Medical Bulletin 17/ June/ 2024

In a new study, published in JAMA Cardiology, researchers at Beth Israel Deaconess Medical Center (BIDMC) conducted a systematic review to determine whether there is a link between climate change-related environmental stressors and cardiovascular disease.

Cardiovascular disease (CVD) is the leading cause of death worldwide, accounting for approximately one in every three deaths, with more than 20 million deaths, according to a 2024 World Heart Federation report.

Climate change can impact cardiovascular health through various mechanisms. Firstly, exposure to environmental stressors can lead to physiological changes, such as an increased heart rate and plasma viscosity during extreme heat, or local and systemic inflammation following the inhalation of airborne particulate matter. Secondly, coping with extreme weather events can heighten stress, anxiety, and depression, which in turn may elevate cardiovascular risk. Together, these pathways pose significant threats to the cardiovascular health of the population.

In the study, researchers screened nearly 21,000 peer-reviewed studies that evaluated associations between acute cardiovascular events, cardiovascular mortality and CVD healthcare utilization and climate change-related phenomena.

The analysis found a strong link between exposure to extreme temperatures and a higher incidence of cardiovascular disease (CVD) and related mortality. The impact, however, varied based on the specific temperature and the duration of exposure. Additionally, extreme weather events were associated with an elevated cardiovascular risk. Some studies indicated that exposure to wildfire smoke, which can affect populations hundreds of miles away from the source, increased the risk of events such as cardiac arrest.

“Climate change is already affecting our cardiovascular health; exposure to extreme heat can adversely affect heart rate and blood pressure; exposure to ozone or wildfire smog can trigger systemic inflammation. We know that these changes have the potential to undermine the cardiovascular health of the population, but the magnitude of the impact, and which populations will be particularly susceptible, need further study,” said corresponding author Dhruv S. Kazi.

Reference: Kazi DS, Katznelson E, Liu C, et al. Climate Change and Cardiovascular Health: A Systematic Review. JAMA Cardiol. Published online June 12, 2024. doi:10.1001/jamacardio.2024.1321

According to a study published in the journal The Lancet Regional Health, Ultra-processed foods made from plants increased the risk of cardiovascular disease by 5% while increasing the risk of early death by 13%.

Cardiovascular disease (CVD) remains the leading cause of premature mortality across the globe, contributing to 18.6 million deaths.

Unprocessed foods include fresh fruits and vegetables, eggs, and milk. Minimally processed foods encompass culinary ingredients like salt, herbs, and oils, as well as canned goods and frozen vegetables that combine these ingredients with unprocessed foods. Ultra-processed foods, on the other hand, undergo multiple industrial processes such as heating, nutrient and protein extraction, molding, and compression. These foods often contain added chemicals to alter their color, smell, taste, and texture.

Designed to be hyper-palatable, ultra-processed foods are typically very convenient, requiring little to no preparation time. Modern plant-based diets may feature a variety of these ultra-processed foods, including sugar-sweetened beverages, snacks, confectionery, and 'plant-based' sausages, nuggets, and burgers, which are marketed as meat and dairy substitutes but are made from plant-derived ingredients.

In the study, researchers utilised data from the UK Biobank participants who completed at least two 24-h dietary recalls between 2009 and 2012 with subsequent data linkage to hospital and mortality records. Food groups were classified as either plant-sourced or non-plant/animal-sourced foods. These groups were further divided into non-UPF and UPF, and expressed as a percentage of total energy intake.

The results showed that every 10 percentage points increase in plant-sourced non-UPF consumption was associated with a 7% lower risk of CVD and a 13% lower risk of CVD mortality. Conversely, plant-sourced UPF consumption was associated with a 5% increased risk and a 12% higher mortality.

The findings revealed that consumption of all UPF was linked to higher CVD risk and mortality. The dietary contribution of plant-sourced non-UPF is inversely linked to CVD risk, while plant-sourced UPF contribution showed a positive association.

Reference: Fernanda Rauber, Maria Laura da Costa Louzada, Kiara Chang, Inge Huybrechts, Marc J. Gunter, Carlos Augusto Monteiro, et al.; Implications of food ultra-processing on cardiovascular risk considering plant origin foods: an analysis of the UK Biobank cohort; The Lancet Regional Health- Europe; DOI: https://doi.org/10.1016/j.lanepe.2024.100948

A recent study published in the European Journal of Clinical Nutrition evaluated the effects of time-restricted eating (TRE) and caloric restriction (CR) on sex hormones.

Time-restricted eating is a weight loss intervention, with a reduced eating window (4–10 hours) and fasting for the remaining time with energy-free beverages.

Despite the health benefits of time-restricted eating, there have been concerns about its impact on sex hormones. Few research claims that time-restricted eating may negatively affect estrogen levels, which might lead to irregularities in the menstrual cycle and fertility issues. Similarly, research on males claims time-restricted eating might reduce testosterone, muscle mass, and libido. However, the impact of time-restricted eating on sex hormones is largely unknown and require further investigation.

For the study, researchers conducted a 12-month study to compare the effects of time-restricted eating (TRE) and calorie restriction (CR) on reproductive hormones in males and females. Participants were divided into three groups: caloric restriction, time-restricted eating, and control. The study had two phases: weight loss and maintenance, each lasting six months.

TRE participants ate freely from 12 PM to 8 PM and fasted until noon, later extending their eating window to 10 AM to 8 PM in the maintenance phase. The caloric restriction group reduced their daily energy intake by 25% initially, then consumed their calculated energy needs. The control group maintained their usual diet and exercise routines.

Fasting blood samples were collected to measure total testosterone, Dehydro-epiandrosterone (DHEA), progesterone, estrone, estradiol, and Sex hormone-binding globulin (SHBG) levels. Changes between groups were analyzed, and the relationship between sex hormones and body weight was examined.

The result showed significant weight loss in both the time-restricted eating and caloric restriction groups compared to the control group after 12 months, with no difference between time-restricted eating and caloric restriction. Sex hormone-binding globulin (SHBG), Dehydroepiandrosterone (DHEA), and total testosterone levels remained unchanged across all groups. In postmenopausal females, progesterone, estradiol, and estrone levels were also unchanged. Weight loss did not correlate with changes in sex hormones for either gender.

The findings suggested that time-restricted eating induces significant weight loss but does not affect sex hormones in males or females with obesity over 12 months compared to caloric restriction and controls. Changes in sex hormones might have occurred during the initial months of the intervention, which gradually returned to baseline levels as body weight stabilized over time.

Reference: Lin S, Cienfuegos S, Ezpeleta M, Pavlou V, Runchey MC, Varady KA. (2024) Effect of time restricted eating versus daily calorie restriction on sex hormones in males and females with obesity. Eur J Clin Nutr,. doi: 10.1038/s41430-024-01461-5. https://www.nature.com/articles/s41430-024-01461-5