Nutrient Absorption in the Stomach: What Is and Isn’t Absorbed

The stomach is a J‑shaped organ in the upper left abdomen responsible for the initial stages of digestion: mechanical churning, acid secretion, and enzymatic breakdown of food. While the stomach absorbs some substances, the majority of nutrient absorption occurs later in the small intestine.

Substances Absorbed in the Stomach

• Alcohol: Absorbed directly through the gastric mucosa into the bloodstream.
• Water and electrolytes: Limited absorption occurs.
• Certain drugs: e.g., aspirin, some lipid‑soluble medications.

Substances NOT Significantly Absorbed in the Stomach

• Proteins: Broken down into peptides and amino acids by pepsin and HCl, but absorption of amino acids occurs primarily in the small intestine.
• Fats: Gastric lipase initiates fat digestion, but fatty acids and glycerol are absorbed almost entirely in the small intestine.
• Carbohydrates: Minimal digestion (salivary amylase inactivated by acid); absorption occurs in small intestine.

Understanding site‑specific absorption helps explain the rapid effects of alcohol and the rationale for certain drug formulations.