But they also present potential problems: bouncing, sagging, soreness, and, in the worst case, cancer.
Indeed, breast cancer is the most common form of (nonskin) cancer in women, and an estimated 200,000 new cases will be diagnosed this year.
Here are the experts' best tips for maximizing breast health, from the skin-deep to the deep tissue.
Your chest has some of your body's most sensitive skin, and it's very thin -- lying close to the sternum, says New York City dermatologist Jody Levine. To treat sun damage and pigmentation, consider getting a photofacial, she says.
Be sure to moisturize the thin, crepey skin on the chest with a really thick lotion -- the equivalent of a night cream. Look for a moisturizer with ingredients that bind water to the skin, such as hyaluronic acid or cocoa butter, says Debra Jaliman, assistant professor of dermatology at Mount Sinai School of Medicine, in New York City.
And don't assume that when it comes to sunscreen, breasts are out of sight and out of mind. Jaliman points out that "sunscreen protects breast skin both from skin cancer and from the breakdown of collagen and elastin that causes sagging."
For the beach, she recommends slathering SPF 60 sunscreen all over when you're undressed; then put on your bathing suit and head out the door.
Shape and Lift
Hold them high.
Gravity is not your friend. "The breasts connect to the chest wall with ligaments and fibrous tissue," says Laurie Casas, clinical associate professor of surgery at the University of Chicago Pritzker School of Medicine. "If breasts aren't properly supported, the ligaments overstretch and sag."
The larger breasts are, the more important it is to support them. "Bouncing stretches out the ligaments, so you want a bra with cups that are positioned properly, one that shapes the breasts and keeps them compressed against the chest wall," Casas says. (When it comes to sports bras, look for ones with shaped cups -- the tighter, the better.)
You might think your bra fits fine and that tugging at dangling straps is a sad fact of life. But you'd be surprised: Eight out of 10 women wear the wrong size bra, according to Wacoal, one of the largest underwear manufacturers.
Often, the ill fit is caused by a band that's too big around the rib cage. "Ninety percent of the support comes from the bra band," says Susan Nethero, owner of Intimacy boutiques and an expert bra fitter. "When the band doesn't fit snugly, it will ride up in the back and cause the straps to fall down. You shouldn't have to cinch down the shoulder straps to try to get more lift."
If your straps do slip off your shoulders, your band is too large. Buy a bra that fits snugly when clasped on the loosest hooks. (You'll use the tighter hooks as the bra stretches out over time.)
When the band is the right size, it should be firm around your rib cage, but you should still be able to comfortably slip a finger under it.
If you haven't had a professional fitting in some time -- and especially if you've recently lost or gained weight, or given birth -- visit a lingerie boutique or department store where a specialist can size you up.
No amount of exercise will increase your cup size or buoy up already sagging breasts, but staying in shape will help maintain breast shape.
"When the upper pectoral muscles in the chest are toned, it creates more of a fullness that will make the breasts look better," Casas says. Make push-ups and inclined chest presses part of your toning routine.
Maintaining your weight -- and not yo-yo dieting -- can also help keep breasts at their best. "When you gain weight, breasts change size, causing the skin to stretch," Casas says. So if you lose weight, that overstretched skin doesn't always snap back into shape, leaving breasts looking saggy.
The benefits of exercise and maintaining a healthy weight have perks beyond perkiness. Exercise may be key in preventing breast cancer, since up to one-third of all cases could be avoided if women exercised more and ate less, according to data presented at a recent meeting of the International Agency for Research on Cancer, part of the World Health Organization.
Exercise can help limit cancer because it reduces the amount of body fat, which in turn lowers the storage levels of estrogen that trigger some forms of breast cancer.
A few supplements can help sore, cystic breasts: Vitamin B6, vitamin E, and two capsules of evening primrose oil may alleviate sensitivity and bumps caused by fibrocystic breast disease, says Mary Jane Minkin, a clinical professor of obstetrics and gynecology at Yale School of Medicine.
Also try to limit other causes of tenderness, such as salt, caffeine, and alcohol. In fact, curtailing your cocktails to no more than one a day may decrease your risk of breast cancer, since "alcohol has been shown to increase hormone levels, which causes a modest increase in breast cancer risk," says Michelle Holmes, associate professor of medicine at Harvard Medical School.
Look for lumps.
Despite a recent study finding that breast self-exams do not reduce breast cancer mortality, doctors still encourage women to do them.
The best time to do one is after your period (since breasts tend to be more cystic or lumpy leading up to menstruation), and Minkin says to pay attention to a lump that feels hard and doesn't wiggle or move around, or to one that wiggles but persists for more than one or two menstrual cycles. "Those are the ones you want to bring to your doctor's attention," she says.
Make a mammogram appointment.
All the recent hoopla aside -- the U.S. Preventive Services Task Force upped its age recommendation for biennial mammograms from 40 to 50 -- the schedule for most women will not change. In fact, the American College of Obstetricians and Gynecologists still advises a first screening at 40, one every year or two throughout your 40s and then annually after age 50.
Early detection is still the best medicine for curing breast cancer, so don't skip this important test.
(Still curious as to whether you should get screened? These five steps can help you make up your mind.)
Fight the Good Fight
How can you help find a cure for breast cancer, which is estimated to afflict one in eight women in their lifetimes?
The following organizations raise funds for important research, as well as offer education about early detection and resources for patients, survivors, and their families.
- Susan G. Komen for the cure, komen.org
- Breast Cancer Research Foundation, bcrfcure.org
- National Breast Cancer Foundation, nationalbreastcancer.org
- Ford Warriors in Pink, fordvehicles.com/warriorsinpink/wip
- Lee National Denim Day, denimday.com
For more about breast-cancer prevention, read Breast Defense: Reduce Your Cancer Risk.