Histamine is a chemical involved in your immune system, digestion, and your central nervous system. As a neurotransmitter, it communicates important messages from your body to your brain, such as waking you up and letting you know when you’re thirsty. It is also a component of stomach acid, which helps you break down food.

Enzymes break down the histamine so that it doesn’t build up. If for some reason you don’t break down histamine properly, it builds up and you develop a histamine intolerance, which can affect your gut, lungs, skin, brain, and entire cardiovascular system.

I certainly know about histamine issues, as both my son and I suffered with histamine reactions in the past. 

I’ve done a lot of research and could write much more, but here’s a summary!

Genetic clues to histamine issues: 

Some of the main genetic SNP’s to look for on a genetic test to show if you have genetic tendency to histamine issues are DAO and HNMT. 

1. DAO is an enzyme that degrades dietary histamine (fermented foods, fish, alcohol, spinach, chocolate etc). If you eat high histamine foods and have a DAO genetic SNP, it makes it harder to break down histamine, so then you can suffer from symptoms such as headaches, anxiety, heart palpitations, sleep issues etc. 

For some a DAO supplement may help (these contain pork and sometimes corn so not good for everyone) or/ and a low histamine diet can help.

Just to mention curcumin which can help some, actually blocks DAO, so if you have DAO mutation, you may not be able to tolerate curcumin

2. HNMT is an enzyme responsible for the breakdown of cellular histamine. If you have environmental, mast cell issues, or non-food related histamine concerns and you have HNMT SNP’s you can be more prone to these issues mentioned above. For this you can use supplements such as nettles, quercetin and making sure your methylation is working with B vitamins. 

Histamine, blood sugar & the adrenal glands

Histamine can also trigger an adrenal stress response as well.

  • There is a link with histamine and blood sugar. There are histamine receptors in the pancreas and there are studies showing elevations of histamine in diabetics.
  • Histamine is a big biochemical stressor of the adrenal gland, cortisol from the adrenals can then raise blood sugar. 

Bacterial overgrowth 

Bacterial overgrowth is another contributing factor for developing a histamine intolerance. Bacteria grows when food isn’t digested properly, causing histamine over production.

Vitamin B3 & histamine

Vitamin B3 deserves an entire heading of its own as it’s amazing for reducing histamine issues! This nutrient has been absolutely amazing in both my family’s histamine issues and my clients. We used to continually react to our dog, but no longer. 

Minerals, vitamins & histamine

DAO enzymes are dependent on vitamin B6, B12, iron, copper and vitamin C. These nutrients therefore play a key role in the breakdown of histamines. 

Copper levels are key to understand to help resolve a histamine issue, although we need ‘bioavailable’ copper for histamine issues, a copper excess (‘toxic’ copper) will block vitamin B6, vitamin C, Magnesium, Zinc and Manganese. 

Calcium is also needed to flush out the histamine. 


What works for one client certainly doesn’t work for all, quercetin for example, is high in salicylates. In order to tolerate B vitamins, you may need more magnesium first, vitamin C isn’t always tolerated either. Treatment should be carefully determined by your practioner.