Lactase Persistence (LP) |
A dominant genetic trait usually associated with continued high levels of lactase production into adulthood. |
Lactase Non-Persistence (LNP) |
A recessive and ancestral genetic trait associated with a decline in intestinal lactase to < 10 u/g of tissue sometime between the end of weaning and adulthood. |
Lactase Deficiency (LD) |
Reduction of intestinal lactase enzyme from any cause, either genetic (LNP) or any secondary causes, like diseases or injury of the proximal small bowel mucosa. |
Lactose Maldigestion (LM) |
Inability to digest lactose for any reason, primary LNP, but also secondary causes. Most common tests for lactase deficiency are actually for LM. |
Lactose Intolerance (LI) |
Adverse symptoms resulting from the ingestion of lactose, including flatus, gas, bloating, cramps, diarrhea and, rarely, vomiting. LI may occur without LM. |
Self-Reported LI (SRLI) |
Persons believing themselves to be lactose intolerant without testing for LM. Nocebo and psychological characteristics may play a role in milk avoidance. |
Lactose Sensitivity (LS) |
Adverse symptoms with or without symptoms of LI and may also include depression, headache, and fatigue, with or without LM. LS symptoms may overlap with Irritable Bowel Syndrome. |