The time of day when we eat is crucial for our health

Although people have always said that having a light and early dinner is better, a study by the Universitat Oberta de Catalunya (UOC) and Columbia University has provided the scientific grounds for this argument. According to a study published in open access format by the Nature group journal Nutrition & Diabetes, consuming more than 45% of our daily calorie intake after 5 p.m. is associated with an increase in glucose levels, with the harmful consequences that this has for health, regardless of the individual's weight and body fat.

The study was carried out at Columbia University's Irving Medical Center in New York, and was led by Dr Diana Díaz Rizzolo, postdoctoral researcher and member of the Faculty of Health Sciences at the UOC.

"Maintaining high levels of glucose over long periods of time can have implications including a higher risk of progressing to type 2 diabetes, an increase in cardiovascular risk due to the damage that high glucose levels do to blood vessels, and increased chronic inflammation, which aggravates cardiovascular and metabolic damage," said Díaz Rizzolo.

Experts had previously believed that the main consequence of eating dinner late in the day was weight gain. This was associated with the fact that people tend to make poorer dietary choices at night, such as consuming more ultra-processed foods, since the hormones that regulate hunger and satiety are altered when people do not eat during daylight hours.

The importance of the study lies in the fact that it shows that the time of day when meals are eaten can in itself have a negative impact on glucose metabolism, regardless of the amount of calories consumed throughout the day and the individual's weight and body fat.

“The time of day when meals are eaten can in itself have a negative impact on glucose metabolism”

Late eaters versus early eaters

The study included 26 participants between the ages of 50 and 70 who were overweight or obese, and had prediabetes or type 2 diabetes. The participants' glucose tolerance levels were compared, and they were divided into two groups: early eaters, who consumed most of their daily calories before the evening, and late eaters, who consumed 45% or more of their calories after 5 p.m. The two groups consumed the same amount of calories and the same foods during the day, but did so at different times. The participants used a mobile app to record their meals in real time.

The main finding of the study is that the late eaters had a poorer tolerance of glucose, regardless of their weight or the composition of their diet. It also found that they tended to eat larger amounts of carbohydrates and fats during the evening.

Díaz Rizzolo, who is an expert on issues related to obesity, diabetes and ageing, explained that "the body's ability to metabolize glucose is limited at night, because the secretion of insulin is reduced, and our cells' sensitivity to this hormone declines due to the circadian rhythm, which is determined by a central clock in our brain that is coordinated with the hours of daylight and night."

 

The importance of eating at the right time

The study therefore contains an important finding in terms of its implications for health and the time of day that people eat their meals. "Until now, personal decisions in nutrition have been based on two main questions: how much we eat, and what foods to choose. With this study, a new factor in cardiometabolic health is beginning to become increasingly important: when we eat," said Díaz Rizzolo.

In view of the results of the study, and considering them with due caution, since further research to gain a greater understanding of the subject will be required, the researcher advises that food should mainly be eaten during daylight hours, and that "the highest levels of calorie intake during the day should be at breakfast and lunch, instead of at teatime and dinner". Díaz Rizzolo also recommends avoiding eating ultra-processed products, fast food and foods rich in carbohydrates, especially at night. 

New research reveals startling shortfalls in dietary nutrition during pregnancy

 

It’s generally estimated that around 10% of pregnant people struggle to meet their nutritional needs—but the real number could be far higher, according to new research from Stevens Institute of Technology.

According to a recent study published in The Journal of Nutrition, over 90% of pregnant individuals are potentially failing to get enough iron, vitamin D, or vitamin E from the food they eat, while over one-third could be short of calcium, vitamin C, and vitamin A. Troublingly, almost two-thirds of pregnant people were also found to be getting insufficient dietary folate—a critical nutrient that helps prevent birth defects in the baby's brain and spine.

“It’s important to remember that many pregnant people take prenatal vitamin supplements, which might help prevent nutritional deficiencies,” says Dr. Samantha Kleinberg, the study’s lead author and a professor at the Charles V. Schaefer, Jr. School of Engineering and Science at Stevens. “Nonetheless, this is a startling finding that suggests we need to be looking much more closely at whether pregnant individuals are getting the nutrients they need.”

Where most previous studies of nutrition during pregnancy relied on a few days of food diaries, or on simply asking people what they remembered eating, the Stevens team asked pregnant people to take before-and-after photos of everything they ate over two 14-day periods. Experts then reviewed the photos to assess the amount of food actually eaten and determine the nutrients consumed during each meal.

That’s a far more accurate approach, because people are notoriously bad at estimating portion size or accurately reporting what they’ve eaten, Dr. Kleinberg explains. A photo-based approach is also much less laborious for pregnant people, making it easy to collect data over a period of weeks instead of just a few days.

“Most surveys only track diet over a day or two—but if you feel off one day and don’t eat much, or have a big celebratory meal over the weekend, that can skew the data,” Dr. Kleinberg says. “By looking at a longer time period, and using photos to track diet and nutrition, we’re able to get a much richer and more precise picture of what people actually ate.”

The study, which was co-authored with Dr. Andrea Deierlein, director of public health nutrition at New York University, found significant dietary variations between individuals, but also among the same individuals from one day to the next, suggesting that shorter studies and population-based reports might be failing to spot important nutritional deficits. “Some people eat really well, and others don’t—so if you just take an average, it looks like everything’s fine,” Dr. Kleinberg explains. “This study suggests that in reality, an alarming number of pregnant people may not be getting the nutrients they need from their food.”

Using food photos also allowed the Stevens team to accurately track the exact timing of meals and snacks, and to explore the way that patterns of eating behavior correlated with total energy and nutrient intake. When pregnant people ate later in the day, the data shows, they were likely to consume significantly more total calories—potentially an important finding as researchers explore connections between eating behaviors and health problems such as gestational diabetes.

The current research didn’t directly study health outcomes, so it’s too early to say whether insufficient nutrition or excessive energy consumption is adversely impacting pregnant individuals or their babies. “We’ll be digging into that in future studies, and looking at possible connections with eating patterns and changes in glucose tolerance,” Dr. Kleinberg says.

The team also hopes to automate the process of assessing nutritional content based on food photos, and is developing large language models capable of automatically asking follow-up questions to obtain more accurate information. “For this study, we often had to reach out to participants to ask what kind of meat they’d put in their sandwich, or whether their coffee had sugar in it,” Dr. Kleinberg explains. “If we can streamline that process, then we’ll be able to capture data more easily—and help shed new light on how pregnant people actually eat.”

Fitness more important than fatness for a lower risk of premature death

 

Individuals classified as fit—even when overweight or obese—showed no significant increase in cardiovascular disease or all-cause mortality.

As rates of obesity, as defined by body mass index (BMI), continue to climb in the United States, so have efforts to lose weight, including a new era of weight-loss drugs. Yet a new systematic review and meta-analysis published today in the British Journal of Sports Medicine found that cardiorespiratory fitness was a stronger predictor of both cardiovascular disease and all-cause mortality than BMI.

The researchers found that fit individuals across all BMI categories had statistically similar risks of death from all causes or cardiovascular disease. By contrast, unfit individuals in all BMI categories showed two- to three-fold higher risks of both all-cause and cardiovascular disease mortality compared with normal weight fit individuals. In fact, obese fit individuals had significantly lower risk of death compared to normal weight unfit individuals.

“Fitness, it turns out, is far more important than fatness when it comes to mortality risk,” said Siddhartha Angadi, associate professor of exercise physiology at the University of Virginia School of Education and Human Development and corresponding author of the study. “Our study found that obese fit individuals had a risk of death that was similar to that of normal weight fit individuals and close to one-half that of normal weight unfit individuals.

“Exercise is more than just a way to expend calories. It is excellent ‘medicine’ to optimize overall health and can largely reduce the risk of cardiovascular disease and all-cause death for people of all sizes.”

The researchers reviewed 20 studies with a total sample size of 398,716 adults from multiple countries. About one third of the participants in the studies were females, an increase of nearly three-fold from previous studies. In the majority of studies, individuals were classified as fit if their exercise stress test score (estimated or directly measured VO2max) placed them above the 20th percentile within their age group.

Obesity is associated with a series of health conditions and weight loss has long been seen as the way to reduce the impact of those conditions. But weight loss is challenging and failing to keep weight off can bring other risks.

“Most people who lose weight regain it,” said Glenn Gaesser, professor at Arizona State University and co-author of the study. “Repetitive cycles of losing and gaining weight—yo-yo dieting—is associated with numerous health risks comparable to those of obesity itself. Improving cardiorespiratory fitness may help avoid the adverse health effects associated with chronic yo-yo dieting.”

Approximately 20% of US adults meet the physical activity guidelines set by the U.S. Department of Health and Human Services. Current guidelines recommend adults perform a minimum of 150 minutes per week of moderate-intensity physical activity or 75-minutes of vigorous physical activity along with muscle strengthening for two days a week. For those who find themselves in the bottom 20th percentile of cardiorespiratory fitness, beginning any kind of aerobic exercise could have a big impact.

“The largest reduction in all-cause and cardiovascular disease mortality risk occurs when completely sedentary individuals increase their physical activity modestly,” Angadi said. “This could be achieved with activities such as brisk walking several times per week with the goal of accumulating approximately 30 minutes per day.”

The researchers note that the study examines data from large epidemiological studies and recommend that it is time to independently assess the value of a fitness-based approach rather than a weight-loss approach in obese individuals to optimize health outcomes.

High cardiorespiratory fitness linked to lower risk of dementia

 

People with a genetic predisposition for dementia could reduce their risk by up to 35% through increased cardiorespiratory fitness

Peer-Reviewed Publication

BMJ Group

High cardiorespiratory fitness is associated with better cognitive performance and lower risk of dementia long term, including in people with a genetic predisposition to dementia, show the findings of a study published online in the British Journal of Sports Medicine.

 

Cardiorespiratory fitness (CRF) is the capacity of the circulatory and respiratory systems to supply oxygen to muscles and declines increasingly with age as skeletal muscle is lost. CRF declines by around  3% to 6% per decade when people are in their 20s and 30s, but this accelerates to more than 20% per decade by the time people reach their 70s. Low CRF is a strong predictor of cardiovascular events such as strokes and heart attacks and mortality from all causes.

Most previous studies investigating the impact of CRF on cognitive function and dementia risk included a small number of participants. For this study, the authors looked at a much larger group by accessing data on 61,214 dementia-free people aged 39-70 years who enrolled in the UK Biobank study between 2009 and 2010 and were followed for up to 12 years. 

At enrolment, a 6-minute submaximal exercise test on a stationary bike was completed to estimate CRF, cognitive function was estimated using neuropsychological tests, and genetic predisposition for dementia was estimated using the polygenic risk score for Alzheimer’s disease. During the follow-up period of up to 12 years, 553 people (0.9%) received a diagnosis of dementia. 

Participants were divided into three equal-sized groups standardised by age and sex according to their CRF scores for the analysis which showed that people with high CRF had higher cognitive function and a lower risk of dementia.

Compared with people with low CRF, the incidence rate ratio (IRR) of all dementia was 0.6 for people with high CRF, and onset of dementia was delayed by 1.48 years. A high CRF also reduced all dementia risk by 35% among people with a moderate/high polygenic risk score.

This is an observational study, and as such, can’t establish cause and effect, and the researchers acknowledge various imitations to their findings.

Most importantly the number of dementia cases may have been underestimated because UK Biobank participants are generally healthier than the general population, plus individuals with certain health conditions were excluded from the exercise test making the population investigated ‘healthier’ still. The reliance on registries to identify dementia cases might have led to a further underestimation. Also, the submaximal exercise test used is considered less accurate than maximal exercise testing which requires participants to exercise to exhaustion, and any association between CRF change and dementia risk could not be examined due to the lack of repeat CRF measurements.

The authors conclude, “Our study shows that higher CRF is associated with better cognitive function and decreased dementia risk. Moreover, high CRF may buffer the impact of genetic risk of all dementia by 35%.”

They add that their findings suggest that, “Enhancing CRF could be a strategy for the prevention of dementia, even among people with a high genetic predisposition for Alzheimer’s disease.”

Further research on the relationship between CRF and brain health, especially in older adults, and on the mechanisms by which CRF modifies the relationship between genetic risk and dementia is needed, they say.

Sitting too long can harm heart health, even for active people

 

Approximately 10 hours or more of sedentary behavior per day is associated with heightened risk of heart failure and cardiovascular death, even in those who regularly exercise

More time spent sitting, reclining or lying down during the day may increase the risk of cardiovascular disease (CVD) and death, according to a study in JACC, the flagship journal of the American College of Cardiology, and presented at the American Heart Association’s Scientific Sessions 2024. More than roughly 10-and-a-half hours of sedentary behavior per day was significantly linked with future heart failure (HF) and cardiovascular (CV) death, even among people meeting recommended levels of exercise.

“Our findings support cutting back on sedentary time to reduce cardiovascular risk, with 10.6 hours a day marking a potentially key threshold tied to higher heart failure and cardiovascular mortality,” said Shaan Khurshid, MD, MPH, a cardiologist at the Massachusetts General Hospital and co-senior author of the study. “Too much sitting or lying down can be harmful for heart health, even for those who are active.”

Insufficient exercise is a known risk factor for cardiovascular disease (CVD). Over 150 minutes of moderate-to-vigorous physical activity per week is recommended by current guidelines to promote heart health. However, study experts say exercise is only a small fraction of overall daily activity, and the current guidelines don’t provide specific guidance on sedentary behavior which accounts for a much larger portion of daily activity, despite evidence that it’s directly linked with CVD risk.

This study examined the amount of sedentary time at which CVD risk is greatest and explored how sedentary behavior and physical activity together impact the chances of atrial fibrillation (AF), heart failure (HF), myocardial infarction (MI) and CV mortality.

Among the 89,530 study participants of the UK biobank, the average age was 62 years and 56.4% were women. Participants submitted data from a wrist-worn triaxial accelerometer that captured movement over seven days. The average sedentary time per day was 9.4 hours.

After an average follow-up of eight years, 3,638 individuals (4.9%) developed incident AF, 1,854 (2.1%) developed incident HF, 1,610 (1.84%) developed indecent MI and 846 (0.94%) died of CV causes, respectively.

The effects of sedentary time varied by outcome. For AF and MI, the risk increased steadily over time without major shifts. For HF and CV mortality, increase in risk was minimal until sedentary time exceeded about 10.6 hours a day, at which point risk rose significantly, showing a “threshold” effect for the behavior.

For study participants who met the recommended 150 minutes of moderate-to-vigorous physical activity or more, the effects of sedentary behavior on AF and MI risks were substantially reduced, but effects on higher risk of HF and CV mortality remained prominent.

“Future guidelines and public health efforts should stress the importance of cutting down on sedentary time,” Khurshid said. “Avoiding more than 10.6 hours per day may be a realistic minimal target for better heart health.”

In an accompanying editorial comment, Charles Eaton, MD, MS, Director of the Brown University Department of Family Medicine, said the use of wearable accelerometers has shown that exercise is significantly over-estimated by self-report and sedentary behavior is under-estimated.

Eaton said that replacing just 30 minutes of excessive sitting time each day with any type of physical activity can lower heart health risks. Adding moderate-to-vigorous activity cut the risk of HF by 15% and CV mortality by 10%, and even light activity made a difference by reducing HF risk by 6% and CV mortality by 9%.

“This study adds to the growing evidence of a strong link between sedentary behavior and cardiovascular health,” said Harlan M. Krumholz, MD, SM, Harold H. Hines Jr. Professor at Yale School of Medicine and Editor-in-Chief of JACC. “The findings strongly suggest that we need to get people moving to promote better health.”

There are several limitations of the study, including the inability to know details on where or why people are sitting or lying down for extended periods, such as at the workplace, which could have different impacts on CV risks. Accelerometers worn on the wrist are imperfect at detecting posture and therefore may misclassify standing time as sedentary time. A longer monitoring period may provide more accurate data on activity habits and patterns.

Other limitations include the potential for confounders in study results, selection bias, the inability to measure the actual effects of reallocating sedentary time to other activities, and differences between data from wrist-worn accelerometers versus thigh-worn accelerometers.

New evidence links gut microbiome to chronic disease outcomes

 

Peer-Reviewed Publication

First Hospital of Jilin University

 

image: 

Functions of the gut microbiome. Created with BioRender.com. SCFA, short chain fatty acids.

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Credit: By Connor Prosty, Khaled Katergi, Jesse Papenburg, et al.

The gut microbiome, an ecosystem of trillions of microorganisms in the human digestive tract, has been increasingly linked to chronic diseases. Research led by Dr. Connor Prosty and his team at McGill University consolidates recent findings that demonstrate a causal role for the gut microbiome in the progression of multiple diseases, ranging from gastrointestinal conditions to immune-related and psychiatric disorders. Published in eGastroenterology, this narrative review examines how manipulating the gut microbiome may open new therapeutic avenues.

The study draws on recent randomized controlled trials (RCTs) and preclinical evidence that reveal substantial advances in understanding how the gut microbiome affects human health. The most promising findings come from studies on Clostridioides difficile infection (CDI), where fecal microbiota transplantation (FMT)—a process involving the transfer of stool from a healthy donor into the gastrointestinal tract of a patient—has shown efficacy in significantly reducing infection recurrence rates. CDI, a severe bacterial infection often triggered by antibiotic use, remains difficult to treat due to its high relapse rate. FMT has emerged as a groundbreaking therapy, with studies showing that it can restore gut microbial balance and reduce recurrence rates by up to 93%.

In addition to CDI, the review highlights the potential role of microbiome-based interventions in cancer immunotherapy and ulcerative colitis (UC). Recent trials suggest that the composition of the gut microbiome may influence how well patients respond to immunotherapy, particularly in cancers such as melanoma and renal cell carcinoma. Findings indicate that individuals with specific gut microbiota profiles, including higher levels of Akkermansia muciniphila and Bifidobacterium, experience better outcomes when undergoing immunotherapy, likely due to the microbiome’s role in modulating immune responses. Supplementation with microbiome agents in cancer treatment may thus enhance the body’s natural ability to fight tumors.

In UC, a chronic inflammatory condition of the colon, FMT and other microbiome therapies have demonstrated potential as alternatives to conventional, often immunosuppressive treatments. Several trials reveal that FMT can improve symptoms, induce remission, and increase the gut microbial diversity of patients with UC, who typically have less diverse gut bacteria than healthy individuals. This evidence supports the potential of microbiome-altering therapies to modulate the immune response and reduce the need for prolonged use of corticosteroids and other immunosuppressive drugs.

Interestingly, the microbiome’s role in obesity is more complex. Although animal studies have shown that changes in gut bacteria can influence weight and metabolic health, RCTs in humans have so far been inconclusive. Trials testing microbiome therapies in patients with obesity and metabolic disorders have not demonstrated significant weight loss or changes in body mass index (BMI), suggesting that while the microbiome plays a role in metabolism, it may not act as a stand-alone solution for weight management.

The review also addresses the challenges and limitations in linking the microbiome to chronic diseases. Factors such as diet, age, and lifestyle contribute to microbiome variability, which can complicate causal analysis. Additionally, differences in microbiome profiles between animal models and humans make it challenging to apply findings directly to human populations. The team suggests that further research is needed to determine the best formulations, dosages, and delivery methods for microbiome therapies, as well as the long-term safety and efficacy of these treatments.

Despite these challenges, Dr. Prosty and his colleagues emphasize the transformative potential of microbiome-targeted therapies. “The gut microbiome is increasingly recognized not only as a biomarker but as a target for therapeutic intervention,” said Dr. Prosty. “These findings validate the microbiome’s role in disease development and pave the way for safe, non-invasive treatments that can enhance patient outcomes.”

With two FDA-approved microbiome therapies already on the market for CDI and multiple ongoing clinical trials exploring microbiome interventions for other conditions, the future of microbiome medicine is promising. Researchers are now focusing on optimizing treatments to ensure patient safety, exploring the impact of diet and lifestyle on microbiome health, and examining how personalized microbiome therapies can be developed to treat or even prevent chronic diseases.

This research positions the gut microbiome as a frontier in healthcare, providing a foundation for therapeutic innovation that could dramatically impact millions of lives worldwide.

 

See the article: 

Prosty C, Katergi K, Papenburg J, et al. Causal role of the gut microbiome in certain

human diseases: a narrative review. eGastroenterology 2024;2:e100086. doi:10.1136/egastro-2024-100086

Too much sitting hurts the heart

New study shows that being sedentary increases the risk of the most common types of heart disease, even among those who get enough exercise

Fitting in a workout after a long day of sitting at a desk might not be enough to compensate for the impacts of sedentary behavior on the heart. Investigators from Mass General Brigham, found that excessive sedentary behavior (waking activity with low energy expenditure while sitting, reclining, or lying down and not including hours spent sleeping at night) was linked to increased risk of heart disease, especially heart failure and cardiovascular death, and that these risks could be significantly reduced by substituting sedentary time for other activities. They also found that meeting guideline levels of moderate-to-vigorous physical activity may be insufficient on its own to reduce cardiovascular risk if one is also sitting too much. Their results are published in the Journal of the American College of Cardiology. 

“Many of us spend the majority of our waking day sitting, and while there's a lot of research supporting the importance of physical activity, we knew relatively little about the potential consequences of sitting too much beyond a vague awareness that it might be harmful,” said lead author Ezimamaka Ajufo, MD, a cardiology fellow at Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system. “Sedentary risk remained even in people who were physically active, which is important because many of us sit a lot and think that if we can get out at the end of the day and do some exercise we can counterbalance it. However, we found it to be more complex than that.”  

Ajufo’s team, which included researchers from across Mass General Brigham, analyzed one week of activity-tracker data from 89,530 individuals from the UK Biobank prospective cohort. They looked at associations between daily time spent sitting and the future risk of four common cardiovascular diseases: atrial fibrillation, heart attacks, heart failure, and death from cardiovascular causes. The team used a machine learning algorithm to classify sedentary behavior. 

They found sedentary behavior was associated with higher risks of all four types of heart disease, with a marked 40-60 percent greater risk of heart failure and cardiovascular death observed when sedentary behavior exceeded 10.6 hours a day (not including hours spent sleeping). Many of the negative effects of sedentary behavior persisted even among those individuals who achieved the guideline-recommended >150 minutes of moderate-to-vigorous physical activity per week. For example, although the study found that the risk of atrial fibrillation and heart attacks could be mostly eliminated by engaging in physical activity, the excess risk of heart failure and cardiovascular death could only be partially offset by physical activity.  

“Our data supports the idea that it is always better to sit less and move more to reduce heart disease risk, and that avoiding excessive sitting is especially important for lowering risk of heart failure and cardiovascular death,” said co-senior author Shaan Khurshid, MD, MPH, an electrophysiologist and faculty member in the Telemachus And Irene Demoulas Family Foundation Center for Cardiac Arrythmias at Massachusetts General Hospital, a founding member of the Mass General Brigham healthcare system.  

The research team hopes these findings will help inform future guidelines and public health efforts. They would like future prospective studies to test the efficacy of public health interventions that help people reduce the number of hours they spend being sedentary and see how that affects cardiovascular health. Next, they plan to extend this research to investigate the impacts of sedentary behavior on a range of other diseases and for longer spans of time. 

“Exercise is critical, but avoiding excessive sitting appears separately important," said co-senior author Patrick Ellinor, MD, PhD, a cardiologist and co-director of the Corrigan Minehan Heart Center at Massachusetts General Hospital. "Our hope is that this work can empower patients and providers by offering another way to leverage movement behaviors to improve cardiovascular health.”