Monday, March 1, 2010

Paleo Diet pH: Does It Matter? – Part II

As I reported in Eskimo Osteoporosis?, I felt astonished when I found that a report by Mazess, commonly cited as documenting osteoporosis among precontact Inuit, actually reported that middle-aged Inuit had an apparently normal bone mineral density. As I said in that post, that report did not give good evidence one way or another for bone density of elderly Inuit. I decided to read some of the other papers published on this topic.

In 1972, Mazess and Jones published data documenting age-related bone loss in skeletons of extinct Sadlermiut Eskimos.[1] In this study 17% of the skeletal remains studied came from a stratum at least several hundreds of years old, 44% came from remains deposited before 1899, and 39% from remains deposited between 1899 and 1903. Contact had very little influence on Eskimo diet and lifestyle through these periods. In these skeletons Mazess and Jones found that skeletons from individuals probably aged 36 years or older showed a more rapid rate of bone mineral loss than comparably aged non-Eskimos.

In 1974, Mazess and Mather published another report, Bone Mineral Content of North Alaskan Eskimos.[2] This report looked at Inuit people living in Wainwright, Pt. Hope, and Pt. Barrow, ranging from age 5 years to 82 years, both male and female. This investigation found that Inuit have bone density comparable to age-matched Caucasians in the U.S. up until the age of 40, after which they show a more rapid loss of bone mass resulting in bone mineral densities averaging 10-15% lower than U.S. Caucasians. The process of bone loss starts in the third decade of life in Eskimos of both sexes, whereas in Caucasians in the U.S. it does not start until the forties in females and fifties in males. In the 70-82 year age group, Inuit men had bone density almost 16% lower than Caucasian men, and Inuit women had bone density almost 30% (29.8%) lower than Caucasian women.

Mazess and Mather state:

“Apparently some continuous process accompanies aging in Eskimos that accelerates and exacerbates the aging bone loss evident in so many other populations. In white females, the rate of bone loss between ages 45 and 74 is approximately 9.5% per decade, and there is a change to almost 4.5% per decade thereafter. In white males, the onset of loss is later, and the rate of loss after age 55 is nearly 4.5% per decade. The present results indicate that Eskimo males lost almost 6 to 7% per decade, and Eskimo females close to 10 to 12% per decade after the late thirties and early forties. The rate of loss in Eskimos appeared to approximate 2 to 3% per decade greater than that of corresponding whites. As the onset of loss was earlier than in whites by age 50, the Eskimos had substantially lower bone mineral than whites.”

Some advocates of Inuit-style diets have criticized this and similar studies, correctly pointing out that it looked only at partially modernized Eskimos. They suggest that Weston Price’s work documented excellent skeletal health among the primitive Inuit and these studies fail to contradict Price’s findings. I do not find this argument persuasive; in fact, I find it very flawed.

According to the diet surveys carried out by the International Biological Programme in 1971 and 1972 which is cited by Draper [3], Wainwright adults at that time (when Mazess collected skeletal data) obtained nearly half of their calories, three-quarters of their protein, and half of their fats from native foods. Carbohydrate provided 32 per cent of their calories, compared to an estimated 2 per cent in premodern Arctic Eskimos. Protein provided 25 per cent of calories, not much less than the estimated 32 per cent in the premodern Eskimos. For comparison, 12 per cent would be typical for US or Northern European populations.

Therefore, the Eskimos ate the most native and least modern foods when compared to Caucasians. Since Mazess and Mather found that the Caucasians (eating the most modernized diet) had the later onset and less severe progression of osteoporosis, their study actually showed that either modernization or Caucasian race protected against the accelerated loss of bone mass found in the partially modernized Eskimos.

I find it hard to imagine any adaptive value of early bone loss in humans, so I don't find it plausible to explain this difference via genetics.

Hence, if the Eskimo diet protected against osteoporosis, we should see the lowest rate of bone loss in the group with the most Eskimo-style diet and activity patterns and the highest rate of bone mass loss in people having the most modernized diet and activity patterns. In other words, Mazess and Mather should have found the greatest rate of bone loss in the Caucasians, not the Eskimos. However, they found the opposite. This means that the fully modernized diet consumed by the Caucasians protected against bone loss.

It follows that some feature of the primitive Eskimo diet accelerates aging-related bone loss, or that some feature of the modernized diet retards aging-related bone loss. According to Draper, at the time of data collection, the Eskimos got 32% of energy from carbohydrate, 43% from fat, and 25% from protein; whereas the modern U.S. diet supplied 46% of energy from carbohydrate, 42% from fat, and 12% from protein. Thus, compared to whites, Eskimos consumed a similar amount of fat, 30% less carbohydrate, and twice as much protein.

Hence this data would generate the reasonable and testable hypothesis that either reducing carbohydrate-rich foods or increasing protein intake promotes early onset and rapid progression of bone loss in Eskimos. It does not support the hypothesis that wild game protects against osteoporosis, because the group with the diet highest in wild game (the Eskimos) had the earliest onset and most rapid progression of osteoporosis. It also does not support the hypothesis that modern carbohydrates promote osteoporosis, because the group with the lowest intake of modern carbohydrates (the Eskimos) had the earliest onset and most rapid progression of osteoporosis.

In short, even if we didn’t already have the earlier Mazess study on precontact Eskimo skeletons showing the same accelerated loss of bone mass compared to modern U.S. citizens, the fact that these Eskimos were partially modernized in diet and lifestyle only more firmly points to their native diet -- specifically, its high protein content -- as the most probable dietary cause for their osteoporosis.

By comparing the Eskimos to fully modernized whites, Mazess demonstrated that the fully modernized diet reduces aging-related losses of bone mass compared to a partially modernized Eskimo diet, which effectively shows that the acceleration of bone loss did not result from the modernized portion of the Eskimo diet or lifestyle.

This does not conflict with Weston Price’s findings. Price focused his investigation on disorders of skeletal development), not disorders of skeletal aging. He did not investigate the effects of the Eskimo diet on the aging skeleton at all. Mazess and Mather also found that the Eskimos have normal bone development, but they found something Price missed, namely, accelerated bone aging, compared to non-Eskimos.

The evidence for the role of dietary protein (as a source of metabolic acid) in osteoporosis goes beyond Eskimos and includes clinical trials.

Stay tuned for the next installment.

Notes:

1. Mazess RB and Jones R. Weight and density of Sadlermiut Long Bones. Human Biology (September 1972) 44;3:537-548.
2. Mazess RB and Mather W. Bone Mineral Content of North Alaskan Eskimos. AJCN (1974) 27:916-925.
3. Draper HH. The Aboriginal Eskimo Diet in Modern Perspective. American Anthropologist, New Series, Vol. 79, No. 2 (Jun., 1977), pp. 309-316.

21 comments:

Stephan said...

Hi Don,

I think it's important to consider that the Inuit may have had a higher susceptibility to European food-induced disease than the Caucasians did. This is something you see in other native Americans such as the Pima, Pacific islanders, etc. There are no Caucasian populations, poor or otherwise, that have the degree of pathology you see in Arizona Pima or on the island of Nauru. Many Inuit also suffered from alcoholism, which reduces BMD.

For these reasons, I think it's important to restrict the analysis to pre-contact Inuit skeletons only, who you can be sure were not affected by Western foodways. I think there is some limited evidence of osteoporosis in pre-contact skeletons, although I don't have the ref on hand. I can try to look it up later.

Another thing to consider is that the Western plant foods eaten by the Caucasians and Inuit in the arctic were acid forming. They had essentially no vegetables up there. Food imports were mostly white flour, sugar and alcohol.

In any case, I think it would be difficult to ascribe low BMD in Inuit specifically to acid load. Their diet was extreme in so many ways. Very high omega-3, extreme 6:3 ratio, vitamin D status may have ranged from excessive to deficient, vitamin A status may have been excessive in some groups, low vitamin C status, low intakes of certain vitamins and minerals, excessive intake of others, nearly zero fiber. Their gut flora were probably pretty bizarre.

In any case, I agree with you that the Inuit diet is probably not a good model for optimal health.

Don said...

Stephan,

The first study I cited was on Eskimos either precontact or not significantly influenced by contact.

I have more evidence (citations) coming along in the next post.

Not sure I understand your point when you correctly point out that both the Caucasians and the Eskimos ate mostly acid forming carbohydrates. If you take a diet high in protein (Eskimo) and add acid-forming plant foods, it increases acidity. I would gues the main grains in both cases were refined wheat and rice, mostly wheat. REfined wheat flour generates 6.9 mEq per 100 g portion, and boiled rice 1.7. Salmon generates 9.4, ox liver 15.4, and rump steak 8.8. IT seems very likely that the Eskimo diet would generate more acid than the Caucasian diet.

I agree that their are multiple factors, and I think metabolic acidity has a demonstrated very strong effect on calciuria and bone health. Most of the other factors you mentioned would not be universal among Eskimos.

Not aware of any research suggesting that high n-3 causes calciuria or bone loss, if you are I'd like to have a reference.

So far I have read about 1/2 dozen studies on Eskimo bone health, and all conclude that they have early and accelerated bone loss and that the most likely explanation is their acid-forming diet. The mechanism is sound and well-established, and also appears to apply to modern populations. Glad to see any research that provides an equally sound alternative explanation.

Don said...

And if you took the Caucasians diets (these were in Wisconsin), and added Eskimo foods, it would make them more acid-forming.

Aaron said...

Thanks for the studies Don.

1. Excess protein = bad for bones. I feel this is in even in the face of tons of calcium to balance it out (just look at Inuit). I feel this was already intuitive for many individuals studying nutrition. You probably don't need tons of base yielding foods if protein is kept lower.


2. Staying in Ketosis 24/7, as the Inuit did, was probably not the best for bone health -- it's an area to be explored.

Stephan said...

Hi Don,

Is there proof that the bones in the Mazess et al. analysis were from Inuit that had no significant Western dietary influence? Did they independently analyze the bones that were in the oldest stratum, or did they lump together the older and newer skeletons?

I remember reading Stefansson's accounts of the Inuit groups he encountered. Typically, as soon as contact was made, they were eating a partially Westernized diet within 5 years. This was generally true even for extremely isolated groups, who would go far out of their way to trade for Western food (it was considered prestigious). The last isolated groups were contacted in the 1930s I believe, but the vast majority were contacted long before. Even during Stefansson's journey, which if I recall correctly was in the 19-teens, there were very few groups that had not been contacted. His expedition was explicitly to search for one of those groups.

The effects of lifelong extreme omega-3 intakes are unknown, but there are probably negative consequences of some sort, and it wouldn't be out of the realm of possibility that it would affect BMD. Very high vitamin A intake would have been common among Inuit and could have contributed to low BMD. Low D status for inland groups is another potential factor. Low calcium intake as well. The point is that the Inuit were extreme in so many ways that it seems difficult to put our finger on one variable as being a major contributor to the (possible) low bone density.

Regarding the acid load of the Caucasians vs. Inuit, I'd be interested to see a comparison between the acid load of the Inuit diet and a US diet similar to the one the people in the comparison groups were eating. They're both acid-forming, but by how much? Is the Inuit diet really more acid-forming than the typical Western diet? Inuit got most of their calories from fat (70-80% typically), which is pH neutral, correct?

Greg said...

I am really enjoying this series! One thing that puzzles me is how a diet could support bone development but not be protective against bone loss. Is it possible that Price's Inuit were fundamentally different than the ones found with low BMD?

Don said...

Stephan,

After I posted the last one, I got what you meant about the Inuit being more susceptible to diseases of civilization. However, right now I would consider some aging-related bone loss unavoidable, like skin thinning, etc., and Eskimos only showing an acceleration of the process. In other words, I know of no evidence that any individuals or groups make it to old age without some bone loss...the question to me is how to minimize it.

Aaron also brought up ketosis, which also increases metabolic acidity, and some researchers I have read also suggest that chronic ketosis played a role in Eskimo bone loss.

I agree that excess VT-A may have played a role, since, again, we have some contemporary evidence for this.

I think the Mazess study of Saldermiut bones lumped the ancient with the 19th century bones together (don't have it with me, will check later). However, I have another that separated them, which concluded that the pattern occured in precontact Eskimos as well -- will discuss in next post. I also have one that compared precontact Eskimo bones with extinct Pueblo and Arikara -- Pueblo had the least bone disorder, Eskimos the most, and Arikara intermediate.

Primitive Eskimo diet would be meat plus fat, no alkaline ash foods at all most of the time. Modern U.S. diet has less neutral fat and more alkaline vegetables and fruits, also white sugar is neutral and brown sugar basic (no figures on corn syrup). So between fats, sugar, and produce, I would guess that the U.S. diet is less acidic. I will see if I can create models and calculate, I could be wrong.

I plan to show that based on experimental data the acidity of the Eskimo diet would cause enough calicuria to more than account for their observed bone loss. We also have good evidence that ingestion of base-yielding stuff can stop calciuria. This effect has been pretty well studied so right now I have fair confidence in it. Still, always open to learn and change my view. Right now I find the metabolic acid hypothesis pretty strong. Have you read Anthony Sebastian's paper on the pathophysiological effects of the inversion of the evolutionary Na:K ratio?

Don said...

Greg,

Musculoskeletal development occurs under the influence of growth hormones. After the age of 25 or so, these decline and this leads to muscle and bone loss (absent intervention). Then the effects of diet and lifestyle accrue. Muscle and bone loss will go faster or slower depending on diet and exercise patterns.

So, I would suggest that in Eskimos prior to 25 years, the hormones counteracted the diet, allowing full development (acknowledged by all studies I have seen) ; then after 25 years, the effects of diet surfaced.

Stephan said...

Hi Don,

Thanks for your response. I'll look forward to your next post. I'm skeptical of the acid-base balance theory but I'll admit I'm not very familiar with the literature. I'll keep an open mind.

I haven't read Anthony Sebastian's papers on Na but they look interesting. I've been thinking about salt and mineral balance lately. High sodium chloride doesn't seem very paleo. Is there a particular paper you'd recommend?

PaleoDoc MD, PhD said...

Hi Don,

Have you considered physical acticity? It is a major factor promoting bone mineralisation. Perhaps younger Inuit did much more physical work, while the older ones were more sedentary? BTW, exercise generates metabolic acid, yet it stimulates bone growth.

Also, it would be interesting to look at their magnesium intake. Magnesium is quite interesting and it is possible that H-Gs in Paleolithic Europe were getting it primarily from invertebrates (snails?). Of course, magnesium in water would have played a role as well.

Don said...

Paleodoc,

Yes, I and authors of the papers I cite have considered physical activity. Since we are comparing Eskimos to whites, most investigators conclude that Eskimos have greater physical activity with aging since they still hunted and to a large extent follow their traditional activity pattern, at least to a much greater extent than whites. IN short, we assume that the U.S. whites in the 1970s, getting almost all or all of their foods from the grocery store, and driving automobiles rather than powering kayaks, etc., most likely exercised less intensely and less overall.

True that exercise generates acid, yet stimulates bone growth. But the acid generated by exercise is minor and intermittent compared to the acid generated by metabolism of acid-ash foods. Moreover, in Eskimos this would only add to the acid load since their diet contains almost no base-yielding foods, whereas the typical U.S citizen eats oranges, bananas, apples, tomatoes, potatoes, etc. regularly.

Also, since exercise stimulates osteoblast activity to lay down more bone mass, yet also generates acid, we're dealing with a stimulus that has a double action, where one aspect favors increase of bone mass while the other may cause a decline of bone mass, and if the exercise intensity is appropriate, the net effect may be increased mass. So we have to look at the net effect of a stimulus.

In an upcoming post I will discuss the experimental data showing we can stop calciuria in people with acidic urine by administering potassium bicarbonate.

Aaron said...

Don, my other question is how you are going to reconcile the fact that it seems like almost every carnivore and omnivore in nature seems to be slated to a heavy acid diet. And even though their diets are fat heavy -- they still usually consume protein in the 25-45% range <------ animals that is. Even with large amounts of bone in their diets -- that does not account for all the acid they would have to neutralize.

If you think about it -- the Eskimo diet is somewhat similar to bears who eat fish/foliage/and and little carbohydrate.

Are we to say that bears experience faster bone loss because of their diets?

I am suspect of these nutrients in the Eskimo diet.

1: pre-formed vitamin A -- because of our primate heritage.

2: large amount of omega 3 -- because of our sub-tropical/tropical heritage.

3: large amounts of protein -- because of our primate heritage (and look to the amount of protein in mother's milk!)

Protein also seems to cause a lot of cellular turnover in the bone -- whether or not this ages bone at the cellular level -- we just don't know yet.

Humans are still primarily plant/fruit/tuber eaters who benefit from some animal protein and fat.

No reason to stray too far from that.

Don said...

Aaron,

I have thought of this. Don't know about bears, but cats have different kidney function than humans, and can excrete a more acid urine, i.e. don't need to reduce acidity of urine by drawing on skeletal calcium. The loss of calcium sustained by humans on high protein/acid residue diets appears due to the fact that our kidneys can't excrete urine more acid than about 6.5 pH, so when urine is very acid they have to draw bases out of the blood to increase urinary pH, which in turn draws down the base content of the blood, which then, in absence of dietary base, draws down skeletal calcium.

PaleoDoc MD, PhD said...

This is not my area of expertise, but I am curiuos to learn as much as possible from you, Stephan et al.

One thing I am aware of is that BMD is not a perfect measure of bone strenght:

BMD measurement remains the most useful clinical tool for identifying patients with osteoporosis. Several organizations, such as the ACOG, ISCD, NOF, and the USPSTF, have published guidelines for BMD testing. Although they are useful in guiding decisions to initiate treatment, subsequent changes in BMD do not fully explain reductions in fracture risk.
http://www.medscape.com/viewarticle/503801_6

To me it sounds like total cholesterol as a predictor of heart disease. Maybe lower BMD in Inuit was never a problem. Perhaps the bone was simply used as a physiological buffer?

BTW, any evidence of gout in the Inuit?

Don said...

Paleodoc,

That is true, it is one of the unresolved issues. For example, Asians have lower BMD than Americans, but lower hip fracture rates. Resistance to fracture depends a lot on the shear strength of a bone, which depends more on the protein content. So it is possible that the lower BMD in Eskimos had no consequence.

However, Eskimos have a peculiar type of osteoporosis of the cortex of bone not found in two other non-industrialized groups, and it could be that the weak link between BMD and fracture risk reflects a failure to distinguish between cortical BMD and medullary BMD. That is, it could be that one or the other more disposes to fracture. Some evidence points to cortical mineral loss as having more hazard than medullary mineral loss.

Don said...

Oh, I don't recall any evidence of gout in Inuit. I think gout is more of a carbohydrate driven disease.

Don said...

REgarding my last comment on gout:

Beneficial effects of weight loss associated with moderate calorie/carbohydrate restriction, and increased proportional intake of protein and unsaturated fat on serum urate and lipoprotein levels in gout: a pilot study

http://ard.bmj.com/content/59/7/539.abstract

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Bruno Bear said...

What i find intresting. cause i found a text which showes mumified inuit or eskimo. with cancer and pinworms and dentalabscess. ITs somehow cause i know a WAPF chapter of my country who is convinced that Wston PRice is the only legal truth out there.

Whatever. Im more and more theopinion. That food isnt anything. And inuit crave CARBS and plant foods. I just saw it from a Fast food restaurant opening in NAnuvat or so. And people love it. 'There is greenhouses in the ARctic now. th first schawarma libanese fast food opend. people love to get accept to carbohydrate foods. And this cant be all the evil civilisation. Whe seeing that the healthiest tribe Abkhasia, Okinawa, Hunza, Vilca Bamba, livon a high carb rich diet its clear. people have a desire tzo live. And when you see the origin of human kind. itsin warm rgion. And beside animal food be it insect or small mamals. there was always plenty of plants. So what i find is human crave plant foods as soon as they get it. This is th reason why Native AMericans love their frybread cause its carbs. Maybe the fried fat remember it to fatty foods of old times. Also inuit another indegeous native tribe with high meat consumption. OR it depends on the area. Wil turtle wrote a article on this on a tribe live in area of newyork new jersey. Who had a lot plants to eat. and little corn grown. but mostly they ate wild foraged plants like acorn. And then also little meat. I find when seeing okinawa. MEat is only an adition to the diet. The main way is plant based. For Tooth decay. some say on a no carb diet oyu get no tooth decay. Also the argument on Ktosis gets in the space. Ketosis also happening on a vegetable juice fast or on a waterfast. Funnywise when my eyes wander to Stephans coment he has same linkin from inuit to caucasian people. Please excuss my spelling.

http://www.diseaseproof.com/archives/diet-myths-are-the-inuit-healthy.html
http://www.bluezones.com/live-longer/
sadly this article is a bit bias and offending. still the resources attached are scientific and written by scientists. THe article is written by a WAPF PALEO hater the resources by scientists.
http://www.scribd.com/doc/76406213/Inuit-Had-Cancer-on-Paleo-Diet-CONFIRMED-Diseases-Found-Rampant-in-Arctic-Greenland-Mummies-500-Years-Before-Western-Contact-WAPF-Crossfit-Tra

I wish to talk on this article. maybe on paleo hacks but there is so much limited discussion. more short questions.

@erikneves said...

Bone mineral density is not the whole story:
http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-0185(199612)246:4%3C423::AID-AR1%3E3.0.CO;2-W/full

Even if it where, there's an explanation for the difference between inuits and westerners:
http://www.sciencedirect.com/science/article/pii/S1094695006603363

Don said...

Erikneves,

Your first reference states: "In general, the various studies have revealed different degrees of low bone mass in past populations; however, the pattern of bone loss and fragility seen in age-related and postmenopausal osteoporosis today is not evident in the past. Bone loss in earlier populations is often found in both sexes, whereas significant bone loss in females occurs often among the young-age categories. In addition, a prevalence of osteoporotic fracture is absent."

Osteoporosis is an age-related disease. Archaeological remains do not provide enough data to conclude that age-related osteoporosis fractures was absent in ancient hunter-gatherers, because a) the fossil record does not preserve all bones of all individuals so as to have adequate population sample, and b) many of the remains found belong to people younger than 50 years; for example, in the HORUS study, of five Aleutian Unangan mummies, only one was aged 47-51, all others were younger, including a child aged 4-5 y, and the mean age was only 29 years old.

www.thelancet.com/journals/lancet/article/PIIS0140...X/abstract‎

You need a representative population sample to make conclusions about prevalence of osteoporosis-related fracture.

Second, this reference states that in the past, "Bone loss in earlier populations is often found in both sexes..significant bone loss in females occurs often among the young-age categories." Does this significant bone loss in both sexes and young females provide evidence that animal-based diets have neutral or positive effects on bone health?

Third, this reference appears to suggest that male bone loss is only common in past populations, but in fact it occurs in both sexes in the modern USA, and actually causes more mortality and morbidity in men than women. "Osteoporosis in men is an important public health problem, and its prevalence is increasing as the population ages.1 Although traditionally considered a women's health issue, osteoporosis-related mortality and morbidity rates are higher in men.1 The consequences of osteoporosis are underestimated, and the condition is often unrecognized and untreated in most men.2" http://www.aafp.org/afp/2010/0901/p503.html

The second study you cite doesn't even address progressive bone loss. When comparing two populations (Eskimos and Caucasians), both of whom have a high risk of osteoporosis, as in that study, it is to be expected that they have similar BMD relative to body mass.

A 2013 study reports that among Greenland Eskimos, "Frequency of fragility fractures increased with age (5.7% vs. 24.3% vs. 30.4%; p=0.02) and the risk of a fragility fracture increased with age (p=0.004; OR, 95% CI: 4.5, 1.6–12.2, reference: below 70 years), when adjusted for smoking, gender and falls. "

http://www.ncbi.nlm.nih.gov/pubmed/23326764

Archaeology is interesting but it can contribute little if anything to the study of nutrition and diet-health connections because its data set is riddled with preservational bias and does not provide detailed diet records. It is a red herring.