Stem cells are the highly versatile spare tires of your body. Once called on, they can replace a damaged cell — and, because they aren't yet directed to become part of a specific organ or tissue type, they not only could become (metaphorically speaking) a new tire, but could also fix a worn-out engine part or a cracked windshield. It just takes the right prodding in the body, or the laboratory! They can do it even after being inactive for a long time.

Those remarkable abilities are promising to provide scientists with a powerful tool to use in conquering disease. That's because normally, cells in organs such as the heart and pancreas do not divide to repair damage that might happen to the organ. But manipulation of stem cells ... well, that could allow doctors to induce self-repair in many parts of the body. No more heart transplants; bye, bye diabetes, macular degeneration, spinal cord injury, osteo- and rheumatoid arthritis. We might even repair third-degree burns and stroke damage that was previously considered permanent.

That promising future became more hopeful in 2006, when researchers figured out how to turn specialized adult stem cells (replacing use of embryonic cells in some research) into what they called "induced pluripotent stem cells" (iPSCs). Since then, the number of experiments using iPSCs has sky-rocketed: Adult mouse stem cells are injected into the damaged ventricular wall of a mouse heart and the stem cells regenerated damaged heart muscle! There have been a few, small, human-based studies that, says the National Institutes of Health, have "demonstrated that stem cells that are injected into the circulation or directly into the injured heart tissue appear to improve cardiac function and/or induce the formation of new capillaries." But — and this is a big but — they caution, "significant technical hurdles remain that will only be overcome through years of intensive research."

Tip: Stem cell clinics promising miracle cures are not a good idea at this time. The International Society for Stem Cell Research says: "Many clinics offering stem cell treatments make claims that are not supported by a current understanding of science."

Fortunately, there's a lot you can do to keep your stem cells healthy and your RealAge younger.

1) Protect your skin from excess sun exposure; use micronized zinc oxide 30 SPF sunscreen. Exposure to ultraviolet radiation from the sun and tanning beds and lamps is a leading cause of melanoma. New research shows that the trigger may be stem cells gone wild; melanoma may be related to the formation of carcinogenic stem cells.

2) Avoid hormone-disrupting chemicals such as BPA in plastics and phthalates in household goods and products. One study found that they disrupt development of stem cells needed for sperm production.

3) Don't overeat; eat whole foods, not chemicals. Steer clear of processed foods that dose you with preservatives, colorings, emulsifiers, added sugars and syrups. Continuous intake of sugary foods reduces stem cell vitality! A lab study found that reducing caloric intake by 20 percent can positively boost stem cell activity. We say, try it five days a month.

4) Get regular exercise. According to a new study out of the University of Rochester, loss of muscle stem cells is the driving force in loss of muscle tone and strength as you age. That makes it increasingly important to get two to three 30-minute sessions of strength-building exercises weekly. Aerobic effort (push it a bit) stimulates some stem cells to produce bone instead of fat.

5) Avoid excess radiation. Exposure to a dental X-ray, PET or CAT scan provides diagnostic benefits without immediate risks. But new evidence shows that accumulative exposure to radiation over a lifetime can have damaging effects on stem cells and organs. Opt for an MRI, not a CAT scan when possible; refuse dental X-rays unless necessary; follow guidelines for mammograms. And make sure your imaging center is accredited, personnel are credentialed, and they use weight-based and indication-based protocols.

Mehmet Oz, M.D. is host of "The Dr. Oz Show," and Mike Roizen, M.D. is Chief Wellness Officer and Chair of Wellness Institute at Cleveland Clinic.