看看 NPR 上的这篇文章，一定要看到最后一段：
When It Comes To Shampoo, Less Is More
Americans love to shampoo. We lather up an average of 4.59 times a week, twice as much as Italians and Spaniards, according to shampoo-maker Procter & Gamble.
But that’s way too often, say hair stylists and dermatologists. Daily washing, they say, strips the hair of beneficial oil (called sebum) and can damage our locks.
Shampoo Is Big Business
The current trend of frequent shampoos may have started on May 10, 1908, when the New York Times published a column advising women that it was OK to wash their hair every two weeks. At that time, once a month was the norm.
Decades later, TV marketing campaigns began to convince us that daily washing was the thing to do. A 1970s Faberge ad for Farrah Fawcett shampoo is one example.
“All you have to do is watch her running in slow motion on a beach with her hair flopping gracefully in the wind,” says Steve Meltzer, a former ad executive. The idea was, “Wash your hair with this stuff, and you, too, can be like Farrah Fawcett,” Meltzer says.
Madison Avenue sold people on the idea that they could shampoo their way back to beauty.
Ads also convinced us that daily hair washing is healthy. Remember the Breck girls? Or how about Christie Brinkley’s body-building for hair ad with Prell?
Skipping Shampoos Is, Well, Un-American
Americans took easily to the idea that we should shampoo frequently. And lots of us find it disgusting to shampoo any less than once a day. Take some fitness-conscious college students from Georgetown University, for example. When I told them about the old-time advice to wash once a month, they almost gagged.
“That is way too little hair shampooing,” laughs Jane Caudell-Feagan.
“If I don’t shower every day, my hair gets greasy, so I think it’s completely heinous,” says her friend Ashley Carlini. After a workout, they say, it would be disgusting not to wash your hair.
Eco-Conscious ‘No-‘Poo’ Movement
Given our cultural propensity to lather up frequently, it may be shocking that in some eco-conscious circles of society, some people are giving up shampoo.
“There’s a lot of people doing this no-shampoo movement,” says 20-something blogger Jeanne Haegele. She writes a blog called LifeLessPlastic.
In an attempt to buy fewer items with plastic packaging, Haegele recently went three months without using any shampoo. Instead, she washed her hair with baking soda twice a week and conditioned it with a vinegar rinse.
She says her hair didn’t smell, and her friends were very supportive. “Maybe they were secretly wondering why I smelled like a jar of pickles,” she says jokingly.
She ended the no-‘poo experiment after developing a bad case of dandruff, but Haegele says she might try it again.
She recalls the biggest surprise was that her hair didn’t get very greasy. For now, she’s using shampoo bars a few times a week.
Dermatologist Recommends Shampooing Less
Experts say Haegele’s observations are not flaky. As she washed less, her sebaceous glands began producing less sebum oil.
“If you wash your hair every day, you’re removing the sebum,” explains Michelle Hanjani, a dermatologist at Columbia University. “Then the oil glands compensate by producing more oil,” she says.
She recommends that patients wash their hair no more than two or three times a week.
There’s also a lot of variation among hair types. African-Americans and people with curly hair can go even longer between washes compared to folks with straight hair.
So, it seems, less is more. And maybe our grandmothers were on to something after all.