—The combined results of the US and British physicians studies were reported by collaborators from those two studies. They stated, "It may be appropriate to consider their results together despite several substantial differences in design."1Mr Nugent's observation that the US study used Bufferin, whereas the British study used "pure" aspirin, is correct. Bufferin (325 mg) contains approximately 57 mg of magnesium, whereas pure aspirin does not contain magnesium (written communication, Robert J. Lipsy, PharmD, Arizona Poison and Drug Information Center, Tucson, Ariz, December 1992). It should be noted that the Recommended Daily Allowance for magnesium is 400 mg. Nugent's suggestion that the beneficial effect of aspirin in the US study was due to the small amount of magnesium contained in Bufferin seems unlikely. The vast majority of studies reporting a beneficial effect of aspirin in patients with coronary artery disease used pure aspirin without magnesium.
Dalen JE, Gore J. Does Magnesium Prevent Myocardial Infarction?-Reply. JAMA. 1993;269(10):1254. doi:10.1001/jama.1993.03500100052025