Introduction
Dietary modification and lifestyle changes play a fundamental role in the management of functional dyspepsia (FD) symptoms and may therefore be considered a first-line therapeutic option1.
Several studies have indicated that certain foods are frequently recognized by patients as triggers of functional dyspepsia symptoms. Among the most commonly reported are dairy products, alcohol, coffee, carbonated beverages, vegetables, spicy foods, gluten, and fats2.
This article explores the role of dietary management and lifestyle modifications in the treatment of FD.
Low FODMAP Diet
Fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) are short-chain carbohydrates that are not absorbable in the intestine. They are present in a wide range of foods, including fruits, vegetables, cereals, dairy products, legumes, and various types of sweeteners3.
In a clinical study of 105 patients with FD, a low FODMAP diet was compared with traditional dietary recommendations over 4 weeks. Both groups improved their overall symptoms, with no significant differences between them (67% vs. 57%; p > 0.05); however, patients with postprandial distress or abdominal bloating responded better to the low FODMAP diet (p = 0.04). Quality of life scores on the SF-NDI (Nepean Dyspepsia Index Short Form) questionnaire, which assesses five main domains (anxiety, interference with daily activities, ability to enjoy meals, knowledge of the disease, and impact on work or academic performance), improved significantly in both groups. The analysis also indicated that bloating and male sex were factors associated with a better response to this diet4.
Staudacher et al.5 evaluated the relationship between a low FODMAP diet and the relief of FD symptoms. The study included 59 patients diagnosed with FD, but the vast majority (81%) also had a diagnosis of irritable bowel syndrome. The patients were divided into two groups: one that received recommendations on a low FODMAP diet (n = 40) and another that received standard dietary counseling (n = 19). Although adherence to the specific diets did not differ between groups, a significant reduction was observed in both the epigastric symptom score and the total symptom score in the low FODMAP diet group compared to the standard diet group (p = 0.026), resulting in a significantly higher proportion of responder patients in the low FODMAP diet group6.
However, in a cross-sectional study of 2,897 adults, FODMAP consumption was estimated using a food frequency questionnaire, and it was found that a low FODMAP diet was associated with an increased risk of uninvestigated chronic dyspepsia in adults (odds ratio [OR]: 1.85; 95% confidence interval [95% CI]: 1.26-2.78), particularly in women (OR: 2.41; 95% CI: 1.46-3.95). Likewise, a significant association was found with an increased risk of postprandial fullness (OR: 1.38; 95% CI: 1.08-1.78; p = 0.046). The authors conclude that the study, although suggesting a relationship between the low FODMAP diet and the risk of chronic dyspepsia and related symptoms, cannot conclusively prove a cause-and-effect relationship, and therefore suggest the need to conduct randomized clinical trials to confirm the findings and better understand the role of FODMAPs and their relationship with upper gastrointestinal symptoms6.
Gluten-free diet
One of the food hypersensitivities most frequently reported by patients with FD is the adverse reaction to wheat, particularly to the proteins commonly known as gluten7.
Among cases of functional diarrhea refractory to pharmacological treatment, gluten-dependent functional diarrhea should be considered as a possible clinical manifestation of non-celiac gluten sensitivity. Shahbazkhani et al.8 reported a randomized, double-blind, placebo-controlled clinical trial in which, of 77 patients with refractory functional diarrhea, 65% did not respond to a gluten-free diet, while 35% showed improvement in gastrointestinal symptoms. Following gluten intake in blinded patients, symptoms reappeared in 6.4% of the total patients with refractory functional diarrhea and in 18% of those who responded to the gluten-free diet, suggesting the presence of non-celiac gluten sensitivity8. As this study demonstrated, non-celiac gluten sensitivity is highly prevalent among patients with refractory functional diarrhea.
In a meta-analysis that included randomized controlled trials conducted in adults with symptoms related to FD to evaluate the effects of gluten challenge, the results indicated a significant increase in the severity of abdominal bloating (weighted mean difference [WMD]: 0.67; 95% CI: 0.37-0.97; I2 = 81.8%; n = 6), early satiety (WMD: 0.91; 95% CI: 0.58-1.23; I2 = 27.2%; n = 5), and epigastric pain (WMD: 0.46; 95% CI: 0.17-0.75; I2 = 65.8%; n = 6). However, the effect of gluten challenge on the severity of nausea (WMD: 0.13; 95% CI: -0.17 to 0.43; I2 = 0.0%; n = 5) was not significant; therefore, they conclude that gluten restriction could help reduce dyspeptic symptoms9.
However, we must consider that a prolonged gluten-free diet may lead to deficiencies in vitamins D and B12, iron, zinc, and magnesium, and that restrictive diets may increase hypervigilance and anxiety, contributing to the onset of symptoms and decreased quality of life10.
Food restriction/elimination diets
Fats
There is a significant association between the ingestion of high-fat foods and symptoms in patients with FD, specifically postprandial fullness and abdominal distension11.
In a systematic review conducted by Duncanson et al.11, it was demonstrated that the consumption of a high-fat diet can induce symptoms such as nausea, epigastric pain, and postprandial fullness. The main mechanisms by which fatty foods could exacerbate the symptoms of FD are related to delayed gastric emptying and gastric hypersensitivity. It is known that an intraduodenal lipid infusion can increase the sensitivity of the proximal stomach to distension, triggering dyspeptic symptoms, due to a specific effect of fat on cholecystokinin release12.
Caffeine
Several studies have linked the increase in gastric acid secretion induced by coffee with gastrointestinal disorders, including gastroesophageal reflux disease, epigastric pain, and heartburn13. In one study, when compared with water as a control, coffee was observed to be a considerable stimulant of acid secretion. Both caffeinated and decaffeinated coffee have been associated with a prolonged elevation of serum gastrin14.
However, in a study of 3,362 adults aged 18 to 55 years, of whom 58.3% were women, a food frequency questionnaire was used to assess dietary intake, and after adjusting for potential confounding factors (sex, age, energy intake, physical activity, smoking, body mass index [BMI]), no significant association was observed between coffee consumption (OR: 1.27; 95% CI: 0.86-1.87) and caffeine consumption (OR: 1.00; 95% CI: 0.99-1.02) with specific symptoms of FD, such as early satiety, postprandial fullness, or epigastric pain15.
Therefore, it is difficult to reach a definitive conclusion regarding the effects of coffee consumption on dyspeptic symptoms, but it has been observed that patients frequently and spontaneously reduce their consumption.
Alcohol
The effects of alcohol on FD have also been contradictory. Some studies have not demonstrated any relationship between the onset of new dyspeptic symptoms and the severity of dyspepsia, postprandial distress syndrome, or epigastric pain syndrome11.
On the other hand, a large cohort study with 4,390 subjects demonstrated that there was a relationship between the consumption of more than seven alcoholic beverages per week and the presence of dyspeptic symptoms (OR: 2.3; 95% CI: 1.1-5.0); thus, it is difficult to determine whether alcohol induces symptoms or not16.
Given that chronic alcohol consumption is not healthy, reducing alcohol intake can be recommended in patients with dyspepsia, as in other conditions.
Capsaicin
Capsaicin is the active compound in chili peppers, responsible for the burning sensation associated with spicy foods. In patients with FD, the consumption of foods containing capsaicin increases symptoms compared with placebo consumption or with healthy controls12.
Studies have been conducted to investigate primarily the effects of capsaicin in the treatment of functional dyspepsia by addressing the relationship between capsaicin and the transient receptor potential vanilloid type 1. It has been proposed that capsaicin could alleviate the symptoms of functional dyspepsia through various mechanisms. These effects include the desensitization of C nociceptive fibers, the regulation of various neurotransmitters, the reduction of epithelial inflammation, the balance of the intestinal microbiota, the inhibition of gastric acid secretion, and the reduction of oxidative stress damage17.
Nevertheless, the evidence regarding its use is limited. Recent studies observed, in patients with functional dyspepsia, that when a dose of 0.50 mg of capsaicin was administered, it induced moderate epigastric pain in 76% of patients. However, in another study, the ingestion of 0.25 mg of capsaicin reported mild symptoms in both patients with functional dyspepsia and healthy controls. It is important to emphasize that the proposed treatment duration should be longer than 1 week; a shorter application may sensitize the chemoreceptors and increase pain perception18,19.
Therefore, it has been proposed that a complete understanding of these mechanisms will aid in the development and utilization of capsaicin in the fields of nutrition and medicine.
Dietary patterns
Meal frequency
Patients with FD are unable to tolerate large amounts of food and, therefore, tend to decrease the number of meals and calories, and increase the number of snacks, with risk of calorie, vitamin, and mineral deficiency. However, Göktaş et al. found no significant differences in meal frequency between subjects with FD and healthy subjects, as both groups reported consuming three main meals during the day (68.5% vs 70.4%)17. Similarly, regarding snack consumption, the investigators found no differences in frequency between the two groups. These results are consistent with those of Çolak et al., who concluded that meal frequency does not influence the triggering of symptoms in patients with FD20.
The preparation, volume, and speed at which food is consumed may also be associated with dyspeptic symptoms21.
Lifestyle modifications: exercise
The association between exercise and digestive symptoms remains inconsistent. In a Japanese study with 30 healthy subjects, it was observed that moderate-intensity exercise, but not low- or high-intensity exercise, induces gastric emptying. However, in a Swedish cohort study with 137 participants, exercise was associated with an increase in reflux and vomiting, and with a decrease in diarrhea and nausea22.
In one study, the prevalence of FD among subjects with no, low, moderate, and high exercise frequency was 2.7%, 1.7%, 1.3%, and 1.3%, respectively. After adjusting for age, sex, BMI, alcohol consumption, smoking, heart murmur, and anemia, an inverse association was observed between low, moderate, and high exercise frequency and FD (the adjusted ORs were: for low frequency 0.69 [95% CI: 0.47-0.997], for moderate 0.53 [95% CI: 0.34-0.81], and for high 0.53 [95% CI: 0.30-0.88]; p = 0.002)23.
Therefore, the relationship between exercise and digestive symptoms, as well as with FD, is neither clear nor consistent. On the one hand, some studies have shown positive effects of moderate exercise on gastric emptying, while others have observed adverse effects, such as an increase in reflux symptoms and vomiting. However, one study suggests that there is an inverse relationship between exercise frequency and the prevalence of FD, indicating that the higher the frequency and intensity of exercise, the lower the prevalence of FD, although this finding requires more detailed analysis and consideration of confounding factors such as age, sex, and BMI, among others.
Conclusions
A low FODMAP diet may be beneficial for FD, especially in patients with abdominal distension and postprandial discomfort, although some studies show no significant differences compared to traditional recommendations. However, FODMAP consumption could increase the risk of chronic dyspepsia, particularly in women. Regarding the gluten-free diet, some patients with non-celiac gluten sensitivity experience improvement, but it should be noted that restrictive diets may cause nutritional deficiencies if not adequately supervised. The consumption of fatty foods worsens FD symptoms, such as postprandial fullness and abdominal distension, while both caffeine and alcohol may trigger digestive symptoms, although the results are not conclusive. Capsaicin from spicy foods could aggravate symptoms in some patients, but its potential therapeutic use is also being investigated. Concerning dietary patterns, the frequency and volume of meals may influence FD symptoms, with some patients opting for more snacks to avoid large amounts of food, which can lead to nutritional deficiencies. Finally, the relationship between exercise and digestive symptoms is ambiguous; some studies suggest that greater exercise could be associated with fewer dyspepsia symptoms, but it is necessary to consider other factors such as age and BMI.
Funding
The authors declare that they have not received funding for this study.
Conflicts of interest
The authors declare no conflicts of interest.
Ethical considerations
Protection of human and animal subjects. The authors declare that no experiments have been conducted on human subjects or animals for this research.
Confidentiality, informed consent, and ethical approval. The study does not involve patient personal data nor does it require ethical approval. The SAGER guidelines do not apply.
Declaration on the use of artificial intelligence. The authors declare that they used artificial intelligence (ChatGPT) for the writing of this manuscript in the abstract and conclusions.
