The depressed second brain

Interesting article on the Scientific American site.

Think Twice: How the Gut’s “Second Brain” Influences Mood and Well-Being

Is is about how our guts function as a second brain, due the immense amount of neurons located in it. A lot of the information relayed through these neurons is processed there, but a large amount of information is sent to the brain as well and can probably influence our mood. It also mentions the effects of serotonin located within the gut and how SSRi’s, serotonine uptake inhibitors, can lead to too much of it and other medication to too litle, causing problems on it’s own.

As histamine is an important neurotransmitter as well, I can only wonder what the effects of histamine will be. If the amount and distressing inflammation effects of histamine is being relayed to the brain. And if this has such a large impact on mood and other functions. It can probably clarify a lot of the distress as experienced by those that are exposed to a high level histamine

Published in: on February 23, 2010 at 1:12 am  Leave a Comment  


Since histamine has a large amount of functions within the human body, the effects of high histamine blood levels can vary widely. I’ve scoured the net to make a good list of these and provide a short explanation as to why histamine causes these.   I’d like to go into these in more detail in later posts. Some of these are widely known and proven by science, others I didn’t put through the scholar search engines yet, but I will try to continuously update this post every time I find out more.

Symptoms affecting muscles

Histamine affects smooth muscle, which acts autonomously,  histamine is the main controlling agent for contractions within this type of muscle. But it can also cause reactions within other types of muscle,

Bladder – As the bladder is made out of smooth muscle, contractions can occur, often people suffer from a weak bladder resulting in needing to pee often.

Bronchioconstriction/wheezing – Smooth muscle is also located in the airways, leading to asthmatic symptoms.

Gastrointestinal trouble – The same goes for the bowel and colon which is mostly made out of smooth muscle. Spasm’s and irritable bowel syndrome can be caused by histamine. As are many other problems. Diarrhea or constipation, bloating, cramps, abdominal pain and nausea to name a few eh.. well most.

dysmenorrhea (menstruation pain) – The uterus consists of smooth muscle, and a heightened amount of histamine can cause more severe menstruation cramps in women. As histamine also tampers with hormonal levels like progesterone and oestrogen, which in turn can influence levels of histamine. The good news is that the placenta in pregnant women produces large amounts of DAO leading to a remission of the intolerance during pregnancy.

Blood pressure and flushing – Smooth muscle is located in the blood vessel, so histamine affects the dilation of blood vessels and the permeability as well. Leading to a variety of symptoms like high or low blood pressure, as well as flushing (blushing) of the skin.

Hyves/eczema/urticaria – These often are immunological responses, but can be caused or exacerbated by high levels of histamine.

Heart tachycardia –  Histamine is also present in the heart, and heart rhythm failures and palpitations can be caused by histamine. If histamine is the cause of this, there is no presence of other heart disease.

(Fibro)myalgia–  It also plays a role in the functioning of other muscles, Leading to muscle aches even without a cause, and also (fibro)myalgia symptoms.

Muscle cramps and spasms – As said it’s import in muscle functioning. It can also cause cramps and spasms of non-smooth muscle mass and muscle soreness. The release of nitrite oxide stimulated by histamine is the main cause of this.

Other effects:

Pain – Histamine decreases the threshold of pain receptors to feel pain, as it sensitizes the pain receptors.

Itch –  Histamine stimulates sensory nerve endings which can cause itching.

Headache/migraine – As histamine stimulates the release of nitrate monoxide, it can cause slight headaches to full-blown migraine attacks.

Joint pain/rheumatic problems – The main cause of these are infections and the holding of fluid, since histamine does exactly does things, these kind of problems will arise as well.

Stomach Acid/Ulcers – Histamine also steers the production of stomach acid, leading to ulcers and other disorders of the stomach. Frequent hiccups are one example of this.

Allergies/sickness – As histamine is an important messenger molecule in immunological responses. it can cause the same symptoms as allergies or a real invasion of some sort can cause.

Mucus secretion – As well as stimulating gastric acid, it also stimulates other mucus secretions,  saliva, mucus of the nose, mucus within the airways and  tears.

Dark circles under the eyes – these results because of the direct influence of histamine on vasodilation, but also the itch histamine can cause leads to scratching and rubbing around the eyes can exacerbate these even more.

Eyesight – Eyesight troubles can occur, making the eyes more and less sensitive to light, as well as interfere with the ability to contract eye muscles and with vasodilation contracting of fluids, the shape of the lens of the eye can change. Resulting in less than perfect vision.

Sweating – Histamine also plays a role in different ways in the regulation of sweat, and most of all the occurrence of sweating.

Hairloss – histamine is also related to the induction of hair loss, by continual inflammation follicles can stop producing hair. This can also result from inner stress and tension occurring direct or indirectly from a high level of histamine.

Fatigue – as the adrenal gland reacts upon histamine within the blood by releasing cortisol, this gland can get exhausted leading to fatigue. The antagonistic effect of adrenaline on histamine as well can cause feelings of fatigue.

Central nervous system

Most of these symptoms just mentioned are within the general body, but histamine also has major functions within the central nervous system. Even though I often see mentioned it doesn’t or badly diffuses through the blood-brain-barrier, it does affect the permeability of the blood brain barrier and as such I figure histamine will be able to cross is. And as certain symptoms t  stem from a feedback system from the rest of the body to the central nervous system which leads to certain reactions with the nervous system. This could be the cause for other symptoms as well.

Thirst – As neurotransmitter histamine is part of the management of water intake and distribution throughout the body it is released if dehydration occurs. As such excessive levels of histamine can occur due to dehydration itself. It will make you crave for fluids, food and carbohydrates (as these help in the distribution of water).

Lack of appetite – Even though in the regulation of water intake histamine plays a role in the need for food, which contains water, it also suppresses hunger. If the gastrointestinal problems in itself didn’t yet do so.

Nausea – Histamine mediates the sending of nausea signals from the body to the brain. And also stimulates the ‘vomiting’ center in the brain. Leading to nausea and vomiting.

Dizziness/Vertigo – Most of these stem from inner ear troubles. Even though in some cases histamine itself can give relief from this. It can also cause dizziness.  As it affects the vestibular responses.

Arousal/insomnia/anxiety – These are in my opinion closely related even though different brain areas are involved. One major function of histamine is in an area of the brain that’s active when awake, it controls wakefulness and circadian rhythm, another one is the anxiety center. There closely correlate in being awake, wakeful, and vigilant for threats. This can lead to insomnia, and anxiety attacks.

Nightmares – Though it is unknown where this stems. I figure the stimulation of the anxiety center and the increase of anxiety can result in nightmares.

Crying – Tears also function as a way to flush stress molecules and toxins from the body. This, the anxiety, and production of tears caused by histamine, can lead to persons being more prone to start crying.

Depression – Histamine inhibits the release of serotonin, leading to the occurrence of depression. In combination with the detrimental effects on healths this occurs even more easily.

Memory – As histamine plays an important role within memory storage and retrieval, problems with memory can occur.

Other trouble that can occur

Weight problems – As metabolism is influenced in a variety of ways by a lot of factors, like immunological stress and other stress factors. The presence of gastrointestinal problems can lead to a lack of nutritional uptake from the bowels. Overstressing of the liver as well, can lead to an excessive storage of fat. Recently an article appeared in which a woman suffered from anorexia was described, but instead of anorexia she suffered from histamine intolerance.

Sexual disorders – With the functions of histamine in vasodilation and arousal, it plays a major role in arousal of mind and body. Leading to high libido and making it easier to achieve orgasm. Especially in males this can lead to premature ejaculation

Adrenaline/panick attacks/fatigue – Adrenaline counteracts the functions of histamine, and vice versa. As histamine increases adrenaline will as well. Messing up chemistry in body and brain even more. Causing panic attacks. fatigue etc.

Sensitivity to stress – As mean there are quite some effects histamine has which can lead to stress sensitivity. One more is that stress itself can cause release of histamine. If there is a high level of histamine, than a little bit of extra released histamine can quickly lead to more severe reactions.

Sensitivity to other factors – A lot of other factors will release histamine, heat, cold, pollen, aggravation of the skin and such, will lead to more severe oversensitive reactions in those with high levels of histamine.

Alcohol intolerance – Alcohol often contains a lot of histamine, leading to any histamine intolerance symptoms. And alcohol also has an inhibiting effect on the activity of one of the enzymes breaking down histamine, which can lead to worse symptoms, and more sensitive reactions over a longer period of time.

Other possible symptoms and comorbities

Restless leg syndrome – As histamine mediates in alertness and wakefulness. It is found that people with restless leg syndrome often have more histamine H2 and H3 receptors within their brain. More histamine can exacerbate and cause this syndrome. Though anti-histamines can also worsen and cause restless legs.

Ménière’s Disease- Ménière is disorder of the inner ear, often due to the containment of fluids within it. histamine can also lead to too much fluid within the inner ear. And lead to Ménière symptoms. As can too little histamine.

ADD/ADHD – ADD and ADHD tend to stem from a lack of dopamine in the brain. As histamine inhibits the release of dopamine, this can lead to ADD and ADHD like symptoms.  Other effects of histamine on neurotransmitters and the brain can lead to these symptoms as well.  People that suffer from ADD and ADHD often show higher histamine levels.

Autism – Even though histamine doesn’t cause autism, it can cause autism like symptoms due to the effect is has on body and brain. Often people with autism suffer from higher histamine levels which exacerbates some of the problems they have.

OCD – It is also said that histamine can cause OCD or worsen it. With the anxiety and arousal, can also lead to perfectionistic tendencies.

Schizophrenia – schizophrenics often show high or low levels of histamine. It is though that some functions of histamine can set of a psychotic episode in schizophrenics.

Published in: on February 17, 2010 at 11:43 pm  Comments (7)  

What is histamine intolerance

When I was told about the histamine intolerance I suffered from, I didn’t believe it at first, I was afraid it was some bogus disease or some well we don’t know what’s wrong, so let’s just call it so and so. Just like former diagnosis I had gotten like irritable bowel syndrome and chronic fatigue syndrome.

But a histamine intolerance is a very real thing. And it’s quite clear what the cause of it is.


Histamine is an amino acid. A very small one even. One of the most well known functions of it is in the mediation of immunological responses. When harm is done to the body or intruders are noticed, histamine is released from specialized storage cells (mast cells) in the bloodstream to widen blood vessels and make their walls more permeable, so more blood and all handy things carried in the blood to fight of harm and intruders can go to the place of the disturbance.

Which is the reason a lot of the symptoms of histamine intolerance mimic allergic responses or real infections.  Mimic, since it isn’t an allergic response or a reaction to a threat at all.  Just a large amount of histamine can cause these responses.

The reason large amounts of histamine can build  up in the body

There are several reasons a large amount of histamine can come into existence in the human body and lead to annoying responses.

Histamine is not just active in the human body. It is also present in most other animal life, and even in plants. Which means that most of our foods contain histamine. So we consume histamine with almost everything we eat and drink. There are also certain substances that are able to aggravate the mast cells in which histamine is stored, so their contents get released  into the blood stream.

There are several enzymes that break down histamine. The main ones are histamine methyltransferase which mostly targets histamine within cells. And there is diamin oxidase (DAO) which is present in the walls of the bowels and within the bloodstream.

Most histamine intolerances are due to a lack of DAO. Ingested histamine is normally filtered within the walls of the bowels, so it doesn’t enter the bloodstream. And the histamine that has entered the bloodstream is filtered away with DAO as well. As the amount of DAO declines, the amount of free histamine in the body can grow rapidly, especially when foods high in histamine are eaten.

DOA can be low due to a genetic disorder. But the production of it can also be impaired when the bowels get damaged due to an infection but also different aggravations (antibiotics, crohn disease, gluten). A third reason the amount of DAO can be low is because it can be inactivated by several different substances, like certain medicines (morphine ) , but also alcohol impairs the working of it. Another reason a shortage of DAO can occur is when the components it is build out of aren’t present in large enough amounts, for example a shortage of copper and B6.

Since the levels of DAO can fluctuate with all these different reasons, the sensitivity to histamine can change depending on the circumstances. After a night of drinking I have to be much more careful with histamine rich foods. Stress can not only release histamine directly but also work against the working of DOA.

Since the response depends on the amount of histamine within the body, and this depends on it’s turn on the amount of DAO, the amount of histamine that can be taken before reactions occur is different for most people. And as most reactions only happen when a certain threshold is passed it will take a while for anyone to find out where that threshold is, and how certain things like stress affect this.

The amount of histamine in foods can also greatly vary, since the longer it is stored the more histamine is made by bacterial activity and other processes. That’s why certain foods like fish are okay if they are very fresh or never got defrosted. The same goes for any other food, like fruits and veggies.

Published in: on February 16, 2010 at 10:37 pm  Comments (23)  
Tags: , , , , , ,

The start of it all

Since information about histamine intolerance and the troubles histamine can cause in one’s body is scarce, I started this blog.

The first step

Summer 2009 I had a little operation done by me GP,  for which I got a local anaesthetic. Afterwards I got terrible allergic reactions, a runny nose so bad I stuck tissues in my nose, eyes that were tearing up, and I was constantly sneezing, which feels exceptionally wonderful if you just got your head stitched up. To be short I  was feeling really awful. And I noticed a lot of these problems got worse or started whenever I was outside.

Hay fever?

I had suspected I had hay fever for quite a while but never bothered to get tested,  I was a healthy girl who loved being outside and studied biology, so of course I couldn’t have hay fever. But after that horrid reaction I started to pay more attention to when and where my reactions started.

I had been suffering from strange reactions and illnesses for quite some years, and it once again had gotten worse that spring. One of those were terrible headaches that had plagued me for years, and that year they had gotten even worse, some days I could only lay down keeping my body very still,  as every movement of my head hurt like crazy.  I was deliberating if I should check myself into a mental hospital since the medical world thought I was either just making it up, as they couldn’t find any prove for my symptoms and thought they were psychosomatic, or just kill myself off or something. Those weird reactions of my body were driving me insane and withholding me from living my life the way I wanted to.

No hayfever?

So finally I got my blood tested for allergies, but I didn’t have any. Weird, since I was pretty sure I reacted badly to the outside air which pointed to a reaction to pollen. And the anti-histamines I squeezed out of my doctor, were really good with keeping certain symptoms in check. An acquaintance said I should visit an allergy specialist, she thought I could suffer from pseudo allergies, which weren’t widely recognized by most doctors but an allergy specialist should know more about this.
So I went. I got my arms splashed with droplets of all kinds of different possible allergens,  some kind of solution as control test as well, and a scratch test which consisted of just scratching my skin with some kind of pencil. Once again I didn’t test positive for any kind of allergy. Though I got quite an oversensitive reaction to control test  and the scratch that had been made on my back.
Once again I thought it was all for naught, and I would just be told it was all in my head, I was oversensitive and should learn to deal with it. Much to my surprise the first thing the doctor asked was if I needed more anti-histamines to help me. She explained I probably had an intolerance for histamine, which could give me bad reactions to even the slightest things like a breeze of fresh air. But also reactions to pollen, since those could lead to a histamine reaction in normal people as well, and with a high histamine load present those reactions could get quite severe and mimic hayfever She also directed me to a nutritionist to help me with a diet to control my intake of histamines.


I was happy to get some recognition, but was very suspicion about the truth of it all. Was this really it? Just like that? As I’m a biology student with an interest in the molecular and neurosciences I read about every paper and site I could find on the internet and the university library. And still do. A world opened up for me, as I found out I wasn’t crazy at all, it wasn’t just in my head. I was suffering from something real.
The diet and anti-histamines turned my life upside down, had I always been feeling tired, sick, depressed and just right out awful I soon started to feel great. So great. I started to be afraid that I was suffering from some kind of manic episode. Luckily I didn’t. 😉

Since there are many misconceptions about histamine and the problems it can cause, or things that can help I decided to start this blog, to keep myself informed by storing all useful information in one place, but also to inform others.

Published in: on February 16, 2010 at 7:15 pm  Comments (8)  
Tags: , ,