New Zealand is a rich source of food components that may have bioactivity on
bone. Docosahexaenoic acid (DHA) from fish oil has been shown to maintain
bone in ovariectomised (OVX) rats. Kiwifruit, a source of fibre and carotenoids may also affect bone via a prebiotic as well as direct cell based mechanisms.
We aimed to 1) ascertain the effects of DHA on two cell models, including
interactions with soy isoflavones; 2) and investigate the specific effects of
carotenoids from kiwifruit as well as whole kiwifruit in cell based and rodent
models as well as in a human study. RAW 264.7 mouse monocytes or mouse
bone marrow were used to generate osteoclasts (OC). Cells were exposed to
the agents between 5 and 21 days and formation and activity of OC measured,
including molecular markers. DHA inhibited OC formation in both cell models, including expression of cathepsin K, NFATc1 as well as actin ring formation.
Combination with isoflavones enhanced these effects. In OVX rats and mice fed
with kiwifruit for 8 weeks, green kiwifruit reduced rate of bone loss after OVX,
and in mice it reduced C-telopeptide of Type 1 collagen (CTX) levels and
RANKL expression while in menopausal women, green kiwifruit affected blood
lipids and bone markers positively.