X-Message-Number: 26296
Date: Tue, 7 Jun 2005 05:37:09 -0700 (PDT)
From: Doug Skrecky <>
Subject: healthy diet makes osteoporosis unlikely [continued]

Pediatrics. 2005 Mar;115(3):736-43.
Calcium, dairy products, and bone health in children and young adults:
a reevaluation of the evidence.
    OBJECTIVE: Numerous nutrition policy statements recommend the
consumption of 800 to 1500 mg of calcium largely from dairy products
for osteoporosis prevention; however, the findings of epidemiologic and
prospective studies have raised questions about the efficacy of the use
of dairy products for the promotion of bone health. The objective of this
study was to review existing literature on the effects of dairy products
and total dietary calcium on bone integrity in children and young adults
to assess whether evidence supports (1) current recommended calcium
intake levels and (2) the suggestion that dairy products are better for
promoting bone integrity than other calcium-containing food sources or
supplements. METHODS: A Medline (National Library of Medicine, Bethesda,
MD) search was conducted for studies published on the relationship
between milk, dairy products, or calcium intake and bone mineralization
or fracture risk in children and young adults (1-25 years). This search
yielded 58 studies: 22 cross-sectional studies; 13 retrospective studies;
10 longitudinal prospective studies; and 13 randomized, controlled trials.
RESULTS: Eleven of the studies did not control for weight, pubertal status,
and exercise and were excluded. Ten studies were randomized, controlled
trials of supplemental calcium, 9 of which showed modest positive benefits
on bone mineralization in children and adolescents. Of the remaining 37
studies of dairy or unsupplemented dietary calcium intake, 27 studies
found no relationship between dairy or dietary calcium intake and measures
of bone health. In the remaining 9 reports, the effects on bone health are
small and 3 were confounded by vitamin D intake from milk fortified with
vitamin D. Therefore, in clinical, longitudinal, retrospective, and
cross-sectional studies, neither increased consumption of dairy products,
specifically, nor total dietary calcium consumption has shown even a
modestly consistent benefit for child or young adult bone health.
CONCLUSION: Scant evidence supports nutrition guidelines focused
specifically on increasing milk or other dairy product intake for
promoting child and adolescent bone mineralization.

Am J Clin Nutr. 2001 Nov;74(5):571-3.
Fractures, calcium, and the modern diet.
    Although high calcium intakes have long been recommended to
prevent osteoporosis, there is little evidence that high calcium
intakes effectively prevent fractures. Osteoporotic fractures are,
like coronary artery disease, largely a disease of Western societies.
Recent evidence that the statins that block the mevalonate pathway,
lower serum cholesterol concentrations, and improve cardiovascular
disease risk also prevent fractures, together with the increasing
evidence that diets high in fruit and vegetables are beneficial in
preventing fractures, suggest common dietary etiologic factors.
Further research in this area should answer the long-standing
question: Why do populations who consume low-calcium diets have
fewer fractures than do Western societies who consume high-calcium
diets?

Am J Clin Nutr. 2003 Feb;77(2):504-11.
Calcium, vitamin D, milk consumption, and hip fractures: a
prospective study among postmenopausal women.
BACKGROUND: Short trials of calcium supplementation show that it
reduces loss of bone density in postmenopausal women; longer
observational studies do not generally find a lower risk of hip
fracture with higher-calcium diets. Fewer studies have focused on
vitamin D in preventing postmenopausal osteoporosis or fractures.
OBJECTIVE: We assessed relations between postmenopausal hip fracture
risk and calcium, vitamin D, and milk consumption. DESIGN: In an 18-y
prospective analysis in 72 337 postmenopausal women, dietary intake
and nutritional supplement use were assessed at baseline in 1980 and
updated several times during follow-up. We identified 603 incident hip
fractures resulting from low or moderate trauma. Relative risks (RRs)
from proportional hazards models were controlled for other dietary and
nondietary factors. RESULTS: Women consuming > or = 12.5 microg vitamin
D/d from food plus supplements had a 37% lower risk of hip fracture
(RR = 0.63; 95% CI: 0.42, 0.94) than did women consuming < 3.5 microg/d.
Total calcium intake was not associated with hip fracture risk
(RR = 0.96; 95% CI: 0.68, 1.34 for > or = 1200 compared with < 600 mg/d).
Milk consumption was also not associated with a lower risk of hip
fracture (P for trend = 0.21). CONCLUSIONS: An adequate vitamin D
intake is associated with a lower risk of osteoporotic hip fractures in
postmenopausal women. Neither milk nor a high-calcium diet appears to
reduce risk. Because women commonly consume less than the recommended
intake of vitamin D, supplement use or dark fish consumption may be
prudent.

J Clin Endocrinol Metab. 2002 Apr;87(4):1527-32
Flaxseed improves lipid profile without altering biomarkers of
bone metabolism in postmenopausal women.
    The risk of cardiovascular disease and osteoporosis drastically
increases at the onset of menopause. Phytoestrogens have been
suggested to inhibit bone loss and protect the cardiovascular
system, in part by improving lipid profiles. The purpose of the
present study was to examine the effects of flaxseed, a rich source
of the phytoestrogens called lignans, on lipid metabolism and
biomarkers of bone turnover in postmenopausal women. Postmenopausal
women who were not on hormone replacement therapy were assigned to
one of two treatment groups in a double-blind randomized study.
Women were asked to consume 40 g of either ground flaxseed or
wheat-based comparative control regimen daily for 3 months. In
addition, all subjects received 1,000 mg calcium and 400 IU
vitamin D daily. Flaxseed supplementation lowered (P < 0.05) both
serum total cholesterol and non-high-density lipoprotein cholesterol
by 6%, whereas the comparative control regimen had no such effect.
Flaxseed regimen reduced serum levels of both low-density- and
high-density-lipoprotein cholesterol by 4.7% and triglyceride by
12.8%, albeit not statistically significant. Serum apolipoprotein
A-1 and apolipoprotein B concentrations were significantly
(P < 0.005) reduced by 6 and 7.5%, respectively, by the flaxseed
regimen. Markers of bone formation and resorption were not affected
by either of the treatments. The findings of this study indicate
that flaxseed supplementation improves lipid profiles but has no
effect on biomarkers of bone metabolism in postmenopausal women.

J Bone Miner Res. 2002 Apr;17(4):709-15
Can vitamin D supplementation reduce the risk of fracture in the
elderly? A randomized controlled trial.
    Randomized controlled trials have shown that a combination of
vitamin D and calcium can prevent fragility fractures in the elderly.
Whether this effect is attributed to the combination of vitamin D
and calcium or to one of these nutrients alone is not known. We
studied if an intervention with 10 microg of vitamin D3 per day
could prevent hip fracture and other osteoporotic fractures in a
double-blinded randomized controlled trial. Residents from 51
nursing homes were allocated randomly to receive 5 ml of ordinary
cod liver oil (n = 569) or 5 ml of cod liver oil where vitamin D
was removed (n = 575). During the study period of 2 years, fractures
and deaths were registered, and the principal analysis was performed
on the intention-to-treat basis. Biochemical markers were measured
at baseline and after 1 year in a subsample. Forty-seven persons in
the control group and 50 persons in the vitamin D group suffered a
hip fracture. The corresponding figures for all nonvertebral
fractures were 76 persons (control group) and 69 persons (vitamin
D group). There was no difference in the incidence of hip fracture
(p = 0.66, log-rank test), or in the incidence of all nonvertebral
fractures (p = 0.60, log-rank test) in the vitamin D group compared
with the control group. Compared with the control group, persons in
the vitamin D group increased their serum 25-hydroxyvitamin D
concentration with 22 nmol/liter (p = 0.001). In conclusion, we
found that an intervention with 10 microg of vitamin D3 alone
produced no fracture-preventing effect in a nursing home population
of frail elderly people.

Am J Epidemiol. 1996 Mar 1;143(5):472-9.
Protein consumption and bone fractures in women.
Dietary protein increases urinary calcium losses and has been
associated with higher rates of hip fracture in cross-cultural
studies. However, the relation between protein and risk of
osteoporotic bone fractures among individuals has not been examined
in detail. In this prospective study, usual dietary intake was
measured in 1980 in a cohort of 85,900 women, aged 35-59 years, who
were participants in the Nurses' Health Study. A mailed food
frequency questionnaire was used and incident hip (n = 234) and
distal forearm (n = 1,628) fractures were identified by self-report
during the following 12 years. Information on other factors related
to osteoporosis, including obesity, use of postmenopausal estrogen,
smoking, and physical activity, was collected on biennial
questionnaires. Dietary measures were updated in 1984 and 1986.
Protein was associated with an increased risk of forearm fracture
(relative risk (RR) = 1.22, 95% confidence interval (Cl) 1.04-1.43, p
for trend = 0.01) for women who consumed more than 95 g per day
compared with those who consumed less than 68 g per day. A similar
increase in risk was observed for animal protein, but no association
was found for consumption of vegetable protein. Women who consumed
five or more servings of red meat per week also had a significantly
increased risk of forearm fracture (RR = 1.23, 95% Cl 1.01-1.50)
compared with women who ate red meat less than once per week. Recall
of teenage diet did not reveal any increased risk of forearm fracture
for women with higher consumption of animal protein or red meat during
this earlier period of life. No association was observed between adult
protein intake and the incidence of hip fractures, though power to
assess this association was low.

Osteoporos Int. 2005 May 11; [Epub ahead of print]
Short-term effects on bone turnover of replacing milk with cola
beverages: a 10-day interventional study in young men.
In the Western world, increased consumption of carbonated soft drinks
combined with a decreasing intake of milk may increase the risk of
osteoporosis. This study was designed to reflect the trend of
replacing milk with carbonated beverages in a group of young men on a
low-calcium diet and studies the effects of this replacement on
calcium homeostasis and bone turnover. This controlled crossover
intervention study included 11 healthy men (22-29 years) who were
given a low-calcium basic diet in two 10-day intervention periods with
an intervening 10-day washout. During one period, they drank 2.5 l of
Coca Cola per day and during the other period 2.5 l of semi-skimmed
milk. Serum concentrations of calcium, phosphate,
25-hydroxycholecalciferol, 1,25-dihydroxycholecalciferol (1,25(OH)(2)D),
osteocalcin, bone-specific alkaline phosphatase (B-ALP) and cross-linked
C-telopeptides (CTX), plasma intact parathyroid hormone (PTH) and
urinary cross-linked N-telopeptides (NTX) were determined at baseline
and endpoint of each intervention period. An increase in serum phosphate
(P<0.001), 1,25(OH)(2)D (P<0.001), PTH (P=0.046) and osteocalcin
(P<0.001) was observed in the cola period compared to the milk period.
Also, bone resorption was significantly increased following the cola
period, seen as increased serum CTX (P<0.001) and urinary NTX (P<0.001)
compared to the milk period. No changes were observed in serum
concentrations of calcium or B-ALP. This study demonstrates that over
a 10-day period high intake of cola with a low-calcium diet induces
increased bone turnover compared to a high intake of milk with a
low-calcium diet. Thus, the trend towards a replacement of milk with
cola and other soft drinks, which results in a low calcium intake, may
negatively affect bone health as indicated by this short-term study.

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