The comments to the pot-stirring post about celiac disease and the gluten-free diet from the inhabitants of Planet Gumshoe require a more comprehensive response than usual, since they touch on just about every kind of interaction between the foods we eat and where we are on the health / illness continuum.
The connection between gluten and celiac disease is a highly specific one, quite different from most other types of reactions to foods, or indeed, from our reactions to most other environmental factors. As Doc Gumshoe tried to explain, gluten triggers an autoimmune reaction that may in some individuals result in atrophy of the villi, which are the little hairlike structures lining our small intestines. These villi are the means through which we absorb nutrients from the mush of stuff passing into the small intestine from the stomach. Without absorption through the villi, we can become seriously malnourished and, in particular, anemic. And, at the same time, the matter left in the small intestine is full of stuff that would normally – that is, in people without celiac disease – have been absorbed and removed from the digestive tract, and thus this matter passes through the large intestine and is expelled as diarrhea of a particularly noxious kind. That’s celiac disease, and, mercifully, clinical celiac disease, resulting in these symptoms, is relatively rare.
Celiac disease is absolutely not the same as wheat allergy, or allergy to any gluten-containing grain, or indeed, allergy of any type. An allergy is a specific kind of reaction, generally involving the release of any of several cytokines from large cells called mast cells. The cytokines in turn trigger a range of immune responses. This happens when something enters our system which has previously been identified as possibly being a harmful invader. To mount an allergic reaction, first the organism has to be primed to recognize the possibly harmful substance – we don’t have allergic reactions to things the very first time we encounter them. As you certainly know, we can have allergic reactions not only to foods, but to things in the air we breathe, and to things that come into contact with our skin. For example, I am violently allergic to East Coast crabmeat, but not to any other seafood – lobster, shrimp, oysters, clams, scallops, mussels, or even Alaska King Crab. But feed me any of those delicious East Coast crabs, and my bronchial passages quickly threaten to shut down, with potentially severe consequences.
Then there is that huge category of foods that some people find it difficult to tolerate, while other people have no problems. My wife, for example, gets migraines occasionally, and has found that monosodium glutamate tends to be a migraine trigger for her, so she stays away from food containing MSG. She has been told by supposedly knowledgeable folks that this is nonsense and that MSG is harmless. Personally, I think that since the glutamate receptor in our brains is known to be associated with epileptic seizures, there is a definite possibility that MSG has a similar mechanism in migraines, so even if there’s no proof, she’s better off avoiding MSG. Therefore, when I go shopping, I read the labels on food products very carefully.
(By the way, I haven’t seen an aisle at the supermarket labeled MSG-free. That hasn’t yet become a trend, I guess.)
And then there is that frustrating, inconvenient dilemma, which is that many or even most foods and nutrients can be both absolutely essential and harmful in excess. We absolutely need salt, but excessive amounts of salt are unquestionably bad for us. We’re equipped with a highly sensitive means of determining the optimum sodium levels in our circulatory system, and when the concentration of sodium exceeds that level, we’re thirsty and take in more fluid to dilute the sodium concentration. We retain the excess fluid in our circulatory system until our kidneys remove the excess sodium from our blood and dispatch it – accompanied by fluid – to the urinary tract, and then you know where it goes. But in the meantime, the increase in fluid intake raises our blood pressure, and, if the excess salt intake is chronic, the increase in blood pressure can become chronic as well – the “new normal,” so to speak – with potentially adverse consequences.
Sugar presents a similar dilemma – or, rather, sugars and carbohydrates that are easily and quickly converted to glucose. Glucose is essential for life. Every cell in our bodies needs glucose as an energy source. Nothing else will work. But we don’t want too much unmetabolized glucose in our bloodstream. The problems it can cause are legion. Doc Gumshoe has discussed them in various blogs, and you are certainly aware of some or most of them. However, it is a gigantic misstatement to call sugar “a poison.
Toxic substances are in a different category. Some substances are so toxic that even tiny quantities can prove fatal. Those are the ones we call “poisons.” I am not going to compose a manual for would-be poisoners here, so I won’t go into detail, but let me just remind you that even some highly toxic substances have been adapted for valuable medicinal uses. The venom of the pit viper, for example, was the basis for the class of blood-pressure medications called ACE inhibitors. When the Brazilian pit viper bites its victim, what happens is that the bitee experiences a sudden and catastrophic drop in blood pressure – enough of a drop in many cases to kill. The discovery of the mechanism led to the development of the first ACE inhibitor, captopril, now no longer used. But this particular relationship – one of many – is an illustration of the principle that “the poison is in the dose.” This is true of many foods. It is a mistake, for instance, to feast on the leaves of the rhubarb plant, which contain an excess of oxalic acid, and can cause internal bleeding. Many leafy greens contain oxalic acid, and people who take anti-clotting medications to protect from the adverse consequences of conditions like atrial fibrillation are warned to go easy on raw greens. And, of course, unless you are an expert mycologist, it is a mistake to eat the mushrooms you see growing in the woods. A few are tasty, most are harmless, but a very small percentage will kill you. And, with the most toxic mushrooms, as with a few other highly toxic substances, the maxim that the poison is in the dose does not apply. In practical terms, there is no dose small enough to be harmless.
But the toxicity of these substances doesn’t depend on an individual’s idiosyncratic reaction. The crab meat to which I am allergic is not toxic to a person without crab allergies, but the oxalic acid in rhubarb, in enough quantity, is toxic, period.
This brings us back to gluten. The gluten intolerance seen in patients with celiac disease is not an allergy. Nor is gluten conceivably toxic. The toxicity of Amanita phalloides applies across the board. It doesn’t trigger an autoimmune response, and it doesn’t set off mast cell degranulation. It kills indiscriminately. With gluten, it’s also not a matter of “the poison is in the dose.” People with celiac disease mount adverse responses – i.e., their intestinal villi are affected – to even small amounts of gluten, whereas the great majority of our species has no problem with gluten, regardless of the dose. (I am not talking here about the adverse consequences of excessive carbohydrate consumption, which is another matter entirely.)
Are there individuals who do not have celiac disease – that is, whose intestinal villi are unaffected and do not have the characteristic clinical symptoms – who are nonetheless gluten-intolerant? I cannot say that there are not, but if there are such individuals, there must be a mechanism through which this non-celiac gluten intolerance operates. As far as I know, no such mechanism has been identified, although a number of possible mechanisms have been proposed. The mechanism for gluten intolerance leading to celiac diseases has been at least partly explained, but, more important, the adverse consequences of this intolerance as manifested in celiac disease is quite well characterized. This is not the case in non-celiac gluten intolerance.
Most of the evidence that I have seen for non-celiac gluten intolerance is of the post hoc propter hoc variety – i.e., “I cut gluten out of my diet and I am now healthy, whereas before, I had a great number of dreadful symptoms, so those must have been caused by the gluten in my diet.” The problem with this line of reasoning is that the connection between the symptoms of ill-health and gluten intolerance is unclear. Is it because gluten makes us gain weight? Is it because the carbohydrates in wheat are metabolized into glucose, resulting in metabolic stress? Are there substances other than gluten causing the symptoms?
While it is certainly possible that some individuals may demonstrate gluten intolerance without the specific symptoms of celiac disease, I find it extremely difficult to accept the position that non-celiac gluten intolerance is widespread. We humans have been depending on wheat for something like 10,000 years – not just consuming wheat, but depending on wheat, as well as on other grains, for survival. The important characteristic of these grains is that they could be stored for long periods; thus, our ancestors could survive winters where there were no fresh fruits and vegetables. Grain that could be stored, along with domesticated animals, made it possible for humans not only to survive but to thrive in climates that were not hospitable to the hunter-gatherer lifestyle. If gluten intolerance were a common human characteristic, our history would have been different.
Doc Gumshoe stands firmly with the contingent that says that good diet is an immensely important part of our health. We are what we eat, and the diet of many of us, not only in the US and other developed regions, but everywhere on the planet, leaves a great deal to be desired. Not only do we consume stuff that we oughtn’t, but we fail to consume stuff that would benefit us. And the guidelines (I’ll say more about those in a future post) are not much help. But on balance it seems to me that the food industry has cottoned to the notion that gluten may be to blame for a lot of health problems, and is pumping up that notion, mostly for their own profit.
And one more thing. There are some persons with celiac disease who do not respond to the gluten-free diet. In an effort to develop a drug that might help those people, Amgen has made a deal with a tiny biotech called Celimmune to do some investigation of their drug AMG714, an IL-15 inhibitor. AMG714 was once upon a time a candidate for treating other autoimmune diseases, but was no better than the other drugs on the market, so it went no place, but it does seem to have some potential in celiac disease. Other pharmas – GSK, AbbVie, and a small biotech called ImmusanT – are also in the running. I’ll keep my ear to the ground.
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