Why Olive Oil (And A Paleo Diet) Increases DAO

October 21, 2014  |  Blog, Histamine Intolerance

This blog post addresses why olive oil (and a paleo diet) increases diamine oxidase (DAO) and helps reduce the symptoms of histamine intolerance.


The intestinal mucosa is a protective layer in the gut that contains a wide range of enzymes used in digestion and nutrient absorption. One of these enzymes is DAO.

DAO protects the body against an excessive buildup of histamines by degrading both ingested and bacterial histamine.

The amount of DAO synthesised can be reduced due to a genetic mutation (DAO deficiency) but it is nutrients which make it bio-available. This means that what we eat will determine whether available DAO is transported into the gut and bloodstream.

This is not speculation. A study examined each of the key nutrients and here is what they found:


Protein is responsible for the release of DAO in the gut.  Protein (unlike other nutrients) helps release DAO from the intestinal mucosa into the gut to deal with ingested and bacterial amines and histamines.


Oleic acid dramatically increases the release of DAO into the blood stream by up to 500%. Olive oil is one of the primary sources of oleic acid. Canola oil is too – but studies show it is also highly inflammatory, so I choose not to eat it.

Interestingly, protein such as poultry, and lamb is also another good source.

Oleic acid (unlike other nutrients) helps release DAO into the bloodstream, to degrade free amines and histamine throughout the whole body. Medium-chain fatty acids only cause a slight increase in DAO in the blood stream.

It is interesting to note that oleic acid is also a primary ingredient in lorenzo’s oil used to treat for ALP, for lowering cholesterol, and regulating blood sugar, such that oelic acid’s reputation as a healthy fat is unsurprising.

A word of caution is also important. Olive oil is often poorly tolerated if you have salicylate intolerance. As the colour is generally a sign of the salicylate levels some people find they can tolerate light olive oil.


Carbohydrates cause no significant change in the release of DAO. From a DAO perspective carbohydrates are empty nutrients.

It is also my experience that this is also a “grey” area. Some people can digest grains and legumes. Others simply cannot. If you cannot digest grains and legumes then they will ferment in the gut and produce histamine.  I am one of those people.

Paleo Diet

From a diet perspective, many people with histamine intolerance find a modified paleo diet helpful. I am one of those people.

Every time I mention that I am eating a modified paleo diet I get a slew of trolls baiting me.

I want to say that my style of eating is based on my own bio-individuality. Eating legumes and grains makes me chronically ill. It is not a question. It is a statement. My body is that sensitive.

I also respect everyone’s right to listen to their own body, not me, and decide what makes their body feel alive. I see one of my core roles as a health coach to be a loving observer of how your body responds to foods.

That said there is an obvious correlation between oleic acid, protein, and DAO in the study. Fat and protein is essential and should be prioritised in the diet including within the histamine tolerance threshold.

Twelve Foods I Prioritise In My Diet

A part of the treatment with histamine intolerance is finding your bio-individual histamine threshold. A lot of focus is put on removing high histamine foods and not enough on including DAO promoting, and anti-inflammatory foods. There are two sides to the equation.

Here are twelve food I eat regularly that have high levels of oleic acid and are high in other nutrients:

Fats: Olive Oil, and Macadamia Oil.

Nuts & Seeds: Raw Cashews, Raw Macadamias, Hemp Seeds. The key here is their freshness.

Fruit: Avocado (yes I know it is high in histamine – but I have found that once my histamine has subsided I have been able to introduce just ripe avocados back into my diet).

Protein: Lamb,  Chicken, Veal, Duck and Duck Eggs

Transdermal: Rosehip Oil (which is bio-mimetic with the skin).

I eat organically, and local, shopping at farmers markets, so this is what is available to me. You may have other foods available to you.

Whilst it was not part of this study, it would also be interesting to experiment, and identify whether by upping olive oil during a histamine induced attack that it helps to dissipate the symptoms. If you try increasing your olive oil intake please leave a comment below.

Additional Reading:

Wollin, Armin, Xiaolin Wang, and Patrick Tso. “Nutrients regulate diamine oxidase release from intestinal mucosa.” American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 275.4 (1998): R969-R975.

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  • aqmhealthcoaching

    Thanks for making this topic easy to understand for those of us who are less familiar with increasing DAO (and histamine intolerance in general) Alison! With food intolerances ever increasing it is important that people have resources available that provide education and specific ways of managing these conditions better.

  • Jessica

    Thanks for this article Alison! i had some genetic testing done and have several DAO mutations. The only thing that was mentioned about them was a propensity to schizophrenia and bipolar depression. Am I thinking of the wrong mutations? I too do better with lower carbs and no grains or beans.

    • Hi Jessica – yes (and no). Histamine CAN be associated with mental health issues as histamine is a neurotransmitter and yes I do know people whom have a diagnoses of schizophrenia when is mediated by histamine however it is not the DAO gene in isolation. The most common symptom however is sort off raise adrenaline (which is experienced as anxiety but is actually just raised adrenaline). DAO’s primary purpose is to breakdown histamine in the gut, prior to it entering the bloodstream, and travelling throughout the body including to the brain. If you have a DAO mutation (and they are not precisely sure which one at this stage) then histamine could be behind a variety of symptoms that typically start with gut issues and hives or uticaria and then progress from there. I have an infographic here of some of them http://alisonvickery.com.au/histamine-intolerance-infographic/. I too feel much better on lower carbs and no grains or beans. It was one of the things that made a profound difference for me. Thanks for your comment (love your screen name; one buff muma!

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  • Philip Clax

    Wow I never knew olive oil increased DAO! Would the effect be greater than DAO supplements, do you think? I take Histame but I still get reactions. Although I have been drinking white tea recently which supposedly lowers DAO so maybe that is why.

    • Hi Phillips – lovely to hear from you. Yes I also believe that olive oil (unlike omega 6 high oils) is highly anti-inflammatory. I do not tolerate Histame (due to the fillers) and so I am unable to compare it. Also there are no trials with it. I believe that a range of things help with histamine intolerance. The biggest thing that helped me was sorting protein, removing grains, removing omega 6 seed oils, and introducing anti-inflammatory foods. I have a chart on that in my blog if you search; which includes pea sprouts (which do produce DAO also). It also however depends on the source of your histamine intolerance. Hope that helps ….

  • Philippa

    My DAO levels are very high … 315HDUml (normal over 80HDUml) .. any ideas why this would be? Thanks

    • Hi Phillipa I am not sure as that is not one of my many problems! As DAO is part of a metabolic pathway have you had any other testing done? Logically I would assume it is high because it is needed within the body.

      • Philippa Vickery

        Thanks Alison. LOTS of testing over 15 months with various dermatologists and digestive consultants who just cant seem to get to the bottom of my allergy like symptoms .. but come and go (which is why they are now looking at histaminosis) .. bloods, stomach bacteria, pin prick, back patches … a couple of months before I visit the consultant again to discuss the results but the DAO looks worryingly high! (PS I am also a Vickery!)

        • WOW! Another Vickery. Must have the same genes…HAHA. Copper Levels? Zinc Levels? Inflammation Markers? Three day stool test for pathogens/composition of the gut. Id be starting there. IMO the DAO is more likely to be a symptom not a cause. Histamine Intolerance is also a symptom not a cause IMO. DAO is a co-factor of copper, copper is part of an inflammatory/pathogen response, regulated by Ceruloplasmin which is a chronic inflammation marker. Zinc balances copper in the cycle. Pls note that the ranges on the blood tests are stupid on these so higher range may also be indicative. Its the total picture which would lead to a diagnosis.

          • Philippa Vickery

            Thank you very much Alison (will look you up in the family tree lol). I will take these suggestions with me when I visit in January. I appreciate your help, and have started following you on Facebook.

          • let me know how you go. Would be interested.

        • Tracey Mansted

          I would suggest a wide genetic test from saliva like USA’s 23andMe. We are Aussies but were in the US and all of us had it done ($99US) and learnt a lot re SNPs. This is how we know that DH and Dd are poor DAO producers. Sounds like you are not processing your DAO…so accumulating.

  • Heidi Doggett

    I’m thinking I can’t tolerate salicylates. It seems like many foods that are supposed to help with high histamine, such as olive oil, are high sal, while foods that are supposed to help with sal intolerance, like fish oil, are high histamine. I’m starting to be concerned that I will either be sick forever or stuck eating iceburg, plantains, cauliflower, cashews, lentils, cabbage, brussel sprouts, peeled pears, and freshly killed fish for the rest of my life–which is working right now, but previous experience tells me that these foods, many of which are newly introduced and tolerated well after some time on a low fodmap autoimmune paleo diet, will turn on me eventually if I eat them every day for long periods of time. The only fats I seem to deal with right now are refined sunflower and safflower oil, which are low sal, but long-term inflammatory.

    • HI Heidi, sorry to hear about your struggle to work this out. Are you working with someone? A low histamine elimination diet is a diagnostic tool only and if you do not respond to it then you probably dont have histamine intolerance. If you think you salicylate intolerance then the RPA Allergy Unit are world leading experts and their lists are the most reliable. Certainly the foods you list are all low in salicylates.

      • Heidi Doggett

        I’m pretty sure histamine is also a problem. I haven’t been able to tolerate most meat for over a year now. I reacted especially badly to game, and I recently bought a bunch of freshly killed local free range chickens, throwing what fit in the freezer and leaving the rest in the fridge for three days before cooking, and then another few days after before stripping and freezing the meat–the ones that went directly in the freezer don’t bother me, and the ones that stayed in the fridge for days make my mouth burn, my gums swell, my stomach bloat, and my body ache. There are also many low sal foods I can’t tolerate, and most are high histamine: banana, etc. I went low hist, low sal 3 weeks ago, and have been doing much better. Also waiting for 23andme results, not working with anyone yet because insurance doesn’t cover and local prices for reputable practitioners range $500-$1000 for the diagnostic session alone.

        • If you have not had this all your life then you should be tested also for lymes/viral infections

          • Heidi Doggett

            I have had trouble getting sick from food as long as I can remember, including being switched to a non-dairy baby formula by Dr.s early on (then my mom let me eat dairy anyway later…sigh), throwing up and feeling sick all the time as a kid, then being taken off wheat and sugar in 2nd grade for severe lethargy, nausea, vomiting, etc (my mom also let me back on those after a few months, sigh again. People just didn’t know as much about how dangerous food problems could be back then). I realized in high school that wheat, dairy, chocolate, and soy could give me problems–seemed to be dependent on form and stress level–but never discontinued any of those things until my health got very bad just a few years ago. About 4 years ago, went off gluten on a DR recommendation in spite of negative biopsy, and finally started to realize what it meant to not feel sick. After that I had to remove more and more foods, but could never add any back in, until things got bad enough that a little over a year ago I even had to drop most meat. So as far as I can tell, it’s been a continuum, nothing sudden.

          • OK so this is not viral/event related. Please speak to your doctor (GP) about whether it would be appropriate to trial a mast-cell stabiliser (Ketitofen/Gastrocrom; preferably compounded) as that may provide relief if the intolerances are widespread. With my clients that can only tolerate a few things this is often the solution. Also you need to keep a food diary and work with someone to identify the actual diagnosis.

  • Jeannine Way

    Hi Alison, There is someone in the Histamine Facebook community that uses olive oil and says she is help by olive leaf in the form of the herb. What are your thoughts on olive leaf extract?

    • It depends on what her diagnosis is as to the answer to this question. Histamine intolerance has many faces. They key to recovery is working out what is the source. I believe histamine intolerance is a symptom. Most of the clinical trials on olive leave extract are done around metabolic syndrome which IS a histamine related disorder. I have got immediate results through using other things with myself and clients if that is the case.

  • Perryn Slighting

    Hi Alison. I am trying to get tho the bottom of my migraines (severe with vomiting), which also cause a feeling of body flu or high levels of inflammation, hot and cold shivers etc. I stumbled across the histamine discussion and am wondering if this is the key (it has been a forever search and forever trial and error, forever treatment approach and to date no cure – yet I am totally determined to find a solution as the impact on my wellbeing is enormous). I follow a Paleo lifestyle but have not responded as well regards health and wellbeing as I had hoped. My search for good health continues – What are the MOST important things to cut out/include? What supplements do you recommend to assist. Thanks in advance

    • Alethea Black

      Perryn Slighting, you posted this a while ago, so hopefully you’re feeling much better now! But if not, with migraines like that, you might look into:
      — copper dysregulation (zinc and B6 helps)
      — latent Epstein Barr virus (Lysine helps)
      — excess oxalates (low oxalate diet helps)
      Excess oxalates (often caused by genetic factors that lead to low B6) can also often be the root cause behind salicylate and histamine intolerance.
      Good luck!

  • Esmée La Fleur

    I have been sick with Chronic Fatigue Syndrome for more than 20 years now. My food intolerances have been the single most significant issue for me. For me, all my issues seemed to begin after a trip to India where I contracted a GI bug. It was after this that I manifested dermetitis herpetiformis (DH) which is diagnostic for celiac disease. I was a vegan at the time for ideological reasons and was eating quite a bit of wheat. It took me 8 years to figure out what the DH was before I eliminated wheat from my diet. At one point, I spent 2 whole years living on only goat milk yogurt because it was the only thing I could eat without feeling like total crap. It is only in the past year that I have identified salicylate and histamine intolerance as the primary, underlying reason for all of my food intolerances. I have been to many doctors over the years and not a single one ever suggested this as a possibility. I have had to figure it all out on my own. I am currently eating an all-meat diet, no plant foods whatsoever. This eliminates salicylates as an issue, but histamines are still very much an issue. As long as I get meat that is complete fresh (un-aged) and frozen immediately, I have very little reaction to it. I cannot eat any meat that is sold in regular supermarkets in the U.S., and I must source all of my meat directly from private ranchers or the independent butchers who sell their meat. Discovering what is actually wrong has been such a huge break through for me. And find others with similar issues is also incredibly helpful. At least I know I am not crazy! I cannot eat any plant foods or their oils because of their salicylate levels. Maybe over time, as I continue to eat just fresh meat (much of which has significant amounts of oleic acid), my abilty to produce endogenous DOA will improve. Time will tell. Thanks for this very interesting post. If others are interested in follow my journey, they can do so here: http://zerocarbzen.com/about-me/

    • moore2come


    • Sarah Jane

      Have you researched GAPS Nutritional Protocol? Also have you considered testing for chronic bacterial infections, for example Mycoplasma (there are others, of course.)

      • Yes on both counts. I do not recommend GAPS for histamine intolerance. Bacterial infections (as well as other gut ‘issues”) are a standard part of my protocolc.

  • FallenLegacy

    So can I eat canned tuna in olive oil? It increases doa so breaks down the histamine that would build up? I know thawing it in brine only increases the histamine. Do you recommend the olive oil tuna? *I have histamine sensitivity

    • I do not recommend you eat tinned tuna in olive oil.

      • FallenLegacy

        Thank you, I’ll go with cod fillets from sustainably fished sources 🙂

  • Philip Clax

    Does the macadamia oil contain any amines?

  • Isabel Marissa

    There is no doubt that paleo diets are extremely effective as i’ve lost around 65 lbs in about a year and half. However, I really can’t emphasise the importance on getting a sustainable long term paleo diet plan that is not gonna have bad effects on your health. The best paleo diet cookbook (with planned diet regimes) I found is newsciencediet*com/paleo (obviously change the * to a dot as it wont let me post links here) and would highly recommend it to anyone looking to paleo diet!


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  • Miren Hary

    Again another great article!

    • thankyou Miren; much appreciated

      • Miren Hary

        Alison , I keep an eye on a number of face book pages from Mastocytosis to Histamine Intolerance and realative to the way my own diet is evolving through trial and error ,,, YOU are the best!

  • impaler

    Im guessing my issue is with salisylates…because this stuff plus others mentioned give me stomach pains later on instead of helping with a low DAO and high histamine issue I was suspecting.

    • There are many reasons that you may not be able to tolerate a food and they are not necessarily due to the composition of the food. I use an Organic Acids Test to try and narrow things down. I do hope you find the source of your issues.

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  • Heather Largent

    I have MCAS and have noticed that when I have olive oil in the mornings, say some potatoes cooked in olive oil, that my mast cell symptoms are almost non existent. I have been trying really hard to figure out a natural way to health/control my Mast cell disorder, olive oil is on the top of my list.

    • thanks for letting me know Heather!

      • Brad Parrotta

        Dipped apple slices in olive oil and drank a glass of OJ… seemed effective at bringing down symptoms!

  • Elias

    Hi Alison, in terms of Olive oil colour, how would one go about identifying the Salicylic Acidity of one oil from another based on colour?

    Just curious because I was having a more gold coloured olive oil and the company that used to make this oil stopped and its oils are now all a greenish hew that I cant quite tolerate

    How can I go about identifying an oil that is lower in this acid so I can use it and therefore keep my DAO nice and high?

    • In Australia, they are marketed as “light” olive oils so light in colour. Some of the olive oil companies have a rating system with full, medium, and light oils. I am not sure what is available in your location.

  • Unfortunately there are no trials on dosage.

  • Im not sure – they keep changing the formulas. I suggest you perhaps email Cobram Estates who do three different strengths and ask them about their light oil.

  • Cameron Jones

    Thank you so much for this!! I have not been able to find any other info on this sort of thing. I’m really struggling with salicylate intolerance and recently, I started making my own mayo (whole egg, light olive oil, apple cider vinegar). I found that when I have any skin or digestive issues and I take a spoonful of this (yum yum) they go away… My full-on bloat becomes a flat belly!

  • Dianne Inman

    I have had digestive problems for forty years, as did my Mum and one of my sons. It’s only in the last 2 months I am beginning to think it may be MCAS. I have been to my Doctor and he knew nothing about it but is interested in learning more. I have been taking Quercetin which seems to help a bit but and certainly helps my brain function but when I go out to friends houses for a meal – as I did last night things go very much downhill. Smoked salmon and crab,a little white wine ( a treat ) and then sorry to say I couldn’t resist some cheese and a small piece of strawberry tart ! The result ? – very bad night and this morning dreadful loser back pain and other symptoms. I was very interested in your discussion about olive oil and am intending to start using much more. What I am confused about is which to use ? Does it matter whether it is light . I cook with that but also use quite a lot of my favourite which is Waitrose Greek. extra virgin. Perhaps you could clarify this for me ?

    • My recommendation would be that you seek out a functional practitioner (some doctors are trained in this also) and get tested as to the root cause. I would check that the olive oil you are buying is 100% olive oil. Many olive oils are dilutred. Beyond that it does not matter.

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  • rawbabymama

    I feel amazing when I eat about 1/2 cup of olive oil per day in my huge salad. The greens by themselves are lovely, but I’ve found the olive oil dressing is key. I always attributed it to being of largely Mediterranean ancestry (Cuban/Italian), but this makes great sense! Thank you for posting!

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  • onigetoc

    Hi, after some research like here i just find out about the power of Olive Oil. After a Histamine attack, i took a tea spoon of light Olive Oil and i felt a lot better after 30 minutes. It’s pretty fast because usually, i may feel bad for up to 6 hours and more.

  • Annette

    Hi Alison, very grateful to have come across your website, thanks for all the information. I have been diagnosed with off the scale histamine and Candida: I am just completely confused as to why my symptoms, bodily itching without an accompanying rash mainly, peaks when I eat healthily? No gluten, wheat, dairy for a few weeks and the itching is at a peak!? The only thing that I haven’t cut out is black organic coffee, not sure if this may be an issue. I can’t get my head around this, have you by any chance come across this predicament? Thanks, Annette