Women who exercise a lot hit menopause earlier

Women who spend a lot of time exercising or eat a heart-healthy diet appear to reach menopause earlier, a new Japanese study shows.

While that doesn't prove work-outs and healthy foods are directly responsible, researchers say the findings could be important for cancer prevention.

For the study, researchers tracked more than 3,100 premenopausal women over 10 years. Those who exercised the most -- about eight to 10 hours a week -- were 17 percent more likely to start menopause during the study than their sedentary peers.

Similarly, women who ate the most polyunsaturated fats