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(Looking at the Science on Raw vs. Cooked Foods--continued, Part 1-I)

Digestive leukocytosis: what a close
reading of Kouchakoff reveals

One of the prime cornerstones of rawist ideology is a very old and dated research paper, Kouchakoff [1930]. In this research, Kouchakoff studied the effect of foods on human blood and observed what was termed digestive leukocytosis, an increase in the number of white blood cells after eating foods heated to a certain temperature, whereas raw, unheated foods did not have this effect. This observation has been widely publicized by raw diet advocates and is often cited as proof that raw foods are "good" whereas all cooked foods are allegedly "bad."

The present section will examine Kouchakoff [1930], as well as a follow-up paper published only in French, Kouchakoff [1937]. This later paper is only rarely cited, if at all, in English-language rawist writings, which is understandable, though unfortunate, as we will see that its omission significantly changes the conclusions to be drawn from Kouchakoff's research overall.

Kouchakoff's experiments on which the phenomenon is based are of questionable validity. The phenomenon termed "digestive leukocytosis" was discovered by Kouchakoff in the 1920s. However, since it has never been confirmed by subsequent scientists, it is not unreasonable to believe that it may have been due to an experimental error. That Kouchakoff's single series of experiments upon which the raw-foodist claims about leukocytosis are based hark back to the 1920s/30s would be enough to raise doubts for any rigorous researcher about the potential oversights early work like this might have had. Without these experiments having been replicated with the benefit of considerably more sophisticated modern techniques and knowledge about the immune system, it is difficult to take these experiments without a large grain of salt today.

Experiments apparently not replicated since. The question of why Kouchakoff's experiments were apparently never replicated is sometimes raised by raw diet advocates. Speculative claims may be made, e.g., regarding the alleged presence of bias among scientists who eat cooked foods (a point-blank claim, which, without specific evidence of such that is relevant to these particular claims, could be considered an example of what might be called "dietary racism"); or that Kouchakoff's results are self-evident. Of course, the latter claim is not only speculative, but self-serving.

Two possibilities come to mind here. First, it may be that the work was replicated (whether successfully or unsuccessfully) but unpublished, or published but obscure today, due to the limitations on searching the scientific literature of that period (much of it cannot be searched via computer databases). Second, and perhaps more likely, is that since the leukocytosis observed by Kouchakoff was short-term in effect, it was (and still is) seen as normal, and in particular, it was/is not seen as a pathological reaction, or one with clinical significance. (As will be noted below, there are at least another couple of examples of short-term leukocytosis that can be observed under conditions most observers would consider "normal.")

In other words, the reaction of the scientific community to Kouchakoff's research might have been, in figurative terms, a collective "so what?" This latter possibility, and reaction, should be considered when one reads rawist accounts of the Kouchakoff research. One can find raw advocates who claim that the Kouchakoff research is of critical importance, and/or supports specific technical claims. However, a careful review of the Kouchakoff paper shows that there is often little or no connection between the actual Kouchakoff research and specific rawist claims allegedly based thereon.

Even at face value, Kouchakoff experiments not an argument against cooked food when some raw foods are also eaten. However, for the sake of discussion, let's look at the Kouchakoff experiments upon which the raw-foodist claims are based. When we do, what we first notice is that Kouchakoff's experiments are not an argument against predominantly raw diets (versus 100% raw)--or even against predominantly cooked diets that include sufficient amounts of raw food--since according to Kouchakoff [1930]:

It has been proved possible to take, without changing the blood formula, every kind of foodstuff which is habitually eaten now, but only by following this rule, viz.--that it must be taken along with raw products, according to a definite formula.

Leukocytosis was avoided if at least 10% raw foods were also eaten. That is, Kouchakoff found (if his results are to be believed) that when a cooked food is ingested, leukocytosis can be avoided simply by adding about 10% of the same raw food [Kouchakoff 1937, p. 336], or a raw food whose "critical temperature" is higher [Kouchakoff 1937, pp. 332-334]. (Note: "critical temperature" here refers to the specific temperature for a specific food above which leukocytosis occurs.) Therefore, by these results, it is by no means necessary to eat 100% raw or even predominantly raw to avoid leukocytosis; even totally cooked meals would be fine provided cooking temperatures are low enough.

Foods cooked below their "critical temperature" did not induce leukocytosis. According to Kouchakoff [1937, pp. 330-332], foods heated below their critical temperature for 30 minutes don't induce digestive leukocytosis. Critical temperatures vary between 87°C (189°F) and 97°C (207°F).

That even water was said to have a critical temperature suggests experimental errors involved. Even water was said to have a critical temperature (of 87°C, or 189°F), which is quite surprising, as pure water is hardly toxic. This, of course, strongly suggests Kouchakoff's experiment may have had systematic experimental errors and thus raises considerable doubt about the validity of the results in general.

Now--still assuming that Kouchakoff's observations are valid, which is somewhat questionable--it is important to understand the meaning of an increase in white blood cells. The naive interpretation of raw-foodists is that cooked food contains foreign substances that the body must fight; and in addition, since the body's immune system is busy with cooked molecules, it can't be fully efficient against germs.

Note that these last assertions demand specific evidence--which probably few if any raw-foodists who espouse this theory would be equipped to supply. That is, such assertions are simply speculation. (A common tactic in raw-foodist thought is to attempt to reverse the burden of evidence by adopting an unproven theory, then demanding that others disprove it; when by logical rules of evidence, the burden of proof is on those making speculative claims, not the other way around.) Efficiency of the immune system depends on a number of factors; it's much more than a simple white blood cell count.

Leukocytosis can occur under normal conditions of health. Next, we note that leukocytosis occurs in other circumstances than infections [Gabriel et al. 1997]: in particular, following exercise. It has been shown that infection-induced and exercise-induced leukocytosis differ in nature, but the phenomenon is still not well understood. No one will say that exercising is bad because of the subsequent leukocytosis. Similarly, it is known that pregnancy induces leukocytosis [Branch 1992], as well as increased levels of adrenalin. The mechanism underlying this phenomenon and its physiological implications are not known.

Additional Kouchakoff article includes dietary advice for avoiding leukocytosis that includes cooked as well as raw foods. Finally, let's mention that an article of Kouchakoff's published in French [1937] includes some dietary advice (pp. 314-316) to prevent digestive leukocytosis. As seen below, the recommended diet is not even predominantly raw, and foods such as grilled meat, bread, coffee, and salt are not prohibited. Of course, we express no opinion concerning the ideas of Kouchakoff here related to food selection, our point being simply to show that, in the eyes of the researcher himself who "discovered" a relation between leukocytosis and cooked food, only minor changes to fully-cooked diets are enough to prevent increases of white blood cells subsequent to meals. Our translation from the French follows:

Here is, along with their preparation method, a short list of the main foods we can use without risk of inducing digestive leukocytosis. For the sake of simplicity, "raw" will designate foods that are unheated, as well as those heated below their critical temperature. Furthermore, to correct the effects of a cooked food with a raw one, we recall that the latter should be added in the proportion of approximately 1 to 10. By "water," we mean ordinary drinking water, such as tap water.

Milk: raw, or heated below 88°C (190°F); if boiled, add raw milk or cream. No sugar. Yogurt, curds: allowed. Tea and coffee: add lemon juice, or water, or raw milk, or cream. No sugar. Wine: should be diluted with two raw products: water, fruits, fruit juice.

Bread: always whole, with butter. Eggs: fresh or soft-boiled. The yolk will remain raw and will correct the white. Butter: fresh, or melted below 91°C (196°F). Cheese: all kinds allowed, but should be taken with bread and butter. Fruits: raw or in salad. If at least two different kinds are used, sugar may be added. Sugar: avoid as much as possible, replace with honey. Remember that sugar should always be balanced with two different raw products.

Condiments: all kinds allowed (nutmeg, pepper, cinnamon, cloves, etc.), but add to cooked foods only when serving. Salad: one, or better, several kinds (lettuce, endive, watercress, dandelion). By increasing the number of different components, several cooked foods can be corrected at the same time. Use (cold-pressed) first-choice olive or walnut oil. No peanut oil. No vinegar, but lemon juice. Salt and pepper unlimited.

Vegetables: raw, finely chopped and prepared at the last minute. As with salad, it is better to mix several vegetables (carrots, beets, turnips, potatoes, etc.), which will perform a multiple correction. Eat with a mayonnaise: from first choice-olive oil. No peanut oil. Fresh eggs, salt, pepper, chives to taste. Lemon juice. No vinegar.

Meats: any raw or rare meats, smoked or salt-preserved meats: herring, ham, bacon. Boiled, braised, or grilled meats will be served with a mixed salad or mixed vegetables. Fish can be steamed (trout). Thus, boiled water will be avoided, since steam is simply distilled water, which is neutral for the organism. When serving, add fresh butter, lemon, parsley, and chopped onions, etc. Serve grilled meats in a similar fashion. For braised meat, cooking water will be discarded and replaced with the juice of the same vegetables that are served with the meat (carrots, tomatoes). The meat will be corrected with fresh butter, lemon, parsley, and the vegetables themselves, or by a mixed salad or a vegetable salad.

Note that we are not here recommending a diet based on food choices like what Kouchakoff suggests above--only demonstrating that his research has been taken considerably out of context by extremists, and used to "prove" things that Kouchakoff's work itself does not support (such as that an all-raw diet is necessary, or is the only way, or the best way, to avoid leukocytosis).


(Conclusion: Assessing the Risks of Cooking By-Products in Context)

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GO TO PART 1 - Is Cooked Food "Toxic"?

GO TO PART 2 - Does Cooked Food Contain Less Nutrition?

GO TO PART 3 - Discussion: 100% Raw vs. Predominantly Raw

Back to Research-Based Appraisals of Alternative Diet Lore

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