Milk primarily consists of protein, fat, lactose, various minerals, and vitamins. It is especially rich in calcium and phosphorus—a single glass of milk (approximately 250 milliliters) provides half of the human body's daily calcium requirement. However, if people fail to follow proper cooking and consumption methods when drinking milk, its nutritional value can be significantly diminished.So, how can you drink milk without causing diarrhea? What are the common misconceptions about milk consumption?
Prolonged High-Temperature Boiling
Milk is heat-sensitive. When heated to 60°C–62°C, the protein particles dehydrate and gelatinize, forming sediment. Simultaneously, the highly unstable acidic calcium phosphate in milk transforms into neutral calcium phosphate, also precipitating.When heated to around 100°C (212°F), the lactose in milk begins to caramelize, turning brown and gradually decomposing into lactic acid and small amounts of formaldehyde. Prolonged high-temperature boiling also causes significant vitamin loss. Therefore, milk should only be heated until it just comes to a boil before removing it from the heat; prolonged boiling is not recommended.
Boiling with Sugar
Under high temperatures, lysine in milk reacts with sugar through the Maillard reaction, producing a toxic substance—fructosyllysine—which harms human health, posing greater risks to children.If you prefer sweetened milk, add sugar only after the milk has cooled slightly following boiling. Similarly, milk should never be boiled with chocolate, as chocolate contains high levels of oxalic acid. When boiled together, the calcium in milk combines with oxalic acid to form calcium oxalate, which is poorly absorbed. This can also cause symptoms like diarrhea. Therefore, these two should be consumed separately.
Drinking Milk on an Empty Stomach
When the stomach is empty, gastrointestinal motility accelerates. Milk passes through the digestive tract quickly, failing to interact sufficiently with digestive enzymes. Its nutrients are rushed into the large intestine before proper digestion, preventing full absorption and utilization.The proper way to consume milk is to pair it with starchy foods like steamed buns, bread, or pastries. The starches help prolong the milk's stay in the digestive tract, allowing proteins, calcium, and other nutrients to be fully absorbed and utilized.
Combining with Acidic Foods
After entering the digestive tract, milk proteins first bind with pepsin and trypsin in gastric juices before proceeding to the small intestine. Consuming acidic beverages or fruits at this stage causes milk proteins to coagulate with fruit acids and vitamin C, forming lumps. This not only impairs digestion and absorption but may also lead to symptoms like diarrhea, abdominal pain, and bloating.
Improper Storage
Some people prefer chilling (or freezing) milk during summer. When milk is chilled below zero degrees Celsius, its fats and proteins separate, causing casein to form a powdery curd. This significantly weakens the flavor and makes nutrients harder to absorb. Regular consumption of chilled milk may also trigger the recurrence of gastrointestinal disorders like ulcers, cholecystitis, or enteritis.Others store leftover milk in thermoses. This creates an ideal breeding ground for bacteria—whether from the milk itself or the air in the thermos—allowing rapid spoilage within hours. Vitamins B and C are also significantly depleted. Therefore, it's best to consume boiled milk promptly after it has cooled slightly.