7 Reasons American's are Ditching Polyester for Cotton in the name of Testosterone

Most underwear sold today is spun from polyester, nylon, or toxic plastic blends linked to plummeting testosterone levels in men over the last 30 years.

A man in a NADS branded hat and sleeveless shirt sits on the sand in front of a backdrop.

Dan B.

UPDATED 2 DAYS AGO

20%

Drop in average male testosterone levels over the last 20 years

23h

A day the average man wears underwear against the most absorbent skin on his body

Mainstream brands willing to talk about what their fabric may be doing

REASON #01

Your boxer briefs are spun from the same petroleum as a bike tire.

Polyester is petroleum. It comes off the same refinery line that makes tires, bottles, and bumpers. They melt it down, spin it into thread, and sell it to you as "performance fabric."

And that's sitting against THE MOST ABSORBENT skin on your body THE LONGEST of any other article of clothing per day.

Nope.

REASON #02

That petroleum carries chemicals linked to lower testosterone.

Phthalates. BPA. Forever chemicals. They're woven into plastic-based fabric, and studies have linked them to disrupted hormone signalling in men. The fabric you're sitting in all day can release them onto skin that's built to absorb.

Source: Environmental Health Perspectives; multiple peer-reviewed phthalate exposure studies.

REASON #03

Microplastics have been found inside human testicles.

A 2024 study confirmed it. The skin down there is some of the most absorbent on your body — and plastic-based fabric sheds particles every time you sweat, move, or wash it. Those particles are now turning up in the tissue responsible for producing testosterone.

Source: Hu et al., Toxicological Sciences (2024).

REASON #04

Polyester traps heat exactly where your body needs to stay cool.

Your testicles hang outside your body for a reason. They need to run a few degrees cooler than the rest of you to make testosterone and healthy sperm. Polyester wraps that area in a heat-and-moisture seal — the worst combination for the job.

A study of 656 men found that those wearing breathable, natural fabrics had up to 25% higher sperm count than men in tight plastic-based alternatives.

Source: Mínguez-Alarcón et al., Human Reproduction.

REASON #05

The hotter you get, the harder your skin pulls those chemicals in.

A close-up of a man's sweaty lower back and shirt in a workshop.

Sweat opens your pores. Sweat also acts like a solvent — it can pull chemicals off plastic-based fabric and drive them into the tissue underneath." Every workout, every summer day, every ten-hour shift turns your underwear into a chemistry experiment.

REASON #06

Men's testosterone has been crashing for forty years.

A line graph on paper showing a steep decline from 1980 to 2020, with men's briefs nearby.

It's dropped roughly 1% per year since the 1980s. Doctors can't explain it with age, weight, or exercise. One suspect researchers keep flagging: plastic-derived chemicals in the environment — and on your skin.

Source: Travison et al., Journal of Clinical Endocrinology & Metabolism (2007); follow-up studies in JCEM and PNAS.

REASON #07

The big underwear brands know. They just don't say anything.

Polyester costs pennies. Organic cotton — grown without pesticides, third-party audited — costs many times more. That's the only reason most underwear on shelves is plastic. The silence isn't an accident — you're cheaper to keep uninformed.

The Alternative

So what should you actually be wearing?

NADS briefs are built around an organic cotton liner — the layer that actually touches your skin. The outer is 95% organic cotton with 5% BPA-free elastane for stretch and fit. No polyester fabrics. No nylon.

Less chemical contact, where contact matters most

Organic cotton at the contact layer means fewer of the chemicals research has linked to hormone disruption sitting on your skin for 16 hours a day.

Sweat moves through cotton — not back at you

Organic cotton pulls moisture away from the skin and lets it evaporate. Plastic-based fabrics push it back at you and trap the heat.

No plastic at ball contact

The crotch liner is 100% organic cotton. There's no plastic on the highest-absorption skin on your body — meaning no microplastic shedding where wear time and absorption are highest.