Zlati Meyer, and Maeve McDermott

USA TODAY

Emily Varnam wants to protect the environment and eschew big business, so she tries to buy local food, dresses in secondhand clothing and doesn't own a car.

The 27-year-old doula also chooses her feminine hygiene products based on her personal philosophies.

She no longer uses tampons and other products made by giant consumer products companies, opting instead for more natural, eco-friendly options made by women. Once a month, she turns to Thinx period underwear, a Lunette menstrual cup and homemade cloth sanitary pads.

"There are products made by people who menstruate for people who menstruate," Varnam said. "I struggled with capitalism and feminism. Capitalism is the language most people speak at this moment and feminism (isn't). We need to find a way that they can intersect. We need to be able to be feminists and succeed."

Feminine hygiene products represent a $5.9 billion industry in the United States and $35.4 billion one worldwide. That number is expected to top $40 billion around the world in the next three years, according to Global Industry Analysts.

Upstart companies, helmed by women and preaching a message of female empowerment, are breaking into the market still controlled largely by brands that have been household names for generations. Among the new niche producers besides Thinx and Lunette, are Lunapads, DivaCups, GladRags, Dear Kate and Flex, which sell menstrual cups, reusable period underwear, cloth pads. Some companies also peddle yoga pants, menstrual-cup cleanser, carrying cases for fresh and used pads, absorbent and waterproof blankets to protect linen and mattresses, dancewear and pad soaking containers.

The average woman has an estimated 500 menstrual cycles in her lifetime, so feminine hygiene product makers have an ever-replenishing customer base. Demands for these products are changing, as women seek not only more environmentally friendly options, but also ones that can accommodate an active lifestyle. Also encouraging the trend: The earlier onset of puberty, technology and fabric advancements and more advertising targeting teenagers and younger women as older brand-loyal women enter menopause.

“It’s been many years of consistently agitating women, attending conferences, advertising, and I definitely think the concept has caught on and a lot of women now know about it,” said Carinne Chambers, vice president and co-founder of DivaCup, who began developing menstrual products with her mother, Francine, over a decade ago. “But we’ve barely scratched the surface, and we’re working hard to try and get women to know that this concept exists, and get over the initial hesitation of trying it."

Similarly, Thinx founder and “she-EO” Miki Agrawal didn’t think sanitary cups were a modern-enough option for busy women like her: "There’s only been three major innovations in the entire 20th century: tampons, pads and menstrual cups. So there was this huge opportunity to disrupt the category that totally needed disrupting."

Are women being played by companies' 'feminist' campaigns?

Yes, there's sexism in tech. Women should go into it anyway.

Johns Hopkins just accepted its first black female neurosurgeon resident

While Thinx has attracted female customers with its eye-catching marketing campaigns and aggressively feminist messaging, Agrawal recently stepped down from her role as Thinx's CEO amid news reports about her poor leadership style and the company's volatile work environment.

Both Chambers and Agrawal credited social media for creating a more fertile space for women to discuss their menstrual health. To reach potential consumers, they identified the importance of strong, positive messaging in their respective ads.

"The average woman spends $150-$300 a year on feminine hygiene disposables, and one DivaCup retails for around $40, and women only need to replace that annually, so you do the math,” Chambers said. “It’s definitely cost-saving compared to the disposable products. The average woman menstruates for over 30 years of her life, so when you add that up, that’s a lot of cost savings, not to mention the amount of waste in landfills.”

The arithmetic is the same for Thinx, which costs $30 a pair on average and reduces worries about dry-cleaning costs and ruined sheets.

For Varnam, embracing the products she uses is all about giving women choices. Next up, she plans to try sea sponge tampons. She estimated she spent $50 to get started with the products she can reuse over and over versus $10 for a box of tampons every month and foresees a day when she makes her own homemade menstrual pads and hosts workshops to teach other women how to, too.

"I can’t imagine using tampons or something disposable now, because it's so expensive and so bad for the earth," Varnum explained, adding that she dilutes the menstrual blood she collects with water and uses it to water her plants, which she says helps them thrive and makes her feel more aligned with the earth. "Once I had this relationship with my blood where this isn’t gross, it makes me feel better and I’m allowed to be a woman."

One reason the feminine hygiene segment was ripe for innovation is the taboo nature of menstruation. But in recent years, marketers have successfully taken aim at other below-the-belt topics-- like incontinence with the Depends ad starring "Days of Our Lives" actress Lisa Rinna and erectile dysfunction with numerous drug companies' print and broadcast campaigns.

Recently, talk of menstruation has extended to the halls of state governments, as advocates have fought to end the so-called tampon tax. They want feminine hygiene products exempted from sales tax, because, like food and prescriptions, they're considered life essentials. Many states have carved out other sales-tax exceptions over the years, often based on local interests or aggressive lobbying.

Feminine hygiene products generate an estimated $120 million in sales tax nationally every year, according to Jennifer Weiss-Wolf, an advocate for menstrual policy and the author of the upcoming book “Periods Gone Public: Taking a Stand for Menstrual Equity.”

In 2015, 10 states didn't tax feminine hygiene products, but five of them have no sales tax at all, she added. In 2016, New York, Connecticut and Illinois also nixed their sales tax on tampons, sanitary napkins, menstrual cups and other products; California Gov. Jerry Brown vetoed a bill that would've ended that state's tax on menstrual products.

"The tampon tax was a way to introduce the thinking about the economics of menstruation into the political sphere," said Weiss-Wolf, who also called it "patently unfair."

Also gaining awareness is the "Free the Tampon" movement, which wants products women need for their periods available for free in restrooms managed by governments. Last year, for example, the New York City Council passed legislation which would offer them gratis in public schools, prisons and shelters

"You've never heard about any talk about the free toilet paper or government-funded toilet paper. The logic is it's a necessity for people whose bodies menstruate, like you have paper towel to dry your hands. We put this in the same category," said Weiss-Wolf. "We all benefit if everyone’s functioning optimally, at their best level. It's to all of our detriment if our fellow citizen is bleeding down their leg on the street next to us."

Follow USA TODAY reporter Zlati Meyer on Twitter: @ZlatiMeyer

Follow USA TODAY reporter Maeve McDermott on Twitter: @maeve_mcdermott