Vitamin K Deficiency and Associated Bleeding in Infants

Vitamin K is essential for procoagulant factors II, VII, IX, and X. Newborns can be deficient in vitamin K because of low transplacental transfer, limited gut synthesis, low breast milk concentration, and poor gastrointestinal absorption. Vitamin K deficiency (VKD) is classified into early VKD (occurring within 24 hours of birth and primarily caused by maternal medications¹), classical VKD (occurring between 2 days and 1 week of life and often presenting as bruising or umbilical bleeding), and late VKD (occurring between ages 1 week and 6 months in breastfed children or those unable to absorb vitamin K). Late VKD carries a 30% to 60% risk of intracranial hemorrhage, which can result in permanent brain damage, seizures, or death.¹

Since 1961, the American Academy of Pediatrics has recommended that all newborns receive a single intramuscular dose of vitamin K, which reduces the rate of late vitamin K–deficient bleeding (VKDB, formerly called hemorrhagic disease of the newborn) by 98%.² However, amid growing public skepticism, parents are increasingly refusing vitamin K injections at birth.³ According to one study, between 2017 and 2024, the proportion of newborns not receiving intramuscular vitamin K increased from 2.9% to 5.2%.³ A Swedish study found that nonreceipt of vitamin K was associated with bleeding epsiodes.⁴ Whether the increase in vitamin K refusal has been accompanied by a higher incidence of VKD or VKDB in the US is unknown. This study used a large national database of integrated electronic health record data to explore whether the incidence of VKD and VKDB changed between 2017 and 2025.

Methods

Data were obtained from Cosmos,⁵ which draws electronic health record data from health systems using Epic, including more than 2300 hospitals and 50 000 outpatient settings. This cross-sectional study used Cosmos records for all US infants aged 0 to 6 months born at 35 weeks’ gestation or later who received care between January 1, 2017, and December 31, 2025. Outcomes included the first diagnosis of VKD or VKDB as well as intracranial or intracerebral hemorrhages (eTable in Supplement 1). Diagnoses included those within the problem list or during an encounter, admission, or billing occurrence. Incidence rates per 100 000 infants with 95% Wald CIs were reported. This study was exempted from review and informed consent by the Virginia Commonwealth University’s institutional review board because it used deidentified data.

Results

Between 2017 and 2025, 11 000 782 infants aged 0 to 6 months met inclusion criteria; 5 614 663 (51.0%) were male and 3 410 358 (31.0%) were publicly insured. During the study period, 2151 were diagnosed with VKD and 5217 developed VKDB (Table). Between 2017 and 2025, the percentage of newborns who received injectable vitamin K decreased from 97.7% to 95.0%, and the rate of VKD and VKDB at ages 0 to 6 months increased by 215.7% (from 11.8 [95% CI, 9.4-14.2] to 37.3 [95% CI, 34.4-40.3] per 100 000) and 347.1% (from 24.0 [95% CI, 20.6-27.4] to 107.4 [95% CI, 102.4-112.4] per 100 000), respectively (Figure). A total of 61.8% of infants with VKD and 87.8% of those with VKDB were diagnosed within the first week of life. Only 39.7% and 19.2% of infants diagnosed with VKD and VKDB, respectively, received vitamin K. Of those with VKD and VKDB, 6.9% and 2.4%, respectively, had a diagnosis of intracranial or intracerebral hemorrhage.

Discussion

In this study of more than 11 million infants in the US, vitamin K supplementation decreased and diagnoses of VKD and VKDB increased between 2017 and 2025. Although association does not prove causality, the data raise concerns about increased parental rejection of vitamin K injections and potential harm to infants. Intracranial hemorrhages, in particular, can have grave and lifelong consequences for infants. Increases in VKD and VKDB—peaking in 2025—occur against the backdrop of eroding trust in public health in the wake of the COVID-19 pandemic, increasing vaccine hesitancy, and growing parental unease about interventions in newborns.^6,7 As with childhood immunizations, vitamin K prophylaxis may be a victim of its own success⁸; the rarity of VKDB may leave today’s families largely unaware of its grave consequences.

In countries such as France, Germany, the Netherlands, Switzerland, and Canada, oral vitamin K is offered either routinely or alternatively to intramuscular vitamin K.⁹ Although the oral form can be less effective in preventing late VKD,¹ a harm-reduction approach that offers oral vitamin K as a second-line alternative may be warranted in the US if rejection of injectable vitamin K continues 

Replacing dairy products w/unfortified plant-based alternatives = deficiencies in nutrients

Replacing dairy products, even partially, with unfortified plant-based alternatives may lead to a deficiency in vital nutrients, a new study from the University of Surrey reports. Mandatory fortification of plant-based alternatives and other foods, including bread, could lessen the risk of deficiencies, particularly iodine deficiency. 

In the first study of its kind in the United Kingdom, researchers from Surrey, in collaboration with colleagues from Queen’s University Belfast, investigated the impact of replacing milk, yoghurt and cheese with commercially available plant-based alternatives on an individual’s micronutrient intake.  

The team used data, from the National Diet and Nutrition Survey, from over 3,500 individuals, aged between 18 months and 100 years old. They then used a novel modelling technique to assess the impact of replacing dairy products with plant-based alternatives on four essential micronutrients found in dairy products – iodine, calcium, riboflavin and vitamin B12.  

Dr Katie Nicol, co-author of the study and a Research Fellow at the University of Surrey, said: 

“With the growing need to address environmental sustainability, many dietary recommendations are focused on plant-based diets and the reduced intake of animal products.  

“With the rise in plant-based alternative foods, we need to know whether they are like-for-like replacements for the micronutrients that are found in dairy products.  This is particularly important for vulnerable groups, including young children and adolescent females, who are more likely to be deficient in certain micronutrients, which could affect their overall health.”  

Researchers found that even modest replacements of dairy intake with plant-based dairy alternatives led to marked declines in all four micronutrients, with iodine in particular being the most sensitive to replacements. For example, replacing just 20 to 35 per cent of dairy products with plant-based dietary alternatives, under current market fortification levels, increased iodine inadequacy among adolescent females from 54 to 65 per cent and from 32 to 42 per cent in women aged 19-49 years old. At full replacement, the prevalence of iodine inadequacy rose to 80 per cent in adolescent females and 72 per cent in adolescent males.  

Dr Sarah Bath, Associate Professor at the University of Surrey, and lead author said: 

“The UK is particularly vulnerable to iodine insufficiency due to a lack of an iodine fortification policy such as universal salt iodisation, which many other countries have.   

“People may also be unaware of the importance of iodine, which is needed to make thyroid hormones to regulate our metabolism, support healthy growth and brain development. Iodine is particularly important during, pregnancy, when the requirement increases, but it is also essential prior to pregnancy to ensure that stores are optimised. People are also unaware that dairy products are a major source of iodine, particularly in the UK, and that plant-based alternatives, unless fortified, have a very low iodine content.”  

Researchers also examined the impact of mandatory fortification of plant-based dairy alternatives with micronutrients as a potential way to prevent deficiencies. It was found that such fortification prevented declines in micronutrient intake when dairy products were replaced, although levels of iodine remained inadequate in 59 per cent of adolescent females. However, iodine- fortified bread was found to improve iodine intake, reducing inadequacy in adolescent females to 37 per cent.  

The results suggest that the most effective strategy in reducing iodine inadequacy is to combine mandatory fortification of plant-based dairy alternatives with iodine-fortified bread. 

Dr Nicol concluded: 

“Nutrition policy must evolve in tandem with environmental targets however it is important that shifts towards more sustainable diets do not compromise on public health. Fortification of foods is one way that this could be achieved however government policy is needed to make this happen.” 

Speaking further on the research, Dr Anne Nugent from the School of Biological Sciences at Queen’s University Belfast said:  

“During the analysis, we first identified all foods and recipes containing dairy produce (milk, cheese and yogurt) in the national food survey for the UK, the National Diet and Nutrition Survey. Next, we conducted a series of replacement scenarios whereby we substituted the dairy present with an equal weight of plant based dairy alternatives. As the nutrient composition of dairy alternatives available on our supermarket shelves can vary, we also applied a condition to make sure that every dairy alternative we had identified in our previous market survey had an equal chance of selection. The last step was to examine the impact on dietary intakes of key nutrients following either the reduction or removal of dairy from the diet, replacing it with the dairy alternatives as above, and asking whether a series of fortification options could mitigate against any shortfalls in intake while avoid situations of excess.” 

This study was published in Lancet Planetary Health 

Cannabis involved in most substance-related emergency visits among teens, young adults

 

A large national study analyzing emergency department visits and hospitalizations related to alcohol or cannabis use across the U.S. has found diverging age patterns: Among people who presented to the hospital for a substance-related problem, cannabis was involved in the majority of visits by adolescents and young adults, while alcohol predominated among older adults.

Led by researchers at Washington University School of Medicine in St. Louis, the study appears Nov. 4 in The American Journal of Psychiatry.

Better awareness of changing patterns of harm from these substances could help clarify the risks involved in using them, according to the investigators, led by Kevin Y. Xu, MD, an assistant professor of psychiatry at WashU Medicine.

For example, the risks of cannabis use are often oversimplified and underestimated in popular media, according to Xu, especially considering the increasing potency of cannabis products readily available for purchase. The new study could help doctors provide better, more nuanced and individualized information to their patients and help them make more informed decisions around the use of alcohol and cannabis.

“In general, we have seen that cannabis use is trending up and alcohol use is trending down; but until now, we haven’t had high-quality data tracking what kind of use is causing immediate harm — emergency room visits and hospitalizations,” Xu said. “Understanding age differences in high-risk use is critical for being able to offer effective and meaningful care for people at different life stages.”

The researchers analyzed de-identified patient data from large health insurance databases, including commercial insurance and Medicaid. The analysis included more than 1.3 million individuals ages 16–64 who had at least one substance-related emergency care encounter between January 2016 and December 2023. The total number of substance-related encounters in the dataset exceeded 5 million. The data included ER visits related to opioids, stimulants and other addictive substances, along with alcohol and cannabis. The data were analyzed by age group: 16–18, 19–24, 25–34, 35–44, 45–54 and 55–64.

Shifts in substance harms by age

Among adolescents ages 16–18 who had a substance-related emergency visit or hospitalization, 84% had at least one encounter involving cannabis — the highest of any age group — compared with 19% among adults ages 55–64.

Young adults between 19 and 24 years old had the greatest increase in the proportion of encounters involving cannabis over the eight years of the study — approximately 1.8 percentage points per year. The proportion of teen encounters involving cannabis rose by about 0.8 percentage points per year over the study period, and older age groups changed very little.

Xu noted that the increased potency of cannabis products available in recent years can make it easy to consume far more THC, the psychoactive ingredient in cannabis, than in the past. One recent study suggested that cannabis use disorder becomes more likely with use above roughly 40 milligrams of THC per week in adults and 30 milligrams per week in adolescents.

According to Xu, the high potency of cannabis products poses particular risks for adolescents and young adults, who are going through critical periods of brain development. Heavy adolescent use has also been associated with increased risk of psychotic symptoms, although most people who use cannabis do not experience these problems.

While many people consume cannabis regularly without needing emergency care, the study found concerning increases in cannabis-related hospital admissions involving psychosis and severe vomiting among younger people.

Notably, when the researchers looked only at hospitalizations where cannabis was the primary reason for admission, the trend among adolescents declined — suggesting that while cannabis is increasingly present in acute care encounters, it may not be the sole driver of hospitalization, which often involved other substances or co-occurring psychiatric conditions.

The study counted any emergency visit or hospitalization where cannabis appeared anywhere in the diagnosis list, so the visit itself could have been for something else entirely, such as injury in a car accident, a psychiatric crisis or an unrelated medical problem. Nearly half of cannabis-related encounters in the study also involved at least one other substance, though the researchers did not analyze which specific conditions were listed as the main reason for admission.

Despite overall downward trends in alcohol use in the U.S. over the study’s time period, the results showed that emergency care and hospital admissions due to alcohol use remained high and tended to increase with age.

Among adolescents, 33% had an alcohol-related encounter, and this percentage rose steadily with each older age group.

Among the oldest group, ages 55–64 years, 70% had an alcohol-related encounter.

The steepest increase of any trend in the study was in alcohol as the primary reason for hospitalization among adults ages 25–34, which rose 3.6 percentage points per year.

The research team included first author Jacob T. Steinle, MD, now a clinical fellow in the department of psychiatry at Mass General Brigham. Steinle initiated and led the study as a resident in psychiatry at WashU Medicine along with co-author Suraj Shankar, MD, now a fourth-year psychiatry resident. Both were able to contribute to the study through the Psychiatry Residency Research Education Program (PRREP), which is funded, in part, by the National Institutes of Health (NIH) and co-led by Nuri B. Farber, MD, a professor of psychiatry; and Alecia Vogel, MD, PhD, an assistant professor of psychiatry.

“There are many lingering questions to answer, especially about understanding why substance use-related harm patterns vary so greatly across the lifespan,” Steinle said. “We plan to continue our research, building upon these foundations so that clinicians can better inform each individual patient and the public at large around the risks of substance use.”

A consistent sleep schedule is important to heart health

 

Research Highlights:

• Sleep regularity may be a critical factor for heart health, researchers said.
• Having highly inconsistent bedtimes or varying sleep duration from night to night was linked to a higher risk of heart attack, stroke, heart failure and other cardiovascular events, according to data analyzed from more than 1 million nights of sleep.
• Note: The study featured in this news release is a research abstract. Abstracts presented at American Heart Association’s scientific meetings are not peer-reviewed, and the findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.

Maintaining a consistent sleep schedule may be an important factor to consider for protecting the heart, according to new, independent, preliminary research to be presented at the American Heart Association’s Scientific Sessions 2026. The meeting, Nov. 6–9, in Chicago, is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in heart and stroke science.

 “While we often focus on getting a full eight hours of sleep every night, having a regular sleep schedule — consistent bedtimes, wake times, and sleep duration from night to night is a practical, actionable step anyone can take that may help protect their heart and blood vessels,” said lead researcher Nguyen Minh Tuan Viet, M.D., Ph.D., a neuroscientist and postdoctoral research fellow at Boston Children’s Hospital and Harvard Medical School.

Researchers analyzed sleep data from more than 10,000 adults who wore an activity tracking device as part of the National Institutes of Health’s “All of Us” Research Program.

What did the analysis track?

• Sleep quantity – how many total hours a person slept each night;
• Sleep quality – how much of the night was spent in light, deep and REM sleep, and how long a person was awake after first falling asleep;
• Sleep regularity – how sleep duration, bedtime and wake-up time changed from night to night;
• Sleep timing – the usual times a person fell asleep and woke up, and the midpoint between them, which is related to chronotype, or a person’s natural tendency to be a ‘night owl’ or an ‘early bird’; and
• Sleep cycles - the number of sleep cycles completed each night (the interval from the end of the one REM period to the end of the next, including the light and deep stages in between) and the duration of each cycle.

What were the main findings?

• Changes in sleep timing from night to night over about a six-month period were linked to a 20% to 23% higher risk of serious heart events, including heart attack, stroke and heart failure.
• Each 29-minute increase in how much a person's sleep length varied from night to night was associated with a 24% higher risk of the combined cardiovascular outcome, including a 29% higher risk of having a disease of the heart muscle, which leaves the heart unable to pump enough blood through the body, and a 20% higher risk of heart failure.
• Having a greater number of complete sleep cycles each night was associated with a 28% lower risk of atrial arrhythmia, a common type of irregular heartbeat.
• An unusually long sleep cycle was linked to a 55% higher risk of heart attack or stroke.

Irregular sleep was linked to a much wider range of heart conditions than expected, Viet noted.

“Sleep irregularity is often due to weekends – we get to sleep a little bit later on a Friday night; or people have shift work. This may not be good for your heart health,” Viet said. “Sometimes the quality of sleep is something we cannot control. But the regularity, consistent bedtimes throughout the week and waking up at the same time every morning, is something some people can control.”

The study findings should be interpreted cautiously, said American Heart Association volunteer expert Marie-Pierre St-Onge, Ph.D., C.C.S.H., FAHA, who chaired the Association’s 2025 scientific statement: Multidimensional Sleep Health: Definitions and Implications for Cardiometabolic Health and was not involved in this study.

”This study highlights another potential important sleep characteristic to consider for heart health, which adds to the body of research we currently have on sleep duration,” said St-Onge, a professor of nutritional medicine and director of the Center of Excellence for Sleep & Circadian Research at Columbia University Irving Medical Center in New York City. “However, contrary to the years of research showing how insufficient sleep affects cardiovascular risk factors, we are still lacking the data to support a causal, independent impact of sleep regularity on cardiovascular disease risk. This study should prompt scientists to further evaluate links between sleep regularity and cardiovascular disease, so that we can make the same recommendations for regularity that we can for duration.

“Sleep duration and regularity often interact in their relation to heart disease risk. This abstract notes an additional tool to consider when working on improving sleep. Adopting stable sleep schedules can be helpful to achieve better sleep duration as well.”

Study details, background, design and limitations:

• Researchers pieced together data for more than 1 million nights of sleep from 10,362 adults participating in the National Institutes of Health’s “All of Us” Research Program.
• Among study participants, average age 53, about 69% were women, and 81.6% self-reported as white adults, 4.6% as Black adults, 3.1% as Asian adults and 10.7% as another race or did not report race. None had heart or metabolic disease at the start of the study.
• Sleep was characterized over a roughly a 6-month baseline window, and participants were then followed for a median of 3.7 years for cardiovascular events.
• The analysis was adjusted for multiple factors, including age, sex, race, education, income, smoking, alcohol use, cancer and mental health conditions.
• Study limitations include that, as an observational study, it could not establish cause and effect. In addition, sleep stages were measured with wearable devices while participants slept at home rather than brain-monitoring equipment in a sleep lab, the standard practice for sleep studies.

Co-authors, disclosures and funding sources are listed in the abstract.

Statements and conclusions of studies that are presented at the American Heart Association’s scientific meetings are solely those of the study authors and do not necessarily reflect the Association’s policy or position. The Association makes no representation or guarantee as to their accuracy or reliability. Abstracts presented at the Association’s scientific meetings are not peer-reviewed, rather, they are curated by independent review panels and are considered based on the potential to add to the diversity of scientific issues and views discussed at the meeting. The findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.

The Association receives more than 85% of its revenue from sources other than corporations. These sources include contributions from individuals, foundations and estates, as well as investment earnings and revenue from the sale of our educational materials. Corporations (including pharmaceutical, device manufacturers and other companies) also make donations to the Association. The Association has strict policies to prevent any donations from influencing its science content and policy positions. Overall financial information is available here.

Additional Resources:

• Multimedia, including video interview clips with American Heart Association volunteer expert, American Heart Association volunteer expert, Marie-Pierre St-Onge, Ph.D., C.C.S.H., FAHA, is available on the right column of the release link.
• Spanish news release
• Link to abstract; and the American Heart Association’s Scientific Sessions 2026 Online Program Planner
• American Heart Association news release: Body clocks matter for heart health (Oct. 2025)
• American Heart Association news release: Sleep matters: duration, timing, quality and more may affect cardiovascular disease risk (April 2025)
• American Heart Association news release: Erratic sleep patterns linked to elevated blood pressure in teens with extra belly weight (March 2023)
• American Heart Association news release: Irregular sleeping habits may increase risk of atherosclerosis in older adults (Feb. 2023)
• American Heart Association health information: American Heart Association adds sleep to cardiovascular health checklist (June 2022)
• About Scientific Sessions 2026
• For more news at the American Heart Association’s Scientific Sessions 2026, follow us on X @HeartNews, #ScientificSessions26

Energy drinks, stimulant products linked to cardiac arrest, heart attack in young adults

 

Research Highlights:

• In a review of more than 28,000 adverse-event reports to the FDA over eight years, 2017-2025, caffeinated energy drinks and stimulant supplements were linked to serious heart conditions far more often than other products.
• Products containing caffeine or other stimulants were associated with higher reporting of cardiac arrest and heart attack, particularly for adults between the ages of 18 and 34, a group not usually considered at high risk for cardiovascular events.
• More studies are needed to understand the relationship between caffeinated products and cardiovascular conditions, as well as systematic safety monitoring of these products, researchers said.
• Note: The study featured in this news release is a research abstract. Abstracts presented at American Heart Association’s scientific meetings are not peer-reviewed, and the findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.

Caffeinated energy drinks and stimulant supplements appeared disproportionately more often in FDA reports of serious cardiovascular events, including cardiac arrest and heart attacks, especially among adults ages 18 to 34, according to new, independent, preliminary research to be presented at the American Heart Association’s Scientific Sessions 2026. The meeting, Nov. 6-9, in Chicago, is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in cardiovascular science.

Sales of caffeinated energy drinks have more than doubled over the past decade, reaching over $20 billion in 2024. While research on energy drinks and other stimulant-containing supplements is limited, available evidence indicates that high doses of caffeine are associated with cardiovascular harm. Healthcare professionals have also described cases of arrhythmias (irregular heart rhythms) or sudden cardiac death in people who had consumed these products, many of them young adults with no known heart disease risks.  

According to a 2026 American Heart Association Scientific Statement on caffeine and cardiovascular disease, consuming up to 400 mg of caffeine per day (the equivalent of up to 5, 8-ounce cups of regular black caffeinated coffee) is generally safe for most adults. Compared with brewed coffee, some energy drinks contain as much as 3 times more caffeine per fluid ounce, and some pre-workout supplements contain more than 12 times as much caffeine per fluid ounce. Since the U.S. Federal Drug Administration (FDA) regulates energy drinks and stimulant supplements as foods or dietary supplements rather than as medications, these products do not go through the same premarket safety testing required for medications.

“These products are marketed as everyday pick-me-ups and sold next to soda and bottled water, so most people assume they carry no real risk,” said study author Sai Samayamanthula, a fourth-year medical student at the University of Virginia School of Medicine in Charlottesville, Virginia. “For many healthy people, if these products are consumed occasionally, the risk is probably small. However, individuals who consume energy drinks or other stimulant-containing supplements regularly can quickly exceed the recommended daily limit for caffeine, so it’s important for people to know that there may be a risk of cardiovascular harm with these products.”

Researchers analyzed data from a government safety database to compare reports of adverse reactions related to products containing caffeine and other stimulants compared to FDA-regulated foods and dietary supplements such as soft drinks, meal replacement shakes, protein bars, smoothies and vitamins. The data included reports from people ages 13 or older between 2017 and 2025.

What are the key findings of the study’s analysis?

• Cardiac arrest was reported about 11 times more often in connection with caffeine- and stimulant-containing products vs. products without these ingredients.
• Reports involving energy drinks and supplements were about 4.5 times more likely to include heart attacks and four times more likely to include ventricular arrhythmias (abnormal rhythm in the heart’s lower pumping chambers) or heart palpitations.
• Similar patterns existed between consumption of caffeinated energy drinks and stimulant supplements and reports of other heart conditions, including elevated heart rate (nearly 3 times more often), chest pain (2.71 times more often) and fainting (about 2 times more often).
• About 45% of reports linking caffeine- and stimulant-containing products to cardiovascular events involved adults ages 18 to 34.
• Similar patterns were observed in reports involving both men and women.

“Our findings support the case for more systematic safety monitoring of caffeine- and stimulant-containing products. In addition, healthcare professionals should remember to ask their younger patients who have palpitations, chest pain or fainting spells if they recently or regularly consume these products,” Samayamanthula said.

Researchers don’t fully understand why the association between caffeine and stimulant products with heart events was so frequent among young adults. The pattern of reports among young adults may reflect how often they consume caffeine- and stimulant-containing products; when or how people tend to consume them (for example, consuming them before intense exercise or mixing them with alcohol or drugs); and/or if they may have an undiagnosed heart condition.

“This study raises concerns that products with very high amounts of caffeine may be harmful to the cardiovascular system,” said Gregory M. Marcus, M.D., M.A.S., FAHA, chair of the 2026 American Heart Association scientific statement on caffeine and cardiovascular disease. “Although there are biological reasons why that connection could be possible, the study does not prove that caffeine products cause these events, because other factors may have influenced the results found in this analysis. More research is needed to understand whether these stimulant products are truly responsible for the reported heart-related events.” Marcus, who was not involved in this study, is also a professor of medicine at the University of California, San Francisco School of Medicine and the associate chief of the Cardiology for Research program at the University of California, San Francisco Health.

What are the details, background, design and limitations of the study?

• Researchers analyzed 28,345 reports made to an FDA safety database regarding possible adverse events from 2017 to 2025. Of those, 854 reports mentioned caffeine or stimulant-containing energy drinks or dietary supplements. Researchers compared these with 27,491 reports about products without caffeine or other stimulants.
• Reports categorized as being related to caffeine and stimulant products included those with these types of ingredients: caffeine, methylxanthines (theobromine, guarana, yerba mate, green tea/coffee extracts) and sympathomimetics (synephrine, yohimbine, ephedra, DMAA, higenamine).
• Researchers grouped products by ingredient not by brand, so the findings point to types of products rather than any single brand or product.
• The study authors emphasized that the analysis’ design only identified associations between caffeinated products and cardiac events voluntarily self-reported to the FDA; the results cannot prove that these products directly caused any heart conditions or events.
• In addition, since the reports of adverse events associated with caffeinated products were submitted by consumers/the general public, doctors and manufacturers who voluntarily told the FDA about these events, it is unknown how many people consumed these products without experiencing any cardiac events, or how many people experienced cardiac events and did not report it.

Co-authors, disclosures and funding sources are listed in the abstract.

Statements and conclusions of studies that are presented at the American Heart Association’s scientific meetings are solely those of the study authors and do not necessarily reflect the Association’s policy or position. The Association makes no representation or guarantee as to their accuracy or reliability. Abstracts presented at the Association’s scientific meetings are not peer-reviewed, rather, they are curated by independent review panels and are considered based on the potential to add to the diversity of scientific issues and views discussed at the meeting. The findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.

The Association receives more than 85% of its revenue from sources other than corporations. These sources include contributions from individuals, foundations and estates, as well as investment earnings and revenue from the sale of our educational materials. Corporations (including pharmaceutical, device manufacturers and other companies) also make donations to the Association. The Association has strict policies to prevent any donations from influencing its science content and policy positions. Overall financial information is available here.

Additional Resources:

• Multimedia, including video interview clips with American Heart Association volunteer expert, Gregory M. Marcus, M.D., M.A.S., FAHA, is available on the right column of the release link
• Link to abstract and the American Heart Association’s Scientific Sessions 2026 Online Program Planner
• American Heart Association Scientific Statement news release: Coffee and heart health: How many cups of caffeinated coffee are safe to drink each day? (July 2026)
• American Heart Association news release: Top Health Experts Release New Drink Recommendations for Kids and Teens’ Overall Health (Jan. 2025)
• American Heart Association news release: Drinking 2 or more cups of coffee daily may double risk of heart death in people with severe hypertension (Dec. 2022)
• American Heart Association news release: Drinking caffeinated coffee has both beneficial and harmful short-term health effects (Nov. 2021)
• American Heart Association Fact Sheet: Caffeine and Cardiovascular Disease
• About Scientific Sessions 2026
• For more news at the American Heart Association’s Scientific Sessions 2026, follow us on X @HeartNews, #ScientificSessions26

Modern hormone replacement therapy not linked to heart disease risk

Research Highlights:

• A large, long-term study of over 52,000 women in Israel found that among women ages 45 to 59, initiation of contemporary hormone replacement therapy did not increase the risk of heart attack, stroke, blood clots or death.
• The independent, preliminary study had an average follow-up of 12 years and included hormone replacement therapy in oral, transdermal (patch) or gel form.
• Note: The study featured in this news release is a research abstract. Abstracts presented at American Heart Association’s scientific meetings are not peer-reviewed, and the findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.

 Contemporary hormone replacement therapy (HRT) was not associated with an increased risk for heart attack, stroke, blood clots or death among women ages 45 to 59, according to a large, long-term study of over 52,000 women in Israel. The findings from this new, independent, preliminary research will be presented at the American Heart Association’s Scientific Sessions 2026. The meeting, Nov. 6-9, in Chicago, is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in cardiovascular science.

“Concerns that hormone replacement therapy may affect the heart is one of the most common reasons women decline hormone therapy to manage menopause symptoms, and why some healthcare professionals may hesitate to offer it,” said lead study researcher Ronen Arbel, Ph.D., a researcher in the community medical services division of Clalit Health Services in Tel Aviv, Israel, and a researcher with Sapir College’s Maximizing Health Outcomes Research Lab in Sderot, Israel.

Previous randomized trials found associations between HRT and cardiovascular harm. However, results were mixed, and much of that evidence was from studies with older HRT formulations that are no longer commonly used, with higher doses and in women who started on HRT long after menopause. Current clinical guidelines from the American College of Obstetricians and Gynecologists recommend starting HRT within 10 years of menopause onset and before age 60. In November 2025, the FDA removed the “black box” warnings from HRT products after a comprehensive review of current scientific data indicating that HRT is not associated with increased risk of cardiovascular disease, breast cancer or dementia.

“For many women, menopause symptoms can significantly affect their quality of life, yet questions about the cardiovascular safety of hormone therapy have remained,” said Stacey E. Rosen, M.D., FAHA, an expert in women’s heart health and past volunteer president of the American Heart Association (2025-2026). “This large, long-term study adds to growing evidence that today's hormone therapy options may not increase the risk of heart disease, stroke or blood clots for healthy women who begin treatment around the time of menopause. These findings can help women and their healthcare teams have more informed conversations about the benefits and risks of treatment based on their individual health needs.” Rosen, who was not involved in this study, is also executive director of the Katz Institute for Women’s Health and senior vice president of women’s health at Northwell Health in New York City.

The study to be presented at the American Heart Association’s Scientific Sessions evaluated data for over 52,000 women, ages 45 to 59, to assess whether the use of contemporary HRT is associated with an increased risk of atherosclerotic cardiovascular disease, venous thromboembolism (blood clots) or premature death (before age 80) in women who had not been previously diagnosed with cardiovascular disease.

After an average of 12 years of follow-up, the health outcomes were similar between the two groups of women, meaning the group who started taking HRT did not show an increase in cardiovascular events or early death compared to the group that was not taking HRT.

What are the study’s main findings?

• 2,311 women in the HRT group (4.4%) experienced a heart attack, stroke or had some type of related heart disease vs. 2,383 (4.6%) of the women in the no-HRT group.
• Death before age 80 occurred in 659 (1.3%) of the women taking HRT vs. 653 (1.2%) of the women not on any form of HRT.
• 0.33% of women in both groups experienced a blood clot (174 women in the group taking HRT vs. 175 from the group that did not take HRT).
• The results were similar across all HRT formulations and administration routes (oral, patch or gel).

“Our results indicate that, for women in their mid-forties to late fifties with no history of heart disease or blood clots, the currently available hormone therapies prescribed to manage menopause symptoms do not appear to raise the risk of heart attack, stroke, clots or early death, even after long-term use,” Arbel said.

Study details, background and design:

• Using records from Clalit Health Services in Israel, researchers evaluated health data for 52,330 women between 45–59 years old with no history of heart disease, blood clots or cancer.
• Half of the women had started HRT, primarily via oral and/or transdermal (patch) methods, while the other half had recently visited a gynecologist but did not begin HRT. The women in the second group did not take HRT throughout the study period.
• The researchers matched the women in both groups by age, BMI, cardiometabolic risk factors (blood pressure, cholesterol levels and whether they had been diagnosed with Type 1 or Type 2 diabetes), smoking status and socioeconomic status and compared their health data.
• Researchers evaluated the health records of both groups for up to 23 years, with an average follow-up period of 12 years, to compare the rate of cardiovascular disease, specifically heart attack, stroke and blood clots, as well as death from any cause before age 80.

The research has several limitations. It is an observational study, so it cannot prove a direct connection between HRT and heart health. The researchers also noted that there may be other differences among the women taking HRT vs. those who do not that was not available or detailed in the health records, such as differences in exercise, diet, other health conditions and severity of menopause symptoms. Additionally, the study grouped women by the first type of hormone therapy they used and did not include any changes in HRT type or formulation throughout the follow-up period.

Co-authors, disclosures and funding sources are listed in the abstract.

Statements and conclusions of studies that are presented at the American Heart Association’s scientific meetings are solely those of the study authors and do not necessarily reflect the Association’s policy or position. The Association makes no representation or guarantee as to their accuracy or reliability. Abstracts presented at the Association’s scientific meetings are not peer-reviewed, rather, they are curated by independent review panels and are considered based on the potential to add to the diversity of scientific issues and views discussed at the meeting. The findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.

The Association receives more than 85% of its revenue from sources other than corporations. These sources include contributions from individuals, foundations and estates, as well as investment earnings and revenue from the sale of our educational materials. Corporations (including pharmaceutical, device manufacturers and other companies) also make donations to the Association. The Association has strict policies to prevent any donations from influencing its science content and policy positions. Overall financial information is available here.

Additional Resources:

• Multimedia, including video interview clips with American Heart Association past volunteer President, Stacey E. Rosen, M.D., FAHA,  is available on the right column of the release link.
• Spanish news release
• Link to abstract and the American Heart Association’s Scientific Sessions 2026 Online Program Planner
• American Heart Association news release: Perimenopause may offer a “window of opportunity” for heart disease prevention in women (May 2026)
• American Heart Association Scientific Statement: Menopause Transition and Cardiovascular Disease Risk: Implications for Timing of Early Prevention (March 2020)
• American Heart Association health information: Menopause and Cardiovascular Risk
• About Scientific Sessions 2026
• For more news at the American Heart Association’s Scientific Sessions 2026, follow us on X @HeartNews, #ScientificSessions26

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Cannabis use linked to an increased risk of cardiovascular disease, especially strokes

 

Research Highlights:

• New research indicates that cannabis use appears to be linked to an increased risk of cardiovascular disease, especially stroke.
• The findings are from an analysis of almost half a million U.S. adults who responded to telephone surveys for the Behavioral Risk Factor Surveillance System. This was limited to jurisdictions with available cannabis-use information between 2020 and 2024.
• The findings suggest considering cannabis use when assessing the risk of cardiovascular disease since its use is increasing. It is important to include this information in counseling patients about heart disease and stroke prevention, researchers said.
• Note: The study featured in this news release is a research abstract. Abstracts presented at the American Heart Association’s scientific meetings are not peer-reviewed, and the findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.

Cannabis use, including marijuana, appears to be linked with increased cardiovascular risk, especially for stroke, making it an important consideration for heart disease and stroke prevention and counseling, according to independent, new preliminary research to be presented at the American Heart Association’s Scientific Sessions 2026. The meeting, Nov. 6-9, in Chicago, is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in cardiovascular science.

Regardless of the form (smoked or edible, etc.), cannabis use, which includes marijuana, was associated with the same outcome. From a scientific standpoint, cannabis is the plant, while marijuana is a common term for cannabis products that contain enough THC to produce psychoactive effects.

“Previous research has indicated that cannabis use is rapidly increasing in the United States, with 1 in 6 adults in 2024 reporting having used it within the last month, up from 1 in 10 in 2020 – a 51% increase,” said study author Aabha Divya, M.B.B.S., M.Ch., an assistant professor in the division of cardiothoracic surgery at the Tulane University School of Medicine in New Orleans.

Between 2016 and 2020, prior research found that cannabis use was linked to poor cardiovascular outcomes, and using cannabis more days per month was associated with an increased risk of poor cardiovascular outcomes.

“We wanted to expand on this earlier work because cannabis use has become increasingly common in the United States, as recreational legalization and commercial availability of various products with cannabis have also expanded. Previous studies have raised concerns about possible cardiovascular effects; however, the results have not been consistent,” Divya said.

For the current study, the researchers analyzed pooled data for almost half a million adults in the U.S. who responded to telephone interview questions about cannabis use as part of the Behavioral Risk Factor Surveillance System (BRFSS). This was limited to jurisdictions with available cannabis-use information between 2020 and 2024. Participants also reported if a health professional had ever told them they had cardiovascular disease — if they had experienced a heart attack or stroke or if they had been diagnosed with coronary heart disease.

What are the main findings?

• Compared with people who reported no cannabis use, those who reported using cannabis on 1 to 5 days per month had 23% higher odds of reporting a history of cardiovascular disease.
• Heavy cannabis users, defined as those who reported using it for 16 to 30 days per month, had 21% higher odds of reporting a history of cardiovascular disease.
• The strongest link between cannabis use and cardiovascular disease was with stroke. Reported low-frequency cannabis use was associated with 40% higher odds of stroke, and heavy use had 25% higher odds of stroke.
• Researchers did not see a statistically significant association between the reported frequency of cannabis use and heart attack.

“We were surprised to find that the link between cannabis use and cardiovascular disease was not straightforward. We expected that the chances of heart disease would gradually rise as people used cannabis more often, but that wasn’t the case. Both low-use and heavy-use groups had higher odds of developing heart disease,” Divya said.

“As cannabis use becomes more common, it is increasingly important that people and their healthcare professionals include it in conversations about cardiovascular health, just as they discuss tobacco, alcohol and other commonly used substances,” she added.

Robert L. Page II, Pharm.D., M.S.P.H., FAHA, chair of the writing group for the American Heart Association’s 2020 cannabis scientific statement, said, “Unfortunately, many patients who use cannabis may also smoke tobacco, which completely clouds the issue when addressing atherosclerotic cardiovascular disease risk. In patients who use both, cannabis has always been considered an innocent bystander; however, this is not the case. This is the second observational study to suggest that cannabis exposure (without tobacco smoking) may be a potential risk factor for developing cardiovascular disease. Overall, cannabis is beginning to emerge as a major contributor to premature heart disease in young and older adults, which can lead to serious cardiovascular events. To this end, clinicians should be addressing cannabis use with their patients as they would tobacco use when considering the risk of cardiovascular disease.” Page is also a professor in the department of clinical pharmacy and the department of physical medicine/rehabilitation at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences in Aurora, Colorado, and was not a part of this study.

What are the study details, background, design and limitations?

• The study included 442,906 U.S. adults (average age of 49 years; approximately half women) surveyed by telephone as part of the BRFSS.
• The study analyzed 2020-2024 BRFSS data from states that included the optional marijuana module in their telephone surveys, with 16-24 states participating each year. The cannabis questions were optional, and the analysis did not include all U.S. states.
• The survey asked about the number of days participants used cannabis (smoking, vaping or ingesting gummies or other cannabis-containing foods) in the previous month. Use was characterized as none; low frequency for 1-5 days in the past 30 days; moderate frequency for 6-15 days of the month; or heavy frequency for 16-30 days out of the previous month.
• Participants were also asked whether they had previously been diagnosed with a heart attack, heart disease, heart-related chest pain or stroke.
• The association between cannabis use and heart disease was calculated after adjusting for several heart disease risk factors, including demographics, tobacco smoking, alcohol use, obesity, diabetes, chronic kidney disease, physical inactivity, level of education and income.
• The study is limited by presenting associations from a single point in time, so it cannot prove that cannabis use causes heart disease. In addition, it relied on participants’ self-reported information about their cannabis use and heart-disease diagnoses (making them subject to potential errors in memory), and the study did not have any information about the potency of the cannabis product used or the amount consumed. People may also have reduced or stopped cannabis use after a diagnosis, and the no-recent-use group could include former users.

Co-authors, disclosures and funding sources are listed in the abstract.

Statements and conclusions of studies that are presented at the American Heart Association’s scientific meetings are solely those of the study authors and do not necessarily reflect the Association’s policy or position. The Association makes no representation or guarantee as to their accuracy or reliability. Abstracts presented at the Association’s scientific meetings are not peer-reviewed, rather, they are curated by independent review panels and are considered based on the potential to add to the diversity of scientific issues and views discussed at the meeting. The findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.

The Association receives more than 85% of its revenue from sources other than corporations. These sources include contributions from individuals, foundations and estates, as well as investment earnings and revenue from the sale of our educational materials. Corporations (including pharmaceutical, device manufacturers and other companies) also make donations to the Association. The Association has strict policies to prevent any donations from influencing its science content and policy positions. Overall financial information is available here.

Additional Resources:

• Multimedia, including video interview clips with American Heart Association volunteer expert, Robert L. Page II, Pharm.D., M.S.P.H., FAHA, is available on the right column of the release link.
• Spanish news release 
• Link to Abstract Poster Mo3041; and the American Heart Association’s Scientific Sessions 2026 Online Program Planner
• American Heart Association news release: Cannabis use linked to increase in heart attack and stroke risk (Feb. 2024)
• American Heart Association news release: Marijuana use linked with increased risk of heart attack, heart failure (Nov. 2023)
• About Scientific Sessions 2026
• For more news at the American Heart Association’s Scientific Sessions 2026, follow us on X @HeartNews, #ScientificSessions26

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