Dairy, especially cow milk, is one of the most common allergy or intolerance foods. If you have a true allergy, your body is reacting to the protein component of milk. If you have an intolerance or sensitivity, your ability to digest lactose, a sugar component of milk, may be lacking or impaired.
Human breast milk contains lactose. To break it down and digest it, babies produce the enzyme lactase. When a baby is weaned, the lactase production gene is often turned off and production stops. From then on, instead of lactose being digested properly, it becomes
food for gut bacteria, which produce gas as a byproduct. This can cause symptoms including abdominal pain, bloating, and diarrhea. A relatively new gene mutation that occurred about 10,000 years ago enables an estimated 35% of people to continue digesting lactose into adulthood. This is called lactase persistence.
Lactase is produced by cells in the small intestine. Due to many factors including our stressful modern lives and po...