If you’re taking a daily low-dose aspirin to prevent heart disease, you should probably weigh yourself. A new Lancet study analyzed data from ten trials with over 100,000 participants. They found that a daily 75-100 mg aspirin only helps people weighing 110-154 pounds (50 -70 kg). Higher dosage only benefitted people weighing over 154 pounds but not those weighing less.
Past research often showed that women and men had different outcomes for cardiovascular interventions. “Interactions between dose and weight probably explain previously reported sex differences in the effects of aspirin on risks of stroke and myocardial infarction,” according to the study. For people weighing over 154 pounds, enteric coated or delayed-release tablets were less effective at preventing cardiovascular events than standard, daily aspirin.
The research also reported that the 20-year risk reduction for colorectal cancer with aspirin is also affected by weight. The low-dose aspirin reduced colorectal cancer in people weighing less than 70 kg, and the higher doses helped those weighing more.
The increased risk of bleeding from the aspirin is important to evaluate on an individual basis. Increased risk factors include a history of gastrointestinal bleeding, ulcer, medications that increase bleeding risk, and hypersensitivity or allergy to aspirin. It is very important to talk to your doctor before you change any over-the-counter medications. Just because you can buy it off the shelf, doesn’t mean it’s harmless.