*** to make the letter easier to follow, I have put the questions in the light graygreen background box, and Dr. Pusztai's answer to each question in the light yellow background box ***
From: Dr Arpad Pusztai
Sent: Saturday, April 07, 2001 11:20 AM
To: Lynne Schuler
Dear Lynne Schuler,
I am trying to give a short answer to some of your questions. Unfortunately, I shall be off for something like 10 weeks, so my opportunities to reply to your e-mail in detail is not easy right now.
What does a noted lectinologist eat? Does his knowledge of lectins influence his choice in foods?
Not in most cases. Obviously, I do not eat uncooked kidney beans.
One of Cheryl's favorite dishes is 'Lecso', a delicious Hungarian concoction of peppers, onions and tomato, cooked down into a thick sauce and served over things like schnitzel, whether made from veal, turkey cutlets, or chicken. Do you eat things like this? Do you place this on the "safe to eat" range?
I grew up on lecso. It is a delicious dish. One must fry the onions properly but then do not overcook the paprika! I think it is one of the safest dishes judging from the fact that the Magyar nation has not yet died out although we have been eating this dish for a long time.
In your book (‘Handbook of Lectins"), you have an entry for GNA (I am sure you are quite familiar with this particular lectin ;-D):
Galanthus nivalis lectin (GNA) agglutinates rabbit but not human erythrocytes. The bulbs have a high concentration of the lectin. But it is present throughout the plant. The lectin is specific for mannose (one of those OTHER sugars on all our cells). GNA shows anti-insect activity -they fed it to several varieties of insect and it had 'anti-metabolic' effects on them. GNA prevents E. coli overgrowth in the rat intestine. GNA administered orally is non-toxic for rats.
If mannose is a sugar in all our cells, why doesn’t it agglutinate human erythrocytes?
The reason for it that glycosylation is modulated on cellular differentiation. Mannose (polymannose) is the first sugar to be attached to the finished polypeptide chains as they come off the ribosomes, but then the Golgi apparatus gets to work on the mannosyl side-chains, removes some while attaching other sugars, more in line with the blood group specificity. Thus mannose in great many cells becomes buried in the glycosyl side chain and therefore is not available to lectins such as GNA.
In your research article: Dietary lectins are metabolic signals for the gut and modulate immune and hormone functions
, you say: Most lectins in our diet are resistant to breakdown during gut passage and are bound and endocytosed by epithelial cells. These lectins are powerful exogenous growth factors for the small intestine, can induce dramatic shifts in its bacterial flora, and interfere with its hormone secretion. In addition, lectins, which are transported across the gut wall into the systemic circulation, can modulate the body's hormone balance, metabolism, and health. Although these physiological effects are mediated or reinforced by immune responses, they are primarily the result of the specific chemical reactivity of lectins with cell surface receptors of the gut.
Do you think we are close to mapping the human gut so that we can transfer the knowledge we have about lectins to humans?
No, I am afraid, the glycosyl map of the human gut surface is mostly unknown. It is unfashionable these days of genetic research to do cell physiology.
In ER4YT, it says:
Lectins found in the diet can cause a variety of problems, especially if they are specific to a particular blood type. For the most part our immune systems protect us from lectins. Ninety-five percent of the lectins we absorb from our typical diets are sloughed off by the body. But at least 5 percent of the lectins we eat are filtered into the bloodstream, where they react with and destroy red and white blood cells. The actions of lectins in the digestive tract can be even more powerful. There they often create a violent inflammation of the sensitive mucous of the intestines, and this agglutinative action may mimic food allergies. Even a minute quantity of a lectin is capable of agglutinating a huge number of cells if the particular blood type is reactive.
In ER4YT, one of the ways that Dr. D'Adamo tested for "bad" lectins was by checking to see if a food agglutinated that particular blood type. The idea being partly that these blood type antigens would also be in the digestive system or that the lectin might get past the digestive system, into the bloodstream and agglutinate the blood. ER4YT pg.30:
I know because the effects of lectins on different blood types are not just a theory. They're based on science. I've tested virtually all common foods for blood type reactions, using both clinical and laboratory methods. I can purchase isolated lectins from foods such as peanuts, lentils, meat, or wheat from chemical laboratories, and the results are visible under the microscope. I can see them agglutinating cells in the affected blood type.
Does the fact that an isolated lectin agglutinates blood under a microscope have any relation to what will happen in your body?
I am afraid, I would not agree to most of this. Some lectins do interact with the gut immune system and some of these effects could be very specific. However, I have never found a single plant lectin which caused intraepithelial lymphocyte infiltration in the gut that happens always in cell-mediated delayed hypersensitivity reactions. However, as practically all lectins (some more than others) are taken up by active transport through the gut epithelium into systemic circulation, they can set up systemic reactions with the humoral immune system. As we have shown it way back in 1979 most lectins are excellent systemic immunogens and stimulate the development of specific antibodies. We have several of such publications in Immunology (2000 & 2001; look them up). Some of these antibodies do come back into the gut and therefore they can interact with food. Although there may be something in what Dr D'Adamo say, the problem is likely to be more complex. Just as I said before because some of the humoral antibodies developed during sensitization with particular lectins, when there is a repeated oral exposure to the same lectin, the homing antibodies on the gut surface may neutralize some but this system can be overpowered if the exposure is high. Like PHA (kidney bean lectin) will be systemically absorbed no matter whether there was a pre-exposure to it or not. Again, this is more complex. You can take it as a guide but it is not foolproof. One ought to have a major study on the systemic absorption of all known food lectins and this has not been done yet.
This is also in ER4YT:
There is also a more direct scientific barometer that can be used to measure the presence of lectins in your system. The barometer is a simple urine test called the Indican Scale. The Indican Scale measures a factor called bowel putrefaction. When the liver and intestines don't properly metabolize proteins, they produce toxics by-products called indols. The level of these toxic by-products is shown on the Indican Scale.
Any scientific basis for this?
I am afraid, I have no idea. However, most lectins will eventually breakdown in the body and only very small amounts may pass through the kidneys into the urine. Whether this is important or not, I am not sure.
Ps. It may take quite some time before I can find a local server to access my e-mail. So, I may be out of circulation for a while.