Health

Study Links Rising Air Pollution to Reduced Health Benefits of Exercise

Published

1 day ago

November 29, 2025

Regular physical activity is widely recognised as a key factor in lowering the risk of chronic illness and early death, but new research suggests that polluted air can weaken some of those protective effects. A large international study has found that the health gains from exercise decline as neighbourhood air pollution levels rise, particularly for heart disease and cancer.

The research, published in the journal BMC Medicine, examined data from more than 1.5 million adults across the United Kingdom, Denmark, the United States, Taiwan, and China. Participants were tracked for over a decade, allowing researchers to assess long-term patterns in physical activity, pollution exposure, and mortality.

The study focused on fine particulate matter, known as PM2.5, a hazardous pollutant produced by vehicle emissions, the burning of coal and other fuels, waste incineration, and several industrial activities. These particles are small enough to enter the bloodstream and affect organs, including the heart and lungs.

According to the analysis, people who engaged in at least two and a half hours of moderate or vigorous exercise each week had a 30 percent lower risk of death compared with those who were less active. But this advantage declined sharply for individuals living in areas where PM2.5 levels exceeded 25 micrograms per cubic metre. In such neighbourhoods, the risk reduction dropped to between 12 and 15 percent. The protective effect eroded even further in regions with PM2.5 concentrations above 35 micrograms per cubic metre — levels that affect more than a third of the world’s population.

Andrew Steptoe, a professor of psychology and epidemiology at University College London and one of the study’s authors, said the findings highlight the growing threat posed by fine particle pollution. “Toxic air can, to some extent, block the benefits of exercise, although not eliminate them,” he said. He noted that the results add to a growing body of evidence showing the widespread harm caused by PM2.5 exposure.

The study also points to several limitations. Much of the data came from high-income countries, which tend to have stronger pollution controls than low-income regions. The researchers did not have detailed information on indoor air quality or diet, two factors that could influence long-term health outcomes. Still, the findings remained consistent after adjustments for income, education, smoking, and underlying medical conditions.

The authors stressed that people should not avoid outdoor exercise. Paola Zaninotto, another UCL researcher involved in the project, said that small changes can help reduce exposure. Choosing cleaner routes, monitoring local air quality, or reducing workout intensity on high-pollution days may help maintain the benefits of regular activity.

The study adds to growing calls for stronger global efforts to reduce air pollution. Steptoe said both clean air and physical activity play an important role in healthy ageing, and urged governments to prioritise measures that reduce harmful emissions.

Health

UK Study Finds Common Chemicals May Harm Gut Bacteria and Human Health

Published

4 days ago

November 26, 2025

Web Reporter

Dozens of widely used chemicals could be toxic to gut bacteria, potentially affecting human health, according to a new study by UK scientists. Researchers tested more than 1,000 chemicals in the laboratory and identified 168 that appeared to prevent healthy gut bacteria from growing, raising concerns about their impact on the gut microbiome.

The gut microbiome consists of thousands of bacterial species and other microorganisms that live in the digestive tract. Scientists have linked it to numerous health outcomes, including cancer, heart disease, type 2 diabetes, insomnia, and complications during pregnancy such as preterm birth.

In the study, researchers tested 1,076 chemical contaminants—including pesticides, herbicides, industrial chemicals, and so-called “forever chemicals” like per- and polyfluoroalkyl substances (PFAS)—on 22 species of gut bacteria. Many of the harmful chemicals, including flame retardants and plasticisers used in everyday products, were not previously known to affect living organisms, the team said.

“We were surprised that some of these chemicals had such strong effects,” said Indra Roux, a researcher at the University of Cambridge and one of the study’s authors. “Many industrial chemicals that we are regularly in contact with weren’t thought to affect living organisms at all, but they do.”

The chemicals can enter the human body through food, water, and other environmental exposures. While the precise level of real-world exposure remains unclear, the researchers noted that environmental pollutants have been linked to changes in the gut microbiome that may contribute to obesity and insulin resistance.

Laboratory tests also revealed that some bacteria altered their functions to survive chemical exposure, which in some cases led to increased resistance to antibiotics. If similar effects occur in humans, this could make infections harder to treat and worsen the growing public health problem of antimicrobial resistance (AMR).

Traditionally, chemical safety assessments focus on the chemicals’ intended targets—such as how effectively a pesticide kills pests—without considering their potential impact on the human gut. “Safety assessments of new chemicals for human use must ensure they are also safe for our gut bacteria, which could be exposed to the chemicals through our food and water,” said Stephan Kamrad, another author from the University of Cambridge.

The study, published in Nature Microbiology, calls for more real-world data to determine whether laboratory findings translate to effects on human gut health. Meanwhile, researchers advise people to reduce exposure where possible, for example by washing fruits and vegetables thoroughly and avoiding the use of pesticides at home.

The findings add to growing evidence that everyday chemical exposures may have unintended consequences on human health, highlighting the need for more comprehensive safety testing that considers the gut microbiome.

Health

One-Week Social Media Break Linked to Lower Depression and Anxiety in Young Adults, Study Finds

Published

5 days ago

November 25, 2025

Web Reporter

A week-long break from social media may help ease depression, anxiety and insomnia among young adults, according to new research that adds to growing concerns about the mental health impact of excessive screen time.

The study, published in JAMA Network Open, tracked 373 participants aged between 18 and 24 as they spent two weeks actively using Facebook, Instagram, Snapchat, TikTok and X. Researchers monitored their usage patterns, then asked them to report their mental wellbeing before, during and after the test period.

After the two-week monitoring phase, almost 80 per cent of participants agreed to take a voluntary one-week detox from social media. Among those who did so, one in four reported reduced symptoms of depression. Sixteen per cent said their anxiety symptoms had eased, while 15 per cent noted improvements in insomnia. The detox appeared most beneficial for those who entered the study with moderate or high levels of depression, anxiety or sleep difficulties.

The researchers noted that the break did not reduce loneliness, a finding they attributed to the sudden loss of regular interactions, such as comments, messages and likes, that young people typically receive on these platforms.

Josep Maria Suelves, a researcher at the Open University of Catalonia, said the findings highlight a wider issue. While social media can support communication and community, he said “frequent and prolonged use of these tools can interfere with healthy behaviours,” including sleep, exercise and meaningful social contact. This, he noted, raises risks linked to sedentary habits, insufficient rest and exposure to negative social pressures that can worsen depression or addiction.

Although participants were asked to restrict their screen time, they did not eliminate it completely. They still spent around 30 minutes per day on their phones during the detox, compared to nearly two hours beforehand. Instagram and Snapchat were the platforms most likely to draw users back during the break, while Facebook, TikTok and X saw fewer logins.

The authors said the results are promising but stressed the need for broader studies to identify how long a social media detox should last to deliver consistent mental health benefits. They also said the study’s demographics — mostly women, university students and highly educated participants — limit how widely the findings can be applied.

José Perales, a psychology professor at the University of Granada, said the voluntary nature of the detox phase was another limitation. Allowing participants to choose whether or not to take a break could skew results, he said, since those who opted in may have been more motivated or more aware of their symptoms.

Perales cautioned that the study’s relevance is “very modest” and may join “the long list of inconclusive and easily overinterpreted studies” in the debate over social media’s impact on young people’s wellbeing.

Health

Genes Behind Impulsive Behaviour Linked to Mental Health, Obesity and Chronic Disease, Study Finds

Published

5 days ago

November 25, 2025

Web Reporter

Genes associated with impulsive decision-making may also increase the risk of mental health disorders, obesity and several chronic conditions, according to a major new study that examines how deeply impulsivity is rooted in human biology.

The research, published in Molecular Psychiatry, suggests that tendencies such as seeking quick rewards are not only inherited but tied to a broad set of physical and psychological health outcomes over a person’s lifetime. The findings come from one of the largest genetic analyses of impulsivity to date.

“Impulsive decision-making is something we all experience, but its biological roots have been surprisingly difficult to pin down,” said Sandra Sanchez-Roige, an associate professor of psychiatry at the University of California San Diego and one of the study’s authors.

The team analysed genome-wide data from nearly 135,000 individuals who participated in 23andMe’s genetic testing programme. They focused on a behaviour known as delay discounting — the preference for smaller, immediate rewards over larger, future ones. Scientists have long linked this trait to impulsivity, but the scale of the dataset allowed researchers to identify 73 psychiatric, cognitive and physical health traits connected to it.

Those traits include indicators of substance use, depression, executive function, chronic pain, cardiovascular health, obesity, immune system complications and insomnia. The study reports that the connections involve “both overlapping and trait-specific biological processes,” with several genes linked to dopamine activity, brain structure and metabolic pathways that shape neural development.

To assess how these genetic patterns translate into long-term health impacts, the researchers built genetic risk scores for impulsive behaviour and studied medical records from more than 66,000 people. They found associations with 212 medical conditions, including type 2 diabetes, chronic pain and heart disease.

Sanchez-Roige said the results show that delay discounting is “measurable, highly heritable and relevant to many aspects of health,” spanning brain development, cognition and physical wellbeing.

The study raises new questions about the degree to which the identified genes directly contribute to health conditions or whether their influence is shaped by environmental factors. The authors said future research should examine whether addressing social or educational factors linked to impulsivity could reduce associated health risks.

“By continuing to investigate this fundamental decision-making process, we may uncover new ways to prevent or treat a wide range of conditions,” Sanchez-Roige said.