The latest recommendation from the US preventive task force is to take aspirin (low dose) to prevent both heart disease and colon cancer in adults aged 50-59, who have significant risk factors.

The guidelines are published in the Annals of Internal Medicine:

• Low-dose aspirin is recommended for adults aged 50–59 who have at least a 10% risk for a cardiovascular event in the next decade, low bleeding risk, and a life expectancy of at least 10 years; patients must also be willing to take aspirin daily for at least 10 years.
• For adults aged 60–69 fitting the above criteria, the decision to start aspirin should be an individual one.
• For patients younger than 50 and older than 69, there is not enough evidence to make recommendations.