Carbohydrates, categorized into simple sugars and complex carbohydrates, are the body’s primary energy source. Simple sugars, such as glucose and fructose, are rapidly absorbed, causing faster spikes in blood sugar, while complex carbohydrates, including fiber, offer more sustained energy. Carbohydrate digestion begins in the mouth with salivary amylase and continues in the small intestine through enzymes like pancreatic amylase. Brush border enzymes then convert complex carbohydrates into monosaccharides. These monosaccharides are then absorbed into the bloodstream through specific transporters. Disorders of carbohydrate digestion and absorption, including lactose intolerance, sucrase–isomaltase deficiency, and glucose–galactose malabsorption, as well as mucosal disorders, can cause symptoms such as bloating, diarrhea, and abdominal pain. Dietary adjustments and enzyme replacements are key components in managing these disorders.