The number in the headlines is 11. A study to be presented at the American Heart Association’s Scientific Sessions later this week found cardiac arrest was reported about 11 times more often for caffeine and stimulant products than for other FDA-regulated products, and the coverage turned that into risk. NBC News wrote that energy drinks are “linked to higher risk of cardiac arrest in young adults,” and US News headlined them a “heart-stopper.”
The study counted reports, not people, and the FDA says reports cannot measure risk.
What Was Counted
Sai Samayamanthula, a fourth-year medical student at the University of Virginia, and colleagues analyzed 28,345 reports from an FDA safety database covering 2017 to 2025, according to the Association’s release. Only 854 involved energy drinks or dietary supplements with caffeine or other stimulants. The other 27,491 involved products without them: soft drinks, meal-replacement shakes, protein bars, smoothies, vitamins.
That makes the products at issue 3.0 percent of the sample (854 divided by 28,345). The release does not give that share. The arithmetic is ours.
Cardiac arrest showed up about 11 times more often in the stimulant group, and heart attack about 4.5 times. About 45 percent of the reports linking the products to cardiovascular events involved adults 18 to 34.
The heat-map in the release says the age breakdown rests on 612 exposed reports with a known age. If those come from the 854, 242 reports carry no age at all.
It is an abstract, not a peer-reviewed paper, and the Association’s own release calls the findings preliminary.
Why 11 Is Not a Risk
A risk needs a denominator: how many people used the product, and how many of them had an event. This study has neither. Its denominator is reports, sitting on top of a market that passed $20 billion in sales in 2024, with no count of drinkers beside either figure.
The release captions its heat-map “Reporting Odds Ratios,” the standard way to compare how often an event appears in one pile of reports against another. That compares piles. It says nothing about how many people sit behind each one.
Here is a thought experiment, ours and not the study’s. Suppose two products carry the same real-world chance of a cardiac event, but one is in the news and the other is not. Doctors and families report the first product’s events and shrug at the second’s. The ratio comes out lopsided and the risk is identical.
The release concedes the structure. Reports were voluntary, it says, and nobody knows how many people used these products without trouble, or how many had an event and never reported it.
The FDA Already Said This
The release names its source only as “a government safety database.” FDA’s system for reports about foods and dietary supplements is the Human Foods Complaint System, and we cannot say that is the one the team used.
We can say what FDA tells everyone who reads it. Its reports “cannot be used to estimate incidence (occurrence rate) or to estimate risk,” and the information in them has not been “scientifically or otherwise verified as to a cause and effect relationship.”
Attention Produces Reports
Voluntary systems respond to the news. A release produces headlines, headlines produce reports, and the next analysis finds more of them. Pharmacovigilance researchers call it stimulated reporting.
That is the second-order problem with reading a count as a rate. Every alarming headline raises the next count, and nobody has to be careless for it to happen.
The Part That Holds Up
The direction fits what the Association already says. Its scientific statement on caffeine, published July 20 in Circulation, says evidence from caffeinated coffee “consumed in normal amounts should not be extrapolated to caffeinated energy drinks,” and that case reports “have generally suggested harm, primarily related to arrhythmias.”
Gregory Marcus, who chaired that statement and was not involved in the new study, said the study “does not prove that caffeine products cause these events.” He also said it “raises concerns that products with very high amounts of caffeine may be harmful to the cardiovascular system.”
Samayamanthula’s own read has two halves. For occasional use: “For many healthy people, if these products are consumed occasionally, the risk is probably small.” For regular use, he says people “can quickly exceed the recommended daily limit for caffeine.”
What We Think, and What to Ask For
We think the headlines got the study wrong and the concern right. The study is a smoke alarm. It tells you to look, and it cannot tell you how big the fire is.
The right ask is Samayamanthula’s own, “more systematic safety monitoring.” In practice that means a denominator, units sold and users, published next to every count so a rate can be computed. Until then, the practical anchor is the Association’s line that up to 400 milligrams of caffeine a day, about four 8-ounce cups of black coffee, is generally safe for most adults. The researchers say some energy drinks carry up to three times the caffeine of black coffee per ounce and some pre-workout supplements more than 12 times, so read the label. A reader with a heart condition or a stimulant prescription should ask a doctor.