And the research has been welcomed by Belgian company BioActor, licensees of the worldwide rights to INRA's patents on using olive polyphenols for osteoporosis prevention in food, supplements and herbal medicines.
Bone health is set to become a major segment of the supplements and functional foods market, as ageing populations and the additional strain from obesity swell the numbers affected by osteoporosis.
But while the World Health Organisation calls the condition its biggest global healthcare problem, the main natural product targeted at bone health – calcium supplements – is entering a mature category, and a report from Frost and Sullivan warns that the supplements are set to see ‘fierce cannibalisation' of sales from therapeutic drugs as consumers look for faster remedies.
At INRA (Institut National de la Recherche Agronomique), researchers led by Dr Veronique Coxam at the Clermont Ferrand unit, were inspired by epidemiological evidence showing that people who ate a traditional Mediterranean diet were less likely to have osteoporosis.
Their early work revealed that both oleuropein and hydroxytyrosol had an impact on inflammation in bones. These findings have since been confirmed in animal studies.
In the most recent studies, published on-line in the journal Clinical Nutrition (doi:10.1016/j.clnu.2006.03.009), Dr Coxam's team looked at the effects of different doses of oleuropein on the bone on inflammation-induced bone loss (osteopenia) in rats that had had their ovaries removed.
This animal model is designed to represent senile osteoporosis, or the bone-wasting condition that affects the elderly, as it combines both hormone deficiency with chronic inflammation.
The researchers divided 78 ovariectomised rats into five groups. 26 were fed a normal diet, while the 52 others were further divided into four groups to receive different doses of oleuropein supplements (2.5, 5, 10 and 15 milligrams per kilogram per day) for 100 days. Another 20 control rats were not ovariectomised, and were fed a normal diet.
Three weeks before the end of the trial, all of the oleuropein rats and 13 ovariectomised controls were given a sub-cutaneous injection of magnesium silicate (talc) to induce inflammation.
The researchers found that removal of the ovaries increased bone loss, and injection of talc enhanced this effect. However, the four doses of oleuropein reduced this bone loss and improved the concentration of inflammatory markers in the blood.
The animals did not fully recover all of their bone density compared to the non-ovariectomised controls. Removal of ovaries plus inflammation but no supplementation, led to an 18 per cent reduction in bone mineral density. Supplementation with oleuropein reduced this reduction to 10 per cent.
When the researchers compared the supplemented rats to the ovariectomised, unsupplemented animals (without inflammation), they found that bone loss was only 1.5 per cent, compared to ovariectomised, unsupplemented animals (with inflammation).
The protective effects of the olive leaf extract were not found to be dose-dependent.
These results appear to show that the polyphenol content of the olives act by reducing inflammation in the rats which worsen the bone loss. This is supported by the observation that fibrinogen concentrations, used as a marker for inflammation, were reduced in the oleuropein-supplemented groups.
“In this light, anti-oxidant and anti-inflammatory micro-nutrients such as polyphenols remain a source for putative new and innovative dietary health intervention in the nutritional prevention of osteoporosis,” concluded the researchers.
Oleuropein is currently used in dietary supplements marketed for their reported benefits for blood pressure and blood glucose levels. But the benefits of the polyphenol in bone health is only being commercialised by BioActor.
Hans van der Saag, the founder and CEO of BioActor, told NutraIngredients.com that their olive leaf extract, BonOlive, is available as a powder and can be used in supplements and some functional foods, depending on the food matrix (olive leaf extracts have an inherent bitter taste).
Van der Saag said that BioActor were continuing to work closely with Dr. Coxam in the drawing up of the study protocol for a human study, which, depending on finishing the protocol design, could be started before the end of the year.
The human trial will be performed in collaboration with a Japanese company, said van der Saag.
