The research also found that the risk of having fatal or disabling bleeds while taking aspirin increased with age.
"But our findings raise questions about the balance of risk and benefit of long term daily aspirin use in people aged 75 or over if a proton-pump inhibitor (PPI) is not co-prescribed".
Half the patients were aged 75 or over at the start of the study, which followed the progress of participants over ten years.
Peter Rothwell, one of the study authors, said that taking anti-platelet drugs such as aspirin prevented a fifth of recurrent heart attacks and strokes but also led to about 3,000 excess-bleeding deaths annually in Britain alone.
During the course of the study, it was noted that a total of 314 patients were admitted to hospital for internal bleeding.The risk of bleeding increased sharply with age.
Rothwell, director of the Center for Prevention of Stroke and Dementia at Oxford University, and his colleagues found that the annual rate of life-threatening or fatal bleeds was less than 0.5 percent in under-65s, rising to 1.5 percent for those aged 75 to 84, and almost 2.5 percent for over-85s.
"While there is some evidence that PPIs might have some small long-term risks, this study shows that the risk of bleeding without them at older ages is high, and the consequences significant, " said Rothwell.
Until now, most research involved people under 75, showing that the risk of serious bleeds was low in this group.
For this group a number of previous studies show that the risk of major bleeding is low.
The NHS warn that the risk of bleeding in the stomach may be higher if you drink alcohol while taking aspirin, so you may want to consider reducing how much you drink, or avoiding alcohol completely.
Aspirin, or acetylsalicylic acid (ASA) is a common drug that is used to treat mild to moderate pain and reduce fever or inflammation.
'In the over-75s the risk is higher - but the key point is that this risk is substantially preventable by taking proton pump inhibitors alongside aspirin'.
"Aspirin is an wonderful little medicine that has been shown to have many potential health benefits". Half of patients were 75 years or older, and 18% were older than 85 years.
Current NICE guidance on NSAID prescribing already recommends co-prescription of PPIs in patients at increased risk of adverse GI effects, which includes those aged 65 or above.
He concluded: 'Since numerous 3,000 excess deaths are preventable by taking proton pump inhibitors, people over-75 should be prescribed a PPI along with their aspirin.
But "the new data should provide reassurance that the benefits of PPI use at older age outweigh the risks".
Even among those who are without any history of heart problems or stroke, risk of gastrointestinal bleeding increases with age for those using aspirin other research has revealed.
But they insist aspirin has important benefits - such as preventing heart attacks - that outweigh the risks. In the United Kingdom, around 40% adults aged 75 and above consume aspirin daily.