Q. My six-year-old grandson insists that I smell like an old person. Do you have any idea what he's talking about?

There was a study that suggests people can tell if you are old by how you smell. The study was done at the Monell Chemical Senses Center in Philadelphia.

Researchers asked volunteers between the ages of 20 and 95 to sleep in T-shirts with nursing pads sewn into the armpits.

After the five nights, the researchers put the pads in jars. Each jar contained cut-up quarters of pads from several people in the same age group. A separate group of volunteers was asked to sniff the jars and rate the odors.

The odor of people 75-95 was judged to be less intense and far more pleasant than the scent of either young or middle-aged adults. In general, men smelled worse than women, but that distinction disappeared in old age, the researchers found.

Johan Lundstrom, co-author of the study and an assistant professor at Monell, said the study "shows that there's yet another signal hidden in the body odor that we are somehow able to extract and make use of."

Previous research had suggested that body odor provides clues to sickness, gender and kinship. In recent years, scientists have shown that humans use their noses when selecting romantic partners.

There is a negative connotation to "old-people smell." Where does it originate?

Here are some possible causes offered by experts on aging:

Ÿ Stale air. Old people tend to keep the thermostat on high, their windows closed and shades down. Their homes are stuffy breeding grounds for mold and bacteria.

Ÿ Dirty digs. Its more burdensome for older people to do house cleaning.

Ÿ Unlaundered clothes. Doing laundry is difficult for many older people, so they tend to have soiled clothes around.

Ÿ Incontinence. Sometimes the aged don't get to the bathroom in time and don't clean up properly.

Ÿ Faulty senses. An older adult's senses of sight and smell have dulled. Older people often don't see dirt or smell bad odors.

Ÿ Bad breath. As we age, the tissues of the mouth produce less saliva, which is the best defense against bad breath. Older people don't brush their teeth as well as they used to. And dentures retain odors if they aren't replaced when they should be. Digestive problems, such as acid reflux, are increasingly common as we age; these send stomach odors up into the mouth.

Ÿ Dehydration. It's common for older people to drink very little without realizing it. When a person is dehydrated, odors from foods such as garlic or onion become more concentrated. Urine is more concentrated, too, so just a drop of leakage can produce a strong smell.

Ÿ The unwashed. Older people take fewer baths because they are viewed as a lot of work when you are just staying at home. And, there is a fear of falling in the tub.

Ÿ Medicinal smell. Older people take a lot of medications, which can cause a subtle chemical odor to come through the pores of the skin. They also use a lot of mentholated products such as Ben-Gay and Vicks Vapo-Rub.

Ÿ Cleaning solutions. We associate ammonia and Lysol with aging because it is used in nursing homes.

If you would like to read more columns, you can order a copy of "How to be a Healthy Geezer" at www.healthygeezer.com [1].

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