Anti-aging enterprises amount to a multi-billion industry in the U.S., and include everything from drugs and supplements to lifestyle changes. But a 50-year Swedish study of centenarians has identified three simple strategies that greatly boost the odds of living to 100:

1. Don’t smoke.
2. Keep your cholesterol levels low.
3. Drink coffee — but no more than four cups a day.

Those recommendations are the key findings from five decades of research by the Sahlgrenska Academy at the University Gothenburg involving 855 men born in 1913 — 10 of whom lived to 100.

Various surveys at the age of 54, 60, 65, 75, 80, and 100 allowed the researchers to identify the factors that appear to promote longevity. Of the original 100, 27 percent lived to celebrate their 80th birthdays, 13 percent lived to 90, and 1.1 percent (10 men) made it to 100.

Among the findings:

• About 42 percent of deaths after the age of 80 were due to cardiovascular disease.
• Approximately 26 percent were caused by infectious diseases, including pneumonia (6 percent).
• Another 8 percent resulted from stoke and cancer.
• About 16 percent were due to to other causes.
• A total of 23 percent of the over-80 group were diagnosed with some type of dementia.

"The unique design has enabled us to identify the factors that influence survival after the age of 50," says Lars Wilhelmsen, who has been involved in the study from the beginning.

"Our recommendation for people who aspire to centenarianism is to refrain from smoking, maintain healthy cholesterol levels, and confine themselves to four cups of coffee a day."

Other minor factors that may contribute to longevity: owning a home at age 50 or paying higher rent (indicating good socio-economic status), reasonably good physical fitness (determined by a bicycle test) at age 54, having a mother who lived for a long time (suggesting genetic factors at work).

Other characteristics of the 100-year-olds:

• None smoked.
• All wore hearing aids, had good temporal and spatial cognition, were slim, had good posture, and used walkers.
• Most wore glasses, and were able to read and watch TV.
• Two lived at home and five in assisted living facilities.
• Two developed dementia.

"Normally we conducted the surveys at hospitals, but we visited the … centenarians at home," Wilhelmsen said. “All of them were clinically healthy, satisfied with their circumstances and pleased to be living where they were."