Medical Bulletin 25/October/2025

Dark chocolate milk helps with exercise by providing a natural mix of carbohydrates and proteins that fuel muscles and aid recovery. Its flavonoids, like catechins and epicatechin, improve blood flow and support cardiovascular health, enhancing energy production and endurance. The sugars offer quick energy for anaerobic activities, while its protein content promotes muscle repair. Additionally, compounds in dark chocolate can reduce fatigue and boost mental focus, supporting overall exercise performance.

The study recruited 20 adults aged 21-35 who exercised regularly and had no recent injuries or medications. Participants completed two trial sessions in a randomized crossover design: one consuming 300 mL of DC milk, the other an iso-caloric white chocolate (WC) milk control, with a 7-day washout between trials. After consumption, participants rested 1.5 hours before performing two sets of the Running Anaerobic Sprint Test (RAST), involving six 35-meter sprints with short rest intervals. Researchers recorded sprint times, heart rate (HR), and rate of perceived exertion (RPE), calculating fatigue index (FI) and power output to compare performance between DC and WC trials.

Findings showed DC milk significantly improved total effort and average sprint times during the second RAST, with higher mean and relative power output, especially in males. Females showed lower resting HR after DC milk, suggesting improved autonomic recovery. No differences appeared in HR or perceived exertion across trials.

Lead author said “The likely benefits stem from DC milk’s flavonoid and sucrose content enhancing blood flow and energy supply, though physiological mechanisms like nitric oxide levels were not directly measured. While performance gains were statistically modest (0.5%-1.5%), such effects could interest competitive athletes seeking small advantages.”

Reference: Balasekaran G., Ng Y. C., Foong S., Ong X. R., Boey P. (2025). Effects of Dark Chocolate on Physiological and Anaerobic Performance Among Healthy Female and Male Adults. Nutrients, 17(21), 3317. DOI: 10.3390/nu17213317. https://www.mdpi.com/2072-6643/17/21/3317

Night-time bright light exposure may raise heart disease risk, study finds

A new study led by Flinders University and published in JAMA Network Open reveals that exposure to bright light at night significantly increases the risk of serious heart conditions like heart attacks, strokes, and heart failure. This groundbreaking research is the largest of its kind, tracking personal light exposure of nearly 89,000 UK adults using wrist-worn sensors over 13 million hours, and following them for up to 9.5 years.

Bright light exposure at night disrupts the body’s natural circadian rhythm, increasing the risk of serious heart problems such as heart attacks, strokes, and heart failure. This disruption leads to metabolic and vascular changes that elevate cardiovascular risk independently of other lifestyle factors. Research shows that people exposed to the brightest nighttime light have a significantly higher chance of heart disease, with women and younger individuals being especially vulnerable. Limiting nighttime light exposure by dimming lights and avoiding screens can protect heart health.

The study highlights how disrupting the body’s internal circadian clock by exposure to bright light during normal dark hours raises cardiovascular risk independently of factors like exercise, diet, sleep, and genetics. People exposed to the brightest night light had a 56% higher chance of heart failure and a 47% greater risk of heart attack. Notably, women and younger participants were more vulnerable, with women’s risk equalizing to men’s despite typically lower heart disease rates.

Methodologically, participants wore light sensors continuously, allowing precise measurement of indoor and outdoor light exposure reflecting real-world conditions. This approach surpasses prior studies relying on satellite data or subjective reports. Researchers used multivariate analyses adjusting for lifestyle and genetic confounders to isolate the effect of nighttime light exposure on cardiovascular outcomes.

Dr. Daniel Windred, lead author, emphasized the importance of mitigating nighttime light exposure through practical measures like blackout curtains and reducing screen time before bed. The findings suggest public health policies should consider light pollution a modifiable risk factor for heart disease. Protecting circadian rhythms may be a powerful, yet underutilized, strategy in cardiovascular prevention—a call to view our modern lighting environments as a major health influence.

Reference: Windred, D. P., et al. (2025). Light Exposure at Night and Cardiovascular Disease Incidence. JAMA Network Open. doi.org/10.1001/jamanetworkopen.2025.39031

Are cancer surgeries unknowingly eliminating the body’s natural defense against cancer?

Scientists from the Peter Doherty Institute for Infection and Immunity have uncovered vital roles of lymph nodes in fighting persistent infections and cancer by orchestrating stem-like T cell activity.

Published in Nature Immunology, these findings reveal that lymph nodes create an optimal environment for stem-like T cells to survive, proliferate, and generate "killer" T cells that attack viruses and tumors.

Lymph nodes play vital roles in fighting persistent infections and cancer by serving as specialized hubs that support and orchestrate stem-like T cell activity. These immune organs provide an optimal environment for stem-like T cells—a crucial subset of immune cells—to survive, multiply, and differentiate into highly effective "killer" T cells that target viruses and tumors. Unlike other organs, such as the spleen, lymph nodes actively train and prepare these T cells, enhancing the body’s immune defenses.

The study used animal models to examine how lymph nodes regulate immune cell dynamics, tracking molecular signals that control stem-like T cells and their differentiation into effector cells. Researchers emphasized that removing lymph nodes during cancer surgery—a common practice to prevent tumor spread—might impair immunotherapy effectiveness, such as checkpoint blockade or CAR T cell treatments. Preserving lymph nodes could enhance immune responses and improve treatment outcomes.

Professor Axel Kallies, senior author, stated, “Lymph nodes aren’t just passive waiting rooms; they actively train T cells to fight disease.” First author Dr. Carlson Tsui added that therapies should focus on maintaining and boosting lymph node function to harness natural immunity more effectively.

This research explains why some patients respond better to immunotherapies, linking lymph node health with the body's ability to produce cancer-fighting T cells. Clinical collaborations aim to translate these discoveries into patient care, potentially revolutionizing cancer treatment by incorporating lymph node preservation and targeted immune activation strategies.

Reference:

1.Carlson Tsui, et.al.; etLymph nodes fuel KLF2-dependent effector CD8 T cell differentiation during chronic infection and checkpoint blockade. Nature Immunology, 2025; 26 (10): 1752 DOI: 10.1038/s41590-025-02276-7

2.Sharanya K. M. et.al.; Lymph-node-derived stem-like but not tumor-tissue-resident CD8 T cells fuel anticancer immunity. Nature Immunology, 2025; 26 (8): 1367 DOI: 10.1038/s41590-025-02219-2