Field Notes

Physical Activity in the Evening Shown to Improve Glucose Regulation in Overweight and Obese Adults

The results, obtained by a team of scientists from the University of Granada (UGR), could have multiple practical implications, especially for people at risk of developing insulin resistance or type 2 diabetes.

The UGR’s PROFITH CTS-977 Research Group, in collaboration with the “San Cecilio” and “Virgen de las Nieves” University Hospitals in Granada, the Public University of Navarre, the Centre for Networked Biomedical Research on Physiopathology of Obesity and Nutrition (CIBEROBN), and the Centre for Networked Biomedical Research on Frailty and Healthy Ageing (CIBERFES), has studied the effect of accumulating moderate-to-vigorous physical activity on glucose levels in overweight and obese adults.

Physical activity is known to have a positive effect on glucose regulation, but does it matter what time of day we do it? The study, which set out to answer this question, was led by researchers Antonio Clavero-Jimeno and Jonatan Ruiz from the UGR’s Department of Physical Education and Sports (Faculty of Sport Sciences) and the Sport and Health University Research Institute. They explain that it was previously unknown whether being more active at a particular time of day (morning, afternoon, or evening) could maximize the cardiometabolic benefits of physical activity. “Choosing the ideal time of day seems to be an emerging strategy to enhance the benefits of physical activity on glucose metabolism, especially for those with insulin resistance or at risk of developing type 2 diabetes,” the researchers note.

The results of the study show that accumulating more moderate-to-vigorous physical activity in the evening, ie, between 18:00 and 00:00, appears to have a positive effect on glucose regulation in men and women who are overweight or obese. In addition, the benefits of physical activity are greater in people who have some form of impaired glucose metabolism, such as elevated levels of glucose, glycated hemoglobin, and/or fasting insulin resistance index. The results were similar for both men and women.

A total of 186 overweight or obese adults (50% of whom were women) with an average age of 47 years took part in the study. These participants wore an accelerometer and a continuous glucose monitor for 14 days in order to measure their physical activity and glucose levels 24 hours a day. Days were classified as “inactive” if no physical activity was recorded; as “morning,” “afternoon,” or “evening” if more than 50% of the recorded minutes of physical activity for that day were registered from 6:00 to 12:00, 12:00 to 18:00, or 18:00 to 00:00, respectively; or as “mixed” if none of these defined time periods accounted for more than 50% of the physical activity for that day.

The results could have several practical implications, especially for those at risk of developing insulin resistance or type 2 diabetes, and highlight the importance of considering the time of day when prescribing physical activity. This information may be crucial in improving the effectiveness of exercise interventions in these groups.

— Source: University of Granada

 

Cleveland Clinic-Led Study Links Sugar Substitute to Increased Risk of Heart Attack and Stroke

Cleveland Clinic researchers found higher amounts of the sugar alcohol xylitol are associated with an increased risk of cardiovascular events like heart attack and stroke.

The team, led by Stanley Hazen, MD, PhD, chair of cardiovascular and metabolic sciences at Cleveland Clinic’s Lerner Research Institute and cosection head of preventive cardiology in the Heart, Vascular & Thoracic Institute, confirmed the association in a large-scale patient analysis, preclinical research models, and a clinical intervention study. Findings were published recently in the European Heart Journal.

Xylitol is a common sugar substitute used in sugar-free candy, gums, baked goods, and oral products like toothpaste. Over the past decade, the use of sugar substitutes, including sugar alcohols and artificial sweeteners, has increased significantly in processed foods that are promoted as healthful alternatives.  

The same research team found a similar link between erythritol and cardiovascular risk last year. Xylitol isn’t as prevalent as erythritol in keto or sugar-free food products in the United States but is common in other countries.

“This study again shows the immediate need for investigating sugar alcohols and artificial sweeteners, especially as they continue to be recommended in combatting conditions like obesity or diabetes,” Hazen says. “It doesn’t mean throw out your toothpaste if it has xylitol in it, but we should be aware that consumption of a product containing high levels could increase the risk of blood clot-related events.”

In this new study, researchers identified that high levels of circulating xylitol were associated with an elevated three-year risk of cardiovascular events in an analysis of more than 3,000 patients in the United States and Europe. One-third of patients with the highest amount of xylitol in their plasma were more likely to experience a cardiovascular event. To confirm the findings, the research team conducted preclinical testing and found that xylitol caused platelets to clot and heightened the risk of thrombosis. Researchers also tracked platelet activity from people who ingested a xylitol-sweetened drink vs a glucose-sweetened drink and found that every measure of clotting ability significantly increased immediately following ingestion of xylitol but not glucose.

The authors note that further studies assessing the long-term cardiovascular safety of xylitol are warranted. The research had several limitations, including that clinical observation studies demonstrate association and not causation. They recommend talking to your doctor or a certified dietitian to learn more about healthful food choices and for personalized recommendations.

The research is part of Hazen’s ongoing investigation into factors that contribute to residual cardiovascular risk. His team follows patients over time and finds chemical signatures in blood that can predict the future development of heart and metabolic disease. He has made pioneering discoveries in atherosclerosis and inflammatory disease research, including the seminal discovery linking gut microbial pathways to CVD and metabolic diseases.

— Source: Cleveland Clinic