Dear friends,

(cross posted)

I. OSTEOPOROSIS IN 20TH CENTURY ESKIMOS
Ward Nicholson started a thread in PALEOFOOD (which I occasionally read):
>One study of the Eskimos showed them to have high rates of
>osteoporosis. [1] ... I believe this study was of Eskimos prior to
>acculturation, eating their traditional diet.
>
This has been found in several studies. From the late 1960s to the late
1970s, Eskimos of Northern Alaska and Canada have been investigated
regarding osteoporosis by use of forearm dual energy absorptiometry and, in
one study, with radiography [1-4]. The findings are consistent and hard to
dispute, although whole body dual energy x-ray absorptiometry (DXA) is a
better method in the living (the best method has yet to be determined).
Bone density (i.e. the volume of bone in relation to soft tissue) is
generally low compared to US Whites, and bone loss starts at an earlier age
and proceeds at a greater rate than in other populations. I am not aware of
any scientific paper which claims the opposite. Osteoporosis is expected to
be a greater health problem in the Eskimos than in other populations in the
future.
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1. Mazess RB, Mather WE. Bone mineral content of North Alaskan Eskimos. Am
J Clin Nutr 1974; 27: 916-925.
2. Pawson IG. Radiographic determination of excessive bone loss in Alaskan
Eskimos, Human Biology 1974; 46: 369-80.
3. Mazess RB, Mather WE. Bone mineral content in Canadian Eskimos. Human
Biology 1975; 47: 45-63.
4. Harper AB, Laughlin WS, Mazess RB. Bone mineral content in St Lawrence
Island Eskimos. Human Biology 1984; 56: 63-78.
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Ward believes that the first study
>was of Eskimos prior to acculturation, eating their traditional diet.
>
which Ron Hoggan put in doubt:
>But this incidence is long after the Inuit had adopted the Western diet ...
>
From what I have read, Ron seems to be close to the truth. To be more
certain please check up further references in the cited literature.
        The 1974 paper of Mazess [1] deals with Wainwright Eskimos in
Northern Alaska studied in 1968-69. According to the diet surveys carried
out by the International Biological Programme in 1971 and 1972 which is
cited by Draper [5], Wainwright adults at that time obtained 32 per cent of
their calories from carbohydrate compared to an estimated 2 per cent in
premodern Arctic Eskimos. Native foods accounted for nearly half of the
calories in Wainwright. Protein intake was 25 per cent of calories, not
much less than the estimated 32 per cent in the premodern Eskimos (12 per
cent would be typical for US or Northern European populations). The authors
do not mention alcohol which provides much of the calories today, at least
in Greenland (and which adversely affects bone mass). Point Hope Eskimos a
bit south of Wainwright obtained 43 and 22 per cent of calories from
carbohydrate and protein, respectively, and had more hypertensives, 13 per
cent compared to 5 in the Wainwright group. A still higher rate, 23 per
cent, was found in the southwestern sister villages of Kasigluk and
Nunapitchuk, and this "was correlated with the increased use of processed
foods and the decay of the traditional life-style".
        In a letter in 1975 [6] George Mann, who had studied Alaskan
Eskimos in 1958 [7], commented on the Mazess study on Wainwright Eskimos
[1]. Mann stated that "the meat diet which we associate with [the Eskimos]
has been importantly diluted by these modern foods", that "Eskimo adults
are [now] a sedentary people" and that "the early loss of bone mineral is
more likely attributable to physical inactivity than to high intake of
phosphate, sulphate, and other anions". Mazess replied that "meat remains a
mainstay of the diet and intakes are quite high".
        Berkes and Farkas provide some insight into the history of changing
dietary patterns among the Inuit of Labrador and they give some references
but no figures on percentages of modern foods since their main focus is on
the James Bay Cree Indians [8]. Resource depletion started to become
intense already in the 1800's due to fur trade (the Hudson Bay Company
started trading fur in the late 1600's) and whaling (land mammals like
caribou and muskox, and sometimes walrus, were depleted from feeding the
whalers).
        Berkes and Farkas also cite Shephard and Godin who in 1976
calculated that the Igloolik Eskimos of North-west Territories (at about
the same latitude as Wainwright) obtained only about 31 per cent of the
needs from wild food energy [9]. Rode and Shephard recently presented
anthropometric data on Igloolik Inuit [10] which shows that lifestyle has
been further deteriorated after 1970. Males aged 40-49 years increased
their percentage of body fat (estimated from triceps, subscapular and
suprailiac skinfolds according to Durnin and Womersley) from 11 per cent in
1970 to 17 and 23 per cent in 1980 and 1990, and corresponding figures for
females were 22, 29 and 38 per cent.
        I have not seen nutritional data from 1920-70 but the Eskimo
lifestyle may have changed a lot in that time period. This is a crucial
question with regard to the Wainwright Eskimos surveyed around 1970.
        Additionally, we must always be aware of secular trends when
interpreting cross-sectional surveys in a group of people who have been
changing their lifestyle for some decades. If a secular trend would explain
the age-related decrease of bone mass in contemporary Eskimos (which I
highly doubt) it would mean that older persons would have lower bone mass
than younger ones not because their bone mass had decreased as they grew
older but because younger persons at the time of the study had higher bone
mass than the old ones had had in their youth.
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5. Draper HH. The Aboriginal Eskimo diet in modern perspective. Am
Anthropol 1977; 79: 309-16.
6. Mann GV (and reply by Mazess RB). Bone mineral content of North Alaskan
Eskimos. Am J Clin Nutr 1975; 28: 566-7.
7. Mann GV et al. The health and nutritional status of Alaskan Eskimos. A
survey of the Interdepartmental Committee on Nutrition for National
Defense-1958. Am J Clin Nutr 1962; 11: 31-.
8. Berkes F, Farkas CS. Eastern James Bay Cree Indians: changing patterns
of wild food use and nutrition. Ecol Food Nutr 1978; 7: 155-72.
9. Shephard RJ, Godin G. Energy balance of an Eskimo community. In:
Shephard RJ, Itoh S (eds). Circumpolar health. Univ Toronto Press, Toronto.
1976: 106-12.
10. Rode A, Shephard RJ. Body fat distribution and other cardiac risk
factors among circumpolar Inuit and nGanasan. Arct Med Res 1995; 54:
125-33.
        See also
Lippe-Stokes S. Eskimo story-knife tales: reflections of change in food
habits (which I have not read). In: Robson JRK (ed). Food, ecology and
culture. Readings in the anthropology of dietary practices. Gordon and
Breach 1976(?): 75-82 (which I have not read).
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II. SOME PROBLEMS OF MEASURING BONE MASS IN ANCIENT POPULATIONS
Studies of osteoporosis in archaeological skeletons are problematic, and
one researcher recently stated that "in archaeological bone, studies of
prosoty, density, and mineralization are almost impossible" [11]. One of
the reasons is that when bones lie in the ground for long periods they
undergo changes (diagenesis) which in our case may result in falsely low or
falsely high levels of bone mass. Another problem is that estimations of
age at death are very unreliable after the age of 50 and the methods have
not been standardized [12-13] (i.e. all investigators do not do it in the
same way). Subjects with estimated ages above 50 years are commonly put in
one group which seriously hampers investigations of disorders which have
limited influence before that age.
        Our group is starting up studies on bone mass in a fairly large
population of prehistoric hunter-gatherers by the sea from Gotland, Sweden
(not Eskimos). My colleague Dr Peter Johansson, who is in charge of these
studies, suspects that dual energy absorptiometry, which mainly measures
trabecular (inner) bone, may not necessarily be the method of choice in
archaeological skeletons. Possibly quantitative computerized tomography
(QCT) is better. Then you can measure cortical (outer) bone as well as
trabecular.
        Osteoporosis is characterized, histologically, by a decrease in
cortical thickness and in the number and size of the trabeculae (the
bar-like inner structures of bone). Trabecular bone has often been
overemphasized in osteoporosis research, partly depending on the used
methods of measurement. A major reason why, in the West, bone loss is
higher in women than in men is that there is a gradual thinning of cortical
bone in women [14]. This is because resorption on the inside is greater and
formation on the outside is less [15]. Furthermore, the strength of a bone
depends not only on bone mass and even here the importance of cortical
thickness may have been underestimated [16-17].
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11. Jackes M. Paleodemography: problems and techniques. In: Saunders SR,
Katzenberg MA. Skeletal biology of past peoples: research methods.
Wiley-Liss, 1992: 189-224.
12. Iscan MH, Loth SR. Osteological manifestations of age in the adult. In:
Iscan MH, Kennedy KAR (eds). Reconstruction of life from the skeleton.
Wiley-Liss 1989:23-40.
13. Stout SD. Methods of determining age at death using bone
microstructure. Skeletal biology of past peoples: research methods.
Wiley-Liss, 1992: 21-35.
14. Kalender WA et al. Reference values for trabecular and cortical
vertebral bone density in single and dual-energy quantitative computed
tomography. Eur J Radiol 1989; 9: 75-80.
15. Ruff CB, Hayes WC. Sex differences in age-related remodeling of the
femur and tibia. J Orthop Res 1988; 6: 886-96.
16. Mazess RB. Fracture risk: a role for compact bone [editorial]. Calcif
Tissue Int, 1990; 47: 191-3.
17. Ruff C. Biomechanical analyses of archaeological human skeletal
samples. In: Saunders SR, Katzenberg MA (eds). Skeletal biology of past
peoples: research methods. Wiley-Liss 1992: 37-58.
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III. OSTEOPOROSIS IN PREHISTORIC ESKIMOS
Archaeological data suggest that even prehistoric Eskimos were at higher
age adjusted risk of osteoporosis than contemporary Westerners [18-21].
Accelerated loss of bone mass after 50 years has been noted rather than low
peak bone mass at early adulthood.
        Harper [4] states that "studies based upon skeletonized
ancestral-antecedent populations of Aleuts, Yupik Eskimos, and Inupiaq
Eskimos have revealed a major cline [i.e. a gradual geographic difference,
my comment] in bone cortical thickness [which] is highest in the ancestral
Umnak-Kodiak homeland of the Bering Sea Mongoloids and decreases in
populations north along the Alaskan coast to the Arctic Circle, the
approximate demarcation point between Yupik and Inupiaq Eskimo. Cortical
thickness values diminish even more in the Inupiaq Eskimos extending east
across north Alaska, Canada and Greenland. The difference between the
terminal isolates, Aleuts and Greenland Inupiaq Eskimos, are as great as
the differnce in cortical thickness between male and female in the same
isolate. Similarly, femoral BMC [bone mineral content of the thigh-bone]
measured by direct photon absorptiometry mirrors the highly significant
differences between the Aleuts, on one hand and northern Eskimos on the
other".
        Merbs found the extinct Sadlermuit to have a high prevalence of
spinal compression fractures (from vertical forces on the vertebral column)
[22-23]. Such fractures were present in 36 of 80 adult Eskimos. The author
considers "the high incidence ... attributable primarily to riding on a
komitak, a simple platform sled lacking any form of shock absorber. As the
vehicle moves rapidly over ice roughened by pressure ridges or rocks hidden
by snow, vertical forces, sometimes quite violent, are transmitted directly
to the vertebral column of the rider. The Eskimo condition is thus similar
to one known in orthopedics as 'snowmobiler's back', also characterized by
vertebral compression fractures...". Thus, as Dean suggests, the commonly
expressed notion that the findings of Merbs are further evidence of
osteoporosis in Eskimos may be open for debate.
        In a study on the non-sledding Aleut Eskimos, cited by Merbs, the
frequency of vertebral compression fractures was 22 per cent [24]. For
comparison, women aged 50 years and over from Rochester, Minnesota, had a
prevalence of vertebral deformity of 25.3 per cent (95% confidence interval
22.3-28.2) [25]. The incidence of clinically diagnosed vertebral fractures
among women in the same population was 5.3 per 1,000 person-years,
suggesting that around 30% of such deformities in women receive clinical
attention.
        I am sure there must be much more data on the occurence of
fractures in arcaeological Eskimo skeletons. It should be noted that the
complete absence of a disease in a non-western population not always occurs
to the author as being important. He or she would nevertheless probably be
delighted to be asked about it. Try e-mail by the Worldwide list of
universities at <http://www.mit.edu:8001/people/cdemello/univ.html>
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18. Mazess RB. Bone density in Sadlermuit Eskimos. Hum Biol 1966; 38: 42-9.
19. Thompson DD, Gunness-Hey M. Bone mineral-osteon analysis of
Yupik-Inupiaq skeletons. Am J Phys Anthropol1981; 55: 1-7.
20. Laughlin WSB et al. New approaches to the pre- and post-contact history
of Arctic peoples. Am J Phys Anthropol 1979; 51: 579-87.
21. Richman EA et al. Differences in intracortical bone remodelling in
three American aboriginal populations: possible dietary factors. Calcif
Tissue Int 1979; 28: 209-14.
22. Merbs CF. Patterns of activity-induced pathology in a Canadian Inuit
population. National Museum of Man Mercury Series, Arcaelogical Survey of
Canada Paper No. 119.
23. Merbs C. Trauma. In: Iscan MH, Kennedy KAR (eds). Reconstruction of
life from the skeleton. Wiley-Liss 1989:161-89.
24. Yesner DR. Degenerative and traumatic pathologies of the Aleut
vertebral column. Arch Calif Chirop Assoc 1981; 5: 45-57.
25. CooperC, O'Neill T, Silman A. The epidemiology of vertebral fractures.
Bone 1993; 14 Suppl 1: S89-97.
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It is not easy to draw conclusions about the role of diet, physical
activity, sunlight and genetics for the allegedly high risk of osteoporosis
in prehistoric Eskimos. If diet is a cause I would not suspect calcium
INTAKE in the first place since absorption and losses of calcium seem to
overshadow intake, at least in westernized populations [26], and
furthermore I would expect the meat and fish diet of Eskimos to provide
sufficient amounts of calcium (In fish the amount of calcium per 10 MJ
averages about 1,000 mg). Calcium absorption would probably be high due to
the absence of phytic acid from cereals (see
http://maelstrom.stjohns.edu/CGI/wa.exe?A2=ind9706&L=paleodiet&O=T&P=850).
The most common nutritional explanation in the literature is the high
protein intake (see below). I suppose vitamin C deficiency would be another
possibility [27].
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26. Nordin BEC. Bad habits and bad bones. In: Burckhardt P, Heaney RP
(eds). Nutritional aspects of osteoporosis '94. Rome, Ares-Serono Symposia
1995: 1-25.
27. New SA et al. Nutritional influences on bone mineral density: a
cross-sectional study in premenopausal women. Am J Clin Nutr 1997; 65:
1831-9.
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IV. BONE LOSS IN HUNTER-GATHERERS
Perzigian studied bone density of the forearm by use of photon
absorptiometry in two prehistoric north American groups of
hunter-gatherers, one of whom were said to supplement its hunting and
gathering with part-time agriculture [28]. He concluded that age related
trabecular bone loss in the latter group was higher than in the exclusive
hunter-gatherers which had similar bone loss as contemporary populations.
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28. Perzigian AJ. Osteoporotic bone loss in two prehistoric Indian
populations. Am J Phys Anthropol 1973; 39: 87-96.
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V. PROTEIN INTAKE AND CALCIUM LOSSES
Many metabolic trials and epidemiological surveys have been performed
regarding the role of dietary protein for calcium losses. Most of them show
that an increased protein intake leads to higher urinary losses of calcium,
possibly because of an increased acidic load [29-33]. In epidemiological
surveys, dietary protein, in particular animal protein (although some
investigators do not differ between protein from meat and milk products),
has been associated with higher rates of osteoporotic fractures across
cultures [34] and among US nurses [35].
        Epidemiological studies are often biased by confounding, when a
hidden cause (like smoking) is related to a variable (like yellow fingers)
which in turn is found to be related to the disease in question (like lung
cancer). Therefore we need intervention studies for proof (although in the
case of smoking we got convinced without them). Such studies have to my
knowledge not been able to show that a change from low/moderate to high
protein intake increases the rate of kidney stones or bone loss in animals
or humans.
        In one study, rats were fed a control diet (15% soy protein plus
0.2% methionine) or a high protein diet (control plus 20% lactalbumin) for
10 months [36]. Rats which were fed the high protein diet exhibited
increases in urinary calcium but no change in bone composition.
        In another study, 99 persons who had calcium oxalate kidney stones
for the first time were randomly assigned to either a control diet or a low
animal protein, high fiber diet and followed regularly for up to 4.5 years
[37]. In the intervention group of 50 subjects, stones recurred in 12 (7.1
per 100 person-years) compared with two (1.2 per 100 person-years) in the
control group (p = 0.006), suggesting that a *low* animal protein diet
increased the risk of urinary stones.
        Furthermore, when Orwoll et al studied growing rats fed a diet low
in protein (5%) for 4, 6, and 8 wks (n = 10 animals/group) and compared
them with animals pair-fed with a protein-replete (18%) diet, skeletal
dimensions were *reduced* in the protein-deprived rats but there were no
significant differences in bone mineral content between control and
low-protein animals at 4, 6, and 8 wks [38]. Hence, they found that dietary
protein deprivation resulted in slower growth but bone mineral density was
maintained when there was a marked reduction in urinary calcium excretion.
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29. Kerstetter JE, Allen LH. Dietary protein increases urinary calcium. J
Nutr 1989; 120: 134-6.
30. Do protein and phosphorus cause calcium loss? J Nutr 1988; 118: 657-60.
31. Burtis WJ et al. Dietary hypercalciuria in patients with calcium
oxalate kidney stones. Am J Clin Nutr 1994; 60: 424-9.
32. Trinchieri A et al. The influence of diet on urinary risk factors for
stones in healthy subjects and idiopathic renal calcium stone formers. Br J
Urol 1991; 67: 230-6.
33. Breslau NA et al. Relationship of animal protein-rich diet to kidney
stone formation and calcium metabolism. J Clin Endocrinol Metab 1988; 66:
140-6.
34. Abelow BJ, Holford TR, Insogna KL. Cross-cultural association between
dietary animal protein and hip fracture: a hypothesis. Calcif Tissue Int
1992; 15: 14-8.
35. Feskanich D, Willett WC, Stampfer MJ, Colditz GA. Protein consumption
and bone fractures in women. Am J Epidemiol 1996; 143: 472-9.
36. Whiting SJ, Draper HH. Effect of chronic high protein feeding on bone
composition in the adult rat. J Nutr 1981; 111: 178-83.
37. Hiatt RA, Ettinger B, Caan B, Quesenberry CP Jr, Duncan D, Citron JT.
Randomized controlled trial of a low animal protein, high fiber diet in the
prevention of recurrent calcium oxalate kidney stones. Am J Epidemiol 1996;
144: 25-33.
38. Orwoll E; Ware M; Stribrska L; Bikle D; Sanchez T; Andon M; Li H.
Effects of dietary protein deficiency on mineral metabolism and bone
mineral density. Am J Clin Nutr 1992; 56: 314-9.
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I do not agree with the following statements of Dean:
>There is no evidence at all that meat proteins cause calcium loss.  Every
>study which has shown loss of calcium and other minerals from high
>protein intake has involved soy and other non-animal-source proteins.
>Studies which use meat proteins show no such loss of calcium. (1,2,3)
>
>1) Spencer H; Kramer L; DeBartolo M; Norris C; Osis D. Further studies of
>the effect of a high protein diet as meat on calcium metabolism. Am J Clin
>Nutr, 1983 Jun, 37:6, 924-9
>2) Osteoporosis, calcium requirement, and factors causing calcium loss.
>Spencer H; Kramer L. Clin Geriatr Med, 1987 May, 3:2, 389-402
>3) Do protein and phosphorus cause calcium loss? Spencer H; Kramer L;
>Osis D. J Nutr, 1988 Jun, 118:6, 657-60

Rather, the debate goes on [39]. When different sources of protein have
been compared it is usually the animal protein diet that has resulted in
the greatest loss of urinary calcium [33, 40], and in epidemiologic surveys
the case is also rather against meat [35, 41].
        From what I know today I would personally not advice a lady to live
only on an Eskimo diet. Nevertheless, my working hypothesis (which some day
may be able to test) is that prehistoric hunter-gatherers from the equator
to the temperate zones had strong bones at old age.
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39. Spencer H, Kramer L. Does dietary protein increase urinary calcium?
[Letter with reply by Kerstetter JE and Allen LH] J Nutr 1991; 121: 152-3.
40. Schuette SA, Linkswiler HM. Effects on Ca and P metabolism in humans by
adding meat, meat plus milk, or purified proteins plus Ca and P to a low
protein diet.
41. Hu J-F et al. Dietary intakes and urinary excretion of calcium and
acids: a cross-sectional study of women in China. Am J Clin Nutr 1993; 58:
398-406.
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Best regards,

Staffan

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Staffan Lindeberg M.D. Ph.D. Dept of Community Health Sciences, Lund
University, Mailing address: Dr Staffan Lindeberg, Primary Health Care
Centre, Sjobo, S-22738 Sweden, +46 416 28140, Fax +46 416 18395
<[log in to unmask]> http://www.panix.com/~paleodiet/lindeberg/
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