Isobel Marshall was about to enter her final year of high school in suburban Adelaide when she and her best friend came up with an idea to tackle two taboos: menstrual stigma and period poverty.

After graduating, the pair took a gap year, turned to crowdfunding and developed a brand of ethically sourced organic pads and tampons, with profits going towards disadvantaged girls and women overseas.

"We had just been introduced to the realities of period poverty around the world — the different ways that women are disadvantaged because of their period," Ms Marshall told ABC Radio Adelaide.

"Girls [are] having to drop out of school as soon as they get their period because they can't access or afford the right products.

Ms Marshall, 22, was last night named the 2021 Young Australian of the Year in recognition of her work to fight period poverty abroad, and menstrual stigma at home.

"The natural biological function experienced by half the world's population is still a major reason for inequality," she said during her acceptance speech.

"Periods should not be a barrier to education. They should not cause shame, and menstrual products should be accessible and affordable. They are not a luxury or a choice."

It was during their school years that Ms Marshall and friend Eloise Hall first heard about the idea of a social enterprise, in which a business's profits go towards a public good.

"Eloise and I, we kind of married up those two ideas and thought, 'Wow, this is such an incredible opportunity to create our own brand of organic cotton pads and tampons and then sell them to the Australian market'," Ms Marshall said.

"We can commit our net profits to make sure these stats and figures decrease and address period poverty."

'Period poverty exists in Australia'

In 2017, Ms Marshall and Ms Hall started their not-for-profit enterprise TABOO, which soon won success in a start-up competition run by the City of Unley.

After working to create community support for their business, they crowdfunded $56,000 to launch a range of sanitary products in 2019.

"That's been so important," Ms Marshall said.

"We were aware that we needed to raise the funds to buy our product so we could sell it on and continue this sustainable social enterprise model."

TABOO's products are ethically sourced, made from cotton and manufactured using power from a Spanish hydroelectric plant.

The profits go to One Girls — a charity that provides education for girls and women in Sierra Leone and Uganda.

But Ms Marshall warned that period poverty is not something that only exists in underprivileged parts of the world.

"In Australia … period poverty does exist, whereby students don't have access to product, but it can also just look like having to miss a day off work because of your period," she said.

Among the many plaudits now coming Ms Marshall's way are words of high praise from South Australia's Premier.

Steven Marshall said while he was "no relation", Ms Marshall was "a true inspiration for our entire nation".

"I think all South Australians should feel immensely proud of what she has achieved," Mr Marshall said.

'We'll take every opportunity'

Ms Marshall said she now plans to discuss with Ms Hall how to leverage the platform she has as Young Australian of the Year.

"We'll be certainly creating some strategy and creating a bit of a vision for this year based on the incredible platform and a lot of other projects that we have in the works — and the amazing work the TABOO team is doing," Ms Marshall said.

Ms Marshall is studying to become a doctor at the University of Adelaide.

She is focusing on the health and education side of TABOO while Ms Hall focuses on developing the business.

"I can see myself going down the medicine route, in conjunction with TABOO," Ms Marshall said.

"I can certainly see myself in the women's health area. That's obviously been inspired by TABOO, and the passion we've built in that space.

"We'll take every opportunity that comes and see how it goes."