The research, which followed the progress of 114,970 participants for around four years, showed that drinking alcohol was associated with an overall 24% reduced risk of heart attack.
Moderate drinkers were more protected than either light or heavy drinkers.
But the study also found that compared with not drinking, alcohol consumption led to a 51% increased risk of developing certain cancers.
These included cancers of the mouth, oesophagus, stomach, bowel, liver, breast, ovary and head and neck.
Drinking was also associated with a 29% increased risk of suffering injury, according to the findings reported in The Lancet medical journal.
High alcohol intake levels and binge drinking both led to significantly higher death rates from all causes.
Lead researcher Dr Andrew Smyth, from McMaster University in Canada, said: "Our data support the call to increase global awareness of the importance of harmful use of alcohol and the need to further identify and target the modifiable determinants of harmful alcohol use."
Co-author Dr Salim Yusuf, director of the university's Population Health Research Institute, said: "Because alcohol consumption is increasing in many countries .. the importance of alcohol as a risk factor for disease might be underestimated. Therefore, global strategies to reduce harmful use of alcohol are essential."
Participants in the study came from 12 countries with different levels of economic development.
High-income countries were represented by Sweden and Canada, upper middle-income countries by Argentina, Brazil, Chile, Poland, South Africa and Turkey, lower middle-income countries by China and Columbia, and low-income countries by India and Zimbabwe.
Weekly alcohol consumption was measured for the study. Low intake was defined as up to seven drinks per week, moderate as seven to 14 drinks for women and seven to 21 for men, and high as more than 14 drinks for women and 21 for men.