Scent of tomorrow


Scientists are going to unusual lengths to discover how your sense of smell influences the way you feel, eat, sleep, interact and reproduce.

When it comes to ranking the senses, smell is the perpetual also-ran to sight, hearing, taste and touch. Yet smell is our most primal sense, and one that holds sway over many aspects of daily life. Researchers know this, and what they are now finding out about scent could one day change the way we treat depression, infertility, weight problems and insomnia.

To this end, scientists are taking some unusual measures, such as collecting men's underarm sweat on cotton pads and sticking them under women's noses, just to see what happens. Last year, George Preti, Ph.D., an organic chemist at Monell Chemical Senses Center in Philadelphia, published a double-blind investigation in Biology of Reproduction showing that the mere act of sniffing men's sweat accelerated fertile periods in female subjects and made them feel more relaxed in the process.

It seems that "male axillary extracts" (compounds made from the sweat of donors) revved the women's menstrual cycles, bringing on the next pulse of luteinixing hormone about 20 percent faster than normal, potentially affecting fertility. (As ovulation approaches, LH pulses become larger and more frequent.) All the female participants also reported reduced tension after sniffing the sweat extract but not after sampling a placebo (ethanol), both of which were disguised by an identical scent.

"The mood changes seem to make sense," says Preti. "Being relaxed in the presence of a mate would be important to fostering intimacy."

This isn't the first time scent and emotions have been connected. Denise Chen, Ph.D., an assistant professor of psychology at Rice University in Houston, previously reported that smelling sweat may lift mild depression. She went on to demonstrate that women (but not men) could accurately smell fear versus happiness in the underarm perspiration of male volunteers who'd watched scary or funny movies.

Together, these studies strengthen the growing scientific interest in human pheromones, invisible airborne chemicals we secrete that may affect our moods and our hormone-controlling endocrine systems. "There's good evidence now that we produce endocrine-influencing primer pheromones and mood-influencing modulator pheromones," says Preti. But he strongly cautions against "all those Internet products allegedly containing 'releaser' pheromones as sex attractants — that's a crock of crap."
smell the weight loss

After the low-carb diet peaks, the next weight-loss craze may come from Alan Hirsch, M.D., director of the Smell and Taste Treatment and Research Foundation in Chicago. At a conference held last October by the American Society of Bariatric Physicians, Hirsch presented research showing that scented powders added to food can help people lose weight to the tune of 5 pounds a month.

Hirsch, a neurologist and psychiatrist by training, says that "to a large degree, people overeat not because they're trying to fill their stomach but to satisfy their need to smell" — and now he has some compelling evidence.

The 108 overweight study subjects (averaging 197 pounds each) were told to eat the way they normally do, and were given two powders a month — one savory, one sweet — to sprinkle on their food. The powders were tasteless but fully loaded with the aromas of cheddar cheese, onion, raspberry, cocoa and other foods. With each spoonful the scent traveled from the mouth to the back of the nose, "so that essentially they ate the smell," says Hirsch. After six months, participants had lost an average of 34.7 pounds each. Meanwhile, a control group of 100 overweight people enrolled in a traditional diet program gained an average of 1.1 pounds.

How could a fragrant powder make someone unintentionally eat less and lose weight? Hirsch doesn't claim to fully understand the mechanism at work here, but it may be that food odors, more than taste or the feeling of a full belly, are what send the all-important message of satiety to the brain, which in turn tells us we can stop eating. Until such powders are available at a supermarket near you, the take-home message for dieters may be to smell your food while eating, serve it hot to heighten the aromas, and use garlic, onions and other pungent seasonings to kick it up an olfactory notch.
the fragrance of sleep

To date, aromatherapy has been considered a pseudoscience, not so much because scientists don't believe scent can have a therapeutic effect but because research in the field has been flimsy at best. Namni Goel, Ph.D., an assistant professor of psychology and neuroscience at Wesleyan University in Middletown, Conn., may provide some needed ballast. At last year's conference of the Associated Professional Sleep Societies, held in Chicago, Goel presented the results of a study showing that getting a whiff of lavender before bedtime significantly increased slow-wave sleep; this is considered the deepest, most restorative stage of sleep.

The study group consisted of 15 women and 10 men (standard size for a sleep study) ages 18 to 30, all good sleepers. In addition to lavender, they sniffed an odorless substance (distilled water) as a control, which they were told might be a scent so diluted as to be undetectable. Rather than rely on self-reporting, Goel used electrodes to measure the brain waves of each participant as they slept.

Goel had her subjects sniff a vial of lavender oil on and off for 30 minutes prior to sleep, providing a "discrete exposure, which is a scientific way to administer odor, and also something you can easily duplicate at home," says Goel. "I would love it if this motivated people having trouble sleeping to go out and buy a vial of lavender oil and try sniffing it before bed or putting a little on their pillow. In fact, that will be my next study."

Goel's project will undoubtedly be one of many upcoming investigations into the nature of scent. For if our sense of smell can really help us sleep better, lose weight more easily, feel more relaxed and even get us ready to mate, we may have to place greater value on what the nose knows.

SEX AND SCENT ARE CLOSELY INTERTWINED, so much so that 25 percent of people who lose their sense of smell also lose the ability to become sexually aroused. In a study of sexual response to extraneous odors, lavender and pumpkin pie had the most impact on penile blood flow, while Good 'n' Plenty and cucumber had the greatest effect on vaginal engorgement, according to researcher Alan Hirch, M.D.

A SCENT IS WORTH A THOUSAND WORDS Women are more likely to remember what they smell than men, according to a recent report in the journal Chemical Senses. Women outperformed men when asked to identify a given smell from a group of four scents no, 30 or 60 seconds after sniffing the original scent. Researchers at the University of Pennsylvania's Smell and Taste Center believe women tend to attribute words to scents, making odors easier for them to recall.



By Trisha Thompson

12 facts about scent

1. Everyone has a unique smell, except for identical twins.
2. Taste is about 75 percent smell.
3. Women are born better smellers than men and remain better smellers over life.
4. Smell acuity peaks in women at ovulation.
5. A 1-week-oid baby can discriminate between the smell of his own breastfeeding mother and another mother.
6. Some people can't smell skunks, while others can't smell freesias.
7. Smell function falls off dramatically in men after their mid-50s, a decade earlier than in women.
8. Recall can be enhanced if learning is done in the presence of an odor and that same odor is present at the time of the recollection.
9. Green apple and cucumber scents create the impression of a larger space, while the scent of roasted meat creates the impression of closer quarters.
10. Astronauts in space tend to lose their sense of smell and taste. Because of the lack of gravity, their sinuses fill up with fluid, causing stuffiness similar to a cold.
11. Schizophrenia is associated with a decreased capacity for olfactory pleasure.
12. A smell receptor has been identified in human sperm.

Compiled with the assistance of Tim Jacob, Ph.D., of Cardiff University in Wales, and Alan Hirsch, M.D., of the Smell and Taste Treatment and Research Foundation in Chicago.

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