Why choose a cotton yoga mat: fertility and health, what the studies actually say
Yoga is a precious practice for body and mind. And as with any object you spend time in contact with, it is reasonable to wonder what the mat you practise on is made of.
This question comes up often with our customers, and it is usually asked from the angle of health. We are going to answer it — but not in the way you might expect.
What the research says about flame retardants
Some household furnishing materials contain organophosphate flame retardants, known by the abbreviation PFRs. They are found in upholstery foams, in furniture, in car seats, and in certain sports items.
A study published in 2017 in Environmental Health Perspectives, carried out among 211 women undergoing in vitro fertilisation, observed that those with the highest urinary concentrations of DPHP and ip-PPP had embryo implantation rates 31% lower and clinical pregnancy rates 41% lower than those whose levels were the lowest.
These findings are serious and deserve to be known. But what they do not establish has to be said too, and just as plainly.
This study did not measure exposure from any particular product. It measured metabolites in urine, without identifying where they came from. No yoga mat was analysed. It looked at a specific population, women undergoing IVF, and observed associations — not causal links. And another paper in the same journal points out that PFRs are so widely present in indoor air that removing a single source would probably make little difference to a person's total exposure.
Our position, and why it is modest
Should you choose cotton for health reasons? Honestly, we do not know, and nobody knows. The literature linking phthalates to fertility exists, but it is a literature of epidemiological associations: it does not establish causation, it identifies no specific source of exposure, and no study has ever looked at yoga mats. Nor is it the case the other way round: nobody has shown that a synthetic mat is harmless. We will not build a sales argument on an uncertainty. What we can say is more modest, and verifiable: you know what is in a cotton mat, and you almost never know what is in the others.
What can be said about a cotton mat
Without any health promise, there are still concrete things to say.
Its components can be named. A MAHOLA mat is GOTS-certified organic cotton — warp thread, weft thread and sewing thread — dyed with plants, fixed using the traditional Indian process, plus a thin layer of natural latex on the back, which accounts for less than 1% of the mass and serves only to stop the mat from slipping. The list fits in three lines. For most mats on the market, it does not exist: the tests carried out in 2019 by the Ecology Center on eleven mats showed that three were made of PVC and that only one said so, and that none of the eleven listed the additives in its polymer.
It washes, and it ages. Cotton can be machine washed, which is not the case with a foam mat. Plant colours shift with time and light: this is not a manufacturing defect, it is how the material behaves, and it is better to know beforehand.
It works with moisture. A woven cotton mat does not grip when dry the way rubber does. That is a choice about how you practise, not a technical superiority.
Its end of life is simpler. A cellulosic fibre and a synthetic polymer do not break down in the same way. This is a difference in kind, not an overall environmental ranking — that would also depend on how the fibre is grown, on transport and on active life.
The criterion that weighs most
If we had to keep just one piece of advice, it would not be that one.
The best-documented factor in a textile's impact is not its material, it is its active life. The British organisation WRAP established in 2012 that extending the active life of a garment by nine months reduces its carbon, water and waste footprints by 20 to 30% each. No life cycle assessment has ever been published on a yoga mat, so no ranking between materials is established. But the principle, carried over from textiles, holds: an object kept for a long time most often beats a better-designed object replaced quickly.
Choose a mat you will keep. It is the only lever that is entirely in your hands.
Going further
We have published a full investigation into what yoga mats are really made of, the market's misleading labels, the applicable European regulations and the end of life of the different materials — including what we cannot prove about our own: What your mat doesn't tell you.
And if you are simply looking for the mat that suits you, our buying guide will help you choose the thickness and texture to match your practice.
