Amped and a little intimidated, I peppered the manager of an outdoor gear store with questions. What kind of rain gear would I need? One walking stick or two? Which freeze-dried snacks were actually tasty enough to eat?
In a week I would be hitting the trail, sleeping under the stars and walking for the better part of two days. Everything I did to prepare seemed to come with a question, right down to which clothes to wear.
My fellow hikers, all of whom had years of experience sweating through backcountry, had one essential rule: no cotton. Clothing made of cotton acts as a sponge. The material soaks up sweat and holds moisture next to the skin, which eliminates the insulating effect of the cotton, causes skin irritation and eventually leads to copious amounts of body odor [source: Bothwell].
Body odor isn't a personal affront. Every adult whose body temperature becomes high enough to cause certain glands to secrete fluid onto the surface of the skin is at risk for emanating this particular smell. And it isn't without purpose: Sweat produced by the eccrine glands that cover most of the body helps regulate body temperature, while the milky fluid released by apocrine glands in the armpits and groin area is a signal that the body is under stress [source: Mayo Clinic].
Apocrine glands are primarily responsible for body odor, and although eccrine glands secrete primarily odorless sweat, the smell produced by this sweat changes over time. Perspiration acts as a magnet to the bacteria on the skin, and these bacteria use it as fuel to multiply. When the growing numbers of bacteria metabolize the sweat, they produce a smelly byproduct commonly called body odor [source: WebMD].
Clearly, cotton isn't the right choice for working up a sweat since it can actually make body odor worse. But what about other types of fabrics? Do all fabrics increase a person's propensity to develop body odor?
Natural Doesn't Mean Odor-Free
The key to using clothing to prevent or lessen body odor lies in the fabric's ability to release sweat quickly -- before bacteria can begin to feast on it. There are natural and man-made fabrics that expertly wick moisture away from the skin and to the edge of the material where it evaporates. Other fabrics, however, will trap moisture in the fabric and on the skin, and make body odor worse.
A fabric's ability to transmit and release moisture is known as breathability, which is the common term for the moisture vapor transmission rate (MVTR). The MVTR is measured by calculating how many grams of moisture move through a square meter of fabric in 24 hours. Generally, the greater the MVTR, the less likely the fabric will absorb and retain odor-causing moisture [source: Commercial Sewing].
You may be thinking, "Great! Now all I have to do is find clothing labeled 'breathable' and BO will be a problem of the past." Not so fast. There's not an industry standard regarding breathability. Nearly any label can carry the term, usually preceded by words like "ultra" or "extremely." This means you'll need to arm yourself with information about fabrics, rather than relying on label hype as a guide.
Natural fabrics -- created from the fibers of animals, bugs or plants -- are a good place to start. You'll want to steer clear of 100 percent cotton fabrics, because they take a long time to dry and will allow body odor to bloom in the meantime. This is largely because 100 percent cotton fabrics are composed of fibers that swell with moisture and thereby reduce the pores of the fabric [source: Das and Kothari].However, other natural fabrics absorb and release sweat quickly, including hemp, a fabric woven from the stem fibers of the Cannabis sativa plant, and linen, woven from flax stems [source: Shop Well With You].
While it sounds counterintuitive to wear wool to prevent body odor, this natural fiber is an excellent choice. Wool can absorb up to 36 percent of its weight in moisture (this includes sweat!) without feeling wet and will dry quickly. Wool also releases minute amounts of body heat as it absorbs moisture, so it will help keep you cool. Plus, wool is naturally antibacterial, which means you can wear it, sweat in it and keep wearing it (sometimes for consecutive days) without reeking of BO. Merino wool has very fine fibers which makes it an excellent fabric for base layers [source: REI].
The Stink About Synthetics
When it comes to making body odor worse, synthetic fabrics tend to trap odors at a greater rate than natural fabrics. Although many of these man-made fabrics, like polyester, are quick to wick moisture away from the skin and equally quick to dry, their construction can up the "stink" quotient.
Within the weave of synthetic, moisture-wicking fabrics are notches designed to pool minute amounts of sweat as it transfers from the inner layer to the outer layer of the fabric. The concept is a good one, as the moisture will generally evaporate once it reaches the fabric's outer layer. The problem is that as sweat collects in the nooks and crannies of the fabric on its way to freedom, it is devoured by bacteria that have made themselves at home in the same recesses. This traps body odor within the fabric.
To reduce rowdy odors, look for synthetic fabrics that have an added antimicrobial ingredient. For example, the addition of silver to polyester or spandex fibers can help prevent body odor from accumulating. Silver nanoparticles (particles so small that 80,000 of them could fit within the diameter of a human hair) are integrated into synthetic fabric. When they get wet, the silver nanoparticles release silver ions that initially slow the growth of odor-causing bacteria and, eventually, kill them off altogether [source: Siauw].
Some fabrics are infused with a different type of odor-inhibiting agent: molecules of volcanic ash. The ash molecules, known by the brand name Minerale, have a pore size that is similar to that of an odor molecule. When the two meet, the odor molecule is absorbed and trapped within the ash molecule. This prevents the odor molecule from releasing its characteristic smell -- until the fabric is washed in warm water [source: Beresini].
To prevent body odor, look for clothing made from fabrics that will help keep you dry and have the added might of antimicrobial helpers. And don't forget the antiperspirant.
Author's Note: Do certain fabrics make body odor worse?
Thinking a synthetic, wicking fabric was synonymous with odor control, I wore the same shirt on both days of my backpacking trip. I wore it the first day, hung it up to dry, then slipped it on the next morning -- only to discover it was not as fresh as I expected. Turns out, wicking and odor control are two very different qualities. And thanks to the research I did for this article, I'll be sure to wear a different shirt next time. I think we'll all be glad.
- Beresini, Erin. "Why do my technical workout clothes stink?" Aug. 27, 2012. (April 21, 2014) http://www.outsideonline.com/fitness/bodywork/fitness-coach/Why-do-my-technical-workout-clothes-stink-so-much.html
- Bothwell, Richard. "Cotton Kills." Outdoor Adventure Club. April 21, 2014. (April 21, 2014) http://www.outdooradventureclub.com/newsletter/cottonkills.htm
- Commercial Sewing. "Breathability Moisture Vapor Transfer 'Sweat-through Rate.'" Outer Armor Technical Bulletin. (April 23, 2014) http://commercialsewing.com/technicalbulletins/CS04-Moisture%20Vapor%20Transfer.pdf
- Das, Subhasis and Kothari, V.K. "Moisture Vapor Transmission Behavior of Cotton Fabrics." Indian Journal of Fibre and Textile Research. June 2012. (April 21, 2014) http://nopr.niscair.res.in/bitstream/123456789/14265/1/IJFTR%2037(2)%20151-156.pdf
- Mayo Clinic. "Sweating and Body Odor." (April 21, 2014) http://www.mayoclinic.org/diseases-conditions/sweating-and-body-odor/basics/causes/con-20014438
- Nicholson, Christie. "Women Smell Better Than Men." April 9, 2009. (April 21, 2014) http://www.scientificamerican.com/podcast/episode/women-smell-better-than-men-09-04-09/
- REI. "Rainwear: How It Works." (April 23, 2014) http://www.rei.com/learn/expert-advice/rainwear-how-it-works.html
- REI. "Underwear (Base Layer): How to Choose." (April 21, 2014) http://www.rei.com/learn/expert-advice/underwear.html
- Shop Well With You. "Fabric Guide." (April 21, 2014) http://www.shopwellwithyou.org/fabric-guide.cfm#f2
- Siauw, Winnie. "Silver Nanoparticles: A Valuable Weapon in Microbial Warfare." (April 21, 2014) http://illumin.usc.edu/printer/244/silver-nanoparticles-a-valuable-weapon-in-microbial-warfare/
- Skurka, Andrew. "Breathability: An Explanation of its Importance, Mechanisms and Limitations." May 1, 2012. (April 21, 2014) http://andrewskurka.com/2012/breathability-its-importance-mechanisms-and-limitations/
- Web MD. "Preventing Body Odor." (April 21, 2014) http://www.webmd.com/skin-problems-and-treatments/preventing-body-odor