Glossary - H


Haemorrhoids, or piles, are swollen veins in the anal canal and rectum. Haemorrhoids can be external (occurring outside the anal verge) or internal (occuring inside the rectum). Symptoms of haemorrhoids include swelling, pain, itching, irritation, and bright red blood. Piles or haemorrhoids are thought to be caused by excessive straining during bowel movements; often due to constipation.

Factors such as increased fluid intake, more exercise, and eating high fibre diets are thought to help prevent the development of haemorrhoids.


HDL (high-density lipoprotein) allows the transportation of fatty substances such as cholesterol and triglycerides around the bloodstream. HDL is small and dense and contains the highest ratio of protein to cholesterol. It is often referred to as the 'good cholesterol' as people with higher levels of this lipoprotein tend to be at lower risk of heart disease. HDL carries cholesterol away from the organs to the liver where it is mixed with bile, broken down and passed out of the body in the stool

Helicobacter pylori

Helicobacter pylori, usually just referred to as H. pylori, is a pathogenic bacteria that grows in the stomach and is the main cause of many ulcers and stomach inflammation. H. pylori can weaken the protective coating of the stomach, leaving it vulnerable to digestive acids and consequent irritation. Many people carry small amounts of the bacteria in their system to no ill-effect but lifestyle factors such as consumption of alcohol, coffee and smoking increase the risk of a H. pylori instigated ulcer.


Histamine is a naturally occurring compound involved in triggering inflammatory pathways. Histamine is also a neurotransmitter involved in regulating numerous functions. 


Homeostasis refers to the coordination of the body's many systems, to maintain and regulate a stable internal environment (affected by temperature, pH, etc) in which the body can function optimally. 


A hormone is a chemical messenger that is released by a gland or cell in one part of the body, which has an action on cells in another part of the body. Hormones work by controlling and regulating bodily functions such as metabolism and digestion.


The term hypoallergenic refers to a limited or decreased tendency to trigger allergic reactions. Many of those with food allergies or intolerances benefit from a diet of hypoallergenic foods.