Medical Bulletin 2/February/2026 - Video

Here are the top medical news for today:

Research Highlights Gut Microbiome’s Role in Cancer Defense Mechanisms

Gut Bacteria May Decide Whether a Dietary Amino Acid Fuels Cancer or Fights It. A new study from Weill Cornell Medicine reveals that gut bacteria can play a crucial role in determining whether a common dietary amino acid helps cancer grow or boosts the immune system to fight it.

The findings highlight the gut microbiome—trillions of microorganisms living in the intestine—as a key regulator of cancer growth and response to treatment.

The research, published on January 2 in Cell Host & Microbe, focuses on asparagine, an amino acid found in many foods. Asparagine supports protein production and cell survival and is needed by both cancer cells and immune cells called CD8+ T cells, which attack tumors. The study shows that gut bacteria can control how much asparagine reaches tumors, shaping whether it benefits cancer cells or immune defenses.

Using mouse models with human gut bacteria, researchers studied Bacteroides ovatus, a common gut microbe. Some strains of this bacterium carry a gene called bo-ansB, which allows them to break down asparagine in the intestine. When this gene was present, bacteria consumed more asparagine, reducing the amount absorbed into the bloodstream and delivered to tumors.

When the gene was removed, more asparagine entered the circulation and reached tumors. Surprisingly, this extra asparagine did not fuel cancer growth. Instead, it was taken up by CD8+ T cells, pushing them into a powerful “stem-like” state linked to long-lasting anti-tumor immunity. These immune cells became better at multiplying and killing cancer cells.

The study also found that higher asparagine levels increased the activity of a key transporter protein, SLC1A5, on immune cells. Blocking this transporter erased the immune benefits, showing its importance in the process.

The findings suggest that future cancer treatments may go beyond targeting tumors directly. Instead, doctors could combine immunotherapy with personalized diets or microbiome-based strategies—such as tailored probiotics—to starve tumors while strengthening immune responses.

REFERENCE: Qiao, S., et al. (2026). Microbiota utilization of intestinal amino acids modulates cancer progression and anticancer immunity. Cell Host & Microbe. doi: 10.1016/j.chom.2025.12.003. https://www.cell.com/cell-host-microbe/fulltext/S1931-3128(25)00522-0

Source of Nitrate Matters More Than Amount Consumed, Study Finds

Vegetable Nitrates May Protect the Brain, While Meat and Water Nitrates Could Raise Dementia Risk. Not all dietary nitrates are created equal when it comes to brain health, according to new research from the Danish Diet, Cancer and Health Cohort Study published in Alzheimer’s & Dementia.

The study suggests that nitrates from vegetables may lower dementia risk, while those from animal sources and tap water could increase it.

Dietary nitrates are found in plant foods like leafy greens and root vegetables, naturally occurring animal foods, processed meat products, and even tap water. In the body, nitrates convert to nitrites and nitric oxide, a molecule that can improve blood vessel function and potentially protect the brain. However, nitrates can also form N-nitrosamines, compounds linked to cancer and possibly neurotoxicity, particularly when consumed with red meat.

The study followed 54,804 dementia-free adults over up to 27 years. Participants’ nitrate intake was assessed via food-frequency questionnaires. During follow-up, 4,750 people developed dementia, including 191 early-onset cases. Higher plant-sourced nitrate intake was linked to a 10% lower risk of dementia, with doubling of vegetable nitrate intake reducing risk by 8%. Conversely, nitrates and nitrites from animal foods and meat additives were associated with a 11–13% higher risk of dementia, while higher tap water nitrate intake correlated with a 12–16% increased risk.

Early-onset dementia appeared more sensitive to nitrate source, showing even stronger associations, though case numbers were small. Polyphenols and vitamin C, present in plant foods, may help counteract harmful nitrosamine formation from animal sources.

The researchers caution that plant-sourced nitrate intake may reflect overall healthier lifestyle and diet patterns, and the observational design cannot establish cause and effect. Yet the findings highlight a potentially modifiable factor in brain health.

Key takeaway: Prioritizing vegetables for nitrate intake, while moderating processed meats and monitoring water quality, may be a simple but meaningful strategy to support long-term cognitive health.

REFERENCE: Bondonno, C. P., Pokharel, P., Erichsen, D. W., et al. (2026). Source-specific nitrate intake and incident dementia in the Danish Diet, Cancer and Health Study. Alzheimer’s & Dementia. DOI: https://doi.org/10.1002/alz.70995. https://alz-journals.onlinelibrary.wiley.com/doi/10.1002/alz.70995

Dermatologists Warn Collagen Supplements May Not Deliver Expected Skin Benefits

Collagen Supplements Aren’t the Skin Miracle They Claim to Be, Experts Say. Collagen powders and pills have flooded the beauty aisle promising youthful skin, but dermatologists warn that the benefits are largely overstated. Research shows that protecting your skin and maintaining a healthy diet does far more for collagen than any supplement can.

The article appears in the Tufts Health & Nutrition Letter, published each month by the Friedman School of Nutrition Science and Policy.

“Oral collagen supplements are not currently recommended to treat skin aging,” says Dr. Farah Moustafa, assistant professor at Tufts University School of Medicine. “They can be considered alongside other well-studied interventions, but on their own, they aren’t a proven solution.”

Studies on oral collagen have produced mixed results. Some suggest hydrolyzed collagen may improve skin hydration and elasticity, but others find no effect. A recent meta-analysis of 23 randomized controlled trials revealed that studies supporting collagen supplements were often low quality or funded by the industry, while high-quality independent studies found no meaningful benefits.

Collagen is a key structural protein in the skin, muscles, bones, and connective tissues. Natural collagen production slows with age, contributing to wrinkles, sagging skin, and joint changes. However, ingesting collagen doesn’t directly replenish it where the body needs it. “Collagen is broken down during digestion, so consuming it does not necessarily deliver it to your skin or joints,” Moustafa explains.

Safety and quality are additional concerns. Marine-based collagen may carry mercury contamination, and supplements are not regulated like medications. Most lack third-party verification or clear ingredient labeling, according to the American Academy of Dermatology.

Experts recommend focusing on natural ways to support collagen. A nutrient-rich diet high in protein and vitamin C—found in strawberries, kiwis, bell peppers, and citrus—helps the body build collagen. Daily habits matter too: sun protection, using topical retinoids, and avoiding smoking are proven ways to preserve skin collagen and prevent breakdown.

Bottom line: Instead of relying on powders or pills, prioritizing diet, lifestyle, and scientifically backed skincare is the most effective way to keep skin healthy and youthful.

REFERENCE: Tufts University. "Dermatologists say collagen supplements aren’t the skin fix people expect." ScienceDaily. ScienceDaily, 29 January 2026. .