I know that technically females don’t sweat; we glisten.  However, because we glisten just as much as the boys sweat, it’s probably a good idea to examine its role in our lives.  I always just assumed their aromatic differences between sweaty people were mostly a matter of hygiene.   As it turns out, how an individual smells is more malleable than I thought.  Deodorants, perfumes,and  hygiene all play a part, but what usually determines someone’s smell are genetics and diet.  To more fully understand we’ll take a look at a few different aspects of how we sweat.

What you sweat out: So, you have these two types of sweating glands: eccrine and apocrine.  Eccrine glands are found all over your body (legs, elbows, face, etc.), and they are used for cooling purposes. They emit sweat, which is simply a mixture of water and electrolytes (mostly sodium chloride, the reason sweat tastes salty.) Apocrine glands are found in axillary areas. We’re focused on the underarm region. They secrete an odorless, oily fluid that contains proteins, cholesterol, steroids, and various lipids.  Now, you also house microorganisms that live all over your body.  These helpful bacteria are different depending on what region of your skin they inhabit, and their prevalence and distribution is determined by genetics.  Those that are in your underarm area break down the fluid secreted from the apocrine glands.  Some of this breaking down causes body odor. All of this is unique to each individual; we don’t all sweat equally (1,2, 3). This is why some have a lesser smell than others.  A recent peer reviewed study found that “the number and the degree of the development of apocrine glands vary among ethnic groups as well as individuals; hence, the strength and type of body odor may differ by ethnic group.”

An annoying myth to debunk: You don’t sweat out toxins.  I’ll tell you two reasons why: 1. By definition, a toxin is “a colloidal proteinaceous poisonous substance that is a specific product of the metabolic activities of a living organism and is usually very unstable, notably toxic when introduced into the tissues, and typically capable of inducing antibody formation” (4).  In other words, venom, botox, poisonous shellfish, lysed byproducts of viruses or bacteria, or any other hazard produced by biological processes are toxins.  Someone somewhere got confused and started using “toxin” as a term to define anything that seemed harmful or toxic to the body.  That mistake caught on, but that usage of toxin has no real meaning(5). Most of those things people are referring to as toxins are broken down and excreted by means of the gut or the kidney.  They are not sweat out.  Neither are calories, while we’re on it. You don’t need to sit in the sauna for hours or wear one of those ridiculous looking sauna/solar suits.

Dietary effects: So here are the components of apocrine gland secretion that smell when they are broken down: steroids, volatile short chain fatty acids, long chain fatty acids, and sulfur containing molecules. Also, sugar is utilized in fermentation, and it could be a precursor to some of those smell causing fatty acids.  Though we can look at foods that contain these components, few studies have tested individual dietary components’ influences on axillary body odor and most results are somewhat vague.  For instance celery contains the steroid androsterone, the hormone thought to produce the most pungent aroma.  Beef, chicken, fish, dairy, wheat, cabbage, beets and beans are all sources of fatty acids, the molecules in axillary sweat that are broken down by bacteria and therefore causing odor. However, we don’t know how any of those foods are broken down once they enter the body or if those fatty acid molecules will break down to produce the same fatty acid molecules that are released in axillary sweat. Be on the lookout for new deodorant technology, as new research is getting specific results of which bacteria deodorants need to block.  There is still a lot to learn as far as effect, timing, and importance of diet on axillary body odor.

However, one specific 2006 study(6) tested the effect of meat on body odor at a more practical level.  The study grouped men into meat-eating and non meat-eating diets, gave them identical diets to follow (excepting meat), and attempted to control outside smell interferences like clothing and hygiene products. Then women smelled swabs taken from the subject’s underarms and rated them. The study found rather conclusively that while meat-eating men smelled more “masculine” (which they defined as stronger smelling), they also smelled less attractive to females. There are a lot of unfounded theories about what to eat to smell good or bad, but I haven’t heard of any others that are proven by science.

Attractive sweat: We’ve all heard of pheromones, the “olfactory-based, chemical messengers”(7), that are underlying pulls of attraction to or repulsion from people.  When women aren’t taking hormone replacement, they are attracted to men who smell most different from them.  This is nature’s safeguard towards genetic homeostasis. Also, several studies have shown that men and women are most attracted physically to the people they think smell the best. Men have been shown to think a woman is most attractive smelling around her most fertile times, too. So when you sweat naturally, you are unwittingly giving signals to everyone around you.  These little subliminal smells are very influential in forming opinions of people. This is one reason why it’s important to meet someone in person before falling for him.

The take away: The way you smell is important, and it is unique to you.  This fact is the basis for choosing deodorant, perfume, and body wash, which we’ll touch on later. You can change the way you smell when you sweat by steering away from red meat.  While sugary food, dairy, and other meat products are suspected culprits of malodour, there isn’t clear scientific evidence to support that theory.  Be confident that if you are eating a balanced, healthy diet and making basic hygiene efforts, you will smell fine.

Upcoming: Scent association and perfume hunting!

1. http://en.wikipedia.org/wiki/Sweat_gland

2. http://onlinelibrary.wiley.com/doi/10.1111/j.1468-2494.2011.00669.x/full

3. http://chemse.oxfordjournals.org/content/31/6/557.long

4. http://www.merriam-webster.com/medical/toxin

5. http://en.wikipedia.org/wiki/Toxin

6.http://chemse.oxfordjournals.org/content/31/8/747.full.pdf+html

7.http://www.amazon.com/See-What-Im-Saying-Extraordinary/dp/0393067602