Diverticular Disease in Africans: Myth or Fact?

Abstract

Diverticulosis coli is an acquired disease of the colon where small outpouchings of the colonic mucosa occur due to mucosal herniation of the colonic wall at sites of vascular perforation. The disease is very common in developed countries and its prevalence increases with age. Risk factors for its development include inadequate dietary intake of fiber, abnormal colonic motility, and elevated pressures within the colon. Studies done in the late 1900s showed that this disease was unknown in the African population who are known to consume a lot of fiber in their diet. With urbanization in the African population, the prevalence of this disease has somewhat increased over the years. Just how common is this condition among African people? This chapter will review the literature regarding this condition in Indigenous Africans.

1. Introduction

Diverticular disease was first described by a French surgeon, Alexis Littre, in the late 1700s. Fleischman, in 1815, described the condition as “divertikel”. Cruveillher described the mucosal herniation in the colon found in diverticular disease in 1849. In 1869, Klebs was the first surgeon to link the “divertikel” to constipation. Graser, in 1899, described the first case of diverticulitis and emphasized that diverticulitis resulted in peri-sigmoiditis and perforation [1]. Painter and Burkitt in 1971 published the first paper on diverticular disease among Africans in a Johannesburg hospital in South Africa. During their 20-year tenure of working in a tertiary hospital in Johannesburg, not even one case of diverticular disease was found among the African population.

Since 1971, there have been a number of reports from the African countries documenting cases of diverticular disease among native Africans. This chapter will explore the published data on diverticular disease arising from Africa. There has been a shift in the socio-economic climate in African countries whereby more and more native Africans are now having better jobs. There is a growing number of them in the middle-income group and they are now more urbanized. With urbanization, a lot more of them have adopted the Western diet.

The exact incidence of diverticular disease in Africans is unknown. However, an increase in the number of cases in Africa could also be due to more awareness of the disease. Lack of resources in Africa does play a role in being a limiting factor to the investigation of patients presenting with symptoms of diverticular disease, hence it is highly possible that the numbers may be slightly higher than reported.

2. Classification

2.1 Asymptomatic

In the Western population, 80-85% of patients with colonic diverticulosis are asymptomatic. Most of these patients are diagnosed as an incidental finding on colonoscopy or imaging when being investigated for other indications.

2.2 Symptomatic

15–20% of symptomatic patients can present symptomatic uncomplicated diverticulitis or diverticulitis with/without complications.

History taking is important in differentiating these phenotypes and identifying risks of diverticular disease. Symptoms of symptomatic uncomplicated diverticular disease include recurrent abdominal pain, bloating, and altered bowel habits^. In addition, acute diverticulitis presents with low-grade fever, left lower quadrant tenderness (Sigmoid colon), possibly palpable mass, and rarely hematochezia. Acute abdomen indicates possibly complicated diverticulitis with perforation and peritonitis.

Clinical evaluation also includes identifying risk factors. Non-modifiable risk factors include age, sex, and genetics. The prevalence of diverticular disease is particularly high in individuals >65 years of age, although the occurrence is currently increasing in people <40 years of age. Increased life expectancy explains the increasing prevalence in non-Western countries, which were previously considered as low risk for diverticular disease. Modifiable risk factors include diet, lifestyle, and pharmacological factors. A low fiber diet has been regarded as a significant risk factor. It results in increased intraluminal pressure and formation of diverticula. Countries with high fiber diets, like Africa and Asia, have lower incidence of diverticular disease, as compared to Western countries. Other risk factors should be considered: Obesity, physical inactivity, alcohol consumption, and prolonged use of NSAIDs and steroids are associated with increased risk of diverticular disease (DD).

3. Diverticular disease in Africa

3.1 Prevalence

There is a paucity of studies done in Africa on diverticular disease, as it is an uncommon condition. Due to this fact, the exact incidence is unknown. There have been few studies done in South Africa, Nigeria, Kenya, and Uganda. These studies have been done mainly in referral (tertiary) hospitals. They all seem to show an increase in the prevalence of this condition in Africa over the past 40 years. Painter and Burkitt [1] published the first paper on diverticular disease in Africa, where they described the fact that there is a close relationship between the incidence of diverticular disease and economic development. Secondly, they alluded to the fact that it would take about 40 years for diverticular disease to develop even after the colon’s environment has been changed. Hence, diverticular disease would not be expected to be seen until that community had departed from their traditional eating habits for approximately 40 years.

Archampong et al. [2] published a study in Ghana, in 1978, of 14 patients diagnosed with diverticular disease in a period of 3 years. The patients were from an urban area in Ghana and presented with features of diverticulitis. The commonest presenting symptom was rectal bleeding. However, the authors described that even though their patients were upper class, their diet had not changed. They still consumed a traditional high-fiber, low-calorie diet.

Calder et al. [3] found 20 cases of diverticular disease over 1 year in Kenya in 1980. He noted that even though the Kenyan subjects were seen to be consuming more refined maize and sugars, their diet was still high in fiber as compared to their Western counterparts.

Segal et al. found 42 cases of diverticular disease over a period of 3 years in Baragwanath Hospital, Johannesburg, South Africa. The patients were from an urban population. The main presenting symptoms were rectal bleeding, abdominal mass, or pain. The average age was 62 years; 16 were men and 26 were women. The mean daily dietary fiber intake of African subjects was 26.5 ± 8.5 g, as compared to the Indigenous White subjects, which was 22.4 ± 6.0 g.

Madiba and Mokoena [4] reported 26 cases of diverticular disease over a period of 5 years in an urban hospital in Durban, South Africa. The commonest presenting symptom was rectal bleeding, and 77% of the diverticulae were left sided. Of note, the study was published in 1994, which was the year when South Africans were all allowed to vote, elected the first democratic government, and there was a definite shift in the socio-economic climate of that country. Urbanization greatly increased as more Black people became affluent as compared to 10 years ago.

Kiguli-Malwadde et al. [5] published a study in 2002 in Uganda, a retrospective and prospective study conducted over 5 years. They found 31 cases of diverticular disease. All the patients were over 40 years of age and consumed a mixed diet, both high and low residue. The commonest presenting symptoms were rectal bleeding, abdominal mass, or pain.

Alatise [6] found 40 cases of diverticular disease over a period of 5 years in Nigeria. The median age of the patients was 64 years. 72.5% of the patients were male and 27.5% were female. The most common symptoms were rectal bleeding, abdominal pain, or mass. All the patients were placed on a high-fiber diet, antibiotics, Ciprofloxacin. and metronidazole. Five patients had a recurrence within 6 months of follow-up, and one required emergency colectomy.

Oluyemi [7] found 28 cases of diverticular disease over a 5-year period in Nigeria. This group also found a higher percentage of males with diverticular disease as compared to females. The most common presentation was rectal bleeding.

Vally et al. [8] found 47 cases of diverticular disease over a period of one year in South Africa in 2017. One can certainly appreciate the rising incidence in Africa from 1971 where no cases were found over a period of 20 years until 2017 when 47 cases were found in a period of only 1 year. The studies by Painter and Vally were conducted in the same province in South Africa. One can appreciate that possibly more awareness of the disease exists now, compared to 50 years ago.

A study done by Golder et al. [9] showed that the risk of diverticular disease in Black Africans was higher than that of their Indigenous counterparts, even if one accounts for an increase in the prevalence of diverticular disease following urbanization in Africa.

Figure 1 shows the world map and the distribution of diverticular disease. One can appreciate that more cases are found in countries like the United States and Australia. In Africa, there are fewer cases that are also found in fewer countries across the continent.

Figure 1.

World map showing incidence of diverticular disease. Source: Violi et al. [10].

4. Location of the diverticulae in Africans

There seems to be a discrepancy regarding the location of diverticulae in Africans. Some studies show a Pancolonic distribution [6, 11]. Ihekwaba [9, 12] and Golder found a predominance of right-sided diverticular disease. Kiguli [5] found that the majority of the diverticulae were found on the left colon. Table 1 is taken from the study by Gelu-Simeon [13] where they compared the distribution of diverticular disease in African Caribbean versus European.

Complete exploration	Group AC with complete exploration N = 106	Group E with complete exploration N = 31	OR (95% CI)	p-value
Pancolonic DD	78 (73.6)	11(35.5)	5.06 (2.15–11.88)	0.0002
Right-side DD^∗	9 (8.5)	1 (3.2)	9 (1.03–78.17)	0.03
Left-side DD^∗	10 (9.4)	18 (58.1)	0.06 (0.01–0.32)	0.0002
Bipolar left and right-side DD^∗∗	9 (8.5)	1 (3.2)	9 (1.03–78.17)	0.03

Table 1.

Complete exploration of the colon in African Caribbean and European patients.

Group AC, African Caribbean; group E, European; DD, diverticular disease. Qualitative values are expressed as n, %. ^∗without diverticula in controlateral side. ^∗∗without diverticula in transverse colon.

5. Risk factors for diverticular disease

5.1 Diet

Dietary deficiency of fiber is a risk factor for diverticular disease. Painter and Burkitt [1] described diverticular disease as a deficiency disease of Western civilization. Indeed, diverticular disease is more common in Western countries like America, Australia, and Europe. Africans have been known to consume a high-fiber and low-calorie diet for centuries, this has been shown to have a “protective” effect against colonic diseases such as diverticular disease as well as colorectal carcinoma. Due to the high fiber in the African diet, the disease has been largely uncommon in Africans. Data has been largely lacking in Africa, regarding the quantity of fiber in the African diet. Urbanization, especially of Native Africans, has resulted in “westernization” of their diet. Kiguli-Malwadde [5] found that their study subjects ate a mixed type of diet that is both low and high-residue food.

Studies done in Africa show conflicting data as to whether diet is the main protective factor against diverticular disease, with some studies like Kiguli [5] showing that despite their patients still consuming a high-fiber diet, they still developed diverticular disease. Other studies show an increase in diverticular disease in patients who had adopted a Western diet. This conflict in data may suggest that there are more factors at play, which may contribute to diverticular disease, e.g., genetics. More data is needed in Africa. A prospective study was done in South Africa by Golder et al. [13] looking at changes in diet between rural men and women versus urban men and women over a period of 5 years. Their findings were as follows:

5.1.1 Beneficial and detrimental changes in food intake

The results of the analysis of changes in foods eaten clearly showed some beneficial effects over the 5 years (more vegetables and fruit, milk and milk products, fish, and foods from animal sources), which will all contribute to improved micronutrient intakes. Unfortunately, these changes were small and did not allow the majority of participants to reach the recommended intakes of vegetables, fruits, and milk and milk products. Furthermore, some detrimental changes were observed, especially an increase in added sugar intake, mainly in the form of sugar-sweetened beverages, increased consumption of beer by women, and increased intakes of processed meat, savory snacks, and hard margarine (and therefore a higher saturated fat intake), illustrating an emergence of processed foods in the diet, which is of concern. More and more global dietary and food recommendations mention the need for home-prepared meals from fresh ingredients because of the high energy content of processed foods and their links to obesity.

There was no evidence of “new” foods eaten in 2010, and the “top ten” consumed foods remained unchanged from 2005 to 2010. Examples of these include white-flesh fruit eaten by 77.6% of rural women in 2005 and by 88.3% of them in 2010. Similarly, more men consumed products such as milk, eggs, organ meats, processed meats, hard margarine, and cooked starchy vegetables with added fat in 2010 than in 2005.

5.1.2 Dietary staples

The group found a decrease in the intake of cooked maize porridge and bread, which was concerning because of the mandatory fortification of maize meal and bread flour to provide micronutrients. However, the data show that porridges are replaced to a certain extent by micronutrient-rich foods such as vegetables, fruit, milk, and animal-origin foods.

5.2 Age

Diverticular disease is most prevalent in old age and in the distal colon. Watters et al. compared the mechanical properties of the colon between African and European patients in vitro. They found that with old age, the distal colon was weaker and less distensible. Furthermore, they found that the distal colon was narrower, weaker, and less expansile than the proximal colon. These factors and more show that the aged sigmoid colon is predisposed to develop diverticular disease because of its aged features, static mechanical changes, and greater intraluminal pressures. Despite the differences in race and ethnicity, one can appreciate that there’s an increase in the prevalence of diverticular disease with increasing age, as demonstrated in Figure 2 below-, taken from the study done by Watters [14].

Figure 2.

Age and probability density by ethnicity in patients diagnosed with diverticular disease. A: White; B: Asian; C: Other Black; D: Black African. Source: Golder et al. [9].

Table 2 summarizes the findings of a paper published by Vally [8] in a Johannesburg hospital in South Africa. One can appreciate the sharp increase in number of cases in the age category (60–80 years). In this study, there was a slight female preponderance as compared to the male subjects. This is in contrast to studies done by Oluyemi [8], which showed a higher percentage of the disease in males.

Age (years)	N	Male	Female
40–49	1	0	1
50–59	6	3	3
60–69	16	6	10
70–79	15	7	8
80+	4	2	2
Unknown	5	2	3
Total	47	20	27
Youngest	—	50	46
Oldest	—	83	86

Table 2.

Summary of cases per decade. Source: Vally et al. [8].

5.3 Abnormal colonic motility and pressures

Watter [14] also found that Africans had a wider and more distensible distal colon. The Edinburgh group had impaired stretch capacity, which made them prone to developing diverticular disease. Furthermore, Africans have shorter stool transit times and greater stool weights than their European counterparts, according to Painter and Burkitt: The stool transit time takes about 48 hours, and they produce a less viscous stool, which passes out easier compared to a Caucasian’s stool. The colonic pressures in the African’s gut are lower compared to their European counterparts, hence the African’s colon would tend to be less “traberculated” and form less diverticulae. Caucasians may also have a tendency to ignore the call of nature, which will lead to drying out of the stools, greater colonic pressure, and increased tendency to form diverticulae.

6. Discussion

Diverticular disease is a disease that is very common in developed countries like the United States and Australia. The incidence thereof increases with age, especially in the 60–80 years category. Risk factors for diverticular disease include age, diet, abnormal colonic motility, and pressures as well as obesity. In Africa, the exact incidence per country is unknown because there have not been a lot of studies done. The reason for this is that diverticular disease has been rare among the Indigenous People of Africa. However, over the past 40 years, the disease is becoming more common. It is postulated that the increase in incidence of diverticular disease in Africans is due to a change in diet of the native Africans, who traditionally consume a high-fiber diet, but are now consuming a more Western diet. The Western diet, being low-residue and high-protein diet.

The most common clinical presentation noted in the African studies is rectal bleeding followed by abdominal pains. This seems to be on par with studies done elsewhere in the world. There is also not much difference in terms of gender distribution in the subjects. The study by Vally et al. however, found a higher male preponderance as compared to females. They also found the incidence of diverticular disease in South Africa to be around 13%, which is more or less the same as that in other parts of Africa, OLuyemi, and Alatise (Nigeria). One can appreciate that the incidence of diverticular disease in Africans is on the increase, however, it is important to note that these studies were conducted in tertiary hospitals, hence there is probably some bias as well.

Furthermore, the studies were conducted in urban areas, and due to urbanization and improved socio-econimic status of Indigenous Africans, it is possible that dietary change has a huge factor, which is accounting for the increase in number of diverticular diseases being diagnosed. The authors of the studies did not go in-depth about the amount of fiber consumed. This would be very interesting to know since it is always thought that the Indigenous African diet (high fiber) is protective against diverticular disease. More research is needed to probe deeper into the question of diverticular disease among Indigenous Africans, whether this is still a myth or a common 21st-century problem.

Acknowledgments

The authors wish to thank God for the opportunity to contribute towards writing the book as well as their families and support staff.