Indigestion describes upper digestive discomfort that may include post-meal fullness, early fullness, bloating, burping, nausea-like uneasiness, upper abdominal pressure, or burning sensations after eating. It is commonly connected to meal size, meal composition, stomach relaxation, gastric emptying speed, intestinal sensitivity, bile flow, microbiome activity, stress signaling, and inflammation. When food remains in the stomach longer than expected, when meals are too large or too concentrated in fat, or when the stomach lining is irritated by dietary triggers, digestion can feel heavy, slow, or uncomfortable. Food pattern is a major factor. High-fat meals, fried foods, oils, meat-heavy meals, dairy-rich meals, alcohol, refined sugar, artificial sweeteners, emulsifiers, highly processed foods, excess sodium, and late-night eating can increase digestive burden. Concentrated fat slows gastric emptying and increases post-meal fullness. Ultra-processed foods can reduce fiber density while increasing additives, sodium, refined starches, and chemical exposures that may affect the gut barrier and microbiome. Low fiber intake can reduce stool bulk and alter microbial fermentation, while rapid eating and overeating can increase stomach distension. A P53 Nutrition approach uses no oils, no meat, no dairy, no toxins, and is 100% whole-food plant-based nutrition. This pattern supports indigestion-related biology by emphasizing foods that are naturally high in water, fiber, potassium, magnesium, antioxidants, and plant polyphenols while keeping meal fat density low. Cooked vegetables, oats, brown rice, quinoa, potatoes, sweet potatoes, carrots, pumpkin, bananas, apples, lentils, chickpeas, beans, and gentle herbs provide structured carbohydrates, soluble fiber, resistant starch, minerals, and phytochemicals that support motility, microbial balance, and epithelial barrier function. Indigestion connects to gut-microbiome, epithelial-barrier-integrity, bile-acid-synthesis, scfa-signaling, stress-response, nfkb-pathway, hydration-electrolyte-balance, and glutathione-defense. The stomach and upper intestine coordinate mechanical mixing, acid exposure, enzyme activity, hormone signaling, and downstream transit. Whole plant foods support these systems through fiber-driven stool formation, short-chain fatty acid production, lower saturated fat exposure, improved meal volume control, and antioxidant activity. Polyphenols such as quercetin, catechin, epicatechin, chlorogenic-acid, apigenin, luteolin, rosmarinic-acid, and curcumin are studied for interactions with oxidative stress, inflammatory signaling, gut microbiota, and mucosal biology. The nutritional focus is gentle, lower-fat, whole-food meals that are eaten slowly, portioned moderately, and built around cooked plants, intact grains, legumes as tolerated, and non-irritating fruits. This supports digestive comfort through reduced gastric load, improved transit, microbiome support, hydration balance, mineral intake, and avoidance of oils, meat, dairy, and toxin-linked processed foods.