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Why you get BO is equal parts gross and fascinating

We spend money on products designed to prevent and mask the smell of it. We take showers in gross gym locker rooms and discreetly sniff our armpits when we’re out in public — all because we’re ashamed of it. But body odor is as natural as breathing, and believe it or not, our own BO is as original to us as our fingerprint.

Our bodies contain 50,000 sweat glands that are constantly working to help release toxins and body fluids. While a bit of body odor is to be expected given that kind of commitment from our bodies, how much do you actually know about why we stink after a workout and what factors contribute to giving us our particular eau de parfum?

Here are eight fascinating facts about body odor that will give you a new appreciation for it.

1. Your sweat isn’t actually smelly. The next time you want to blame your sweat for that less-than-pleasant scent emanating from your body, give it a break. Sweat without the influence of bacteria is odorless. “Body odor occurs because certain bacteria that normally reside on our skin produce certain products from skin gland secretions that are malodorous,” says Dr. Amesh Adalja at the Division of Infectious Diseases at the Department of Medicine University of Pittsburgh Medical Center and School of Medicine. “It is important to remember that the skin is a major immune system organ and the compounds that are produced by sweat glands, as well as the presence of ‘good bacteria’ that live on the skin, can help stop more nefarious bacteria from gaining a foothold.”

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2. Your scent is special and unique. It may take a canine’s nose to truly distinguish one person’s scent from another, but your BO is unlike the BO of your BFF. “Each person has a unique scent, and while most humans don’t use [that] sense anymore, animals (especially dogs) can identify people by the way they smell,” says Dr. Aaron Braun, the medical director at SignatureCare Emergency Center in Houston.

3. We choose partners based on their scent. Sure, at first we fall in love with their eyes and it’s important that our partners are good people with goals and positive intentions, but let’s be real for a minute. As animals, the way our partners smell has a lot to do with our attraction to them and whether we decide to stick it out in a long-term relationship. Scientists have even found that we prefer to choose mates with immune systems that are different from ours, which may stem from the evolutionary benefits of keeping our children healthy and protected from disease.

4. Vegetarians and meat eaters smell different. We’re not suggesting one is better than the other, but Braun says diet is definitely one of the biggest influences on body odor. “Diets that are filled with spices like curry or cumin can linger in the pores and influence the way you smell,” Braun says. “Red meat is another culprit. Red meat takes a long time to digest throughout the body, and actually rots throughout. This rot in your digestive tract affects perspiration and body odor.”

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5. Women love smelly men — OK, not exactly. But science has revealed that women can experience emotional and physiological changes after smelling a man’s scent. A male chemical called androstadienone can boost women’s moods and cortisol levels and can even regulate the menstrual cycle and stimulate hormones responsible for ovulation. So the next time you’ve had a crappy day, just take a sniff of your boyfriend after a workout session and — heaven.

6. Your cultural background can influence your BO. The number of hair follicles, which contain apocrine glands, you have helps determine your level of body odor. If you are Caucasian or African-American, you probably have more hair follicles than someone of Asian descent, which means you sweat more and, yes, may smell more, as well.

7. Women and men smell like onions and cheese, respectively. A study conducted by researchers at a Swiss company called Firmenich actually got 24 men and 25 women to either relax in a sauna or spend 15 minutes working out on an exercise bike. They then tested women’s armpit sweat and found it contained high levels of sulfur when compared to the men. When mixed with bacteria, this sulfur compound produced an onion smell. Men, on the other hand, have more of an odorless fatty acid that, when mixed with bacteria, creates a cheesy smell. If you’re on the fence about which is preferable, let’s clear that up right now — the answer is neither one.

8. Vaginal odor plays a big role in a woman’s scent. It makes sense that a woman’s vagina should influence her scent, given the huge starring role it plays in creating life and just being generally awesome at everything. But you may not be aware of how external (and internal) factors change the scent of the vagina.

“If a woman exercises a lot or wears tight-fitting clothes, her vagina may have a strong musky smell (due to the sweat glands surrounding the vagina),” says Astroglide TTC’s sexual health advisor Dr. Draion M. Burch. “Foods like pineapples can create a sweeter odor, while foods like asparagus may be off-putting. As semen smells like chlorine, the vagina can take on a ‘bleachy’ smell after having sex without a condom. A ‘yeasty’ scent — almost bready — can be indicative of a yeast infection, and yes, bacterial vaginosis does have a rancid tuna smell. During her period, a woman’s vagina may take on a strong blood scent.”

Onions, cheese, blood, bleach — is there anything more powerful than the human body responding to its environment with a vengeance?

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