Medical Bulletin 23/January/2026

The findings are published in The American Journal of Clinical Nutrition. Vitamin D is often associated with bone strength, but it also plays a key role in how the immune system fights infections. Researchers say this nutrient helps the body mount antibacterial and antiviral responses, which may reduce the severity of infections that affect the lungs. Despite this, vitamin D deficiency remains widespread, particularly in countries with limited sunlight exposure during winter months.

To explore this connection, scientists from the University of Surrey, working with researchers at the University of Reading and the University of Oxford, analyzed health data from 36,258 participants in the UK Biobank. The study focused on middle-aged and older adults—groups already at higher risk of respiratory infections. Vitamin D levels measured in blood samples were compared with NHS hospital records to track admissions for respiratory tract infections over time.

The findings were striking. Individuals with severe vitamin D deficiency—defined as blood levels below 15 nmol/L—were 33 percent more likely to be hospitalized for respiratory infections than those with sufficient levels of at least 75 nmol/L. The analysis also showed a clear dose-response relationship: for every 10 nmol/L increase in vitamin D, the risk of hospitalization dropped by around four percent. These patterns remained consistent even after accounting for factors such as age, sex, lifestyle, and existing health conditions.

Lead author Abi Bournot explained that the results provide strong real-world evidence supporting the idea that vitamin D helps protect against serious respiratory illness. Senior author Dr. Andrea Darling added that reducing hospital admissions through better vitamin D status could ease pressure on already stretched healthcare systems like the NHS.

The researchers emphasize that supplementation—particularly during winter when sunlight exposure is low—along with vitamin D–fortified foods, could be a practical public health strategy.

Older adults and ethnic minority communities, who are at greater risk of deficiency, may benefit the most.

This large-scale study highlights how maintaining healthy vitamin D levels could be a simple yet powerful tool to reduce severe respiratory infections and hospitalizations.

REFERENCE: Abigail R Bournot, Kathryn H Hart, S Johnsen, D Ian Givens, Julie A Lovegrove, José M Ordóñez-Mena, Simon de Lusignan, David B Bartlett, Susan A Lanham-New, Andrea L Darling; Association between serum 25-hydroxyvitamin D status and respiratory tract infections requiring hospital admission: unmatched case-control analysis of ethnic groups from the United Kingdom Biobank cohort; The American Journal of Clinical Nutrition; 2025; https://doi.org/10.1016/j.ajcnut.2025.101179.

Study Finds No Link Between Long-Term Proton Pump Inhibitor Use and Stomach Cancer

For decades, patients taking long-term medication for acid reflux and stomach ulcers have wondered whether their treatment could carry hidden risks—particularly the fear of stomach cancer. A new large-scale study from the Nordic countries, published in The BMJ, brings reassuring news: long-term use of proton pump inhibitors (PPIs) does not appear to increase the risk of developing gastric cancer.

PPIs are among the most commonly prescribed drugs worldwide, helping reduce stomach acid and manage conditions like gastroesophageal reflux disease (GERD) and peptic ulcers. While their benefits are clear, concerns about a possible link to stomach cancer have persisted since the 1980s.

Some previous studies suggested a twofold increase in risk, but methodological limitations made it difficult to draw solid conclusions. This latest research aimed to clarify the issue using robust data and rigorous methods.

Researchers collected healthcare registry information from Denmark, Finland, Iceland, Norway, and Sweden spanning 26 years, from 1994 to 2020. They identified 17,232 patients diagnosed with stomach cancer and matched each with 10 healthy controls—totaling 172,297 individuals—accounting for age, sex, calendar year, and country. Long-term use of PPIs and histamine-2-receptor antagonists (another class of acid-reducing drugs) was recorded, excluding the 12 months prior to diagnosis to avoid falsely linking short-term use with cancer.

The team also considered other factors that might influence risk, including previous Helicobacter pylori infection, peptic ulcers, smoking, alcohol-related illnesses, obesity, type 2 diabetes, and the use of other medications. After adjusting for these variables, the analysis found no evidence that long-term PPI or histamine-2-receptor antagonist use increases the likelihood of developing gastric cancer.

These findings offer reassurance for patients who rely on long-term acid-reducing therapy. They highlight that PPIs remain a safe option for managing chronic acid-related conditions and provide valuable guidance for clinicians making decisions about long-term treatment strategies.

REFERENCE: Onyinyechi Duru, Giola Santoni, Dag Holmberg, Helgi Birgisson, Joonas H Kauppila, My von Euler-Chelpin, Eivind Ness-Jensen, Jesper Lagergren; Long term use of proton pump inhibitors and risk of stomach cancer: population based case-control study in five Nordic countries; BMJ 2026; doi: https://doi.org/10.1136/bmj-2025-086384

Spiking Blood Sugar After Meals May Raise Alzheimer’s Disease Risk, Study Reveals

Sharp spikes in blood sugar after meals—something many people experience without noticing—may quietly increase the risk of Alzheimer’s disease, according to a new study from the University of Liverpool. This research highlights the potential importance of managing post-meal glucose levels for long-term brain health.

The findings are published in the journal Diabetes, Obesity and Metabolism. For years, scientists have observed that metabolic conditions such as type 2 diabetes, insulin resistance, and chronic high blood sugar are linked to cognitive decline and dementia. Yet, the exact ways in which fluctuations in blood sugar affect the brain have remained unclear. This study provides fresh insight into how specific patterns of blood sugar regulation may influence Alzheimer’s risk.

The researchers analyzed genetic and health data from over 350,000 UK Biobank participants aged 40 to 69. They focused on key measures of sugar regulation, including fasting glucose, insulin levels, and blood sugar two hours after meals. To assess potential causal relationships, the team used Mendelian randomization, a genetic method that helps determine whether a biological trait is likely to play a direct role in disease development.

The results were striking. Individuals with higher blood sugar levels after meals—known as postprandial hyperglycemia—were found to have a 69% higher risk of developing Alzheimer’s disease. Interestingly, this increased risk was not linked to overall brain shrinkage or white matter damage, suggesting that elevated post-meal glucose may impact the brain through subtler biological pathways that are not yet fully understood.

Published research like this opens the door to new approaches for reducing dementia risk, particularly in people with diabetes or those prone to high post-meal blood sugar. By paying closer attention to how our bodies respond to meals, we may find simple yet powerful ways to protect brain health over the long term.

REFERENCE: Andrew C. Mason, Nasri Fatih, Reecha Sofat, Christopher T. Rentsch, Liam Smeeth, Krishnan Bhaskaran, Nish Chaturvedi, Victoria Garfield. Disentangling the relationship between glucose, insulin and brain health: A UK Biobank study. Diabetes, Obesity and Metabolism, 2025; DOI: 10.1111/dom.70353