Aspirin, also known as acetylsalicylic acid (ASA), is a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, or inflammation. Aspirin given shortly after a heart attack decreases the risk of death. Aspirin is one of the most widely used medications globally, with an estimated 50 to 120 billion pills consumed each year.
A precursor to aspirin found in leaves from the willow tree has been used for its health effects for at least 2,400 years. In 1897, scientists at the Bayer company began studying acetylsalicylic acid as a less-irritating replacement medication for common salicylate medicines. By 1899, Bayer had named it “Aspirin” and sold it around the world.
Aspirin works similarly to other NSAIDs but also suppresses the normal functioning of platelets, tiny plate-shaped cells in your bloodstream. Platelets enable clotting when a blood vessel is damaged. This is usually good, except for those with atherosclerosis and higher risk of heart attacks. When a blood vessel is damaged by an external or internal wound, platelets get a signal to rush to the spot, where they grow sticky, octopus-like tentacles that create a blood clot, plugging the wound to stop the bleeding. That’s usually good. But it’s bad if you have atherosclerosis, a narrowing of the arteries caused by buildup of fatty deposits. When part of a fatty deposit breaks off, as they are prone to do, platelets do their usual work, creating a clot. But a clot in an already narrowed artery can severely restrict or even block the blood flow to the heart or brain, causing a heart attack or stroke.
Aspirin inhibits the function of platelets, so doctors often prescribe a low dose — typically around 80 milligrams a day — to people diagnosed with atherosclerosis or who have had a heart attack or stroke. That dosage has been shown to reduce the risk of subsequent clots and decrease the risk of death.
For healthy people, including those over the age of 70, who are not at high risk for cardiovascular problems, there is not likely sufficient benefit to supplementing with daily aspirin compared to the known risks. There are differing opinions on the effectiveness in slowing or preventing various cancers.
In March 2019, the American College of Cardiology (ACC) and the American Heart Association (AHA) released new guidelines that suggest that most adults without a history of heart disease should not take low-dose daily aspirin to prevent a first heart attack or stroke. Based on the ASPREE, ARRIVE, and ASCEND trials, the ACC/AHA guidelines concluded that the risk of side effects from aspirin, particularly bleeding, outweighed the potential benefit.
If you are already taking daily aspirin for primary prevention, it would be a good idea to meet with your physician and see if you might be better off stopping. There are elevated serious risks to discontinuing and to irregular or intermittent usage.
For people at high risk, daily aspirin is prescribed by many physicians to prevent further heart attacks, ischaemic strokes, and blood clots.
Lower doses of aspirin have also been shown to reduce the risk of death from a heart attack, or the risk of stroke in people who are at high risk or who have cardiovascular disease, but not in elderly people who are otherwise healthy.
For people who have already had a heart attack or stroke, taking aspirin daily for two years prevented 1 in 50 from having a cardiovascular problem (heart attack, stroke, or death), but also caused non-fatal bleeding problems to occur in 1 of 400 people. Low dose aspirin appears useful for people less than 70 kg while higher dose aspirin is required to benefit those over 70 kg.
As of 2016, the United States Preventive Services Task Force (USPSTF) recommends initiating low-dose aspirin use for the primary prevention of cardiovascular disease and colon cancer in adults aged 50 to 69 years who have a 10% or greater 10-year cardiovascular disease (CVD) risk, are not at increased risk for bleeding, have a life expectancy of at least 10 years, and are willing to take low-dose aspirin daily for at least 10 years.
In those with no previous history of heart disease, aspirin decreases the risk of a non-fatal myocardial infarction but increases the risk of bleeding and does not change the overall risk of death. Specifically over 5 years it decreased the risk of a cardiovascular event by 1 in 265 and increased the risk of bleeding by 1 in 210.
Aspirin appears to offer little benefit to those at lower risk of heart attack or stroke—for instance, those without a history of these events or with pre-existing disease.
Scientists surveyed 14,000 adults age 40 and older. About 23% of people without heart disease were taking a daily aspirin for prevention. Almost a quarter of these did so without a health care provider’s recommendation!
Nearly half of people age 70 and older who did not have heart disease reported using aspirin daily. So did a quarter of people with a history of stomach ulcers.
Aspirin inhibits COX enzymes which produce inflammation. Because of this, it slows the spread of cancers.
However, many large research studies have led to differing opinions on the effectiveness of daily aspirin in preventing or slowing cancer.
- Aspirin is thought to reduce the overall risk of both getting cancer and dying from cancer.This effect is particularly beneficial for colorectal cancer (CRC) but must be taken for at least 10–20 years to see this benefit. It may also slightly reduce the risk of endometrial cancer, breast cancer, and prostate cancer — Wikipedia
- A meta-analysis through 2019 found that daily aspirin reduces the risk of cancer of the colorectum, esophagus, and stomach. — Wikipedia.
- The ASPREE study, which enrolled healthy older individuals (median age, 74), demonstrated an increased risk of death in patients randomized to receive aspirin, driven primarily by a 31% increased risk of cancer mortality. This finding is in contrast to an individual patient data meta-analysis of primary and secondary prevention aspirin trials that demonstrated a 15% reduction in cancer mortality associated with aspirin use. While the reduction in cancer mortality emerged after at least 5 years of follow-up, this result was not replicated in the ASCEND trial that followed up 15 480 participants with diabetes for a mean of 7.4 years. The findings of this study suggest that the association of aspirin with cancer outcomes is neutral, with no suggestion of harm or benefit from the available current evidence. — JAMA
- Randomized and epidemiologic studies show that people—especially guys over 40 who don’t practice extreme sports and women over 50—who take a low-dose aspirin or more a day (there’s a benefit to doing so morning and night) see a 10–40% decrease in 9–11 types of cancers, including cancer of the breast, colon, esophagus, rectum, and more, and a 10–35% reduction in recurrent heart attacks or strokes. — Dr. Mike Roizen
- A 2018 Chinese study of more than 400,000 people found that a daily 80 mg aspirin over 7.7 years also significantly reduces the incidence of cancer of the liver, stomach, colon, rectum, lung, pancreas, and esophagus, and of leukemia. It didn’t find any benefit for multiple myeloma or cancer of the kidney, bladder, prostate, or breast, but other studies have found a significant decrease in breast cancer.
Adult aspirin tablets are produced in standard sizes, which vary slightly from country to country. Smaller doses are based on these standards, e.g., 75 mg and 81 mg tablets. The 81-milligram (11⁄4-grain) tablets are commonly called “baby aspirin”, because they were originally – but no longer – intended to be administered to infants and children. No medical significance occurs due to the slight difference in dosage between the 75 mg and the 81 mg tablets. The dose required for benefit appears to depend on a person’s weight. For those weighing less than 70 kilograms (150 lb), low dose is effective for preventing cardiovascular disease; for patients above this weight, higher doses are required.
Complicating the use of aspirin for prevention is the phenomenon of aspirin resistance. For people who are resistant, aspirin’s efficacy is reduced. Some authors have suggested testing regimens to identify people who are resistant to aspirin.
If your doctor says it’s okay, take an 81 mg non-coated aspirin twice a day with half a glass of warm fluid before and after… as long as you don’t do extreme sports, take recreational drugs or certain prescription meds, or have medical conditions such as uncontrolled liver or kidney disease that decrease the benefits of the aspirin or increase its risks. — Dr. Michael Roizen, CMO of the Cleveland Clinic.
Alternatively, you can get the benefits of aspirin by eating fruits, vegetables, herbs and spices. The aspirin phytonutrient salicylic acid isn’t just found in willow trees, but throughout the plant kingdom.. This explains why the active ingredient in aspirin is found normally in the bloodstream even in people not taking aspirin. The levels of aspirin in people who eat fruits and vegetables are significantly higher than the levels of those who don’t.
Foods that are high in salicylates include:
- Fruits – apples, cherries, oranges, strawberries
- Vegetables – asparagus, spinach, onions
- Herbs and spices — Red chili powder, paprika, and turmeric. Cumin is about 1 percent aspirin by weight. Eating a teaspoon of cumin is about 1 baby aspirin!
- Condiments – mustard, ketchup
- Drinks – coffee, tea, fruit juice
Side Effects and Adverse Interactions
One common adverse effect is an upset stomach. More significant side effects include stomach ulcers, stomach bleeding, and worsening asthma. Bleeding risk is greater among those who are older, drink alcohol, take other NSAIDs, or are on other blood thinners. Aspirin is not recommended in the last part of pregnancy. It is not generally recommended in children with infections because of the risk of Reye syndrome. High doses may result in ringing in the ears.
Salicylate sensitivity or intolerance is not as common as, say, lactose intolerance, but it can produce a more extreme reaction: some people experience asthma, hives, or inflammation. The most common symptoms are inflammation in the nose and gut, polyps, gas, and diarrhea. These symptoms are often mistaken for allergies.
This sensitivity is increased in those who have asthma, inflammatory bowel disease, leaky gut, or irritable bowel syndrome, which raises the question of whether avoiding salicylate can improve the symptoms of these conditions.
ConsumerLab has not yet done a study evaluating the different brands of acetylsalicylic acid.
The ASPREE study randomized 19,114 healthy people 70 or over (65 or over for African Americans and Hispanics) to receive either 100 milligrams of enteric-coated aspirin or placebo. After an average of almost five years, there was no significant difference in the rate of fatal coronary heart disease, heart attack, stroke, or hospitalization for heart failure. There was a significant 38% increase in major bleeding with aspirin, though the actual rates were low. The serious bleeding included bleeding into the head, which can lead to death or disability. Again, the actual rates were very low, but they are still a concern when thinking of the millions of patients to whom the ASPREE results apply.
Rates of dementia were also examined, and again, there was no benefit of aspirin. Quite unexpectedly, there was a significantly higher rate of death in the patients taking aspirin. This had not been seen in prior primary prevention trials of aspirin, so this isolated finding needs to be viewed cautiously. Still, with no benefits, increased bleeding, and higher mortality, at least in this population of older healthy people, aspirin should no longer be routinely recommended.
Another unexpected finding in ASPREE was a significantly higher rate of cancer-related death in the people randomized to aspirin. The prior thinking had been that aspirin might actually prevent colon cancer, though generally after many more years of being on aspirin. The ASPREE trial was terminated early due to lack of any apparent benefits. And even though five years is a relatively long period of follow-up, it may not have been long enough to find a benefit on cancer. Thus, the increase in cancer deaths may be a false finding. Nevertheless, the overall picture from this trial is not a compelling one for aspirin use for prevention of either cardiac or cancer deaths.
From Dr. Michael Roizen:
In the ARRIVE (Aspirin to Reduce Risk of Initial Vascular Events) study, of around 12,550 folks who were randomly assigned to the group of aspirin-takers or no-aspirin-takers, only 7,800 actually did what they were supposed to do! Among folks in the ARRIVE study who stuck with the prescribed dose of 100 mg aspirin daily… there was a 47% reduction in heart attacks!
Only when you figure in the large group of people who didn’t stick with the regimen (which is what the researchers did), you could conclude that aspirin isn’t effective or that the risks (bleeding, gastro troubles) are greater than the benefits.
Of those who followed the protocol, took the aspirin or didn’t, there was a 47% reduction in heart attacks if they took the aspirin (table 2 per protocol population), (significant) and a 19% reduction in all cardiovascular events—they needed more patients to make that finding statistically significant.
Of note, those who broke protocol and didn’t follow the group they were assigned had higher risk (by about 20% in those assigned to the aspirin group who didn’t take it at least 60% of the time).
This may be the most important point as rebound from irregular aspirin use has been shown to increase clotting risk in all studies I have read of that risk. People should either take aspirin or not. Taking it irregularly is hazardous. I’m not sure if our patients are more compliant than those in the study or not, but I suspect you (the person reading this) are very diligent in aspirin taking.
Those doubts were confirmed in three clinical trials that examined the risks and benefits of aspirin. One of these trials followed 19,114 healthy people ages 65 and up who had no previous cardiovascular events, for an average of 4.7 years. One group took a low dose of aspirin daily; the other group was given placebos.
During the study, 5.9% of the people taking aspirin died, and 5.2% taking the placebo died. The higher death rate in the first group was due mostly to cancer. “The increase in cancer deaths in study participants in the aspirin group was surprising, given prior studies suggesting aspirin use improved cancer outcomes,” study team member Leslie Ford of the National Cancer Institute said in a statement.
Here was a key finding: Significant bleeding — in the brain and in the gastrointestinal tract — occurred in 361 people (3.8%) on aspirin and in 265 (2.7%) taking the placebo, the researchers wrote in the New England Journal of Medicine. However, among the people taking aspirin, 448 experienced fatal or nonfatal heart attacks, strokes, or other cardiovascular events during the study, compared to 474 people in the placebo group — which the researchers determined as too close to declare a clear benefit for daily aspirin, especially given the bleeding risk.
- Aspirin (Wikipedia)
- Harvard Health on aspirin risk and proper usage: Aspirin for primary prevention of cardiovascular disease, part 2 – Harvard Health Blog
- NIH.Gov against daily aspirin: Millions Taking Aspirin Without Clear Benefit
- American Heart Association against daily aspirin: Why the ‘Daily Aspirin’ Hype Is Over | by Robert Roy Britt
- How to Get the Benefits of Aspirin Without the Risks
- The Risks and Benefits of Taking Low-Dose Aspirin
- The Foods with the Highest Aspirin Content
- JAMA: Association of Aspirin Use for Primary Prevention With Cardiovascular Events and Bleeding Events; A Systematic Review and Meta-analysis
- Dr. Mike Roizen
- Self-Hacked on Salicylate intolerance
This concludes today’s article. As your reward for reading, we recommend watching the amazing eight episode Netflix series Our Planet, narrated by David Attenborough. These creatures and places are the true wonders of our world.