1 00:00:01,920 --> 00:00:06,480 Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey 2 00:00:06,519 --> 00:00:09,400 Speaker 1: brain Stuff, Lauren vogel Bomb here with another classic episode 3 00:00:09,400 --> 00:00:13,360 Speaker 1: from our archives. Lots of athletic wear and outdoors gear 4 00:00:13,640 --> 00:00:16,200 Speaker 1: is labeled with claims that it will help wig away 5 00:00:16,280 --> 00:00:18,560 Speaker 1: sweat and keep you smelling as fresh as if you 6 00:00:18,640 --> 00:00:21,759 Speaker 1: just stepped out of the shower. In this episode, we 7 00:00:21,880 --> 00:00:25,120 Speaker 1: look at how those claims can possibly be true and 8 00:00:25,160 --> 00:00:30,440 Speaker 1: how they can sometimes fall through. Hey there, brain Stuff, 9 00:00:30,480 --> 00:00:33,320 Speaker 1: Lauren vogel bomb here. If you're preparing for a hike, 10 00:00:33,560 --> 00:00:36,760 Speaker 1: especially one that involves sleeping under the stars, every last 11 00:00:36,800 --> 00:00:39,840 Speaker 1: thing you pack should be questioned, will you need rain gear? 12 00:00:40,120 --> 00:00:43,479 Speaker 1: One walking sticker to which freeze dried snacks are actually 13 00:00:43,560 --> 00:00:48,239 Speaker 1: tasty enough to eat. One essential rule from experienced hikers 14 00:00:48,360 --> 00:00:52,000 Speaker 1: is no cotton clothing. Clothes made of cotton can act 15 00:00:52,040 --> 00:00:55,080 Speaker 1: as a sponge. The material soaks up sweat and holds 16 00:00:55,160 --> 00:00:58,360 Speaker 1: moisture next to the skin, which eliminates the insulating effect 17 00:00:58,360 --> 00:01:01,760 Speaker 1: of the cotton, causes skin ear tation and eventually leads 18 00:01:01,800 --> 00:01:05,520 Speaker 1: to copious amounts of body odor. A body odor isn't 19 00:01:05,520 --> 00:01:09,039 Speaker 1: a personal affront. Every adult whose body temperature becomes high 20 00:01:09,160 --> 00:01:11,960 Speaker 1: enough to cause certain glands to secrete fluid onto the 21 00:01:12,000 --> 00:01:14,600 Speaker 1: surface of the skin is at risk for emanating at 22 00:01:14,680 --> 00:01:18,160 Speaker 1: least a little bit, and it isn't without purpose. Sweat 23 00:01:18,160 --> 00:01:20,440 Speaker 1: produced by the acrine glands that cover most of the 24 00:01:20,480 --> 00:01:23,760 Speaker 1: body helps regulate body temperature, while the milki or fluid 25 00:01:23,800 --> 00:01:26,360 Speaker 1: released by the apocrine glands in the armpits and growing 26 00:01:26,440 --> 00:01:28,560 Speaker 1: area is a signal that the body is under stress. 27 00:01:29,520 --> 00:01:33,199 Speaker 1: Apocrene glands are primarily responsible for body odor, and although 28 00:01:33,240 --> 00:01:37,280 Speaker 1: acrine glands secrete primarily odorless sweat, the smell produced by 29 00:01:37,319 --> 00:01:41,640 Speaker 1: this sweat changes over time. Perspiration acts as a magnet 30 00:01:41,680 --> 00:01:44,640 Speaker 1: to bacteria on the skin, and these bacteria use it 31 00:01:44,680 --> 00:01:47,640 Speaker 1: as a fuel to multiply. When the growing numbers of 32 00:01:47,640 --> 00:01:51,880 Speaker 1: bacteria metabolize the sweat, they produce a smelly byproduct commonly 33 00:01:52,040 --> 00:01:55,800 Speaker 1: called body odor. Clearly, cotton isn't the right choice for 34 00:01:55,840 --> 00:01:57,920 Speaker 1: working up a sweat, since it can actually make body 35 00:01:57,920 --> 00:02:01,000 Speaker 1: odor worse. But what about other types of fabrics? Do 36 00:02:01,120 --> 00:02:04,440 Speaker 1: all fabrics increase a person's propensity to develop body odor. 37 00:02:05,120 --> 00:02:07,880 Speaker 1: The key to using clothing to prevent or lessen body 38 00:02:07,880 --> 00:02:11,320 Speaker 1: odor lies in the fabric's ability to release sweat quickly 39 00:02:11,639 --> 00:02:14,720 Speaker 1: before bacteria can begin to feast on it. There are 40 00:02:14,800 --> 00:02:18,240 Speaker 1: natural and manmade fabrics that expertly wick moisture away from 41 00:02:18,240 --> 00:02:20,520 Speaker 1: the skin and to the edge of the material, where 42 00:02:20,600 --> 00:02:23,960 Speaker 1: it can evaporate. Other fabrics, however, will trap moisture in 43 00:02:23,960 --> 00:02:26,919 Speaker 1: the fabric and on the skin and make body odor worse. 44 00:02:27,919 --> 00:02:31,760 Speaker 1: Fabric's ability to transmit and release moisture is known as breathability, 45 00:02:31,919 --> 00:02:35,560 Speaker 1: which is the common term for the moisture vapor transmission rate, 46 00:02:35,800 --> 00:02:38,720 Speaker 1: or m v TR. The m v TR is measured 47 00:02:38,720 --> 00:02:41,520 Speaker 1: by calculating how many grams of moisture move through a 48 00:02:41,520 --> 00:02:45,000 Speaker 1: square meter of fabric in twenty four hours. Generally, the 49 00:02:45,120 --> 00:02:47,679 Speaker 1: greater the m v t R, the less likely the 50 00:02:47,720 --> 00:02:52,160 Speaker 1: fabric is to absorb and retain odor causing moisture. You 51 00:02:52,200 --> 00:02:54,640 Speaker 1: may be thinking, great, now, all I have to do 52 00:02:54,760 --> 00:02:57,480 Speaker 1: is find clothing labeled breathable, and bo will be a 53 00:02:57,520 --> 00:03:01,040 Speaker 1: problem of the past. Not so fast. There's not an 54 00:03:01,040 --> 00:03:05,519 Speaker 1: industry standard regarding breathability. Nearly any label can carry the term, 55 00:03:05,800 --> 00:03:09,600 Speaker 1: usually preceded by words like ultra or extremely. This means 56 00:03:09,639 --> 00:03:12,760 Speaker 1: you'll need to arm yourself with information about specific fabrics, 57 00:03:12,880 --> 00:03:16,040 Speaker 1: rather than relying on label hype as a guide. Natural 58 00:03:16,080 --> 00:03:19,040 Speaker 1: fabrics created from the fibers of animals, bugs, or plants 59 00:03:19,200 --> 00:03:21,760 Speaker 1: are a good place to start. You'll want to steer 60 00:03:21,800 --> 00:03:24,520 Speaker 1: clear of one percent cotton fabrics because they take a 61 00:03:24,560 --> 00:03:27,080 Speaker 1: long time to dry and will allow body odor to 62 00:03:27,200 --> 00:03:31,080 Speaker 1: bloom in the meantime. This is largely because one cotton 63 00:03:31,120 --> 00:03:34,360 Speaker 1: fabrics are composed of fibers that swell with moisture and 64 00:03:34,400 --> 00:03:38,040 Speaker 1: thereby reduce the pores of the fabric. However, other natural 65 00:03:38,080 --> 00:03:41,800 Speaker 1: fabrics absorb and release sweat quickly, including hemp, a fabric 66 00:03:41,840 --> 00:03:44,800 Speaker 1: woven from these stem fibers of the Cannabis sativa plant, 67 00:03:45,040 --> 00:03:49,520 Speaker 1: and linen woven from flax stems. While it sounds counterintuitive 68 00:03:49,560 --> 00:03:52,280 Speaker 1: to wear wool to prevent body odor, this natural fiber 69 00:03:52,360 --> 00:03:54,960 Speaker 1: is an excellent choice. Wool can absorb up to thirty 70 00:03:54,960 --> 00:03:57,600 Speaker 1: six percent of its weight and moisture without feeling wet, 71 00:03:57,840 --> 00:04:01,160 Speaker 1: and will dry quickly. Will also pass minute amounts of 72 00:04:01,160 --> 00:04:03,640 Speaker 1: body heat as it absorbs moisture, so it will help 73 00:04:03,720 --> 00:04:07,600 Speaker 1: keep you cool. Plus, will is naturally antibacterial, which means 74 00:04:07,640 --> 00:04:09,840 Speaker 1: you can wear it, sweat in it, and keep wearing 75 00:04:09,880 --> 00:04:13,760 Speaker 1: it sometimes for consecutive days without reeking. When it comes 76 00:04:13,800 --> 00:04:16,719 Speaker 1: to making body odor worse, synthetic fabrics tend to trap 77 00:04:16,760 --> 00:04:19,840 Speaker 1: odors at a greater rate than natural fabrics. Although many 78 00:04:19,880 --> 00:04:22,520 Speaker 1: of these man made fabrics, like polyester, are quick to 79 00:04:22,600 --> 00:04:25,560 Speaker 1: wick moisture away from the skin and equally quick to dry, 80 00:04:25,960 --> 00:04:29,480 Speaker 1: their construction can up the stink quotient within the weave 81 00:04:29,560 --> 00:04:33,320 Speaker 1: of synthetic moisture. Waking fabrics are notches designed to pool 82 00:04:33,480 --> 00:04:36,120 Speaker 1: minute amounts of sweat as it transfers from the inner 83 00:04:36,200 --> 00:04:39,200 Speaker 1: layer to the outer layer of the fabric. The concept 84 00:04:39,240 --> 00:04:41,760 Speaker 1: is a good one, as the moisture will generally evaporate 85 00:04:41,800 --> 00:04:44,920 Speaker 1: once it reaches the fabrics outer layer. The problem is 86 00:04:45,000 --> 00:04:47,160 Speaker 1: that as sweat collects in the NOx and crannies of 87 00:04:47,200 --> 00:04:49,680 Speaker 1: the fabric on its way to freedom, it is devoured 88 00:04:49,680 --> 00:04:52,800 Speaker 1: by bacteria that have themselves made a home in those 89 00:04:52,839 --> 00:04:56,680 Speaker 1: same recesses. This traps body odor within the fabric. To 90 00:04:56,760 --> 00:04:59,360 Speaker 1: reduce rowdy odors, look for synthetic fabrics that have an 91 00:04:59,400 --> 00:05:03,000 Speaker 1: added a a microbial ingredient. For example, the addition of 92 00:05:03,080 --> 00:05:06,440 Speaker 1: silver to polyester or spandex fibers can help prevent body 93 00:05:06,440 --> 00:05:10,719 Speaker 1: odor from accumulating silver nano particles. That's particles so small 94 00:05:10,760 --> 00:05:13,080 Speaker 1: that eighty thousand of them could fit within the diameter 95 00:05:13,120 --> 00:05:16,640 Speaker 1: of a human hair can be integrated into synthetic fabric. 96 00:05:17,200 --> 00:05:19,799 Speaker 1: When they get wet, the silver nano particles release silver 97 00:05:19,920 --> 00:05:23,160 Speaker 1: ions that initially slow the growth of odor causing bacteria 98 00:05:23,440 --> 00:05:28,040 Speaker 1: and eventually kill them off altogether. Some fabrics are infused 99 00:05:28,040 --> 00:05:31,640 Speaker 1: with a different type of odor inhibiting agent, molecules of 100 00:05:31,800 --> 00:05:35,440 Speaker 1: volcanic ash. The ash molecules have a poor size that's 101 00:05:35,440 --> 00:05:38,120 Speaker 1: similar to that of an odor molecule. When the two meat, 102 00:05:38,200 --> 00:05:42,040 Speaker 1: the odor molecule is adsorbed and trapped within the ash molecule. 103 00:05:42,360 --> 00:05:45,599 Speaker 1: This prevents the odor molecule from releasing its characteristic smell 104 00:05:46,000 --> 00:05:49,120 Speaker 1: until the fabric is washed in warm water. To prevent 105 00:05:49,160 --> 00:05:51,560 Speaker 1: body odor, look for clothing made from fabrics that will 106 00:05:51,560 --> 00:05:54,039 Speaker 1: help keep you dry and have the added mite of 107 00:05:54,080 --> 00:06:06,159 Speaker 1: antimicrobial helpers, and don't forget the antiperspirant or deodorant. Today's 108 00:06:06,160 --> 00:06:08,159 Speaker 1: episode was written by Laurie L. Dove and produced by 109 00:06:08,160 --> 00:06:11,000 Speaker 1: Tristan McNeil and Tyler Clang. For more on this and 110 00:06:11,000 --> 00:06:13,919 Speaker 1: lots of other fresh topics, visit how stuff works dot com. 111 00:06:13,960 --> 00:06:16,280 Speaker 1: Brain Stuff is production of I Heart Radio. Or more 112 00:06:16,320 --> 00:06:19,680 Speaker 1: podcasts my heart Radio, visit the iHeart Radio app Apple podcasts, 113 00:06:19,760 --> 00:06:21,520 Speaker 1: or wherever you listen to your favorite shows.