Three of the nation’s top killer diseases – heart disease, diabetes, and cancer – have common risk factors.

Therefore, when you make a lifestyle change to prevent one of them, you're helping to prevent all of them, a top doctor tells Newsmax Health.

The three diseases are leading causes of death that, when taken together, kill more than 1.27 million people in the U.S. each year.

Heart disease is the nation’s leading killer, causing 611,015 deaths a year, with cancer second at 584,881, and diabetes coming in seventh, at 75,578, according to the U.S. Centers for Disease Control and Prevention.

“Very often, we view these diseases separately, and so people tend to think they need make a lot of different lifestyle changes to prevent them, which can be discouraging," said Tim Byers, M.D., associate director for cancer prevention and control at the University of Colorado Cancer Center. "But it turns out that these diseases share some risk factors, so if you make changes to prevent one, you can reduce your risk of developing the other diseases as well.

“People tend to know about the link between heart disease and diabetes, but often they don’t realize that there is a connection between them and cancer as well.”

Even medical researchers fail to note the connection, noted Dr. Byers, who recently made a presentation on the topic at the American Association for Cancer Research’s annual meeting in Philadelphia.

Exactly how the common risk factors work to produce the individual diseases is not fully understood, but, “We believe that systemic inflammation is probably the driver for all of them,” said Dr. Byers.

When you cut your finger, the redness and swelling that comes from the immune system’s inflammatory response signals that the body is healing, which is a helpful sign that disappears within in a few days.

But the inflammation blamed for heart disease, cancer, and diabetes occurs unseen within the body.

According to Dr. Byers, these are the top three things you can do to lower your risk of heart disease, cancer, and diabetes:

1. Stop smoking. “Tobacco use is Number 1 in terms of the impact it has not only on the risk of these three diseases, but also on stroke as well. It’s best not to start smoking, but even if you're 50, quitting smoking can largely reverse the damage done by tobacco use.”

2. Lose weight. “Obesity is the second biggest contributor. We know that obesity contributes to the risk of heart disease and diabetes, but it also is linked to breast cancer and, although we don’t know why, kidney cancer as well.”

3. Become more active. “Being sedentary is a risk factor for heart disease and diabetes, and it’s also linked to some cancers as well, such as colon cancer. But most people hardly do any activity at all, and tend to get discouraged because they aren’t ever going to be athletes. Just 30 minutes of brisk walking a day will appreciably lower risk.”