Medical Bulletin 26/August/2026

Here are the top medical news for today:

Small Trial Finds Daily Vinegar Drink May Improve Constipation Symptoms

Daily consumption of a vinegar-based beverage was associated with more frequent bowel movements in adults with mild constipation, according to a randomized controlled study conducted in Japan.

The study, accepted for publication in Scientific Reports, examined whether a beverage containing acetic acid, the main active component of vinegar, could improve defecation frequency in otherwise healthy adults experiencing mild constipation.

Researchers conducted a randomized, double-blind, placebo-controlled trial involving 44 Japanese adults aged 20 to 69 years. Participants had bowel movements three to five times during the week before the study and were randomly assigned to consume either a vinegar beverage or a placebo drink every morning for four weeks.

The vinegar beverage contained 750 milligrams of acetic acid in 200 milliliters of water, while the placebo contained 30 milligrams of citric acid. Both drinks had apple flavoring and sucralose. Participants otherwise maintained their usual diets and lifestyles and recorded their bowel movements throughout the study.

After four weeks, participants who consumed the vinegar beverage had significantly more bowel movements than those in the placebo group. The difference was approximately 1.2 additional bowel movements per week.

Researchers also observed possible improvements in some bowel measures earlier in the study. During the first week, the vinegar group tended to have more frequent bowel movements and more defecation days, while stool volume also showed a tendency to increase during the first two weeks. Some participants reported a better sensation of complete bowel emptying.

However, the researchers found no significant changes in gut microbiota diversity following the intervention. They suggested that vinegar may instead influence the gastrocolic reflex or intestinal movement, although these mechanisms were not directly measured.

The researchers cautioned that the study was small, used a single vinegar dose and relied partly on self-reported bowel diaries. Dietary intake was also not closely monitored.

Further studies involving larger and more diverse populations are needed to determine whether vinegar can provide a sustained benefit for constipation and clarify how it may affect bowel function.

REFERENCE: Aoki Y, Yoshimoto J, Tokushige A, et al. (2026). Vinegar beverage consumption improves defecation status in constipation-prone healthy adults: a randomized, double-blind, placebo-controlled trial. Scientific Reports. DOI: 10.1038/s41598-026-67164-y

Gut Microbes Could Explain How Vegetables Improve Health, New Study Suggests

Gut bacteria may transform nutrients found in vegetables into powerful molecules that could help protect the heart, blood vessels and metabolism, according to researchers at Karolinska Institutet.

The study, published in Cell, identified a previously unknown pathway in which gut microbes combine nitrate and non-haem iron from food to produce compounds called dinitrosyl iron complexes (DNICs). Nitrate is naturally abundant in vegetables such as beetroot, spinach, rocket and lettuce, while non-haem iron is found in foods including beans, whole grains and green vegetables.

Researchers found that DNICs can be absorbed through the gut and transported to organs including the liver and kidneys. The compounds were completely absent in germ-free mice, indicating that gut bacteria play an essential role in their formation.

The team conducted experiments involving mice, cells, bacteria and human samples. When researchers increased DNIC levels using nitrate and iron supplements or synthetic DNIC, animals with cardiovascular and metabolic disease showed improvements in several health markers. These included lower blood pressure, improved blood vessel function, better blood sugar control and reduced fat accumulation in the liver.

The findings could help explain why diets rich in vegetables have been associated with a lower risk of cardiovascular and metabolic diseases. However, researchers caution that much of the evidence comes from experimental models, and it is not yet known whether increasing DNIC levels would provide similar benefits in humans.

The researchers now plan to develop reliable methods for measuring DNIC levels in people and investigate how diet and gut microbiota influence their production.

Future studies will also examine whether modifying the gut microbiome or dietary intake could increase DNIC formation and potentially offer new approaches for preventing or managing cardiovascular and metabolic diseases.

REFERENCE: Andrei L. Kleschyov et al.; Gut microbiota generate dinitrosyl iron complexes with cardiometabolic benefits. Cell, 2026; DOI: 10.1016/j.cell.2026.07.055

Study Finds Peppermint Oil May Lower Blood Pressure Within Just 20 Days

A small daily dose of peppermint oil may help lower mildly elevated blood pressure, according to new research from the University of Lancashire.

The study, published in PLOS One, found that taking 100 microliters of peppermint oil twice daily for 20 days reduced systolic blood pressure by an average of 8.5 mmHg in adults with prehypertension or stage 1 hypertension.

High blood pressure is a major preventable risk factor for cardiovascular and metabolic diseases, including heart disease and stroke. Current treatment generally focuses on lifestyle changes and, when necessary, prescribed medications.

Researchers enrolled 40 adults aged 18 to 65 and randomly assigned them to receive either peppermint oil or a peppermint-flavoured placebo. Participants in the peppermint oil group experienced a reduction in blood pressure, while those receiving the placebo showed no meaningful change.

Peppermint naturally contains compounds such as menthol and flavonoids, which may contribute to its biological effects. However, the precise mechanism through which peppermint oil could influence blood pressure remains unclear.

The researchers also examined several other health measures, including diastolic blood pressure, heart rate, body measurements, blood test results, sleep quality and mental well-being. The study was designed primarily to assess the potential effect on blood pressure.

The findings raise the possibility that peppermint oil could become a simple, inexpensive approach for managing mildly elevated blood pressure. However, the researchers caution that the study involved only a small number of participants and lasted just 20 days. Larger, longer-term clinical trials will be necessary to confirm the results, determine whether the blood pressure reduction persists and establish the appropriate dose and safety profile.

Researchers say peppermint oil could potentially complement established approaches if future studies confirm its benefits. However, people with hypertension should not stop or replace prescribed medication with peppermint oil without consulting a healthcare professional.

REFERENCE: Jonathan Sinclair, et al.; Effects of peppermint (Mentha x piperita L.) oil on cardiometabolic outcomes in patients with pre- and stage 1 hypertension: A placebo randomized controlled trial. PLOS One, 2026; 21 (4): e0344538 DOI: 10.1371/journal.pone.0344538