Medical Bulletin 04/December/2025

Obesity, recognized as a chronic and relapsing disease, significantly heightens risks for cardiovascular diseases like heart attacks and strokes, type 2 diabetes, various cancers, fatty liver disease, osteoarthritis, sleep apnea, and worsened infectious disease outcomes—potentially doubling global cases by 2030 without urgent interventions.

The guideline, developed via extensive evidence review and stakeholder consultations including those with lived experience, stresses multisectoral strategies: healthier environments, high-risk screening, and lifelong person-centered care.

WHO's guideline panel analyzed clinical trials showing GLP-1 therapies yield 15-25% weight loss, improved metabolic health, and reduced complications. Two key conditional recommendations emerged: (1) long-term GLP-1 use for adults, based on strong efficacy but tempered by gaps in long-term safety, discontinuation data, high costs, and equity issues; (2) pairing with intensive behavioral interventions like structured diet/exercise programs, supported by low-certainty evidence of enhanced outcomes.

Implementation focuses on equitable access amid supply limits—projected to reach <10% of eligible people by 2030. WHO urges pooled procurement, tiered pricing, and voluntary licensing, plus health system readiness to prioritize high-need cases. In September 2025, GLP-1s joined the Essential Medicines List for high-risk type 2 diabetes.

While groundbreaking, the guidance warns medications alone won't reverse obesity's societal crisis. Regular updates will incorporate emerging evidence, supporting WHO's acceleration plan to halt obesity through policy, prevention, and fair treatment access worldwide.

REFERENCE: WHO issues global guideline on the use of GLP-1 medicines in treating obesity; https://www.who.int/news/item/01-12-2025-who-issues-global-guideline-on-the-use-of-glp-1-medicines-in-treating-obesity

Study reveals Dietary iron deficiency impairs lung immune cells' viral defense

Early iron deficiency during childhood doesn't merely cause temporary weakness—it can create lasting scars on the lungs' immune defenses, making kids more vulnerable to viruses like flu even years later. Researchers at Columbia University uncovered this by examining memory T cells, the immune system's "memory keepers" that rally against repeat infections.

Their detailed findings, published in the Journal of Immunology, explain why iron-poor children face heightened risks of severe illness and chronic respiratory issues.

Iron deficiency, the world's most common nutritional shortfall affecting nearly 10% of U.S. children and disproportionately young ones globally, strikes during critical immune maturation phases.

Without sufficient iron, lung-resident immune cells fail to produce essential proteins like interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α). These signaling molecules alert and activate defenses to destroy viruses, but low iron disrupts their production, impairing both immediate responses and long-term memory.

To pinpoint iron's isolated role, the team fed mice iron-rich or iron-poor diets, then challenged them with influenza virus. Iron-deficient mice developed severe symptoms, with sluggish T cell activation in the lungs compared to well-nourished peers. Surprisingly, even severely iron-starved mice formed apparently normal-looking memory T cells.

However, rigorous functional tests revealed these cells produced far less IFN-γ and TNF-α upon re-exposure to the virus—a critical defect persisting even after iron levels normalized. This "immunological memory impairment" was lung-specific, highlighting how early shortages reprogram local defenses irreversibly.

Nearly a decade of human data links iron deficiency to worse flu outcomes, asthma, and recurrent infections. Routine anemia screening detects late-stage harm, but prevention demands proactive steps: iron-rich foods (red meats, beans, fortified cereals, spinach paired with vitamin C for absorption), balanced diets, and regular pediatric checks during growth spurts when immune systems solidify.

Looking ahead, Columbia plans human studies on iron-deficient kids' lung immunity and tissue effects to combat chronic conditions. Prioritizing early iron sufficiency builds lifelong viral shields, underscoring nutrition's profound role in child health.

REFERENCE: Bradley, M. C., et al. (2025). Dietary iron deficiency impairs effector function of memory T cells following influenza infection. The Journal of Immunology. doi: 10.1093/jimmun/vkaf291. https://academic.oup.com/jimmunol/advance-article/doi/10.1093/jimmun/vkaf291/8305832

Air pollution cancels exercise health benefits, new study reveals

Your daily workout slashes death risk by 30%, but breathing toxic air can wipe out nearly half those lifesaving gains—especially against cancer and heart disease. A groundbreaking international study published in BMC Medicine, featuring UCL researchers, tracked over 1.5 million adults for more than 10 years across the UK, Taiwan, China, Denmark, and the US, proving pollution seriously weakens exercise's power.

PM2.5—microscopic particles from cars, factories, fires, and construction smaller than 2.5 micrometers—slip deep into lungs and bloodstream, causing inflammation, oxidative stress, and organ damage.

Nearly half the world's population (46%) lives where yearly PM2.5 averages hit 25 micrograms per cubic meter (μg/m³) or higher, dramatically reducing physical activity's protective benefits. At 35 μg/m³ or above—affecting 36% globally—exercise perks fade even more, particularly for cancer prevention.

The team pooled data from seven large cohorts (three previously unpublished), combining summary statistics with fresh individual-level re-analysis from three studies. They adjusted for confounders like smoking, income, education, diet, and pre-existing conditions.

Active participants cut all-cause mortality by 30% compared to inactive ones. But in high-PM2.5 areas, protection dropped to just 12-15%. Cancer and cardiovascular death reductions weakened most sharply. UK participants averaged cleaner 10 μg/m³, but urban/winter spikes often crossed danger thresholds.

Lead researcher Professor Po-Wen Ku emphasizes exercise still delivers value in smoggy spots, but pristine air unlocks full rewards. UCL's Professor Andrew Steptoe warns pollution doesn't fully cancel benefits, calling for urgent emission cuts to support healthy aging.

Some Practical tips include checking air apps, picking low-traffic routes, or going lighter on bad days. While high-income data limits broader applicability, findings stress dual needs—exercise plus clean air—for top health.

REFERENCE: Po-Wen Ku, Andrew Steptoe, Mark Hamer, Paola Zaninotto, Emmanuel Stamatakis, Ching-Heng Lin, Bin Yu, Ulla Arthur Hvidtfeldt, Xiang Qian Lao, Hsien-Ho Lin, Wei-Cheng Lo, Ole Raaschou-Nielsen, Shengzhi Sun, Linwei Tian, Su-Fen Wang, Yiqian Zeng, Yunquan Zhang, Shang-Ti Chen, Chien-Fong Huang, Yang Xia, Li-Jung Chen. Does ambient PM2.5 reduce the protective association of leisure-time physical activity with mortality? A systematic review, meta-analysis, and individual-level pooled analysis of cohort studies involving 1.5 million adults. BMC Medicine, 2025; 23 (1) DOI: 10.1186/s12916-025-04496-y