Life
by AZ on November 22, 2010

Our Interview with Dr. Avery is below. 

BB: In layman's science, what is body odor and how's it caused?

Dr. Gilbert: It all starts with sweat, which is a fluid that's kind of like a rich broth of salts, minerals, lipids, and oils and is a naturally secreted product by the sweat glands. It’s pretty much an innocuous fluid when you first sweat. What happens after is, the bacteria that naturally inhabits the armpit feeds on that broth of sweat. And in doing so they take these large molecules of sweat that are odorless and basically chomp them to pieces. And the little scrapes of the molecules that they leave behind are what stick and are quite stinky. That’s the ‘action.’ Scientifically, its all relatively new. I mean, it was only in the 50's, the early 50's that we had good experiments on this. A guy named Walter Shelly worked for the government at Fort Knox and figured that out. Now in recent years, we found out more about the exact kind of bacteria, people have done the whole genotype of these bacteria, we've found out which enzymes they use to chop up, which kind of big molecule and the little stinky molecules and so on. So that's the ‘reaction.’ You know, so it also sets up what you can do about it and how you can control it.

BB: Interesting. So before this science, were people even managing body odor going back into the early 20th century?

Dr. Gilbert: That's a good question. I think it's varied over history. You had the Greeks and Romans in classical societies, who were big bathers, the hot baths, the Baths of Caracalla in Rome and Greece. They did a lot of plumbing and heating. So you had hot tubs you had cold baths or public baths. They were very big on washing and keeping clean. The Middle Ages in Europe turned into a different story. There was not a lot of bathing going on or cleaning of clothing in a cold climate. You'd get an acc*mulation of these stinky materials on the fabric of your shirt, which you were sleeping in, wearing around a lot. So those were probably pretty stinky times. Nowadays, with indoor pluming, we've gone back to the Greek or Roman ideal.

BB: Very cool. So you mentioned you have three myths about body odor that you’re going to dispel. The first one is that everybody thinks that sweat is the real cause of body odor, and you've kind of answered this question already, so it’s not the sweat, but the bacteria that causes body odor, right?

Dr. Gilber: Yes, it’s the bacteria and it also brings another factor into the equation. Say for instance, when you’re working out, you've just finished at the gym, and you’ve showered fairly recently. If you work up a big sweat you aren’t that stinky – you don't disgust yourself or everybody around you, but if you don't do anything and then a couple of hours later it builds. That's when the bacteria have the time to start doing that digestive thing and really pump out the stinky stuff.

BB: And then the second myth is that antiperspirants are the solution and antiperspirants alone.

Dr. Gilbert: Yeah, not just alone. It’s one step. That’s what the Gillette Odor Shield technology has going for it. It’s big on antiperspirancy. So the first thing you would do is you cut down the amount of broth, the amount of food that's available for the bacteria, which then produces less of a stinky substance. There are also other measures you can take. You can cut down on the amount of surface area that the bacteria can live in. Trimming or shaving body hair reduces the number of bacteria that are at work. Odor Shield technology also has a fragrance that's associated with it to signal that its working, to counteract some of the bad smell, it can block some of the mal odor that's right there. It also has a time-release fragrance and the smell releases over time. So it tracks the problem as it evolves and pounds it down.

BB: Interesting. Is there any particular fragrance or smell that works better against body odor or is it pretty much anything that has a nice scent to it?

Dr. Gilbert: My experience in the fragrance business, I’ve been on both sides, basic research and human odor perception and I've done applied work for perfume companies and personal care companies. I've answered just that kind of question: What's the best kind of scent? Perfumers would give you a list of ingredients that work best. You need something that's got a little bit of a kick to it and can stand up to the mal odors. We know the target molecules very well now. We know exactly what they are so you can do tests where you can see which one stands up best and knocks it down. That's what’s been done here. You can't just throw any nice smell at random against it and hope that it works. There's a lot of testing that goes through this.

BB: The final myth is that the only difference between body odor of men and women is that men have more of it? That's not the case so what is that difference?

Dr. Gilbert: The difference is actually subtler than that. It turns out to be a difference in the quality of the odor, the odor character. And this is pretty new research that just happened in the last few years. Scientists are looking at the odorless molecules in the sweat that get broken up to make the sweaty ones. As it turns out, there's a couple different kinds, there's one three hydroxy methylhexanoic acid. If you smell the pure form of this it smells like you shoved your nose into a really ripe sweaty shirt that's been three days in the laundry hamper. It’s just amazing. It’s like being in somebody's armpit. This is a specifically male kind of smell. Men produce more of this than women do and the result is you get this kind of cheesy, almost rancid note. Women on the other hand have a different molecule, a more common molecule, and when it gets broken down you get something totally different. Its called pre methylsulphonyl hexonoic, which sounds similar, but its a totally different molecule. It has a totally different spin on it. When you smell this one it’s got a kind of onion-y, tropical fruit smell. On average, women smell more of that style and guys smell more of the cheesy rancid type. So it’s a different problem to be tackled.

BB: So either way, there's rancidness. How do you effectively manage that body odor?

Dr. Gilbert: So, besides washing and applying the product, Odor Shield measures that it gives 16 hours of protection and the smell counteracts it right there. You can also watch diet. There's a Czech study right now showing that people who eat a lot of meat have a distinctive body smell. Something about the diet component of that might leak out and might be an issue. What interests me in this whole question, is the whole social consequence of BO. There was a study on Zoosk recently about pet peeves on first dates and 45% of women said that their date smelled bad somehow. So you know, it’s right up there. There's a distinction between guy's natural body smell, between you, your genetics, your diet, whatever, and people can find that attractive or not. Women definitely use body odor as a cue when looking at a guy and sizing him up. It’s sort of mate selection signal. I'm in this weird business where I can tell people I study smell and they tell me all these personal stories… all these women say oh my husband or my boyfriend, his natural body odor smells so good or his cologne smelled so good. They were just hooked by the nose right away. It’s a very common story.

BB: Pheromones, right?

Dr. GIlbert: Yeah, that kind of stuff and the individual scent that everybody has. When you let these two common molecules go run wild, that's not your individuality that's just bad hygiene. That's just a negative signal. And right there, you're losing the game.

BB: Moving beyond the armpit, do different body parts require different management? People have their feet; people have their hair; people just smell bad in other places.

Dr. Gilbert: Yeah, feet and scalp have different strains of bacteria than the armpit. So with stinky feet, you get a butyric acid smell, the same as a smelly sneaker smell. There's a lot of individual variation. Some people have grotesquely smelly feet and other people, not particularly. The bacteria that inhabit the feet and also the scalp are different species of bacteria so you wouldn't be rubbing any antiperspirant on your head. Not a useful way to go.

BB: So when looking at the Odor Shield line, is the body wash enough for the feet? Or are there other measures that need to be taken?

Dr. Gilbert: So what's effective there is the the body wash itself. Because you’re pretty much rinsing off the colonizing bacteria that time and it takes them a long time to rebuild. If you have stinky feet you need to change your socks more too.

BB: Obviously what drives every guy at the end of the day is going to be female attraction. What are the basic steps that guys should take to make sure they're not turning girls off through smell?

Dr. Gilbert: You don't want to let that three hydroxy methylhexanoic acid build up to noticeable levels — that's your killer right there. That's the index molecule that will turn your date off, that will knock your chances down exponentially – it’s that rancid armpit smell. So, basically, use the product. By doing so, you minimize that smell and then you’re free to be you. You can layer on top of that whatever cologne, pheromone that makes you like or let your own body scent do the speaking for you. That's probably your best bet.

BB: Awesome, any other cool facts you can leave us with? 

Dr. Gilbert: Some recent studies in Germany show that people can detect another person’s state of mind, state of emotion, from their body odor. So if you’re stressed out, like from an academic test versus just working out from a treadmill, you produce different reactions in the brain. So you’re signaling all the time with your body odor, which can be an issue. What women are looking for, not looking for, you are all the time signaling with your body odor, whether you like it or not. It really merits paying attention to and tuning into that channel as much as you can.