The world's most expensive spice, Saffron, has been shown to help people suffering from depression when taken in combination with pharmaceutical antidepressants, a new Australian study revealed on Monday.

Often referred to as red gold, the fragrant seasoning grown mainly in Iran can sell for around $3,000 per kilo, making it more valuable than some precious metals, like silver.

"In our research, depressive symptoms decreased more in participants taking saffron compared with a placebo, with reductions of 41 and 21 percent, respectively on the clinician-rated scale," Murdoch University researcher Adrian Lopresti said.

"In addition, improvements occurred in sleep quality, initiative and motivation, and interest and pleasure in activities."

While scientists involved in the independent study, funded by saffron extract manufacturer Pharmactive Biotech, said simply adding more saffron to one's diet is unlikely to improve a person's mental health on its own, the findings may give doctors a wider range of treatment options.

"Saffron can be used at the outset in conjunction with antidepressants or it can be added to antidepressants if symptoms do not fully resolve," Lopresti said.

"Now, a new option is to take antidepressants and saffron together."

Despite the intriguing results however, researchers admitted more studies need to be done to fully corroborate the results.