Why you should NEVER eat licorice if you're trying for a baby

Licorice wreaks havoc on women's fertility, a new study claims.

The sweet aniseed-based treat contains a compound called iso (or, isoliquiritigenin) that interferes with sex hormones in the ovaries, diminishing estrogen levels.

And new research shows the effects could even render a woman infertile.

In particular, expression of a gene for aromatase, an enzyme that converts testosterone to estrogen, dropped by 50 percent or more. 

The findings by the University of Illinois call into question the validity of marketing campaigns that urge women to drink licorice tea to combat estrogen deficiency during menopause. 

'In general, when you start to have lower hormone levels, you could start to have problems with reproduction,' co-lead author Professor Jodi Flaws said. 

'And because estrogen is also important for healthy brains, healthy bones, a healthy cardiovascular system, if the levels are depleted for too long, you could have problems with those systems.

'We haven't shown that to be the case. That's just a possibility.

'I would say, though, that a 50-plus percent drop in aromatase in humans would be a serious problem for fertility and for other things.' 

There are benefits to iso, Professor Flaws points out.

Previous studies have shown iso to be an effective way of preventing some cancers. 

However, those same properties are the ones that hamper ovary development. 

'This could lead to a good outcome in certain tissues, depending on dose and timing of exposure,' Professor Flaws said. 

'In the ovary, though, if you reduce aromatase, you're also reducing estrogen, so you could be interfering with fertility.'

The research is in its early stages; Professor Flaws and her fellow researcher Sharada Mahalingam are now doing more studies into how iso interacts with other organisms.

But they warn the preliminary findings should be cause for concern. 

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