Peptide in onion may prevent bone loss

Analysing the active chemical components of white onions, scientists at the University of Bern concluded the peptide compound GPCS present in onions appears to retard bone loss.

Their findings provide a further boost for food formulations looking to pierce the buoyant market for functional foods with a bone health hook; forecast to grow by 7.6 per cent annually, reaching £86.4 million in the UK alone in 2007, according to figures from Datamonitor.

The category is enjoying growth on the back of growing awareness of the bone-wasting disease osteoporosis, described by the World Health Organisation as the leading global healthcare problem after heart disease, and affecting 30 million people (predominantly women) worldwide.

For this latest study, researchers analysed the active chemical components of white onions and found that the most likely compound responsible for the decreased bone loss was a peptide called GPCS.

Peptides are the family of molecules formed from the linking, in a defined order, of various amino acids.

The researchers then obtained a group of isolated bone cells from newborn rats and exposed the cells to parathyroid hormone to stimulate bone loss, then exposed some of the treated cells to GPCS.

Treatment with GPCS "significantly inhibited the loss of bone minerals, including calcium, when compared to cells that were not exposed to GPCS,"​ report the researchers.

Human trials are now required to determine whether GPCS will have a similar effect in people, how much onion or GPCS is needed for a positive effect on bone health, and to determine the mechanism of action of GPCS on bone cells.

The Swiss study joins previous findings that have focused on the health benefits of onions. In October last year, for example, researchers in the US concluded that flavoured onions could be better cancer-fighting foods than their mild-flavoured cousins.

Onions contain the flavonoid quercetin and a raft of recent science has uncovered the role polyphenols, to which quercetin belongs, can play in preventing the onset of various diseases, notably certain cancers and cardiovascular disease, that annually kills 17 million people in the world.

Researchers at Cornell University found, in preliminary lab studies, that members of the onion family with the strongest flavour - particularly New York bold, western yellow and shallots - are the best varieties for inhibiting the growth of liver and colon cancer cells.

World onion production has increased by at least 25 per cent over the past 10 years with current production at around 44 million tonnes, making it the second most important horticultural crop after tomatoes, according to researchers at the department of plant genetics and biotechnology, Horticulture Research International in the UK.

Because of their storage characteristics and durability for shipping, onions have always been traded more widely than most vegetables. Onions are versatile and used as an ingredient in a wide range of dishes, accepted by almost all traditions and cultures.

Horticulture Research International claims that onion consumption is increasing significantly, particularly in the USA, on the back of heavy promotion that links the vegetable to flavour and health benefits.