April 2010
Vol. 9 Issue 4

Should You Be Taking Daily Aspirin? And How Much?

Tens of millions of people taking a daily aspirin to prevent heart attacks and strokes, often with doctor’s advice to do so, are making a serious mistake. I recommend that people who have not already suffered heart disease (a heart attack or heart surgery) or an ischemic brain event (TIA or stroke) not take aspirin for prevention. This type of therapy is called primary prevention. Meaning, prevention before any vascular events have occurred. There is much controversy surrounding this topic. However, I would not be telling you my medical view unless I believed it was correct.

One of the chief effects of aspirin is to “thin the blood” by inhibiting the activities of blood-clotting elements called platelets. With inhibition, a blood clot (thrombus) is less likely to form suddenly within an artery, causing a heart attack or stroke. Along with beneficial effects come adverse effects. “Blood-thinning” increases the risk of hemorrhage. Low-dose aspirin therapy substantially increases the likelihood of gastrointestinal (primarily stomach) bleeding and bleeding within the brain tissues. In the daily routine practice of medicine, the benefits of aspirin for a reduction in risk of heart attacks, primarily in men, and strokes in women, must be weighed against an increase in the risk of major bleeding and, in men, an increase in the risk of hemorrhagic stroke. Weighing the benefits and risks means guessing—and hoping that more good than harm will have been done at the end of the day.

Respected Recommendations for Primary Prevention

For the Use of Daily Aspirin:

The U.S. Preventive Services Task Force encourages men aged 45 to 79 years to use aspirin when the potential benefit of a reduction in myocardial infarctions outweighs the potential harm of an increase in gastro-intestinal hemorrhage, and women age 55 to 79 years to use aspirin when the potential benefit of a reduction in ischemic strokes outweighs the potential harm of an increase in gastrointestinal hemorrhage.1

The American Diabetes Association and the American Heart Association recommend aspirin therapy for persons with diabetes who are older than 40 years or who have additional risk factors for cardiovascular disease and no contraindications to aspirin therapy.2

Against Use of Daily Aspirin:

The Medical Letter on Drugs and Therapeutics says, for healthy patients, at least those without cardiovascular risk factors, aspirin prophylaxis might do more harm than good.3

A 2008 Cochrane review did not recommend aspirin for primary prevention in patients with raised blood pressure because the benefits were negated by the harms.4

The Drug and Therapeutic Bulletin (British Medical Journal) says, “In particular, there have been doubts about whether any benefits of aspirin in people with no history of CVD outweigh the risks (e.g. the fact that long-term low-dose aspirin therapy almost doubles the likelihood of gastrointestinal hemorrhage).5

Don’t Use Aspirin for Primary Prevention of Cardiovascular Disease

The April 21, 2010 issue of the British Medical Journal carried an article with just that title: “Don’t use aspirin for primary prevention of cardiovascular disease.” The authors explained, “Published evidence does not support the assumption that the benefits clearly outweigh the harms. So the routine practice of starting patients on such treatment for primary prevention of cardiovascular disease should be abandoned… this conclusion holds regardless of such individuals’ gender, blood pressure, or predicted risk of cardiovascular disease, or of whether they have a history of diabetes.”6 A recent thorough review of the scientific literature looking specifically at people with diabetes, who are known to have an increased risk of heart attacks and strokes, found. “A clear benefit of aspirin in the primary prevention of major cardiovascular events in people with diabetes remains unproved.”7

For Secondary Prevention Benefits from Aspirin Outweigh Harms

For the person who has already had heart disease (a heart attack or heart surgery) or an ischemic brain event (TIA or stroke), aspirin use is justified. This kind of therapy is called secondary prevention. The reason aspirin works here is because once a patient has had such a serious vascular event the risk of another one is much higher; thus benefits from treatment will be more easily seen than in a low-risk population. Note that the risks from taking daily aspirin are also greater in people who have had such a prior event, because those falling into the category for secondary prevention are usually older and sicker.

Overall, among these high-risk patients the use of daily aspirin reduces risk of any serious vascular event by about one quarter; non-fatal myocardial infarction is reduced by one-third, non-fatal stroke by one quarter, and vascular mortality by one sixth.8

Low-Dose Is Much Better Than High Dose

The full preventative effects of aspirin are accomplished at a very low dosage, because essentially all of the platelets in the body are permanently deactivated with 30 mg of aspirin. New platelets with activity begin to appear in the blood after about four days following taking a single dose of aspirin.

A low dosage of 30 mg has a more favorable effect on platelet activity and fewer side effects (stomach pains and bleeding) than a higher dosage of 300 mg of aspirin.9 As the dosage of aspirin is increased from 30 mg up to 1000 mg the side effects increase from 5% to 25% of patients, with no additional benefits for prevention of secondary events, including no reduced risks of dying and/or heart attacks.10 Higher dosages, such as 1000 mg (3 adult aspirins daily), may even cause more heart attacks (reinfarctions). In one study, the total reinfarction rate was 22.5 % higher for people taking 1000 mg in comparison to the 30 mg group. The non-fatal reinfarction rate was 50% lower in the 30 mg group compared with the 1000 mg group.11 The reason for this escalated risk is dosages higher than 30 mg inhibit hormone activities that protect the heart.12 Thus, the ideal dosage may be one-third of what is commonly prescribed to patients, a baby aspirin, containing 81 mg of aspirin, daily.

How to Stop Aspirin Safely

There appears to be a rebound from reversing the “blood thinning” effects of aspirin when it is stopped suddenly. Over three times the expected risk of stroke occurs in patients with a previous history of heart disease when they suddenly stop taking aspirin.13 A similar increase in risk of heart attack has been reported when aspirin was stopped.

No one has determined a safe regime for discontinuing this therapy. I suggest that people needing to stop long-term use of aspirin should do so slowly. Since as little as 30 mg (1/3 of a baby aspirin) will deactivate all of the bodyĺs platelets, slow withdrawal should begin at about this level. Cut a baby aspirin into quarters (now 20 mg). Take 20 mg then wait for 4 days to take the next 20 mg dose. Increase the interval between 20 mg doses by one day until a 10-day interval between doses is reached, and then stop taking the aspirin. This is not an easy task since the tablets are so small. Reduction or discontinuation should be done after obtaining a doctor’s advice on the risks and benefits for each individual patient. Even before reducing the aspirin, patients should change to the McDougall Diet in order to most effectively reduce their risk of strokes and heart attacks.

Don’t Overlook the Best Tool for Primary and Secondary Prevention

The most effective, safest, and inexpensive way to “thin” the blood and prevent blood clots that cause heart attacks and strokes is to avoid the most powerful blood-clotting substances people contact daily, which are animal (saturated) fat and hydrogenated “trans” fats.14,15 By avoiding meat, poultry, eggs, dairy products, and processed foods people naturally and safely thin their blood and prevent tragedies with no side effects, no extra costs, and no rebound effects. Plus this no-cholesterol, low-fat diet is the same one that heals the underlying artery disease, atherosclerosis, and improves overall health and longevity.


1) US Preventive Services Task Force. Aspirin for the prevention of cardiovascular disease: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2009 Mar 17;150(6):396-404.

2) Buse JB, Ginsberg HN, Bakris GL, Clark NG, Costa F, Eckel R, et al; American Heart Association; American Diabetes Association. Primary preven- tion of cardiovascular diseases in people with diabetes mellitus: a scientific state- ment from the American Heart Association and the American Diabetes Association. Circulation. 2007;115:114-26.

3) Aspirin for primary prevention of cardiovascular disease (revisited). Med Lett Drugs Ther. 2006 Jul 3;48(1238):53.

4) Lip GYH, Felmeden DC. Antiplatelet agents and anticoagulants for hypertension. Cochrane Database Syst Rev 2008;(4):CD003186.

5) DTB 2009;47:122-125 doi:10.1136/dtb.2009.10.0045

6) Barnett H, Burrill P, Iheanacho Don't use aspirin for primary prevention of cardiovascular disease. BMJ. 2010 Apr 21;340:c1805. doi: 10.1136/bmj.c1805.

7) De Berardis G, Sacco M, Strippoli GF, Pellegrini F, Graziano G, Tognoni G, Nicolucci A. Aspirin for primary prevention of cardiovascular events in people with diabetes: meta-analysis of randomised controlled trials. BMJ. 2009 Nov 6;339:b4531. doi: 10.1136/bmj.b4531.

8) Antithrombotic Trialists' Collaboration. Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. BMJ 2002;324:71-86

9) A comparison of two doses of aspirin (30 mg vs. 283 mg a day) in patients after a transient ischemic attack or minor ischemic stroke. The Dutch TIA Trial Study Group. N Engl J Med. 1991 Oct 31;325(18):1261-6.

10) Fˆrster W, Hoffmann W. Superior prevention of reinfarction by 30 mg per day aspirin compared with 1000 mg: results of a two years follow-up study in Cottbus. Prog Clin Biol Res. 1989;301:187-91.

11) Two year Cottbus reinfarction study with 30 mg aspirin per day. Hoffman W, Fˆrster W. Prostaglandins Leukot Essent Fatty Acids. 1991 Nov;44(3):159-69.

12) Reevaluation of the Cottbus Reinfarction Study with 30 mg aspirin per day 4 years after the end of the study. Hoffmann W, Nitschke M, Muche J, Kampe W, Handreg W, Fˆrster W. Prostaglandins Leukot Essent Fatty Acids. 1991 Feb;42(2):137-9.

13) Maulaz AB, Bezerra DC, Michel P, Bogousslavsky J.† Effect of discontinuing aspirin therapy on the risk of brain ischemic stroke.† Arch Neurol. 2005 Aug;62(8):1217-20.

14) de Moraes Mizurini D, da Costa Maia I, Lucia de Carvalho Sardinha F, de Queiroz Monteiro R, Ortiz-Costa S, das Gra┴as Tavares do Carmo M. Venous thrombosis risk: Effects of palm oil and hydrogenated fat diet in rats. Nutrition. 2010 Apr 2.

15) Hornstra G. Influence of dietary fat type on arterial thrombosis tendency. J Nutr Health Aging. 2001;5(3):160-6.


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