The task force, a panel of 16 independent experts in disease prevention appointed by the US Department of Health and Human Services, also said evidence was insufficient to say that low-dose aspirin use reduces the occurrence or death due to colorectal cancer.
The recommendation, if finalised, would replace an earlier one from the panel, which in 2016 said daily low-dose aspirin may also help protect against colorectal cancer in people who are taking it to prevent heart attacks and strokes.
The new recommendation does not include people who have previously suffered a heart attack or stroke and taking daily aspirin to prevent a subsequent cardiovascular event. The panel said they should continue the regimen unless told otherwise by their clinician.
“It’s hard to know the degree to which any particular piece of evidence, whether an individual study or a practice guideline, will ultimately move the field,” said Caleb Alexander, professor of epidemiology at Johns Hopkins Bloomberg School of Public Health, who was not a member of the task force.
Aspirin, used for decades for pain and fever and available without a prescription, was seen as a convenient and cheap option to help those at risk of serious heart problems.
Researchers have been assessing daily low-dose aspirin use for people who do not have a history of heart disease but who are at high risk of developing it due to health issues such as high cholesterol and blood pressure.
“It’s important that people who are 40 to 59 years old and don’t have a history of heart disease have a conversation with their clinician to decide together if starting to take aspirin is right for them,” task force member John Wong said in a statement.
For people aged 50 to 59, the USPSTF previously recommended the pill only for those who have at least a 10 per cent risk of heart attack or stroke over the next decade and who do not have a higher-than-average risk of bleeding.