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Eat your vegetables. Exercise. Don't drink so much beer. Blah. Blah. Blah.

Even fewer Americans in their middle and later years adhere to this healthy lifestyle advice than they did two decades ago.

Despite the well-known benefits of a lifestyle that includes physical activity, eating a diet high in fruits and vegetables, maintaining a healthy weight, moderate alcohol use and not smoking, only a small proportion of older adults follow this healthy lifestyle pattern, a new survey finds.

In fact, the numbers of those who do are declining, even though it's medically clear that positive lifestyle choices are associated with reducing the risk of cardiovascular disease as well as diabetes.

The number of people adhering to five healthy habits (exercising 12 times a month or more, not smoking, eating five or more fruits and vegetables daily, moderate alcohol use and maintaining healthy weight) has decreased from 15 percent to 8 percent between the period 1988-1994 and then 2001-2006. The results come from a comparison by investigators from the Medical University of South Carolina of results from two large-scale studies of the U.S. population.

"The potential public health benefits from promoting a healthier lifestyle at all ages, and especially ages 40-74 years, are substantial," Dr. Dana E. King and colleagues wrote in a published report on the study results.

Here are the details:

In the intervening years, the percentage of adults aged 40-74 years with a body mass index greater than 30 has increased from 28 percent to 36 percent.

Physical activity 12 times a month or more has decreased from 53 percent to 43 percent.

Eating five or more fruits and vegetables a day has decreased from 42 percent to 26 percent. smoking rates have increased slightly (26.9 percent to 26.1 percent).

Moderate alcohol use has increased from 40 percent to 51 percent.

The study also concluded that people with cardiovascular disease, diabetes, high blood pressure or high cholesterol, or risk factors for those conditions, were no more likely to adhere to a healthy lifestyle pattern than people without such risk factors.

The results are detailed in the June 2009 issue of The American Journal of Medicine. The study was supported in part by a grant from the Health Resources and Services Administration, which is part of the U.S. Department of Health and Human Services.

The National Health and Nutrition Examination Survey (NHANES) is a national survey conducted regularly by the National Center for Health Statistics. The researchers used data from a sub-sample of the NHANES surveys, focusing on adults aged 40-74 years, because this age span is the primary time for initial diagnosis of cardiovascular risk factors and disease.

In the NHANES 1988-1994, the number of respondents 40-74 years old was 7,340. For NHANES 2001-2006, the number of respondents was 7,811.

"Regular physical activity and a prudent diet can reduce the risk of premature death and disability from a variety of conditions including coronary heart disease, and are strongly related to the incidence of obesity," King and his colleagues wrote in response to their findings. "In the U.S., medical costs due to physical inactivity and its consequences are estimated at $76 billion in 2000 dollars. Research indicates that individuals are capable of adopting healthy habits in middle age, and making an impact on cardiovascular risk."