The Self-Repairing Body
By: Matt Bean

If humans were like salamanders, that careless carpenter down the street would have a full set of fingers. But soon after our primordial ancestors slithered out of the muck, limb regenesis was chucked out of our genetic portfolio like John Bobbitt's . . . well, you get the picture. The good news: Our bodies still retain some important repair mechanisms.

"Regeneration is actually a default state when we're embryos," says David L. Stocum, Ph.D., a regenesis researcher and dean of the school of science at Indiana University?Purdue University in Indianapolis. "We gradually lose that ability as we develop-except in certain kinds of tissues."

The holdouts? Your arteries, skin, liver, lungs, and digestive tract, and certain parts of your brain. They're all continually refreshed-if you're healthy. "It's called maintenance regeneration. It's kind of like working on your car," says Stocum. "You've got something going on-you're low on oil, you buy a quart. A taillight goes out, you replace it. The clutch is acting up, you fix it. It's the same thing with your body."

(A few parts-including the liver and severed bits of fingertips-can even grow back. Studies suggest that adult stem cells in those areas play a role.)

Make sure your body has all the tools and parts it needs for a tune-up. Sometimes it's as simple as revving your engine. Here's how to mend broken bones, bypass clogged arteries, sprout new brain cells, and more-by optimizing your body's regenerative powers.

Your Arteries
The damage:
Narrowing blood vessels

The natural defense:
When your pipes start to clog like I-405 at rush hour, a healthy body can handle the traffic by enlarging existing arteries and even growing new ones. It's a natural process called angiogenesis, and here's how it works.

Links between blood vessels, called arterial anastomoses, normally supply local tissues with blood, like exit ramps shunting traffic away from expressways. These exit ramps can be pressed into service as full-fledged arteries. "The cells in the vessel are able to detect when stress is increased, and that prompts signals that enlarge the anastomoses," explains Ronald L. Terjung, Ph.D., associate chairman of the University of Missouri's department of biomedical sciences. "Blood can cross over (to an unclogged vessel) and keep going."

What you can do:
First clean your pipes. Cholesterol can hinder the repair process. Researchers at Harvard medical school compared tissues from two groups of open-heart patients-one group with clogged vessels and the other with clear ones-and found that the clogged blood vessels weren't able to respond to growth signals. "Angiogenesis can't occur if the cells in the blood vessel are damaged or blocked by cholesterol," says author Roger J. Laham, M.D., director of the Angiogenesis Research Center at Harvard medical school. So keep your cholesterol low.

Make your own detours by running, swimming, shooting hoops-whatever it takes to get your blood pumping. A 2004 study published in the journal BMC Physiology found that endostatin, a factor involved in arterial growth, shot up by an average of 73 percent in healthy volunteers after about 10 minutes on a treadmill at an average of 5 mph. Even better: The effects lingered for up to 2 hours, and the harder the subjects worked, the more endostatin was released.

An injection may one day help. Scientists at the University of Cincinnati injected three heart patients with something called "growth factor FGF1," the "on" switch for arterial growth. After 3 months, all three were growing new arteries and had increased bloodflow. "They're very, very small branches of arteries that are growing into an area just like a bush. They're almost microscopic," says Lynne Wagoner, M.D., the lead study author. "Some patients are able to do this naturally on their own, but in the patients we're studying, we're basically doing that for them." The treatment is slated for approval in 2006.

Your Bones
The damage:
A broken bone

The natural defense:
"The healing response is generated by the living parts of the bone, the cells that live within the matrix," says Sherwin S.W. Ho, M.D., an associate professor of orthopedic surgery at the University of Chicago. No, Keanu, healing faster isn't a matter of choosing the red or blue pill. The matrix Dr. Ho is talking about is the lightweight but durable calcium carbonate structure that makes up most of your bone. Inside little pockets in the matrix are living cells, including bone-building osteocytes. "When you break a bone, they're released from the pockets," explains Dr. Ho.

What you can do:
Eat your greens. They'll give you loads of vitamin K, a compound that helps lock bone cells into place as they lay down new scaffolding. One serving of spinach or broccoli provides more than the recommended intake. And break out the guacamole-avocados and tomatoes are good sources of vitamin K, too. Never heard of vitamin K? No surprise: Less than 50 percent of all men ages 18 to 44 get enough of it, researchers at Tufts University found.

Don't take it lying down. A busted bone isn't a 6-month excuse to sit on your butt. "At some point, you have to introduce a modicum of stress on the bone to stimulate those osteocytes to lay down more bone," says Dr. Ho. Most breaks are ready for light stress at 6 weeks. Initially, Dr. Ho gives his patients squeeze balls and a regimen of light curls for arm breaks, and crutches for leg breaks. "Once you're ready for heavier exercise, you should do a couple of sets of 15 to 20 repetitions per day at the highest resistance you can complete without pain," says Dr. Ho.

Go ultra. If you're a competitive ice-skater, power forward, or stripper and need to get back on the floor immediately, consider an ultrasound bone-healing system like the Exogen, which has been shown to help bones heal as much as 38 percent faster. Some insurance plans will cover sessions.

Your Liver
The damage:
Years of drinking. Or just a binge.

The natural defense:

Your liver is one of the only organs that can spring back after part of its tissue dies (the process is called compensatory hypertrophy). But that's only if you don't booze it to the point of cirrhosis, a chronic liver disease in which normal liver tissue is replaced with scarred, nonfunctional tissue. "People who are at risk consume more than 14 drinks a week or regularly have more than five at a time," says Mark Mailliard, M.D., director of the hepatitis C program at the University of Nebraska.

What you can do:
Balance your liver. It's really just a sponge full of chemicals, and a compound called glutathione (GSH) helps keep everything in check. Not only does GSH detoxify things like Tylenol (which is why alcoholics should never pop one while drinking-the by-product is toxic), but it's also essential for liver regeneration. Rats unable to create GSH are also unable to grow back liver tissue, a University of Southern California study found.

"We're not sure how it works. That's the black box," says Shelly Lu, M.D., the lead author of the study. "We know it helps with cell growth, and we know it's involved in cell death, too." Dr. Lu also knows that popping SAM-e-a supplement that converts to glutathione in the liver-can bring your GSH levels back to normal. In Europe, where SAM-e is actually prescribed for liver disease, the standard dosage is 1.2 grams (g), or about three tablets, per day. "If you're a drinking man, you should also be taking folic acid and a B-vitamin complex, because they're essential in the formation of SAM-e and glutathione," adds Dr. Lu.


Your Guts
The damage:
Intestinal distress-there's a five-alarm fire down below.

The natural defense:
Torch your gut with booze, barbecue, or both, and the lining of the intestine will simply slough it off. Cells there have one of the fastest cellular turnover rates in the body-each one clocks out after only a couple of days of (very, very dirty) work, making room for a new one.

What you can do
Rough it and you'll speed up the changing of the intestinal guard. "Having some roughage in your diet helps knock off a few of the older cells, almost like pruning a tree," says Kenneth Koch, M.D., a professor of internal medicine and chief of gastroenterology at Wake Forest University school of medicine. Aim for 25 to 30 g fiber a day, starting with a whole-grain breakfast cereal, followed by whole-grain bread at lunch and lots of fruits and vegetables all day long. Dr. Koch recommends foods containing bran because they produce the most "stool bulk." Delicious!

Your Brain
The damage:
You scorched your gray matter in ways you can't even remember.

The natural defense:
For years, it was thought that we stopped making fresh neurons in puberty, meaning that sometime in high school a long die-off of brain cells commenced. Turns out it only seems that way. "The brain is just another organ," says Fred H. Gage, Ph.D., a professor in the laboratory of genetics at the Salk Institute and the first researcher to demonstrate new neuronal growth in mammals. "The brain is attempting to fix itself, just as skin tries to heal itself after a nick or cut."

What you can do:
Work your body. Animal studies have shown that exercise can induce neurogenesis (the formation of new neurons) in two key areas of the brain: the hypothalamus, which helps form new memories and learning; and the olfactory bulb, where your sense of smell is located. The studies were done on rats, but what's good for a rodent should be good for your brain: Try to get at least 30 minutes of exercise 2 or 3 days a week.

Your Lungs
The damage:
Bad air, from smoke or smog, has clogged your air-exchange system.

The natural defense:
The lungs come equipped with a self-cleaning cycle, but overloading them with smoke or smog will gunk up the works. The cilia, or hairlike structures in your lungs, flagellate (that's move) upward, coaxing the bad stuff out of the alveoli (little air sacs) and into the trachea, where the gunk grows into a frightening reminder of why you should have been better to your lungs to begin with. "It's like a mucus escalator," says Norman Edelman, M.D., a scientific advisor to the American Lung Association. "That's a major form of defense. Within a few days to a week (after quitting smoking], you start feeling better, and you start coughing up all that bad mucus you have down there."

What you can do:
Exercise will help loosen the large chunks after you first come clean. But you should be exercising already. Retinoic acid, or vitamin A, could actually help your lungs rebuild. Rats and mice with emphysema (they smoked tiny little cigarettes) given the compound were able to restore alveoli, which swap carbon dioxide for fresh oxygen to pre-emphysema levels, according to a recent study published in the European Respiration Journal. You'll get several times the recommended daily allowance (900 micrograms) in only one serving of carrots, sweet potatoes, or mango.