Research consultancy
CHAPTER TWO
LITERATURE REVIEW
2.0 Overview
This chapter reviews relevant literature aligned with the study objectives, focusing on the global and regional prevalence of peptic ulcer disease (PUD), its underlying causes and pathophysiology, and the identification of anti-ulcer agents derived from selected medicinal plants.
2.1.1 Prevalence of Peptic Ulcer Disease
The lifetime risk of developing peptic ulcer disease (PUD) is estimated at approximately 10% (Hein et al., 2017). Globally, peptic ulcer-related mortality declined from 320,000 deaths in 1990 to 250,000 in 2010 (Rickard, 2022). By 2020, over four million individuals were affected annually, with a lifetime prevalence estimated between 5% and 10% (Kang et al., 2011). In Western countries, the prevalence of Helicobacter pylori (H. pylori) infection—one of the leading causes of PUD—increases with age: 20% at age 20, 30% at 30, up to 80% by age 80 (Kamada et al., 2021). Conversely, developing nations report a prevalence of up to 70%, compared to a maximum of 40% in developed regions. Mortality rates from PUD are especially high in countries like Cambodia (20.8%), Kiribati (20.71%), Lesotho (18.88%), Laos (16.83%), and the Central African Republic (15.3%) (Slemrod, 2019).
According to Azhari et al. (2018), the global burden of PUD reached approximately 8.09 million cases in 2019, representing a 25.82% increase from 1990. However, the age-standardized prevalence decreased from 143.37 per 100,000 in 1990 to 99.40 per 100,000 in 2019 (Kavitt et al., 2019). Incident cases rose from 2.82 million in 1990 to over 3.59 million in 2019, though the global age-standardized incidence rate declined from 63.84 to 44.26 per 100,000 over the same period (Azhari et al., 2022; Ren et al., 2022).
Infection rates of H. pylori have generally declined, particularly in high-income nations, due to improved sanitation and medical interventions such as acid suppressants and antibiotic therapies (Wu et al., 2021; Gralnek et al., 2021). Despite this, in the United States, over 4 million people live with active ulcers and 350,000 new cases are diagnosed annually (Xie et al., 2022).
In Germany, the prevalence of PUD is estimated between 5–10%, but has declined due to better diagnosis, treatment, and a reduction in H. pylori infections (Loffroy et al., 2021; Botija et al., 2021). A 2014 study in Germany reported a 0.75% prevalence among over 33,000 individuals (Okoye, 2021), with higher rates among older adults and those using NSAIDs, consuming alcohol, or smoking (Azhari et al., 2018).
Globally, the annual incidence of physician-diagnosed PUD ranges from 0.10% to 0.19%, with a one-year prevalence estimated between 0.12% and 1.5% (Salari et al., 2022). The World Gastroenterology Organization estimates global prevalence between 10% and 15%, with higher rates in developing nations due to contributing factors such as NSAID use, smoking, alcohol consumption, and chronic stress (Kamada et al., 2021; Ren et al., 2022).
Although PUD often presents with abdominal pain, bloating, and nausea, up to 19.5% of cases may remain asymptomatic, increasing the risk of severe complications such as hemorrhage or gastrointestinal obstruction (Dadfar & Edna, 2020; Malfertheiner & Schulz, 2020).
In African countries, prevalence varies widely. In Ghana, studies have shown rates as high as 19.5% among patients undergoing endoscopy. In Nigeria, estimates range from 4% to 16.7%, depending on the region and diagnostic method used (Zibima et al., 2020; Kayode et al., 2019). In Uganda, a study in Kampala found that 78.6% of dyspeptic patients were H. pylori-positive, and 50.6% had peptic ulcers. In southwestern Uganda, 32% of patients with upper gastrointestinal symptoms were found to have ulcers (Milivojevic & Milosavljevic, 2020; Tarasconi et al., 2020).
2.1.2 Overview of Peptic Ulcer Disease
Peptic ulcer disease refers to mucosal lesions ≥3–5 mm in size penetrating the submucosa, typically occurring in the stomach or duodenum (Bereda, 2022). Primary causes include H. pylori infection, NSAID use, and excessive gastric acid secretion. Peptic ulcers are classified as either primary (linked to intrinsic gastric dysfunction) or secondary (associated with stress, medications, or systemic illnesses).
Risk factors include genetic predisposition, lifestyle choices (e.g., smoking, alcohol use), and underlying diseases. NSAIDs and other medications can compromise mucosal defenses by inhibiting prostaglandins, increasing the risk of ulceration (Verma et al., 2010; Pahwa et al., 2011). Epidemiological data suggest that while PUD incidence peaked in the 19th century, it has declined due to medical advancements (Kowada & Asaka, 2022).
PUD complications include bleeding, perforation, and obstruction. In elderly patients, NSAIDs and analgesics may mask symptoms, increasing risk (Sisay Zewdu & Jemere Aragaw, 2020). Furthermore, studies suggest up to 15% of H. pylori-infected individuals may develop ulcers, and a small percentage may experience malignancies (Romstad et al., 2022).
2.1.3 Medicinal Plants with Anti-Ulcer Properties
There is growing global interest in herbal medicine, particularly in Africa where over 80% of the population relies on medicinal plants for primary health care (Russell et al., 2020; Kaggwa et al., 2022). In Uganda and neighboring countries like Tanzania and Burundi, herbal remedies are widely used due to accessibility, affordability, and cultural acceptance (Ssenku et al., 2022; Mao et al., 2019).
Plants such as Aloe vera, Glycyrrhiza glabra (licorice), Zingiber officinale (ginger), Althaea officinalis (marshmallow), Matricaria chamomilla (chamomile), and Ulmus rubra (slippery elm) have shown anti-ulcer activity in experimental models. These plants act via mucosal protection, anti-inflammatory effects, antioxidant mechanisms, or by promoting mucus production (Dinat et al., 2022; Shahrajabian & Cheng, 2019; Tabuti, 2018).
In Uganda, local vegetables and herbs are also used in folk medicine. Traditional greens like Amaranthus viridis and Celosia argentia are believed to relieve digestive issues. Callistemon citrinus (Lemon Bottlebrush), native to Australia but cultivated in Uganda, has shown potential anti-ulcer properties in animal models, attributed to its flavonoids and tannins (Daharia et al., 2022; Tanveer et al., 2020).
The therapeutic value of these medicinal plants is supported by ethnobotanical knowledge passed down through generations, although modern scientific validation remains limited. Due to increasing reliance on herbal medicine, documentation, sustainable harvesting, and conservation efforts are urgently needed (Fakhri et al., 2021; Zougagh et al., 2019).
