If you wanted to characterise glutamate with one word, "cheating" would have a good chance of coming out on top. It's not only in research that glutamate is cheated like a soup spoon, many companies also like to use the flavour enhancer as a trick, and the label is allowed to disguise the whole scam with clever wordplay. But it gets even worse.
by Udo Pollmer November, 2024
The Chinese restaurant syndrome is just the tip of the iceberg. Chronic effects, such as the aforementioned release of cortisol, have more serious consequences than headaches. The link between glutamate and depression, anxiety and dementia is now the...
...subject of increasingly lively debate in the scientific literature.1 One key is the enzyme glutamate dehydrogenase, or GDH for short, which can provoke high glutamate levels.
Dysregulated Glutamate dehydrogenase activity in the central nervous system”, say Korean physiologists, “is highly correlated with neurological disorders,”2 such as cognitive deficits, memory loss and psychiatric symptoms.3-5 Mutations in the GDH genes have already been identified in patients with Alzheimer's, Parkinson's, epilepsy and ataxia.6-9 This explains the genetic component that is being discussed in many neurodegenerative diseases.
However, it is important to differentiate here: "The glutamate dehydrogenase (GLDH) activity of patients with degenerative disorders," confirm Slovenian researchers, "is exceedingly lower in comparison with other neurological diseases.”10 The lower the activity of the enzyme, the more glutamate is available and the faster and more severe the course of the disease.9-11
Glutamate levels are often only elevated in the brain, but in some diseases such as multisystem atrophy or autism this is also reflected in the blood.8,12-14 It remains to be seen whether eliminating glutamate from food would be therapeutically effective. There is only experience with severe depression, in which glutamate levels in the blood are also elevated.15 When Gulf War veterans gave up glutamate, it is said that after one month of abstinence every second person felt considerably better; their depression disappeared.16 Antidepressants also effectively reduce glutamate levels.3,17 Perhaps this is the mechanism of action.
Jekyll and Hyde send their best regards
Can it really be that a single enzyme causes so many different symptoms? The fact that only some patients have a mutation in the GDH gene also seems to speak against this. In addition, other causes have also been established, such as aluminium in Alzheimer's patients or neuroviruses in severe depression.
However, diseases with similar symptoms can have very different causes. When the public is led to believe that disease X has "many faces", this always describes different causes that are stuffed into one and the same diagnostic bag. This enables symptomatic treatment with expensive biologics, which promises great revenues in the absence of a cure.
The second reason is the many mutations of the GDH enzyme. Hence the variety of symptoms.18 Strictly speaking, there are actually two enzymes with many mutants, and with pronounced allostery. Allostery means that the enzymes can change their conformation and thus also their activities. The mechanisms are so convoluted that even the specialised press speaks of a "nightmare".19 Others refer to the substrate of the enzyme, glutamate, as the "Jekyll and Hyde molecule".20,21
There are other players in this game, such as glutamate decarboxylase or glutamate pyruvate transaminase, known as alanine transaminase (ALT) and renamed alanine amino transferase (ALAT). Not forgetting the many other regulators such as the glutamate transporters.22
When the blood-brain barrier opens
This means that high glutamate levels in the blood not only affect the aforementioned circumventricular organ, but possibly the entire CNS. In the case of stroke, dementia and neurodegenerative diseases, as well as after injuries such as traumatic brain injury, glutamate levels in the brain can increase endogenously to such an extent that the nerve cells die.3,23
In response, the blood-brain barrier opens and the brain tries to drain the excess glutamate into the bloodstream. "The permeability of the blood-brain barrier", according to Israeli neurologists, "is a vital component in regulating levels of glutamate levels in the brain."24 Contrary to theories, glutamate can also pass from the blood into the brain, albeit less than in the other direction.25 Once the barrier is damaged, it often takes years, some say decades, before it is sealed again.3
If the life-threatening glutamate is to be removed from the brain of stroke patients, haemofiltration or treatment of the blood with a modified enzyme (GOT) sometimes works wonders.26,27 Up to 80% of the neurotransmitter can be removed from the brain via the arm vein.28,29 It works best when the patient is sober.29 If the claims about the impermeability of the intestinal wall and the blood-brain barrier were even halfway true, this effect would not exist.
Brain Food: When Mrs. Nutritionist starts to think
According to the AOK, a German obligatory insurance, glutamate cannot cause any damage in the upper brain of its members because it denies this amino acid access. This is in stark contrast to brain food, which simply slips into the brain box: "For smooth functioning", the brain needs a "large amount of nutrients". Vitamins and trace elements in particular enable those in need to boost their brains without being hindered by their blood-brain barrier.30
Under the heading "What does an optimal brainfood diet look like for the brain?" we learn that glucose from food, previously the energy source of every intact CNS, is apparently not that important. Terms such as "starch" or "sugar" are missing.30 And obscene treats such as confectionery have long been on the index. The pious nun says ugh.
To keep the blood sugar level in our upper storey happy, we need three undefined meals as well as fruit, vegetables and yoghurt. Anyone who thinks of "vegetables" as potatoes, from which our body obtains blood sugar, is barking up the wrong tree. According to today's nutritional definition, the potato no longer counts as a vegetable due to its calories, which is why it is no longer mentioned here. The DGE recommendation is only 250 grams of potatoes per week anyway.31 This corresponds to 50 grams of crisps, or seven grams a day. Even a frugal AOK brain can't get very far with that.
Instead of the tried and tested blood sugar suppliers such as chips or baguettes, secondary plant substances are now considered brain food - presumably because they are calorie-, sugar- and fat-free. Fortunately, the blood-brain barrier, together with the liver's detoxification enzymes, protects the sensitive brains of keen cooks and clever drinkers from this (alcohol-free) boozy idea.
When it comes to brain food, the jack-of-all-trades "wholemeal" is a must. An obvious delicacy for every AOK member who has a birdcage on their neck instead of a head. If you want, you can feed it to your bird, which appreciates grains. For a sparrow's brain, this bird food is super brain food.
Gout: glutamataemia
Glutamate in the blood is elevated not only in depression or autism, but also in gout.32 According to the medical press, "hyperglutamataemia" is a typical manifestation of primary gout, "appearing before the onset of symptoms and apparently in conjunction with the onset of hyperuricemia."33.34 It is striking that glutamate levels rise sharply in gout with milk protein (casein), which was always considered impossible.35
The researchers suspect a lack of glutamate dehydrogenase,34 because this produces more glutamate. And this "may be causally related to the overproduction of purines in gout ".32 Glutamate turns into glutamine, from which the body forms the two purines inosinate and guanylate.36 Incidentally, these are also used as flavour enhancers in the kitchen. The purines produce uric acid, which is officially recognised as the cause of gout.37
The link between glutamate, uric acid and gout, which has been known for over half a century, is of no interest. Some therapists only recognise inosinate and guanylate as purines and warn against eating soup cubes. Why doesn't anyone actually look at the cause of increased glutamate levels - even before gout becomes painfully noticeable? Surely this would be a simple method for early detection?
Glutamate meets aluminium - an unfortunate combination
The suitability of glutamate as a transport vehicle for aluminium is controversial. The light metal piggybacks into the brain - despite the blood-brain barrier. This makes a differentiated assessment of the chronic toxicity of glutamate difficult. This is because aluminium is itself an established neurotoxin and a cause of Alzheimer's dementia. It is possible that the ubiquitous foreign substance also "modulated" the results of some glutamate studies unnoticed.38
The handling of aluminium shows parallels with glutamate: when increased aluminium levels were detected in Alzheimer's brains years ago, doctors explained that these were false analyses. Aluminium could not even reach the brain, it would not even make it from food or gastric acid binders into the blood. Acids such as citrate, malate or glutamate, for example, can increase absorption in the intestine sixfold.39
If glutamate is fed to experimental animals together with soluble aluminium (AlCl3), the red blood cells absorb it and take it into the brain.39 Ferritin, also a carrier through the blood-brain barrier, also acts as an aluminium collector.40-42 Exosomes offer a further transport option.43 Glutamate can also form a complex directly with aluminium, which can reach the brain.44-46 Aluminium also damages the blood-brain barrier.44,47
Glutamate: a warning signal
Glutamate levels are also elevated in many diabetics. Once again, the more glutamate in the blood, the more advanced the disease and the more severe the complications.48 After all, glutamate plays an important role in the ß-cells of the pancreas.49 Pharmacologists are already looking for drugs to give dehydrogenase a leg up. They are convinced that this could be used to treat “a wide range of pathologies from insulin disorders to tumor growth”. 50
Glutamate actually feeds breast, lung and bowel cancer, leukaemia and gliomas. If the tumor does not have enough glucose available, it supplies itself with material by producing more glutamate dehydrogenases. These stimulate the production of ATP, which provides the tumor with the energy it needs.51 The more active the enzyme, the faster the tumor proliferates and forms metastases.52 At the same time, the tumor protects itself from cytostasis.53
The cancer drug vinblastine in particular is prevented from reaching the inside of the tumor by an extra dose of glutamate because it uses the same transport systems and slows down the competitor.54 This could explain why glutamate also reduces the neurological side effects of vinblastine.55
Fibromyalgia
These patients often have slightly elevated concentrations of amino acids in their blood, particularly glutamic acid.56 If they drastically restrict their glutamate intake, however, only a small proportion of those affected experience a lasting improvement. When these people were given glutamate again, their symptoms returned.57,58 A causal relationship can be assumed here. Analyses of the activity of glutamate dehydrogenase are lacking.
However, most fibromyalgia patients do not notice any difference. This is also due to the fact that fibromyalgia is considered a "concessionary diagnosis". After analysing countless patient histories, rheumatologist Christof Specker came to the conclusion that it is less an organic condition and more a "social problem". However, he is not talking about malingerers.59 So that annoying patients finally give up, they are offered the label "fibromyalgia". This has apparently replaced the old, similar label "fructose intolerance".
In the past, an overdose of fructose was often administered during the H2 breath test and healthy people promptly developed digestive problems. Customers were happy with that. When she went to the next doctor and openly explained that she suffered from a fructose intolerance, the doctor thought, "aha, the old lady is not quite in her right mind”. Problem: This intolerance does exist, albeit only rarely. As a result, real patients were unfortunately not taken seriously. There are now more reliable tests.
Fibromyalgia “is a collective pool that fills up social media, an exchange platform for symptoms.60 Not only the sick, but also the disappointed are finally given a way to demand the consideration of their social environment with a super diagnosis. As the medical diagnosis comes up empty time and time again, some therapists fall for the clever idea of assuming sexual abuse as the cause. With this fashionable suspicion, they further disrupt the patient's difficult family life.
The nutritionists' advice is an additional complication. As always, she advises a calorie-conscious wholefood diet with plenty of fibre. Sweeteners instead of sugar. Ignoring nothing ruins the gut more than indigestible fibre combined with sweeteners. Even the most stable microbiome is ruined.61,62 (This would not have happened so easily with sugar.) Many fibromyalgia patients promptly complain of irritable bowel syndrome.57,63-65 And the industry wonders why their great expert advice, again, does not work.66
If that's not enough for you, stay away from salt as much as possible. Instead, there's plenty of potassium, usually in the form of fruit and vegetables. Many diabetics believe they can satisfy their hunger for sweets in a "healthy" way with fruit. In addition, the doctor prescribes diuretics so that the little bit of salt is excreted and potassium is "saved" instead. In addition, water is diligently drunk without thirst in order to excrete even more salt. The result is hyponatraemia or hyperkalaemia. The consequence of this bad behaviour: neuropathies.67-69 What a surprise that every second fibromyalgia patient suffers from this!70
Many people continue to adhere to the "healthy diet" even when they have already become ill from it. Victims are then prescribed multivitamins and alkaline powders - even though there is no evidence of any benefit for fibromyalgia.71 In their distress, they willingly consume food supplements.72 Perhaps they are doing harm?
In fact, pyridoxine, commonly known as "vitamin B6", also causes neuropathies and bone pain.73,74 Isn't it strange that these neuropathies are also typical of irritable bowel syndrome?75 According to this, there is not only a minority of fibromyalgia patients who react to glutamate, but presumably many who became ill as a result of "wholefoods", "vitamins" and the like.
According to Christof Specker's analysis, fibromyalgia is a logical consequence of the zeitgeist: it is "a social and socio-medical problem of a society characterised by the media (advertising), in which providers of wellness and anti-ageing products or paramedical health services want to suggest to people that they can always remain young, fresh and free of complaints, even in old age. Mercantile interests, delusions of feasibility and misconceptions deny the limits and imperfections of human existence."59
Following the lure, many people step onto this slippery slope and slide into their misfortune. Every time they reach for a vitamin supplement to save them, every time they eat a low-salt plate of raw vegetables and a potassium-saturated fruit salad, preferably in combination with diuretics, they sink deeper until they are sick for good. And the counsellors wash their hands of it all.
Of mice and men
In view of the consequences of defective glutamate dehydrogenases, these enzymes should be the subject of research. And they are - for example in plants, insects and parasites. In the case of maize, they can be used to increase yields through genetic engineering.76 EFSA, the responsible European Food Safety Authority, is playing dumb. In its 90-page report on glutamate, it knows next to nothing about these key enzymes.77 Yet the committee has sufficient expertise that it cannot have remained unaware of the connections.
In the case of glutamate, the EFSA relies only half-heartedly on the numerous experiences in humans: “The Panel assessed the suitability of human data to be used for the derivation of a health-based guideline value (HBGV)”, but the agency concluded that "a clear dose–response relationship could not be established".77 This is why the authority prefers to rely on animal experiments. They transfer them to humans. However, not even mice metabolise glutamate in the same way as rats - so the results are already "controversial" among rodents.78
So why does the EFSA issue maximum levels, known as ADI (Acceptable Daily Intake) for additives? Is it to prevent mice in the larder from suffering from cranial hum? Humans are considered to be the most sensitive species, being 5 times more sensitive than mice and 20 times more than monkeys.79,80 If, for whatever reason, there is no dose-response relationship, then we should find other ways to protect citizens from harm.
Since, according to the EFSA, as little as 3 grams can trigger a reaction in some people, a dose of 2 grams would be more appropriate than the previously permitted 10 grams per kilo. The customer would not even notice this if glutamate is combined with ribonucleotides (E 626 - E 635). These are also approved as flavour enhancers and have a synergistic effect, so that a smaller amount is sufficient.81 As ribonucleotides are apparently not able to inhibit glutamate dehydrogenase, the risk would be reduced.
Ribonucleotides
High levels are found in dried bonito flakes, a Japanese speciality: the dried fish is impregnated several times with mould, preferably with aspergillus and the related genus Eurotium, which likes to live in the dust of mattresses in bedrooms.83 It is said to protect against asthma, but84 can also form mould toxins.85
Eurotium also thrives on dried fish. It releases glutamate (E 621) from the protein and the ribonucleotide inosinate (E 630) from the RNA. The ribonucleotide guanylate (E 626) is provided by dried shiitake mushrooms.86 Soya sauce, on the other hand, mainly contains glutamate. It was traditionally obtained by fermenting soya beans with aspergilli, but is now produced from wheat gluten and soya expeller with proteases.
In Germany, yeast flakes (Saccharomyces cereviseae) were available as a seasoning from health food shops. They were not very popular because of their pungent, yeasty flavour. This changed when yeast autolysates and extracts became available, which had miraculously lost their yeast flavour. Genetic engineering was used to create a wide range of mutants: with lots of glutamate or with little, with ribonucleotides or with oligopeptides. An autolysate is a preparation that has been produced by self-digestion of the yeast; in the case of extracts, the cell walls have also been removed.82
Due to the traditional consumption of bonito flakes and shiitake mushrooms in Japan, ribonucleotides were still considered safe when they were already biotechnologically produced by Candida utilis and other microorganisms. The EFSA complained that it has no reliable information on which microbes are currently in use.87 This now also applies to glutamate. A strain of Synechocystis is being genetically engineered as a producer.88 Synechocystis is a cyanobacterium that can produce nasty toxins.89,90
Equally explosive is the question of the cephalic phase response: does the taste in the mouth cause hormone levels to rise rapidly before the ribonucleotides have even entered the bloodstream?91-93 Agricultural scientists have researched the fact that guanylate (E 627) is an excellent pesticide for controlling the poisonous fire ant (Solenopsis invicta).94
Declaration: The art of deception
Perhaps the failure of a low-glutamate diet is also due to the fact that hardly anyone knows how glutamate gets into food? Customers depend on being correctly informed - not only if their dehydrogenases deviate from the norm, but also because flavour enhancers disguise the quality. If a dish simply tastes lousy thanks to lousy ingredients, cheap flavour enhancers create a full-bodied taste. This allows considerable savings to be made, especially with expensive raw materials such as meat. The result is a distortion of competition in which decent producers fall by the wayside due to their higher production costs.
Anyone who relies on the label has already been abandoned. The labelling is deliberately misleading. Examples are slogans such as "Without the additive glutamate" or "Without flavour-enhancing additives". This only signals that glutamate has obviously been added after all - but not in its legal form as an "additive", but as "yeast extract", "seasoning", "vegetable stock", "tomato serum" or who knows what else. To make the addition of glutamate less easy to detect analytically, some people add glutamate in the form of glutamyl dipeptides.
Since the enlightened buyer avoids glutamate, but does not like the taste of inferior food without glutamate and does not buy it either, the business is done by those who use glutamate but do not declare it as "glutamate". That's why there are so many camouflage names for it: hydrolysed vegetable protein, autolysate, HVP, soya extract, soya sauce, to name but a few. Until now, only one declaration could be considered a correct indication of the absence of glutamate - in any form whatsoever: "without flavour-enhancing additives".82
The flavour enhancer can now be produced directly in the product, e.g. by glutaminases, ohmic heating, pulsed electric fields or, in the case of ribonucleotides, by AMP deaminase or ultrasound.95-99 There is no need for any declaration.
Blinkers on the eyes
"A particularly high amount of bound glutamate," says a health insurance company (AOK), "is contained in meat and fish (more than 2 grams per 100 grams of food), but also in peas, for example (around 5.5 grams per 100 grams)."100 This means that peas contain almost three times as much glutamic acid as meat. Wow! In fact, fresh peas contain just one per cent, compared to 4 per cent in pork or beef.101 The vegetarian zeitgeist is driving even experts crazy.
"Vegetables, on the other hand, contain comparatively high levels of free glutamate," says the AOK.100 That's nonsense, of course. Perhaps the author was thinking of her "vegetable stock cubes", which she uses to make her vegetarian stew more enjoyable - for the purpose of eating more. However, "vegetable stock" is not made from vegetables. The cubes are nothing more than liquid seasoning (known as "Maggi") that has been dried, glued together with a little fat and coloured accordingly. The pretty vegetable crumbs may fire the imagination of healthy eaters, but they have nothing to do with the flavour.
"In addition," says the AOK, "glutamate is formed in large quantities through enzymatic maturation, such as in tomatoes or Parmesan cheese. Both are therefore considered ideal natural flavour enhancers, for example for sauces."100 This is absolutely true for Parmesan cheese. But for tomatoes? They consist of 94 per cent water. The protein content is less than one per cent. They contain some glutamic acid, around 300 milligrams in 100 grams of tomato, most of which is bound in the protein.101 The flavour-enhancing effect is therefore minimal.
In the past, the content of tomato paste from the south of Italy was higher because the barrels were allowed to ferment in a warm climate. This resulted in the formation of some free glutamic acid and a little guanylate. As our processors now pay attention to freshness when purchasing, increased levels are probably due to a subsequent addition - an adulteration that is hardly detectable analytically. Tomatoes are "enzymatically ripened" according to the AOK if they are rotten.
"Tomato serum", which awaits interpretation in the list of ingredients, is something else again, namely a clever idea in view of rising wastewater charges. The liquid that escapes during the processing of tomatoes is collected, filtered and concentrated. It takes no imagination to realise that adding glutamate is highly profitable but hardly detectable. Anyone caught out claims to have "standardised" the serum. The products offered to our processors taste, oh wonder, logically not like tomato.82
The current statement by the Federal Institute for Risk Assessment (BfR) on glutamate seems cynical in places: “People intending to reduce their glutamate intake can check foods’ list of ingredients to see if glutamate is listed as an additive and limit the consumption of such products."102 Why does the authority not mention that glutamate can even be declared simply as a "flavouring"? How are consumers and therapists supposed to see through these evil tricks of cunning food lawyers? This is where the tax-funded authority could have shown that it is still acting in the interests of the public. What a pity!
Conclusion
The fact that there are people who react to glutamate with headaches or sweating shows that this neurotransmitter is not "inert". It quickly enters the bloodstream from food and thus automatically reaches those areas of the brain (CVO) that are not protected by the blood-brain barrier but are of central importance.
In addition, glutamate levels are increased or rise disproportionately in the case of defective glutamate dehydrogenases. Many neurological diseases are associated with hyperglutamataemia, such as autism or severe depression. Glutamate is also elevated in diabetes, gout, tumours and coronary heart disease.103 It is always more explosive than cholesterol.
In the long term, there is no way around lowering the authorised dose as an additive in food. In combination with ribonucleotides approved for this purpose, this would not even result in a loss of flavour due to their synergistic effects.
Last but not least
In addition to its sensory and neurotoxic effects, glutamate also offers positive options: In the drinking water of rats, it prevented lung damage caused by silica dust (silicosis).104 It also protected the rodents from poisoning by formaldehyde vapours.105 Glutamate facilitates the artificial fertilisation of goats: it promotes the maturation of egg cells, an effect that probably also occurs in other female herbivores.106
For the sake of completeness, its suitability as an additive in baking powder should be mentioned, although the enzyme glutamic acid decarboxylase is required to release the carbon dioxide. This produces another neurotransmitter from glutamate: gamma-aminobutyric acid (GABA).107
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English editor: Josef Hueber
