diverticulosis was rare. However, the researchers did not actually measure diet nor diverticulosis; it was just a hypothesis. Research in this area then stagnated for some time, but has picked up during the last two decades.2
Fibre
When a patient with acute diverticulitis comes to the hospital, their diet will consist of liquids (e.g., juice, broth, jello) to give the colon a rest. Gradually, the person can expand to a low fibre diet as symptoms improve and they start to feel better. Before hospital discharge, a registered dietitian will advise the patient to increase their fibre intake gradually, toward a high fibre diet at home, with the hope of reducing the risk of recurrent diverticulitis.
Current guidelines still recommend a high fibre diet to prevent diverticular disease, despite being based on low quality evidence from observational studies.5,6,7 A review of several studies (meta-analysis) published last year in the European Journal of Nutrition8 concluded that a high fibre diet may reduce the risk of diverticular disease. They found that people who consumed 40 g of fibre per day had a 58% reduction in risk of diverticular disease when compared to those who consumed only 7.5 g of fibre per day. They also noted that people who eat higher fibre diets tend to have healthier lifestyles in general.
Another study, published in 2019,9 looked at the association between fibre intake and risk of diverticulitis in 50,019 women, 43-70 years of age, from the Nurse’s Health Study that took place from 1990 to 2014. They found that a higher fibre intake was associated with a reduced risk of diverticulitis in women, especially when they consumed more whole grains and whole fruits, particularly apples, pears, and prunes.
Fibre might help reduce the risk of diverticular disease through its anti-inflammatory effects and by how it alters the intestinal microbiome versus how it helps reduce constipation and promote bowel regularity.5,7,9,10 Clearly, to confirm this, we need more high-quality research, and it will be interesting to see what is discovered.
Table 1 – High Fibre Diet (40 g) Example
| Food | Fibre | |
| Breakfast | ¾ cup cooked oatmeal (using quick oats)
½ cup raspberries (from frozen) 1 tbsp. whole flaxseeds |
3.5 g
4.8 g 2.9 g |
| Lunch | two slices rye bread, toasted
two slices of aged cheddar cheese one medium apple, with skin |
2.2 g
0 g 3.5 g |
| Dinner | ½ cup roasted chickpeas
1 cup cooked quinoa ½ cup canned tomatoes 1 cup raw spinach |
9.6 g
5.5 g 1.0 g 0.7 g |
| Snack | one medium pear, with skin
¼ cup walnuts |
5.3 g
1.7 g |
| Total | 40.7 g | |
*Source = Canadian Nutrient File
Nuts, Seeds, and Popcorn
My grandmother had diverticulosis and she ended up avoiding nuts and seeds for years, including the fresh blueberries and strawberries that she loved so much. A large groundbreaking study published in 200810 set out to test the theory that nuts, seeds, and popcorn cause diverticulitis. They followed 47,228 men from the Health Professional’s Follow-up Study from 1986 to 2004 and found that these foods were not associated with a risk of diverticulitis or diverticular bleeding.
They also specifically did not find any association between eating blueberries and strawberries and diverticular complications. What they found instead, was that men who ate more of these foods actually had fewer cases of diverticulitis than those who didn’t. They concluded that nuts and seeds may actually be protective against diverticulitis, perhaps due to their anti-inflammatory effects. 2,6,10,11 The NICE guidelines from the UK, and the PEN Guidelines from Dietitians of Canada, state that there is no need to avoid nuts, seeds, popcorn, or fruit skins for diverticulosis.12 It turns out that my grandmother could have enjoyed those berries that she loved so much after all!
Red Meat, Poultry, and Fish
Some studies have shown that red meat intake increases the risk of diverticular disease, whereas others have found no association.2,5 A large prospective cohort study, published in 2018, looked at 51,529 men from the Health Professional’s Follow-up Study from 1986 to 2012. The researchers observed an association with red meat intake and an increased risk of acute diverticulitis but observed no association with a higher consumption of poultry or fish.13 Overall, whether red meat increases the risk remains controversial. However, given the many other health benefits of limiting red meat intake, I would suggest decreasing consumption anyway.
Caffeine, Alcohol, and Smoking
Consuming caffeine or alcohol does not affect your risk of diverticular disease.2,6,7 Smoking might increase the risk of diverticulitis, and current guidelines recommend that people stop smoking, even though no significant association has been found.6,7,12
Vitamin D
A risk factor for diverticular disease that might play a role in the development of diverticulitis is low levels of serum vitamin D (25-OH D).2 A similar connection exists with low vitamin D levels playing a role in other inflammatory conditions, such as Crohn’s disease.3 The PEN guidelines from Dietitians of Canada currently recommend ensuring adequate vitamin D levels in those who have diverticular disease.6
Probiotics
There is insufficient evidence for the use of probiotics in acute diverticulitis. The 2015 American Gastroenterology Association guidelines actually recommend against the use of probiotics for uncomplicated diverticulitis.3,6 A systematic review looking at eleven studies with various probiotics in the treatment of diverticular disease showed a positive trend in the reduction of abdominal symptoms; however, given the various strains and doses of probiotics used, the study authors could not make any recommendations.3
Physical activity
Physical activity is associated with a reduced risk of diverticulitis and diverticular bleeding, 2,5,7 and the NICE guidelines from the UK recommend exercise to reduce the risk of symptomatic diverticular disease.12 The American Gastroenterology Association recommends vigorous physical activity, such as running, for people who have experienced diverticulitis.3 It is important to note that these associations and guidelines are based on low quality evidence,7 but given the numerous health benefits of being physically active, if you’re not already active and can be, why not give it a try?
Obesity
There is an increased risk of diverticular disease in obesity, especially abdominal obesity, including complications such as diverticular bleeding and diverticulitis.2,3,5,7,8 Obesity is considered to be an inflammatory state, so eating foods rich in fibre, some of which have anti-inflammatory effects, might help reduce obesity-induced chronic inflammation.9
Conclusion
It’s time to say goodbye to popular but unproven theories about diet and diverticular disease. If you have diverticulosis, there is no need to restrict yourself by avoiding nuts, seeds, and berries, which are nutrient dense and have anti-inflammatory effects that may actually help prevent diverticulitis from occurring in the first place. I am looking forward to new research that will delve deeper into the role diet plays in inflammation and altering the intestinal microbiome, and what this will mean for preventing and treating diverticular disease in the future. In the meantime, there are many healthy lifestyle strategies that may help reduce our risk of diverticular disease, and they are worth giving a try.
Ten lifestyle strategies that might help reduce the risk of diverticulitis
- Eat a high fibre diet (35-40 g/day).
- Eat more insoluble fibre (e.g., whole flaxseeds, nuts, berries, raw vegetables, skins of fruits and vegetables).
- Eat whole fruits regularly, especially apples, pears, and prunes.
- Add nuts and seeds to the foods that you love (e.g., walnuts on oatmeal, sesame seeds on top of asparagus, toasted pumpkin seeds on top of a spinach salad).
- Eat chicken and fish more often than red meat.
- Do you have constipation? Consider a fibre supplement (e.g., psyllium) and drink more water.
- Maintain adequate vitamin D levels and consider supplementation if blood levels are low.
- Be physically active (e.g., jogging, running).
- Lose weight if greater than normal/ideal.
- Stop smoking.