Histamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by basophils and by mast cells found in nearby connective tissues. Histamine increases the permeability of the capillaries to white blood cells and some proteins, to allow them to engage pathogens in the infected tissues.
from the Department of Biology, Davidson College
The release of histamine (hist = because it’s made up of histidine residues, amine = because it’s a vasoactive amine) causes several allergic symptoms. 1) It contributes to an inflammatory response. 2) It causes constriction of smooth muscle.
Histamine can cause inflammation directly as well as indirectly. Upon release of histamine by an antigen activated mast cell, permeability of vessels near the site is increased. Thus, blood fluids (including leukocytes, which participate in immune responses) enter the area causing swelling. This is accomplished due to histamine’s ability to induce phosphorylation of an intercellular adhesion protein (called (VE)-cadherin) found on vascular endothelial cells (Andriopoulou et al 1999). That is why histamine is known as being vasoactive. Gaps between the cells in vascular tissue are created by this phosphorylation, allowing blood fluids to seep out into extracellular space. Indirectly, histamine contributes to inflammation by affecting the functions of other leukocytes in the area. It has been suggested by Marone et al that histamine release triggers the release of cytokines and inflammatory mediator by some neighboring leukocytes (1999). These chemicals in turn increases the inflammatory response.
from Allergy UK
We all have an enzyme (diamine oxidase) which breaks down any histamine that we absorb from a histamine-containing food. When we eat a food which contains histamine it does not affect us. However, some people have a low level of this enzyme. When they eat too many histamine-rich foods they may suffer ‘allergy-like’ symptoms such as headaches, rashes, itching, diarrhoea, and vomiting or abdominal pain. This is called histamine intolerance.
from Healthy Pixels
I am astounded at how many of us unknowingly suffer from excess histamine. Some of us itch or sneeze while others get headaches, migraines, joint pain, or nausea – within minutes or several hours after exposure! Our “histamine bucket” fills up based on factors such as genetics, allergies, medication, diet, environment, nutritional deficiencies, intestinal damage, and UV exposure. When our body cannot break down excess histamine, we suffer with histamine intolerance and increased inflammation. When we realize what is really happening, we can better prevent and treat this misunderstood condition!
Histamine and its receptors are constantly engaged in a vital balancing act, preventing excessive inflammation while promoting homeostasis and healing. A variety of inflammatory diseases involve histamine activity.
Most of us know histamines through antihistamine drugs that relieve our suffering from allergies to pollen, insect bites, and even foods. Histamine is naturally produced in our body by mast cells or white blood cells, and it performs different functions by binding with histamine receptors. Depending upon their location, histamine receptors control very different body functions.
So why haven’t we heard about this?
Histamine intolerance is hugely underestimated in the population. Most people respond to symptoms of histamine intolerance with an aspirin, antacid, or other quick-fix pill that does not address the root problem. Sometimes histamine levels are raised due to allergy, but histamine intolerance is not a true allergy and it won’t show up on allergy tests.
Unlike allergy testing, confirming a serious histamine intolerance isn’t easy or profitable for doctors. An elaborate study discovered that “histamine-intolerant subjects reacted with different organs on different occasions.” Each person has a unique set of symptoms that may not always recur in the same location or intensity. The only true test for histamine intolerance requires a strict histamine-free diet followed by a double-blind food challenge. With a true diagnosis, the standard treatment is even more dismal – a low-histamine diet for life. But don’t give up yet!
WHAT CAUSES HISTAMINE LEVELS TO RISE?
Reduced or Inhibited Enzymes
One of the more common reasons we suffer from histamine intolerance is the lack of enzymes diamine oxidase (DAO) and histamine-N-methyl transferase (HNMT). These enzymes break down histamine and keep it in check. DAO and HNMT levels may be genetically low in some individuals, blocked by drugs, or reduced from intestinal damage or diseases such as celiac. Caffeine also inhibits DAO.
Many factors affect the body’s histamine levels, and there are ways we can help reduce the load. Our exposure to allergens, diet, drug use, temperature, hormones, and nutritional deficiencies dramatically impact our histamine levels throughout the day. Imagine your histamine as a “bucket” that fills up and only reveals symptoms after overflowing.
Large amounts of histamine are promptly released when we are exposed to our allergens, and the most common allergens include mold, dust mites, animal dander, pollen, medications, insect stings, latex, and food. Interestingly, scientists are beginning to suspect that these allergies have developed in order to protect us from environmental toxins. It is important to avoid exposure to known or suspected allergies, especially when histamine levels are a potential problem. Get tested and avoid the triggers to start emptying the bucket!