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(Comparative Anatomy and Physiology Brought Up to Date--continued, Part 8D)

Drawbacks to Relying Exclusively
on Clinical Studies of Diet

Exclusive reliance on clinical studies is narrow-minded and discounts other important evidence

There is a tendency among most conventional veg*n dietary advocates to rely heavily and/or exclusively on clinical studies in discussing the health effects of diets. This is unfortunate and, quite frankly, narrow-minded, as it ignores the other important scientific information currently available, e.g., the evidence of evolution and anthropology. (Of course, some formal dietary studies are ecological [epidemiological] and are based on the aggregation of large amounts of data. However, such studies require followup clinical studies to confirm hypotheses suggested by the ecological data. So, one ends up right back [again] with clinical studies.)

One example of the information to be gained from evolutionary and/or "paleo"-type studies is the data available from research on hunter-gatherers regarding the health effects of their omnivorous diets (which are much different than various versions of the SAD/SWD omnivorous diet utilized in most clinical research), which was discussed earlier here in Part 8. Another area of research, one closely related to evolutionary studies, is the newly emerging biomolecular study of genes and their effects. These offer the promise of not simply new information but also a new way of thinking about dietary problems.

Genetic studies offer a new paradigm for giving insights into optimal diets for INDIVIDUALS, rather than blanket recommendations based on clinical studies of GROUPS. With the mapping of the entirety of the human genome currently in progress, insights will be (and are already beginning to be) gained into the actual purpose and design of the human organism's functioning at the level of genes/molecular biology (the most fundamental "physiological" level possible). In conjunction with paleoanthropological insights regarding evolutionary adaptation, this understanding of the body's actual genetic design--when applied to nutritional questions--stands to give us a newly detailed understanding of the consequences of various eating patterns at the lowest nuts-and-bolts level. Eventually this will result in the ability to ascertain the actual step-by-step mechanisms governing the consequences of how foods are handled in the most unmistakable, fundamental way, and how their operation may vary from one individual to another.

Because they are based on studies of groups, clinical trials are vulnerable to yet-to-be-discovered confounding factors based on individual (genetic) differences. By definition, of course, these confounding factors can unfortunately be discovered only after the fact. Nevertheless, clinical studies are based on the assumption that with tightly-enough-controlled protocols, eventually all confounding variables can be eliminated. The desired objective in this is to be able to make dietary recommendations based on the outcomes of such trials that can be applied more or less equally to all individuals fitting the parameters controlled for. In itself, this is certainly logical.

However, controlling for all--or progressively more and more--confounding variables may eventually show that beyond a certain level of commonality, individual uniqueness becomes more important. Indeed, in Part 7 of this paper, we saw how there may be significant, telling differences between different individuals at the genetic level in regard to the problems both of insulin resistance and hereditary hemochromatosis, depending on one's evolutionary heritage. It's important to note here, also, that these types of genetic differences are not "genetic disorders"--they are normal (polymorphic) variations in genes that can occur between human populations or individuals depending on their evolutionary background. (Also see The Late Role of Grains and Legumes in the Human Diet, and Biochemical Evidence of their Evolutionary Discordance for a few other examples of genetic differences that may play a role in diet and disease.)

Genetics should greatly individualize the study of diet. One outcome of the unique insights to be had from the new paradigm of evolutionary and genetic studies should be the potential to greatly individualize the study of diet. This is something that clinical studies by their nature--as studies of groups based on statistical averages, rather than of individuals based on the interaction of actual (and unique) genetic mechanisms--are not as readily geared to explore.

Of course, clinical studies may still be required to test hypotheses about the interaction of genes with diet (by including controls for genetic differences between individuals) if such effects cannot be ascertained from genetic research at the physiological level alone. However, ultimately, the consequence of increasing genetic insights into diet will be the ability to evaluate which diets, or dietary patterns, work best for different individuals. To some extent, this places limits on the currently prevailing paradigm of clinical studies based on the statistically averaged results of groups. In so doing, it highlights the tendency of dietary idealists to use clinical studies as fodder for blanket recommendations meant to apply equally to everyone, or that assume one type of "ideal" diet can, should, or will work optimally for everyone.

Common sense and anecdotal evidence deserve consideration in certain circumstances

Relying exclusively on clinical studies also ignores anecdotal evidence. Although anecdotal evidence is indeed unreliable, at times it is the only evidence available. Despite its unreliability, it may be useful, under some circumstances, when no published studies are available on the topic of interest or when clinical data is skimpy or equivocal. Again, similar to what was noted above in regard to genetic issues, such circumstances may well depend on individual differences that escape the notice of clinical trials.

Hateful approach of certain fruitarian extremists. In contrast to the reliance on clinical studies by conventional vegans, the approach of many raw veg*n advocates differs. Some quote clinical studies very selectively, ignoring any that challenge their dogma (the usual rationalization is that it is from a "mixed" diet, and hence non-representative of results one might achieve on a raw vegan diet), while aggressively promoting any studies that appear to support their dogma (even if the results are for "mixed" diets).

A few fruitarian extremists reject (effectively) all clinical studies and science, and certain fruitarian crank science promoters selectively reject scientific research that challenges their dogma, on the hateful grounds that (the particular) science in question is the product of the minds of people who eat cooked foods (i.e., is "cooked science"), hence is wrong, worthless and/or cannot be trusted. The analogy to racism is obvious here; recall Hitler denouncing "Jewish science" if the analogy is not clear to you.

Other factors in evaluating clinical studies

Some of the limitations and problems inherent in clinical studies that may be relevant depending on the situation are:

Thus one should be cautious in interpreting the results of clinical studies. It is good to use multiple studies, review papers (those that look at or analyze the overall data from a wide range of studies), or standard reference books whenever possible, to avoid the problems of relying on only one study.

In summary

Clinical studies are a tool, to be used in an appropriate manner. Like any other tool, they can be used incorrectly. Finally, no number of clinical studies based on SAD/SWD data can overcome the logical fallacy (common in raw/veg*n circles) of claiming that results from such studies (SAD/SWD data) apply to all possible omnivore/faunivore diets.


(The Cornell China Project: Examining the Vegan Claims)

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GO TO PART 1 - Brief Overview: What is the Relevance of Comparative Anatomical and Physiological "Proofs"?

GO TO PART 2 - Looking at Ape Diets: Myths, Realities, and Rationalizations

GO TO PART 3 - The Fossil-Record Evidence about Human Diet

GO TO PART 4 - Intelligence, Evolution of the Human Brain, and Diet

GO TO PART 5 - Limitations on Comparative Dietary Proofs

GO TO PART 6 - What Comparative Anatomy Does and Doesn't Tell Us about Human Diet

GO TO PART 7 - Insights about Human Nutrition & Digestion from Comparative Physiology

GO TO PART 8 - Further Issues in the Debate over Omnivorous vs. Vegetarian Diets

GO TO PART 9 - Conclusions: The End, or The Beginning of a New Approach to Your Diet?

Back to Research-Based Appraisals of Alternative Diet Lore

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