Fasting’s effect on diamine oxidase (DAO) & histamine intolerance

man's fingers holding tiny fork and eating from a tiny plate

Two important questions regarding fasting for those with histamine intolerance are: does not eating affect the function of the histamine degrading diamine oxidase (DAO) enzyme, and is the stress of not eating so extreme as to negate the benefits of it? 

All references at the bottom of post.

Why a post on fasting? I’ve long used fasting as a tool for dealing with histamine related inflammation. A history of eating every few hours, even getting up from bed in the middle of the night to do so, had left my body in a constant state of excitability and chronic histamine release.

The reasons for this is very simple: histamine is involved in the digestive process and eating triggers generalised inflammation, regardless of  whether you have histamine intolerance or mast cell activation.

University of Southern California Longevity Institute director Dr. Valter Longo has created a fasting mimicking diet that has the benefits of water fasting while allowing about 800 calories a day. My interview with him revealed that up to 40 percent of the immune system can be regenerated in just five days. Longo told me that would include “faulty” mast cells that are leaking histamine indiscriminately. Read the post here.

I’ve long experimented with and written about fasting for my histamine intolerance and mast cell activation because I discovered early on, even before I was diagnosed, that very short bursts of it made me feel better.

PLEASE NOTE – there is a difference between fasting for health once in a while and anorexia. Don’t even think of trying it if you have ever had repeatedly negative thoughts of food, negative body image or any kind of eating disorder, no matter how long ago it was. Either way, a doctor needs to be involved. 

But there’s still an unbelievable lack of research on fasting’s effect on the histamine degrading diamine oxidase (DAO) enzyme. Residing in the gut, where histamine is released every time we eat (or even think of food), DAO’s job is to break down histamine once it’s not needed anymore, or presumably when there’s just too much of it for us to handle. DAO relies on a number of nutrients to function normally – things like magnesium (a lack of this can cause major histamine release), copper, vitamin B6 and others. It’s at its peak during pregnancy where it helps prevent uterine contractions that could end in miscarriage (read more here).

Histamine intolerance is considered to be an excess of histamine caused by or coupled with a lack of DAO. Genetic testing can reveal if we’ve inherited genes that predispose us to low DAO production, but a lack of it may simply be triggered in women as we age and hormones decline because we no longer need DAO’s help in preventing miscarriage.

A study published in the journal Digestion found that levels of the histamine degrading DAO enzyme in starved rats did not decrease during fasting. (I can’t find any human studies).

That’s a start.

But what about the very valid concern regarding fasting increasing histamine levels?

Well, that could depend on a number of factors.

We know for sure that stress causes histamine release from mast cells. These white blood cells contain not only histamine but also a number of other inflammatory agents that you really don’t want to have dumped into the blood stream unless needed to fight infection or heal you from injury.

It’s also known that fasting in animals has been shown to cause stress, which in turn causes histamine release.

In my case, water fasting has been hugely stressful in the past. The fear I’m doing something stupid, the fact that it was done in a haphazard fashion when my histamine rose to intolerable levels, and basically being too weak to move or do anything other than lie around obsessively tracking every minute (or scary) symptom.

Juice fasting/feasting was more successful because it took the stress away, but I still had the energy problem (and I was using too many fruits).

My approach and mindset (ie my stress level) going in to the fast dictated how successful it would be. In other words, we’re not the animals in the studies. We choose to fast rather than being starved, we are not held in restraints or have scientists devising ways of freaking us out.

That’s all good and well, but yes, we can be just as stressed as the animals, because let’s face it, dealing with these health issues can create a lot of anxiety.

I came to realise a few things could made for a successful fast:

(Please note, these are my observations and should not be a substitute for medical advice.)

  • – Liquids put less stress on the body and (according to Dr. Fuhrman) were less demanding of my stomach enzymes
  • – I stopped fasting when I was at my sickest. Planning fasts and being mentally prepared for them was essential
  • – Meditation is an essential component
  • – Reading materials or motivational documentaries and films should be planned in advance
  • – Getting in touch with nature is really helpful for lowering stress levels
  • – I didn’t need to starve myself. A cut of about 20-30 percent of my usual calories sufficed
  • – Focusing on nutrient dense foods with antihistamine and anti-inflammatory soups and low fruit juices regardless of calories was extremely healing to me
  • You’ll find most of the recipes I used in the Anti-Detox.

My (non-medical but totally been there myself) advice is, if you’re experiencing a moderate to significant amount of stress, then fasting probably isn’t a great idea.

There are exceptions of course, but really, there’s a good chance that getting the stress under control might reverse much/most of the histamine symptoms anyway and you might not need to fast!

If you don’t have the patience or time for it, check out how to create your own personalised healing plan here.


Irie, Masahiro, Shoji Nagata, and Yutaka Endo. “Effect of isolation on classical conditioned histamine release in guinea pigs.” Neuroscience Research 44.1 (2002): 31-35. Web.

Irie, Masahiro, Shoji Nagata, and Yutaka Endo. “Fasting stress exacerbates classical conditioned histamine release in guinea pigs.” Life Sciences 72.6 (2002): 689-98. Web.

Erdman, Steven H. “Effects of Starvation and Difluoromethylornithine (DFMO) on Diamine Oxidase Activity in Rat Ileum.” Digestion 46.2 (2009): 396-402. Web.

“Digestion itself is a histamine trigger | Healing Histamine.” Healing Histamine | Histamine Intolerance Diet Foods Recipes. N.p., 04 Apr. 2014. Web. 13 June 2017.


Check out these other Healing Histamine blog posts


Yasmina was an award-winning broadcast journalist with a decade of experience covering war zones for CNN and the BBC. She devoted her journalism skills to researching and writing about histamine. Click here to learn about her. Each post is carefully and fully referenced with the latest scientific research. Not sure where to start? Here’s a four week meal plan and overall Histamine Reset.

4 Week Histamine Reset

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