Animal protein and osteoporosis myth

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This is a compilation of my past discussions (2007). Since this issue comes back so often, I decided to re-post it here, as the reference [or just to annoy] 8-:) . 

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Myth 1: "Populations which consume a very high amount of dairy get more hip fractures than those which don't."

and

Myth 2: "It isn't only the calcium that comes in which is important but the calcium which is leached out due to high animal protein diets.

I am sorry to disappoint the true believers, but it is just the opposite! People who avoid animal protein believing that they are saving their bones are in fact increasing the risk of osteoporosis.

The following study found that women who consumed the most animal protein (+43%) had only one-fifth risk of hip fractures:

"Prospective study of dietary protein intake and risk of hip fracture in postmenopausal women"
by Ronald G Munger, James R Cerhan, and Brian C-H Chiu Am J Clin Nutr 1999;69:147-52.

Results: Forty-four cases of incident hip fractures were included in the analyses of 104 338 person-years (the number of subjects studied times the number of years of follow-up) of follow-up data. The risk of hip fracture was not related to intake of calcium or vitamin D, but was negatively associated with total protein intake. Animal rather than vegetable sources of protein appeared to account for this association. In a multivariate model with inclusion of age, body size, parity, smoking, alcohol intake, estrogen use, and physical activity, the relative risks of hip fracture decreased across increasing quartiles of intake of animal protein as follows: 1.00 (reference), 0.59 (95% CI: 0.26, 1.34), 0.63 (0.28, 1.42), and 0.31 (0.10, 0.93); P for trend = 0.037.

Conclusion: Intake of dietary protein, especially from animal sources, may be associated with a reduced incidence of hip fractures in postmenopausal women.

Table 4 of the study shows some really interesting data on the risk of hip fractures (from 6-th column). Namely, in addition to much lower (factor of 0.31) risk for the 43% higher consumption of animal protein, they found 1.9 times HIGHER risk associated with the 31% higher consumption of VEGETABLE protein!

Carbohydrate consumption turned out to have been a much bigger factor, perhaps the biggest factor:

23% higher consumption of carbohydrates was associated with 3 times higher rate of fractures!

If we recalculate (normalize) those risk factors per 100% (i.e. per doubling) increase of the consumption of each: total protein, animal protein, veg protein and carbohydrates, then we obtain the following:

Hip fracture risk correlation:

• Total protein: - risk reduction 3.6 times
• Animal protein:- risk reduction 4.5 times
• Vegetable protein:- risk INCREASE 2.9 times
• Carbohydrate:- risk INCREASE 4.9 times

In addition, women who experienced hip fractures (as opposed to those who didn't) consumed less animal fat, less saturated fat, less alcohol, had lower body mass index, had fewer pregnancies, smoked less, consumed more calcium, more vegetable fat and more vit D.

Heretic

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REFERENCES

Papers:

"Controlled High Meat Diets Do Not Affect Calcium Retention or Indices of Bone Status in Healthy Postmenopausal Women"

"Protein intake: effects on bone mineral density and the rate of bone loss in elderly women"

"Effect of Dietary Protein on Bone Loss in Elderly Men and Women: The Framingham Osteoporosis Study"

"Factors associated with calcium absorption efficiency in pre- and perimenopausal women"

Quote: "Women in the lowest tertile of the ratio of dietary fat to fiber had 19% lower fractional calcium absorption values than did women in the highest tertile of ratio of dietary fat to fiber"

Articles:

"Protein Saves Bone in Elders"

"New Data on Dietary Protein and Bone"

------ More references, update 1-Aug-2001 ---------------------------------------

This is based on the most recent blog article by Denise Minger quoting various peer-reviewed publications using China Study data. This is a MUST READ!

Some of the papers were co-authored by the well known expert vegan scientist Dr. T.Colin Campbell but unlike in his popular book, those papers are based on individual rather than county-averaged data. They also state completely opposite conclusion regarding heart disease, cancer and bone health which is quite remarkable for a senior mainstream academic scientist! The same man but two opposite views! Now to the subject of osteoporosis, bone density, calcium and diet:


* Dietary calcium and bone density among middle-aged and elderly women in China" by Ji-Fan Hu, Xi-He Zhao, Jian-Bin Jia, Banoo Parpia, and T. Colin Campbell.

Quote:

However, decline in bone mass after menopause for women in county WA (higher dairy calcium) was at a somewhat slower rate than for women in the nonpastoral areas (without dairy calcium).
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Thus. differences in the rate of bone loss between these areas may be related to differences in dairy calcium intake, given that 34.6% ofealcium in county WA and none in the other nonpastoral areas was from milk. Indeed, dairy calcium was found to be more significantly correlated with bone mass than was nondairy calcium (Table 7), even though these analyses only included women with dairy food intake in counties YA and WA (n= 253). Nondairy calcium. in contrast, showed no association with bone variables after age and/or body weight were adjusted for (Table 7).

BMC and BMD at the distal and midradius were positively associated with consumption of milk (r = 0. 1 5-0.26, P [less than] 0.003) and with consumption of hard cheese and other dairy foods (r = 0.22-0.29, P [less than] 0.01) (data not shown). These results agree with those reported in other cross-sectional studies (35, 37). A similar association between daily milk intake and bone density was also reported by Yano et al (10) in Hawaiian Japanese males and females and by Shiehita (23) in 85 healthy Japanese males and females, whose calcium intakes were as low as in our study. Increasing calcium intake with calcium-rich foods (milk and cheese) was found to reduce bone loss in adolescent (34), osteoporotic (38), premenopausal (14), and lactating (39) women.

* Veganism and osteoporosis: A review of the current literature. "The findings gathered consistently support the hypothesis that vegans do have lower bone mineral density than their non-vegan counterparts."

* A Comparison of Bone Mass Measurements of Vegetarians and Omnivores. "In this review of 9 cross-sectional and 1 longitudinal study, little statistical significance between bone density and bone content was found between vegetarians and omnivores."

* Effect of vegetarian diets on bone mineral density: a Bayesian meta-analysis. "The results suggest that vegetarian diets, particularly vegan diets, are associated with lower BMD, but the magnitude of the association is clinically insignificant."

* Long-Term Vegetarian Diet and Bone Mineral Density in Postmenopausal Taiwanese Women. "Long-term practitioners of vegan vegetarian were found to be at a higher risk of exceeding lumbar spine fracture threshold … and of being classified as having osteopenia of the femoral neck."

The rest of Denise article quotes more papers co-authored by T.C.Campbell, that conclude a positive protective role of dairy, meat and fish rich diets against cancer, heart disease and other disease in China. Read it all!

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