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(Fire and Cooking in Human Evolution--continued, Part H)

P O S T S C R I P T :   S I G N I F I C A N T   R E S E A R C H   U P D A T E S   ( c o n t .)

(EDITORIAL NOTE: Triple-asterisked items in boldface below refer to passages in the interview as originally published, which are followed by updated comments based on additional observations or more recent scientific research.)

Why do cooked or denser foods
often improve raw/vegan health?

*** "If it is true that most people do better with the inclusion of some of these cooked items in their diet that we've mentioned--and I believe that it is, based on everything I have seen and heard..."

In retrospect, I want to make clear here that this was true of the vegetarians I was in contact with during the time I ran the Natural Hygiene M2M (and others since). My opinion at this point is that the improved health observed in most otherwise raw-foodist vegetarians who later include some amount of cooked food in their diet occurs because cooking simply allows additional foods to be eaten that broaden the diet. Just as importantly, it also increases the nutrient density of the diet by making available more concentrated nutrition in an otherwise restricted spectrum of nutrient intake brought about by eating only the bulkier, less-dense foods that compose most vegetarian fare that is edible raw.

For those who do not thrive on raw vegan diets, do the benefits experienced from grains/dairy outweigh any downsides? With the previously discussed evidence that grain and milk consumption can carry with them certain health ramifications, an interesting question presents itself. Considering our earlier observation above that vegetarians on raw-food diets often experience improvement when adding dairy products, or cooked items to their diet that allow more concentrated and nutrient-dense foods such as grains or legumes, one now has to ask: For vegetarians who otherwise refuse animal products such as meat--which is the primary Paleolithic adaptation to foods of animal origin--and eat a diet whose macronutrient content (higher carb and lower protein) is out of line with the evolutionary past, how much do the possible benefits of getting a wider spectrum of more concentrated nutritional intake in consuming grains, legumes, and/or milk or milk by-products outweigh their disadvantages? Certainly in the short run it seems to help many vegetarians, based on anecdotal observations, especially those we observed in the Natural Hygiene M2M. (There will be more about this in Part 3 of the interview.)

Long-term concerns. In the long-term, however, it appears from the recent evidence coming in, especially regarding hyperinsulinism, that there is a price to pay. While Americans have only been experimenting with vegetarianism in larger numbers since the 1960s and 1970s, epidemiological studies of populations in Southeast Asia where cultures have lived on grain and legume-based diets for centuries (often supplemented by dairy)--which is not so different in character to many vegetarian diets--show high rates of heart disease and widespread nutritional deficiencies. That we saw numerous health problems in the Natural Hygiene M2M that were often called "detox," but would appear to clinicians more like deficiencies, adds at least some anecdotal support that similar results might prevail among vegetarians. (There is unfortunately a lack of any controlled studies of predominantly raw-foodists who also include some dairy and/or grain/legume products in their diets.)

Mitigating circumstances. Two observations worth noting that cloud the picture a bit, however, are the following:

*** "...the more interesting and more pressing question, to my mind, is not whether we are adapted to cooking of certain foods, which seems very likely, but how much we have adapted to the dietary changes since the Neolithic agricultural transition, given the 10,000 years or less it's been underway."

Information about cooking's ultimate impact on health at the biochemical level of detail is still inconclusive. While as we've noted above, the detrimental repercussions of grains on health have now been implicated in a number of ways, the picture about cooking is more unclear than I had thought at the time of the interview. And this is not only due to the uncertainties over when cooking began. As I have since found, there have been no "review" papers summing up the research on cooking in modern food science studies that have taken a unified look at the subject, and what other studies there are, are fragmented and scattered widely. (But see Looking at the Science on Raw vs. Cooked Foods on this site, as a first attempt to remedy this lack.) This lack of unified study on the subject shows, in one way, just how new the evolutionary perspectives embodied in Paleodiet research are to the field of mainstream nutrition. (Though of course, the question of raw vs. cooked foods has been around in modern times in the alternative health movement, particularly within Natural Hygiene, since probably at least the mid-1800s.)

Big picture is more clear: Impact of cooking is likely to be much less important than other overarching considerations. One interesting observation here, however, which may serve to put the cooking question in more realistic perspective is that studies of modern hunter-gatherers (many of whom seem to cook about half their food) that have been performed show them to be probably among the most free of chronic degenerative diseases of all peoples on the planet. This suggests that whatever negative (or positive) effects cooking may or may not have, it probably just does not play a very large role adding to, or mitigating, the overall health factors that determine freedom from the degenerative diseases of civilization.

Magnitude of effect from macronutrient ratios likely plays the most influential role. Indeed, as we outlined above, more and more Paleodiet-relevant research seems to be showing that it is the overall macronutrient profile of a diet, in terms of:

It seems likely that these factors plus avoiding to the degree possible known non-evolutionary foods play the largest role in health, overshadowing what effect cooking may have. (Within reason, of course: There is evidence that overcooking to the point of charring should definitely be avoided since taking it that far produces carcinogenic by-products in fats/proteins such as meat. At the same time, however, it should be remembered that even raw uncooked plant foods also contain a certain natural level of mutagens and carcinogens. Again, these two points about cooking taken together with the fact cooking can also eliminate toxic antinutrients suggest that, as was pointed out in Part 2 of the interview itself, the issue of potential toxic by-products from cooking is far from a clear or cut-and-dried one.)

Eating all natural foods or all-raw by itself does not automatically result in a prudent diet. The upshot is that the obsession with a total raw-food diet in some sectors of the vegetarian community--while certainly not bad in the strictly technical sense--is considerably overhyped, assuming, that is, that, say half the diet is raw to begin with (particularly getting sufficient amounts of fresh vegetables and/or fruits). It is becoming more clear that the idea among vegetarians that if a person just eats all natural or all raw foods and they'll be okay ignores important factors, such as:

*** "Especially where people are avoiding flesh products which is our primary animal food adaptation, these animal by-products [cheese, eggs] may be helpful [for some vegetarians]..."

Again, while this may be true enough in the short-term, long-term is a different story, although eggs are something of an exception, and should not be lumped in with dairy when analyzing their effects. However, while eggs are native to the human diet, they would have been consumed only seasonally and in limited quantities, not daily or year-round like people do today. While the nutritional content of eggs is quite high and they contain complete protein of high bioavailability, they also contain the antinutrients avidin and conalbumin in the egg-white, the former of which inhibits biotin and other B vitamins; the latter of which binds iron. Egg-white is also allergic for some individuals. Thus not everyone can benefit from eggs, and those who can should still keep in mind that while natural and a food early humans would have eaten, they would only have been available in limited amounts.

*** "This [differing adaptation between population groups to Neolithic practices begun 10,000 years ago, specifically grain consumption] means it is going to be more likely right now in this particular historical time period that individuals will be somewhat different in their responses to diet. And as we saw above (with the two genes ACE and apolipoprotein-B) these genetic differences may even confound attempts to replicate epidemiological dietary studies from one population to another unless these factors are taken into account."

While this is of course true, the fact that most of the detrimental repercussions of grains that we have outlined above hold across all population groups implies that--whatever genetic advantages there may be within certain groups--they have apparently so far conferred only minimal (physiological) adaptive advantages, which, overall, fall well short of complete genetic adaptation. Note, however, on the other hand, that grains have conferred considerable cultural selective advantages. That is, they have built the agricultural base that has enabled the rise of settled, hierarchical civilizations, which support the social stratifications and specialized pursuits that have given rise to the huge technological advances since then.

The problem here, of course, where physical health is concerned is that genetic (physiological) adaptation always lags behind cultural selection in the behavior/culture evolutionary feedback loop (see discussion on the feedback loop between evolution and culture elsewhere on the site for more information on this evolutionary process). Even assuming that civilizations worldwide were to remain based on grains indefinitely into the future, it would still probably be many more thousands, perhaps tens of thousands, of years before a fuller physiological adaptation can have taken place.

*** "In experimental settings, purified, isolated protein extracts do significantly increase calcium excretion, but the effect of increased protein in natural foods such as meat is smaller or nonexistent."

A recent posting on the PALEODIET list by Staffan Lindeberg, M.D., Ph.D. about this concern citing more studies than I had access to at the time of the interview [see next point for title and date of post] indicates that taken as a whole, studies on calcium excretion due to increased protein intake do in fact indicate animal protein has a more pronounced effect than other sources. (This is due primarily to the sulfates contained in animal protein [Breslau et al. 1988, as cited in Barzel and Massey 1998].)

Paradox of high bone mass in pre-agricultural skeletons despite large animal protein intake. As stated in the body of the H&B interview, however--and as Lindeberg implies in his remarks--the debate as to animal protein's potential role in osteoporosis continues since it seems that hunter-gatherers in equatorial and temperate zones (excluding those in arctic regions such as Eskimos eating the highest levels of animal protein) have good bone mass parameters. (Archaeological specimens prior to the Neolithic certainly substantiate the picture of robust skeletal development in primitive hunter-gatherers.)

This would point to compensating factors in the complete picture of a Paleolithic diet that may render the protein/calcium loss issue something of a non-concern when the diet as a whole is assessed. What the physiological mechanisms are that lead to this net result, however, have not been fully worked out by researchers, although the role of a number of other factors besides protein that also influence calcium balance is becoming more clear in recent years. (For a more in-depth discussion of the paradox of high bone mass in Paleolithic skeletons despite high protein intake, see "Are Higher Protein Intakes Responsible for Excessive Calcium Excretion?" elsewhere on this website.)

*** "Studies of Eskimos have shown high rates of osteoporosis eating an almost all-meat diet (less than 10% plant intake) but theirs is a recent historical aberration not typical of the evolutionary Paleolithic diet thought to have averaged 65% plant foods and 35% flesh."

I did not know at the time of making this statement that the modern studies showing Eskimos to have high rates of osteoporosis are unfair because, in this case, the more recent epidemiological studies were performed with Eskimos already partway along the road to Western habits and diets, which has not been generally noted. Thus these particular studies are not reliable indicators of the effect of their native diet, for which one has to go back to observational reports in the early part of this century and before. Unfortunately, information on the Eskimos from this era is limited to observational reports from which no rigorous physiological data is apparently available.

On the other hand, studies of prehistoric Eskimo skeletons do show some degree of osteoporosis, although how much may be due to diet vs. other lifestyle factors such as reduced sunlight exposure, compression fractures due to traumatic vibrations from extensive sledding, etc., is not known. The rate of osteoporosis is increased in prehistoric Eskimo populations living furthest north, and among these furthest-north-living Eskimos, this rate increases as one moves further east from Alaska, across Canada, and into Greenland compared to those living in the western end of their range. [See the post of 7/29/97 on the PALEODIET list titled "Osteoporosis in Eskimos" by Staffan Lindeberg, M.D., Ph.D. for an extensive discussion plus scientific references.]

*** "W.N.: I would say my diet right now is somewhere in the neighborhood of about..."

It should go without saying that given the above updates to the Paleodiet research discussed here, I have made attempts to bring my current diet more in line with what is now known, although I certainly don't claim to be perfect in my habits, and recommend people make up their own minds about what to do. There is also the problem that economics, as well as current agricultural practices in how animals are raised, slaughtered, processed, and made available for sale (the dearth of organ meats available is one problem) introduce difficulties in approximating a true Paleolithic diet today.

*** "...low- or no-lactose cultured forms like goat cheese and yogurt."

While cultured forms of milk do indeed have little or no remaining lactose, the other drawbacks of milk products outlined in the postscript above in all likelihood also would apply to goat dairy, even if the nutritional profile of goat's milk may be somewhat closer to human milk than is cow's milk, as is often asserted. [See Loren Cordain's post of 10/15/97 on the PALEODIET list for a brief summary of what is currently known and unknown about the nutritional composition of goat's milk compared to cow's milk.]

*** "...sprouted forms of grains, or breads made from them, that eliminate the gluten otherwise present in wheat, barley, oats, and so forth."

Although I have not been able to confirm the following to my complete satisfaction with documentation, sprouting of grains is probably as important for deactivating the antinutrients (presumably phytates) they contain. Whether sprouting is as effective in reducing the gluten content as sprouting enthusiasts believe is something I am no longer so sure about. For either process, however, much undoubtedly depends on how many hours or days the sprouts are allowed to germinate and what stage the growth process is allowed to reach before consumption.

Next issue we conclude our 3-part interview series by taking an eye-opening look at "the psychology of idealistic diets," including lessons learned from people's real-life experiences in the Natural Hygiene Many-to-Many.


(The Psychology of Idealistic Diets / Successes and Failures on Vegetarian Diets)

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