Unexpected findings add new insight on cannabis and heart health

UCSF trial found fewer premature heartbeats after cannabis inhalation, with potential implications for atrial fibrillation risk

University of California - San Francisco

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Habitual cannabis users experienced about 9% fewer premature heartbeats on days they inhaled cannabis compared with days they abstained, a counterintuitive finding that adds to the complex and evolving understanding of how cannabis affects the heart, new UC San Francisco-led research found.

The study, published Aug. 12 in the Journal of the American College of Cardiology, is among the first  to examine the acute cardiovascular effects of inhaled cannabis in people living their normal daily lives. While the findings challenge assumptions drawn largely from observational studies, the researchers caution these findings should not influence medical or behavioral decisions around cannabis use.

With millions of Americans using cannabis, studies like this are increasingly important to understand its health effects, said researchers.

"We were surprised by the results because they contradicted our original hypothesis," said Gregory Marcus, MD, MAS, an endowed professor in atrial fibrillation research in the UCSF Division of Cardiology. "That's why randomized trials are so important. When the data challenge our expectations, our job as scientists is to understand them, not ignore them."

The trial enrolled 108 adults who regularly smoked or vaped cannabis but had no history of clinically diagnosed cardiac arrhythmias. Over 14 days, participants were randomly assigned each day to either inhale cannabis or abstain while wearing a continuously recording electrocardiographic monitor, activity tracker, sleep monitor, and continuous glucose monitor. Participants served as their own control, allowing investigators to compare physiological changes during cannabis-use and abstinence days.

Greatest predictor of premature atrial contractions

Unlike previous studies that relied largely on participants' self-reports or medical records, this randomized crossover trial, the gold standard for trials, continuously monitored every heartbeat, enabling researchers to measure physiological changes in real time under everyday conditions.

Researchers found that cannabis inhalation was associated with a statistically significant reduction in extra or early heartbeats, knowns as cardiac ectopy. The reduction was driven by fewer extra heartbeats that began in the heart's upper chambers, known as premature atrial contractions (PACs). The frequency of PACs is the single most potent predictor of atrial fibrillation, while PVCs can predict heart failure. Although these early heartbeats are common, researchers still know relatively little about what determines their frequency.

No significant change was observed in extra heartbeats originating in the lower chambers, called premature ventricular contractions (PVCs).

The researchers found no significant differences in daily step counts, sleep duration, or glucose levels, also surprising. Together, the findings illustrate how randomized trials can produce a different and more nuanced picture than observational research alone.

Marcus emphasized that the findings should not be interpreted as evidence that cannabis benefits cardiovascular health.

"This study examined the acute effects of cannabis in people who use it regularly and was not designed to evaluate the long-term health consequences," he said. "The overall health effects of inhaled cannabis may still be net negative, but these findings suggest there may be something about cannabis that can teach us more about the biological mechanisms that produce premature atrial contractions. That knowledge could eventually lead to new approaches for preventing or treating abnormal heart rhythms."

 

Authors: In addition to Gregory M. Marcus, MD, MAS, the study authors are Adi Elias, MD, MPH; Gabrielle C. Montenegro, BA; Hannah H. Oo, BS; Isabella J. Peña, BA; Dylan A. Lowe, PhD; Catherine Lee, PhD; Janet Tang, PhD; Kara L. Lynch, PhD; Lilly Lim, BS; Mirna Maamou, BS; Nhung Nguyen, PhD; and Matthew L. Springer, PhD, of UC San Francisco.

Funding: The research was supported by the UCSF Cardiology Scholars & Innovation Award. Dexcom donated continuous glucose monitors used in the study.

Disclosures: The authors report no relevant conflicts of interest or disclosures.

About UCSF: The University of California, San Francisco (UCSF) is exclusively focused on the health sciences and is dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. UCSF Health, which serves as UCSF’s primary academic medical system, includes top-ranked specialty hospitals and other clinical programs, and has affiliations throughout the Bay Area. UCSF School of Medicine also has a regional campus in Fresno. Learn more at ucsf.edu.
 

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Journal

Journal of the American College of Cardiology

DOI

10.1016/j.jacc.2026.07.014 

Method of Research

Randomized controlled/clinical trial

Subject of Research

People

Article Title

Acute Effects of Cannabis Inhalation on Cardiac Ectopy, Physical Activity, Sleep, and Glucose

Article Publication Date

12-Aug-2026

Smokers still largely unaware of heart disease risks

A new study covering 46 countries found significant gaps in awareness about smoking and second-hand smoke

University of Waterloo

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An international study has found that despite two decades of global tobacco control efforts, the message still is not getting through to enough smokers that smoking and second-hand smoke cause heart attack and stroke. 

Researchers at the University of Waterloo and the Global Tobacco Control Program at the U.S. Centers for Disease Control and Prevention (CDC) conducted the study, which is the largest of its kind.  

Tobacco use is the leading preventable cause of disease and death worldwide. Up to two-thirds of people who smoke throughout their lives die from a smoking-caused disease, and lose more than a decade of life, on average.

The research team analyzed data from more than 240,000 adult smokers across 46 countries over two decades. While more than 90 per cent knew that smoking causes lung cancer, only about 80 per cent knew it causes heart disease or heart attack and 70 per cent knew it causes stroke. In several high-income countries — including Australia, Germany, England, the U.S., New Zealand, and Canada — fewer than half of adults who smoke knew that second-hand smoke causes heart disease or heart attack. China, a country of 300 million smokers, was among the countries where awareness was lowest.

“Knowledge gaps about the major health effects of smoking and second-hand smoke are deeply concerning,” said Dr. Janet Chung-Hall, Research Scientist for the International Tobacco Control Policy Evaluation Project (ITC Project) at Waterloo and the lead author of the study. “The low awareness of the cardiovascular harms of smoking and second-hand smoke is particularly troubling given that smoking causes more than 2 million cardiovascular deaths worldwide each year. Increasing public awareness of these risks should be a greater public health priority.” 

Across two decades, the study found almost no progress in knowledge of the health risks of smoking and second-hand smoke. Although knowledge about the cardiovascular risks of smoking and second-hand smoke increased in some countries, including Bangladesh, India, Thailand and Vietnam, knowledge of those second-hand smoke risks actually decreased in the majority of high-income countries studied, including Canada, the U.S., New Zealand, England, and Japan.  

The study also examined knowledge about lung cancer, finding that although about 90 per cent knew that smoking causes lung cancer, fewer knew that secondhand smoke does, with little progress over time. 

“Knowledge is an important first step toward quitting smoking and protecting others from second-hand smoke,” said Dr. Geoffrey T. Fong, Principal Investigator of the ITC Project and University Professor of Psychology and Public Health Sciences at Waterloo. “Our findings highlight the need for governments to implement stronger, sustained public education about the cardiovascular as well as cancer risks of smoking and second-hand smoke. Policies such as large pictorial warnings and sustained media campaigns can increase awareness, encouraging quitting among those who smoke and discouraging young people from starting to smoke.” 

Those policies are part of the global tobacco control treaty, the WHO Framework Convention on Tobacco Control, to which more than 180 countries are signatories.

The study appears in BMJ Open. 

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Journal

BMJ Open

DOI

10.1136/bmjopen-2025-107667 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Smokers still largely unaware of heart disease risks

Article Publication Date

4-Aug-2026

 

Aston University research sheds more light on the antimicrobial properties of mānuka honey

Aston University

• Mānuka honey has been proven to be effective against respiratory pathogens but researchers do not fully understand the mechanisms
• New research led by Dr Jonathan Cox with New Zealand mānuka honey firm Comvita has shown that a variety of bioactive compounds contribute
• As antibiotic resistance rises, understanding how possible alternatives work will be important for their effective use and application.

New research at Aston University has shown that a variety of compounds is responsible for the antimicrobial action of mānuka honey, not just the sugar content and methylglyoxal (MGO) alone, as previously thought.

Mānuka honey has already been proven to be effective against numerous disease-causing bacteria. As many bacteria become increasingly resistant to antibiotics, new approaches and treatments are required. Mānuka honey has so far not been associated with the development of resistance in the same way as antibiotics and is attracting interest. Understanding what makes mānuka honey effective is important if it is to be used consistently and effectively in future healthcare applications.

The researchers, led by Dr Jonathan Cox, a senior lecturer in biosciences at Aston University and head of the Mycobacterial Research Group, worked in partnership with scientists at New Zealand mānuka honey producer Comvita Limited to test honey with different Unique Mānuka Factor (UMF) ratings. UMF ranges from 5+ to 20+, representing a measure of the amount of MGO in the honey and guarantees that it meets the New Zealand government regulatory standard. The team tested the different honeys in the laboratory on a range of bacteria that cause respiratory infections.

The antimicrobial activity of the honey increased with increasing UMF, which was unsurprising. Dr Cox and the team also tested the antimicrobial activity of artificial formulations containing equivalent concentrations of sugar and MGO, but the antimicrobial effect could not be replicated, suggesting that additional bioactive compounds, or interactions between compounds, are responsible.

It was previously thought that the antimicrobial activity came from the MGO and the sugar content, but Dr Cox and the team have now shown that this is not the case.

The team are continuing to work closely with Comvita to identify and characterise the additional compounds that are responsible for the enhanced antimicrobial activity found in higher UMF mānuka honey. They will also look to determine how the compounds interact. Understanding these active components may support the development of more effective honey-derived therapeutics and antimicrobial products.

Dr Cox said:

“Mānuka honey is often viewed through the lens of a single compound, methylglyoxal, but our findings show that the story is far more complex. High-grade mānuka honey appears to derive its antimicrobial activity from a combination of factors working together, and understanding those interactions could help unlock new approaches to tackling infection in an era of increasing antimicrobial resistance.

“It turns out, the very nature of mānuka honey, in all its complexity, may hold a powerful solution to the emerging global AMR crisis. We just need to learn how best to use it."

Dr Jackie Evans, Comvita Limited chief science officer, said:

"Mānuka honey has long been recognised for its unique antimicrobial properties. This exciting new research shows that methylglyoxal (MGO) is only part of the story. Comvita is proud to be at the forefront of mānuka honey science, and while this is early-stage research, it highlights the importance of understanding the other bioactive compounds that contribute to its unique antimicrobial properties. Discoveries such as these are helping unlock the full potential of mānuka honey."

To read the full paper, 'UMF-dependent antimicrobial activity of Mānuka honey against respiratory pathogens cannot be explained by sugar and methylglyoxal alone' in Microbiology, visit www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.001746.

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Journal

Microbiology

DOI

10.1099/mic.0.001746 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Unique Mānuka Factor (UMF)-dependent antimicrobial activity of Mānuka honey against respiratory pathogens cannot be explained by sugar and methylglyoxal alone

Article Publication Date

11-Aug-2026

COI Statement

T.L.M. and J.E. are employees of Comvita Ltd. Comvita Ltd. co-funded the PhD studentship of G.J.A., supplied the Mānuka honey samples and performed the HPLC analysis used to determine methylglyoxal concentrations. The remaining authors declare that there are no additional conflicts of interest.

 

BMJ Group retracts research published in 2024 on excess deaths

On the grounds of misinformation on causes of death and limited original work conducted by the authors

BMJ Group

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BMJ Group has retracted a data analysis highlighting excess deaths in Europe, North America, Australia and New Zealand in the wake of the pandemic.

This has been done due to misinformation on the possible reasons for the excess mortality and limited original work conducted by the authors.

The research was published in the open access journal BMJ Public Health in June 2024 and its findings press released, generating widespread media coverage.

But shortly after publication, concerns were raised about the quality, originality, and messaging of the research, prompting an expression of concern to be posted in June 2024.

This explained that the research didn’t investigate or establish a causal link between COVID-19 containment measures, vaccination and excess deaths.

The Princess Máxima Centre in Utrecht, listed as the institution of three of the four authors at the time of publication, carried out its own investigation and shared the anonymised findings with BMJ Group in May 2025.

These findings, which are attached to the retraction notice, did not report on the individual who was the corresponding author and guarantor of the work.

The institution found no evidence of malicious intent, fabrication or falsification of data, or plagiarism by the authors who were investigated. However, it concluded that the authors’ explanations for the possible causes of the excess deaths didn’t reflect scientific consensus at the time and considered their conclusions to be misleading, selective, and disproportionately focused on the negative effects of vaccination.

The journal eventually made contact with the corresponding author and guarantor in October 2025, enabling it to understand her perspective. BMJ Group’s own investigation concluded that the discussion lacked sufficient balance; the explanations for the possible causes of excess deaths included misinformation; and the amount of original work conducted by the authors was limited.

Dr Helen Macdonald, publication ethics and content integrity editor at BMJ Group, commented: “This case was complicated because of the multiple issues requiring investigation, some of which had been partly investigated by the institution, and involved unpicking how the research came to be conducted and presented as it was.”

Dr Macdonald also emphasised the importance of hearing from the corresponding author and guarantor, adding: “We understood she wasn’t available to contribute to the Princess Máxima Centre’s investigation. The Centre has not made its full report publicly available, therefore we have attached the report sent to the journal to the notice.”

The institution and two of the four authors of the research support the decision to retract the work

 

Meridian secures thumbs up on New Zealand wind farm revamp

/ Zbynek Burival - UnsplashFacebook

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By bne IntelliNews August 11, 2026

Meridian Energy has secured the final major resource consent needed to repower its 172-MW Te Rere Hau Wind Farm in Manawatū, New Zealand.

According to POWERLINE, the approval was granted by Palmerston North City Council. It permits the relocation of an Airways communication facility, a key requirement for the project.

Meridian ism however, still awaiting additional approvals for minor road upgrades before work can begin. The repowering is intended to improve the wind farm’s efficiency and increase its generation capacity.

The consent marks a significant step towards the project’s construction phase. The company must complete the remaining approvals before repowering works can commence.

The Te Rere Hau project forms part of Meridian’s efforts to improve the performance of its existing wind generation assets. The 172-MW facility is located in Manawatū, where the repowering will focus on replacing or upgrading existing infrastructure to improve efficiency and generation.

Meridian’s latest approval removes a key regulatory hurdle, leaving the company to secure the outstanding permissions for road works before proceeding with the project.

BAN DEEP SEA MINING

Glomar Minerals targets deep-sea production before end of Trump term

Amanda Stutt | August 7, 2026 | 

The RV Tangaroa at sea. Image: Earth Sciences New Zealand.

This week, Glomar Minerals announced its wholly owned subsidiary UK Seabed Resources Limited (UKSR) departed from Tahiti for the Pacific Clarion-Clipperton Zone (CCZ) to survey its license area for polymetallic nodules. 

Nodules found within the company’s two CCZ license areas – together the size of Louisiana – are rich in manganese, cobalt, nickel, copper, and rare earths – minerals critical to defense, aerospace, energy, and modern manufacturing, Glomar said.   

The campaign is the first comprehensive geological and biological survey of the UK2 license area in more than 40 years, the company said in a news release.

The 65-day campaign is being run with Earth Sciences New Zealand aboard the RV Tangaroa, which the company says is one of the most capable deep ocean research vessels in the world.

Glomar Minerals aims to begin processing polymetallic nodules before the end of US President Donald Trump’s term as it evaluates regulatory routes beyond the International Seabed Authority (ISA), chief executive Chris Williams told MINING.com in an interview.

The US seabed minerals company is looking at exclusive economic zones where it could launch a relatively small operation while the ISA continues negotiations over rules governing commercial mining in international waters.

“There’s a real question about whether there’ll be regulations at the ISA during that timeframe, so we are looking actively at other jurisdictions to see whether there is a faster regulatory path to production.”

The ISA has spent years trying to finalize its mining code and was still working through several outstanding regulatory issues during its July 2026 session. Its latest draft covers environmental protection, compliance, inspections and the financial terms that would apply to mining in international waters. The ISA released a third revision of the draft exploitation regulations in June..

Pacific campaign underway

Glomar owns UK Seabed Resources (UKSR), which holds two UK-sponsored exploration contracts covering about 133,000 sq. km in the Clarion-Clipperton Zone, a mineral-rich expanse of the Pacific Ocean between Hawaii and Mexico.

The company acquired UKSR from the bankruptcy estate of Norway’s Loke Marine Minerals in 2025. Lockheed Martin, which had previously owned UKSR, sold the subsidiary to Loke in 2023.

Williams managed Lockheed’s seabed minerals program from 2015 until the sale. He said Glomar’s licences cover the same areas he oversaw at the defence contractor.

UKSR has launched a 67-day expedition aboard the Earth Sciences New Zealand research vessel Tangaroa, including 45 days of active survey work. 

Historical US data indicates that UK2 contains a potentially strong nodule resource, Williams said, although the licence remains at an earlier exploration stage than UK1.

“UK1 is really pretty far advanced,” he said. “It doesn’t require an enormous amount of work to be ready for an application for a production licence — or an exploitation contract, as it’s known at the International Seabed Authority.”

US processing plans

In March, Glomar and Australian critical minerals developer Cobalt Blue Holdings said they plan to build a US refinery to process critical minerals extracted from the bottom of the Pacific Ocean within three years,  dubbed Project Infinity. 

The modular facility is being designed to process about 200,000 tonnes of polymetallic nodules and 7,500 tonnes of terrestrial cobalt hydroxide annually. Its proposed flowsheet would produce manganese, cobalt sulphate, nickel and copper, as well as a rare-earth-rich residue.

The companies said they have shortlisted four sites across Louisiana, North Carolina and Texas after reviewing more than 30 locations.

“We’d like to see nodules going through that processing plant before the end of the Trump term,” Williams said.

The facility would operate at roughly one-tenth the scale of a plant supplied by a full-size collection vessel working continuously, Williams said. Glomar sees the smaller initial development as a way to reduce risk before expanding capacity.

“The idea is that it’s modular and scalable, which lowers the risk out of the gate but gives us lots of opportunity to scale,” he said.

The company has not announced customers, financing arrangements or any talks with the US government concerning project funding.

Environmental debate

Deep-sea mining remains fiercely contested. Environmental groups and several governments have called for a moratorium or precautionary pause, arguing that too little is known about abyssal ecosystems to permit commercial extraction.

The UK, which sponsors Glomar’s ISA contracts, has supported a moratorium on exploitation licences until sufficient scientific evidence and strong environmental rules are in place.

Williams argues mining is likely to proceed regardless, driven partly by governments seeking secure supplies of critical minerals.

 “Anyone who spends time at the International Seabed Authority and hears how some member states — particularly China — are talking about it would recognize that there’s a really strong imperative to get these regulations done to enable seabed mining.”

“Given that it’s happening anyway, let’s make sure we do it the right way. Let’s lead by example.”

Williams pointed to research examining a 1979 pilot mining test in the Clarion-Clipperton Zone as evidence that some biological recovery is possible. Scientists returning to the site 44 years later found animals had begun recolonizing the disturbed ground.

The findings were not uniformly positive. The peer-reviewed study found persistent physical changes to the seabed and a mixed recovery among animal groups, underscoring the long duration of mining impacts. The research was published in Nature in 2025.

“The environment was a little different where the nodules had been taken away, but the recolonization was very real over that 40-year period,” Williams said. “That changes, I think, the assumption that after you do this, you’ve got a barren desert with no life.”

Glomar has pledged to submit its environmental findings for peer review and, where possible, fund open access to the resulting academic papers.

“We’d like people to see what we’re doing, and we’d like to be transparent about it,” Williams said.

American flown to New Zealand hospital in rare midwinter Antarctic rescue mission

Copyright AP Photo

By Gavin Blackburn

Published on 07/08/2026 -  EURONEWS

The sun last set at the geographic South Pole on 23 March and will not rise until 21 September.

An Australian air crew flew a US national from an Antarctic base to a New Zealand hospital in a rare midwinter rescue.

The Airbus A319 Long Range aircraft, with the call sign Snowbird 1, flew from the Australian city of Hobart to the US McMurdo Station in Antarctica on 31 July in response to an “urgent request for assistance,” the jet’s Melbourne-based owner Skytraders said in a statement.

The jet landed after a five hour and 30 minute flight at the Phoenix Airfield near McMurdo in darkness and with temperatures as low as -43C, the statement said.

The American was flown on the same day to a hospital in Christchurch as weather conditions at the Antarctic air strip worsened, said Skytraders, which is contracted by the Australian Antarctic Division.

The US National Science Foundation told the ABC that the patient was admitted to the Christchurch Hospital in a “serious condition.”

The AAD said in a statement on Friday the patient continued to receive medical treatment in Christchurch.

A sign at McMurdo Station in Antarctica, 4 December, 2018 AP Photo

“This was a complex operation carried out in the depths of the Antarctic winter and it highlights both the capability of our people and the strong partnerships that underpin Antarctic programmes around the world," the head of AAD, Emma Campbell, said.

New Zealand’s Health Ministry on Friday would not comment on the American’s condition or say whether the American remained in hospital.

The mission’s copilot, Louise Robertson, said conditions were close to the limit of the aircraft’s capabilities.

“We had some what’s called nautical twilight, which is a very minimal amount of light that is pretty much pitch blackness and also the extreme cold temperatures. We are right on the verge of the limitation of the aircraft,” Robertson told ABC.

Related

• ‘Irreversible on any human timescale’: Scientist reveals best and worst-case scenario for Antarctica

“It was very close to being too cold,” she said. ”It got down to -43, which is the coldest I’ve ever felt. It was about 8 knots of wind, so quite a bit of wind-chill as well.”

Robertson said plans to fly to the base on the Ross Ice Shelf a day earlier were aborted due to a snow storm.

“There…was really just such a narrow window of opportunity,” Robertson said.

“To get there in complete darkness in these extreme cold temperatures is very, very rare. I believe it hasn’t been done before,” she added.

The sun last set at the geographic South Pole on 23 March and will not rise until 21 September.

McMurdo Station in Antarctica, 27 October, 2014 AP Photo

The New Zealand Air Force evacuated a New Zealand citizen working on the US Antarctic Programme from the Phoenix Airfield in a C-130 Hercules in a medical emergency in April, which is the Southern Hemisphere autumn.

In August last year, the final month of the Southern Hemisphere winter, New Zealand used the same type of four-engine turboprop transport aircraft to evacuate three people on a flight from McMurdo for medical treatment.

McMurdo shares its airstrip with New Zealand's nearby Scott Base.