IMHO, there is also a possibility that the reduction in bone resorption
markers can be accounted for myricetin or gamma-tocopherol in walnuts. The
study group ate 37 grams walnuts, 15 grams walnut oil and ~ 20 grams
flaxseed oil daily. Walnuts are an exceptionally high source of myricetin
and a good source of gamma-tocopherol.

The study is interesting, but needs to have more subjects and extend
over a longer time and actually measure changes in bone strength.

There is a reduction in saturated fat for omega 6 and omega 3 cases, so
the paper claims some benefit from that.

The omega 3 test has a very low omega 6/omega 3 ratio so it may be
difficult to achieve under normal diets and may be counter productive
in terms of cardiovascular disease.

The article mentions that previous studies used EPA and DHA from fish
oil. I found two studies. Are there any more?

Effect of fish oil on bone mineral density in aging C57BL/6 female mice.

Bhattacharya A, Rahman M, Sun D, Fernandes G.
J Nutr Biochem. 2006 Sep 7
Division of Clinical Immunology and Rheumatology, Department of
Medicine, University of Texas..

Life expectancy has increased considerably over the last century in the
United States. It is expected that this longevity will be accompanied by
an increase in the prevalence of osteoporosis and accompanying
complications in the elderly population. Age-related loss of bone mass
and bone fragility are major risk factors for osteoporosis, leading to
an increased risk of fractures. Therefore, nutritional strategies and
lifestyle changes that prevent age-related osteoporosis and improve the
quality of life for the elderly population are urgently needed. Hence,
the present study compared the effects of corn oil (CO; n-6 fatty acids;
commonly present in Western diets) and fish oil (FO; n-3 fatty acids) on
bone mineral density (BMD) in aging C57BL/6 female mice. After 6 months
of dietary treatment, we found that 18-month-old FO-fed mice maintained
higher BMD in different bone regions compared to CO-fed mice. These
findings were accompanied by a decreased activity of pro-inflammatory
cytokines, tumor necrosis factor-alpha and interleukin-6 in stimulated
splenocytes; a nonsignificant but greater increase in bone formation
markers alkaline phosphatase and osteocalcin in the serum; and lower
osteoclast generation in bone marrow cell cultures in FO-fed mice. In
conclusion, these findings suggest that providing n-3 fatty acids may
have a beneficial effect on bone mass during aging by modulating bone
formation and bone resorption factors.
http://pmid.us/16963250

Dietary n-3 fatty acids decrease osteoclastogenesis and loss of bone
mass in ovariectomized mice.

Sun D, Krishnan A, Zaman K, Lawrence R, Bhattacharya A, Fernandes G.
J Bone Miner Res. 2003 Jul;18(7):1206-16.
Department of Medicine, Division of Clinical Immunology, University of
Texas.

The mechanisms of action of dietary fish oil (FO) on osteoporosis are
not fully understood. This study showed FO decreased bone loss in
ovariectomized mice because of inhibition of osteoclastogenesis. This
finding supports a beneficial effect of FO on the attenuation of
osteoporosis. INTRODUCTION: Consumption of fish or n-3 fatty acids
protects against cardiovascular and autoimmune disorders. Beneficial
effects on bone mineral density have also been reported in rats and
humans, but the precise mechanisms involved have not been described.
METHODS: Sham and ovariectomized (OVX) mice were fed diets containing
either 5% corn oil (CO) or 5% fish oil (FO). Bone mineral density was
analyzed by DXA. The serum lipid profile was analyzed by gas
chromatography. Receptor activator of NF-kappaB ligand (RANKL)
expression and cytokine production in activated T-cells were analyzed by
flow cytometry and ELISA, respectively. Osteoclasts were generated by
culturing bone marrow (BM) cells with 1,25(OH)2D3. NF-kappaB activation
in BM macrophages was measured by an electrophoretic mobility shift
assay. RESULTS AND CONCLUSION: Plasma lipid C16:1n6, C20:5n3, and
C22:6n3 were significantly increased and C20:4n6 and C18:2n6 decreased
in FO-fed mice. Significantly increased bone mineral density loss (20%
in distal left femur and 22.6% in lumbar vertebrae) was observed in OVX
mice fed CO, whereas FO-fed mice showed only 10% and no change,
respectively. Bone mineral density loss was correlated with increased
RANKL expression in activated CD4+ T-cells from CO-fed OVX mice, but
there was no change in FO-fed mice. Selected n-3 fatty acids
(docosahexaenoic acid [DHA] and eicosapentaenoic acid [EPA]) added in
vitro caused a significant decrease in TRACP activity and TRACP+
multinuclear cell formation from BM cells compared with selected n-6
fatty acids (linoleic acid [LA] and arachidonic acid [AA]). DHA and EPA
also inhibited BM macrophage NF-kappaB activation induced by RANKL in
vitro. TNF-alpha, interleukin (IL)-2, and interferon (IFN)-gamma
concentrations from both sham and OVX FO-fed mice were decreased in the
culture medium of splenocytes, and interleukin-6 was decreased in
sham-operated FO-fed mice. In conclusion, inhibition of osteoclast
generation and activation may be one of the mechanisms by which dietary
n-3 fatty acids reduce bone loss in OVX mice.
http://pmid.us/12854830