| Credit: Laurie Frankel

What aging can bring: Cardiac disease, heart attack, stroke.

What the research shows: Heart health depends on monitoring and controlling both blood pressure and cholesterol. "High blood pressure is the number one culprit when it comes to heart trouble," says Michael F. Roizen, M.D., coauthor of You: On a Diet: The Owner's Manual for Waist Management. "If you know only one number besides your spouse's birthday and your anniversary, it should be your blood pressure." (The ideal is 115/76.) A diet high in sodium is linked to high blood pressure. As for cholesterol, the numbers to aim for are a total count of less than 200, with an HDL greater than 60 and an LDL around 70. The two risk factors are linked: High blood pressure causes little nicks to form in arteries, which the body then plasters over with cholesterol. That attracts inflammatory cells, creating arterial plaque that can lead to clots and ultimately heart attacks and strokes.

What you can do: Keep your diet low in salt and saturated fat and high in fruits, vegetables, and whole grains. Aim for 30 minutes of aerobic activity four or five days a week.