A new study presented at the American Heart Association’s 2025 Scientific Sessions suggests that long-term prescription melatonin use could be associated with a higher risk of heart failure, hospitalization, and death.

While the findings are attention-grabbing, experts say they’re preliminary and don’t prove that melatonin directly causes heart problems.

Study Finds Higher Risk Among Long-Term Users

The five-year study tracked 130,828 adults with insomnia and found that people who took prescription melatonin for at least one year had a 90% higher chance of heart failure. Researchers analyzed data from the United States and the United Kingdom. While melatonin is available over-the-counter in the U.S., it’s prescription-only in the U.K.

Since the “melatonin” group in the study only included people who had been prescribed melatonin, it did not account for OTC use.

Since this was an observational study, it does not prove that melatonin directly caused heart failure. More studies, including gold-standard randomized controlled trials, are needed to validate these findings.

The new findings did not explain why melatonin may harm the heart. People who take melatonin long-term may have stress or sleep-related issues that actually cause heart failure.

“It may not necessarily be the melatonin, but it’s just the fact that sleep is extremely important and necessary for not just cardiovascular health, but overall health and well-being,” said Tochukwu M. Okwuosa, DO, FACC, FAHA, a cardiologist and a professor of internal medicine at Rush University, who was not involved with the study.

Why Long-Term Melatonin Use Isn’t Recommended

Estimates suggest that 5 million U.S. adults and 4 million U.S. children take melatonin each month, making it one of the most commonly used sleep aids. Its perceived safety and accessibility have driven growing use in recent years. These new findings underscore the importance of talking with a healthcare provider before using melatonin for an extended period.

Anyone who relies on melatonin nightly should consider seeing a sleep specialist to determine potential underlying issues like chronic insomnia or stress, Okwuosa said. People who don’t get enough sleep have a higher risk of high blood pressure, heart disease, and stroke.

Short-term melatonin use can help with certain sleep issues and may offer some cardiovascular benefits. Human and animal studies have suggested that melatonin can help relieve oxidative stress and improve left ventricular function in people with heart failure.

“If a patient is taking melatonin for a few days or a few weeks, I would not have any problems with it,” Okwuosa said.

Are There Alternatives to Melatonin?

Short-term melatonin use is generally safe, but it may interact with certain medications or cause daytime drowsiness, nausea, dizziness, or headaches in some people.

“The long-term implications of melatonin are unclear, and more studies should be done. At this time, I would recommend using it at the lowest dose possible, and for the shortest duration possible,” Jamie Alan, RPh, PharmD, PhD, an associate professor of pharmacology and toxicology at Michigan State University, told Verywell in an email.

There are other medications, such as Benadryl (diphenhydramine) and Ambien (zolpidem), that can help with sleep. Talk with your healthcare provider if you are worried about melatonin or interested in these other medications, since they also come with risks, Alan added. Cognitive behavioral therapy for insomnia may help address sleep problems without long-term medication use.

A new study has experts cautiously excited about the potential benefits of vitamin D supplementation for people living with heart disease.

“I think people are opening their minds to the concept that vitamin D might be something that is good for heart health,” says Heidi T. May, PhD, the study’s principal author and an epidemiologist and professor of research at Intermountain Health in Salt Lake City.

“It does need more study, but I think there’s the opportunity to reevaluate vitamin D levels — how we’re actually prescribing it and monitoring it, and that it shouldn’t just be a fixed dose for everyone,” says Dr. May.

An unexpected trio — green tea, walnuts and a tiny aquatic plant called Mankai — might help keep the brain young, new research suggests.

In an 18-month randomized trial of nearly 300 adults, a plant-heavy “green Mediterranean” diet was linked to lower levels of Galectin-9, a blood protein associated with markers of faster brain aging on MRI, according to a study published in the journal Clinical Nutrition.

Researchers from Harvard University, Ben-Gurion University in Israel and the University of Leipzig in Germany looked at blood proteins and compared them with MRI scans that estimated participants’ “brain age.” 

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Those who followed the green Mediterranean diet, which was rich in plants and lower in red and processed meat, showed the biggest drop in Galectin-9, a protein tied to faster brain aging — and the MRI scans suggested a “younger” brain compared to their actual age.

“Reducing Galectin-9 may mean dampening the inflammatory processes that contribute to cognitive decline, memory loss and neurodegenerative diseases like Alzheimer’s,” senior study author Iris Shai, an adjunct professor of nutrition at Harvard’s T.H. Chan School of Public Health, told Fox News Digital. 

“It’s an early sign that nutrition can influence brain biology at the molecular level, offering a non-pharmacological path to protect cognitive function as we age.”

Shai said researchers “wanted to test whether an enhanced, more plant-forward Mediterranean diet, richer in natural polyphenols and lower in red and processed meat, could actually slow the biological aging of the brain.”

ALZHEIMER’S DECLINE COULD SLOW DRAMATICALLY WITH ONE SIMPLE DAILY HABIT, STUDY FINDS

The green Mediterranean diet included more polyphenols, plant compounds that help fight inflammation and protect cells and are found in foods such as nuts, olive oil, red wine, tea, fruits and vegetables. 

A second group of participants followed a traditional Mediterranean diet rich in vegetables with red meat replaced by poultry and fish, while another followed standard healthy eating guidelines.

Walnuts, rich in healthy fats and antioxidants, were among the top foods linked to healthier brain aging in the study. (iStock)

Shai said green tea’s EGCG antioxidant compounds, along with the healthy fats and polyphenols in walnuts, likely drove the change, with Mankai adding support through gut–brain and metabolic pathways.

While Mankai is harder to find, green tea and walnuts showed the strongest benefits, suggesting most people could gain comparable benefits by focusing on just those, even without specialty ingredients.

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Mankai caught the researchers’ attention because it packs an unusually dense nutritional profile. It’s a complete plant-based protein and contains easily absorbed vitamin B12 and iron. 

Previous studies by the same team have linked Mankai to better blood sugar control, improved metabolism and gut health, and reduced inflammation, all factors that can influence brain and cognitive function.

“It is plausible that green tea and Mankai could reduce markers linked to neurodegeneration, but we still need more human trials that measure actual cognitive outcomes.”

“When we designed the green Med diet, we deliberately sought a new kind of green — something unfamiliar to the Western gut microbiome,” Shai said. “Introducing this novel plant, originally from the Far East, likely triggered a stronger microbial and metabolic response than we initially expected.”

The findings come from the 18-month DIRECT PLUS trial, one of the longest-running studies on diet and brain health.

Most participants were men with obesity or cholesterol issues, so more research is needed to see if the results apply to women and healthier populations. Still, the data add to growing evidence that eating more plants and less red and processed meat may help slow brain aging.

Mankai, the world’s smallest flowering plant, added a unique green boost to the diet. (iStock)

The researchers hope future blood tests could use proteins like Galectin-9 to flag early brain risks. 

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They caution, however, that the findings are also preliminary and don’t prove the diet prevents Alzheimer’s or cognitive decline.

“Based on this study, it is plausible that green tea and Mankai could reduce markers linked to neurodegeneration, but we still need more human trials that measure actual cognitive outcomes,” said Jenny Finke, a Connecticut-based metabolic health dietitian and owner of The Metabolic Dietitian. She was not involved in the new study. 

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“Green tea provides antioxidants and walnuts offer healthy fats, including omega-3 fatty acids — both of which can be incorporated into a mid-morning snack or an afternoon pick-me-up to support metabolic health and enjoy anti-inflammatory benefits,” Finke told Fox News Digital. 

Green tea’s natural compounds, including EGCG, have been shown to fight inflammation and may help protect the brain from age-related decline. (iStock)

She also recommended keeping red meat consumption to no more than two times per week. 

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“While these adjustments won’t completely change the brain in one week, over time, they can support overall brain health as part of a balanced diet,” she added.