Roundup: New Study Intensifies Debate Over Intermittent Fasting and Possible Heart Health Risks; and More News

A Type of Intermittent Fasting Linked to Higher Cardiovascular Risk, New Study Finds

People who limit their eating across less than eight hours per day – time-restricted dieting that is also known as a type of “intermittent fasting” – had a 91 percent higher risk of death from cardiovascular disease, compared to people who ate across 12 to 16 hours per day, according to new research presented this week by the American Heart Association (AHA).

Researchers caution: The study does not conclude that time-restricted eating causes cardiovascular death. But the observational study determined an association. Individuals with underlying health issues such as heart disease or diabetes, or those under cancer treatments, should consult with their healthcare professional regarding potential effects of intermittent fasting, which has gained popularity in recent years as a way to lose weight and improve heart health.

“Time-restricted” plans involve limiting the hours for eating to a specific time-frame each day, which may range from a 4- to 12-hour time window over 24 hours. Most people follow eating plans across 12 to 16 hours a day.

“While this study has strengths, including the large, diverse sample and linkage to mortality data, the observational design and unexpected findings raise important questions,” explains Adedapo Iluyomade, M.D., a preventive cardiologist who helps lead the Cardiometabolic Clinic and other programs at Baptist Health Miami Cardiac & Vascular Institute.  “The results should be interpreted cautiously and do not provide definitive evidence that TRE (Time Restricted Eating, particularly an 8-hour or less eating duration, increases cardiovascular mortality risk.”

Many people who follow a time-restricted diet follow a “16:8 eating schedule” when they eat all their foods in an eight-hour window and fast for the remaining 16 hours each day, the researchers stated. Previous studies have indicated that time-restricted eating can improve several cardiometabolic health measures, such as blood pressure, blood glucose and cholesterol levels.

In the new study, researchers focused on the “potential long-term health impact” of following an 8-hour time-restricted eating plan, states a news release from the AHA.  They reviewed information about dietary patterns for 20,000 study participants in the annual 2003-2018 National Health and Nutrition Examination Surveys  in comparison to data about people who died in the U.S., from 2003 through December 2019, from the U.S. Centers for Disease Control and Prevention’s National Death Index database.

“It’s crucial for patients, particularly those with existing heart conditions or cancer, to be aware of the association between an 8-hour eating window and increased risk of cardiovascular death,” said senior study author Victor Wenze Zhong, Ph.D., a professor and chair of the department of epidemiology and biostatistics at the Shanghai Jiao Tong University School of Medicine in Shanghai, China, in a statement. “Our study’s findings encourage a more cautious, personalized approach to dietary recommendations, ensuring that they are aligned with an individual’s health status and the latest scientific evidence.”

The preliminary research was presented this week at the AHA’s “Epidemiology and Prevention/Lifestyle and Cardiometabolic Scientific Sessions 2024” in Chicago, an annual conference on the latest science on population-based health and wellness.

According to Dr. Iluyomade, here are some of the limitations of the study:

1. One major drawback is that the study has not yet undergone peer review or been published in a scientific journal, which makes it challenging to thoroughly assess its methodological rigor and the reliability of its conclusions.
2. The researchers relied on just two dietary questionnaires to estimate participants' usual eating patterns over the entire study period, which may not sufficiently capture long-term variations in dietary habits.
3. The study appeared to focus solely on the timing of meals and did not take into account the nutritional quality or composition of the foods consumed, which are critical factors in determining health outcomes.
4. The group following an eight-hour eating window was relatively small, with only 414 participants, and had notable differences in demographics and lifestyle factors compared to the other groups. Although the researchers adjusted for these differences, the potential for residual confounding cannot be entirely dismissed.

New Research Links Healthy, Plant-Based Diet to Slower Pace Of Aging, Lower Dementia Risk

A new study adds to the growing evidence that a healthy diet over the years contributes to a slower pace of aging – and reduced risk of dementia.

Previous research has linked both poor diets and dementia risk to an accelerated pace of biological aging,

“Our findings suggest that slower pace of aging mediates part of the relationship of healthy diet with reduced dementia risk, and therefore, monitoring pace of aging may inform dementia prevention,” said the study’s first author Aline Thomas, Ph.D., in a statement.

The new study from the Columbia University Mailman School of Public Health and The Robert Butler Columbia Aging Center used data from the second generation of the Framingham Heart Study, originating in 1971.

Study participants were 60 years of age or older and free of dementia. They also had available dietary and other key follow-up data. There were monitoring during nine examinations, about every four to seven years. At each follow-up visit, data collection included a physical examination, lifestyle-related questionnaires, blood sampling, and, starting in 1991, neurocognitive testing.

“Much attention to nutrition in dementia research focuses on the way specific nutrients affect the brain” said Daniel Belsky, PhD, associate professor of Epidemiology at Columbia School of Public Health and the Columbia Aging Center, and a senior author of the study, in a statement. “We tested the hypothesis that healthy diet protects against dementia by slowing down the body’s overall pace of biological aging.”

The researchers highlighted the Mediterranean-style diet, which is highly rated by dieticians and physicians. The Mediterranean diet is primarily a plant-based eating plan that includes whole grains, olive oil and healthy fats, fruits, vegetables, beans and other legumes, nuts, herbs, and spices. Meat and dairy are eaten in smaller quantities, with the preferred animal protein being fish and seafood, followed by poultry. Red meat is eaten infrequently.

The U.S. government’s dietary guidelines, also known as My Plate, also focus on plant-based options. About half of the government’s My Plate is fruits and vegetables, while the other half consists of grains and protein.

NIH Study Finds Brain Connections Linked to Attention Deficit Hyperactivity Disorder (ADHD) in Youth

In the largest and most consequential study of attention deficit hyperactivity disorder, or ADHD, in youth, the National Institutes of Health (NIH) has determined that “atypical interactions between the brain’s frontal cortex and information processing centers deep in the brain” are responsible for ADHD symptoms

The researchers examined more than 10,000 functional brain images of youth with ADHD and published the study’s results in the American Journal of Psychiatry. ADHD symptoms usually include a combination of persistent problems, such as difficulty sustaining attention and sporadic hyperactivity and impulsive behavior.

The researchers indicated that previous, smaller studies may not have been able to reliably detect the brain interactions leading to the behavioral symptoms associated with ADHD. Earlier studies have returned mixed findings, possibly due to the small scale of participants – about 100 or so subjects.

Researchers at NIH’s National Institute of Mental Health (NIMH) and National Human Genome Research Institute found that young people with ADHD had heightened connectivity between “structures deep in the brain involved in learning, movement, reward, and emotion and structures in the frontal area of the brain involved in attention and control of unwanted behaviors.”

They analyzed brain images from six different functional imaging datasets  of more than 8,000 youth with and without ADHD. By studying the images, the researchers examined associations between functional brain connectivity and ADHD symptoms.