Navigation bar--use text links at bottom of page.

(Comparative Anatomy and Physiology Brought Up to Date--continued, Part 7B)

Key Nutrients vis-a-vis Omnivorous
Adaptation and Vegetarianism (cont.)

Vitamin B-12: Rhetoric and Reality (CONT., 2 OF 5)

Vitamin B-12 deficiency in natural hygienists

Dong and Scott [1982] took blood samples at the 1979 annual convention of the American Natural Hygiene Society (ANHS), and tested the samples for serum B-12 levels and other parameters of interest. A total of 83 volunteers provided blood samples. Each individual in the study provided detailed dietary information via a survey form, which asked about the individual's consumption of animal foods (including eggs and dairy), and also asked for a typical daily diet.

Description of natural hygiene diet, and diets of those in survey. For readers unfamiliar with the term "natural hygiene," in this context the classical definition refers to a predominantly raw diet of fruits, vegetables, nuts, and seeds. Note that the data were collected in 1979, at which point the ANHS had a long history of strongly emphasizing raw plant foods. Since then, the ANHS has revised their position. While still emphasizing plant foods (veganism), the stress previously placed on raw foods has been deemphasized; and adding cooked starches (grains, legumes, tubers, squashes) to the diet is now recommended.

Based on the dietary data provided in the survey form, subjects were classified according to their diet, with vegans being defined as those who consumed no animal foods, lacto-vegetarians as those who consumed dairy as their only animal food, lacto-ovo-vegetarians as those who consumed dairy and eggs, and semi-vegetarians as those who consumed animal flesh foods two or less times per month. It should be noted here that because the subjects were recruited at an ANHS convention, and the ANHS emphasized raw foods at the time, at least some of the subjects in the vegan category presumably were raw or predominantly raw vegans.

Serum B-12 levels of vegan natural hygienists below lower limit of normal range. Dong and Scott [1982, pp. 214-215] report:

Among subjects who did not supplement their diets with B-12 or multiple vitamin tablets, 92% of the vegans, 64% of the lacto-vegetarians, 47% of the lacto-ovo-vegetarians and 29% of the semi-vegetarians had serum B-12 levels less than 200 pg/ml [the lower limit of the normal range]. Mean serum B-12 levels of the dietary groups increased with increasing dietary sources of B-12...

Some cases of mild macrocytosis [pernicious anemia] were seen among the vegetarians, but fewer than expected...

The data indicates that increasing diversity of animal products consumed increased the serum B-12 level.

Dong and Scott [1982, p. 210] report the average serum B-12 levels found as shown below. In the following, note that the normal serum B-12 level is 200-900 pg/ml.

Mean Serum B-12 Levels (pg/ml)
Observed at 1979 ANHS Annual Convention

from Dong and Scott [1982]



















Note that the B-12 serum levels observed for the vegans is in the range regarded as deficient [Dong and Scott, pp. 213-214].

Vitamin B-12 levels in "living foods" and other vegan/vegetarian diets

Negative review paper critical of studies pointing to deficient B-12 status in vegetarians found to be inaccurate and outdated

Immerman [1981], a study of vitamin B-12 status in vegetarians, is subtitled, "A critical review," and attempts to review the clinical studies of vitamin B-12 deficiencies in vegetarians published before 1981. Immerman's approach is to check each study against a criteria list. His reference list had 7 criteria, of which the first 5 were considered essential for a study to be credible. After a detailed review of the studies, Immerman concludes [1981, p. 47], "When judged by these criteria, most of the studies which have found inadequate B-12 status in lactovegetarians and vegans are unconvincing."

However, a retrospective and analytical review of Immerman [1981] shows that his assessment criteria are logically flawed, and there may be bias present in his review. A summary of the flaws in Immerman's review is as follows.

A review of Immerman's "critical review" finds it outdated and invalid. Immerman's "critical review" does show that some of the older B-12 studies are not as convincing as more recent studies, i.e., in light of newer knowledge, the shortcomings of the older studies are readily apparent. Similarly, a retrospective review of Immerman [1981] finds it to be seriously flawed, logically invalid, and potentially biased. If any reader thinks it unfair to judge Immerman [1981] using more recent knowledge, please recognize that this is also what Immerman himself was attempting to do when assessing the earlier B-12 studies. However, note that Immerman's review is invalidated not solely or simply on grounds of more recent knowledge. The criticisms made here (above) of criterion 5 were relevant at the time of Immerman's review article; i.e., Immerman's study was logically flawed at the time it was published in 1981.

[Note: Despite the risk or reality of belaboring the point here, I have discussed Immerman [1981] at length because it is occasionally cited by raw/veg*n diet advocates who wish to discount the published studies showing B-12 deficiencies in veg*ns, and/or deemphasize the importance of B-12 in veg*n diets.]

Steer clear of dietary extremists who rationalize B-12 deficiency concerns. The above evidence of apparent vitamin B-12 deficiency in vegans (both raw and conventional) should serve as a warning to fruitarian/veg*n extremists and their followers who claim adequate vitamin B-12 can be obtained by eating unwashed plant foods or from intestinal bacterial synthesis (the latter topic is discussed later herein).


(Is Vitamin B-12 Available from Spirulina or Intestinal Synthesis?)

Return to beginning of article



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

   Beyond Veg home   |   Feedback   |   Links