Medical Bulletin 30/ May/ 2024

A new study by researchers from Arizona State University and their colleagues highlighted a dietary strategy for significant health improvement and weight management.

The findings, published in the journal Nature Communications, could advance the understanding of the relationship between the gut microbiome and metabolism and improve strategies for managing obesity.

Intermittent fasting is an eating pattern that cycles between periods of fasting and eating. The method has recently gained popularity for its potential health benefits, including weight loss, improved metabolic health and enhanced brain function.

During fasting periods, the gut gets a break from constant digestion, which allows the gut lining to repair and regenerate. This reduction in gut inflammation and enhancement in the gut barrier function leads to better nutrient absorption and a more efficient metabolism.

Additionally, intermittent fasting can reduce the growth of harmful bacteria while encouraging the proliferation of beneficial bacteria. These positive changes in the gut microbiome contribute to improved digestion, reduced bloating, and better regulation of appetite hormones, all of which help with weight loss.

In the study, researchers compared the effects of two low-calorie dietary interventions: a heart-healthy continuous calorie-restricted diet and a calorie-restricted regimen incorporating intermittent fasting and protein pacing. The trial involved 41 overweight or obese individuals over a period of eight weeks.

The results showed that participants following an intermittent fasting and protein-pacing regimen, which involves evenly spaced protein intake throughout the day, experienced better gut health, weight loss, and metabolic responses. These benefits were notably greater than those observed with simple calorie restriction.

The intermittent fasting protocol increased beneficial gut microbes linked to a lean body type and improved overall health. Additionally, it elevated levels of certain proteins (cytokines) in the blood associated with weight loss and amino acid byproducts that promote fat burning.

"Given the gut microbiota's location and its constant interaction with the GI tract, we have been gaining a deeper understanding of its pivotal role in dietary responses these last several years. While limited in duration and sample size, this comprehensive investigation — which included the analysis of the gut microbiome, cytokines, faecal short-chain fatty acids and blood metabolites — underscores the intricate interplay between diet, host metabolism and microbial communities,” said Alex Mohr, lead author of the new study.

Reference: Mohr, A.E., Sweazea, K.L., Bowes, D.A. et al. Gut microbiome remodeling and metabolomic profile improves in response to protein pacing with intermittent fasting versus continuous caloric restriction. Nat Commun 15, 4155 (2024). https://doi.org/10.1038/s41467-024-48355-5

People who regularly eat fish or take fish oil supplements are getting omega-3 fatty acids, which play a critical role in brain function. Research has long shown a basis in the brain for aggressive and violent behaviour, and that poor nutrition is a risk factor for behaviour problems.

According to a study published in the journal Aggression and Violent Behavior, Omega-3 can modestly but significantly reduce aggression in children and adults.

There is growing interest in the use of nutritional supplements to ameliorate aggressive and antisocial behavior. In particular, omega-3 has been hypothesized as one nutritional component that could explain the link between poor nutrition and aggressive/violent behavior. Importantly, experimental research in humans based on randomized controlled trials (RCTs) have argued that omega-3 supplementation can reduce aggression in a wide variety of human populations.

The study analyzed 35 samples from 29 studies across 19 labs from 1996 to 2024, involving 3,918 participants. It found significant reductions in aggression during an average treatment period of 16 weeks, based on data from experimental and control groups. Only one lab conducted follow-ups after supplementation ended.

The meta-analysis showed that omega-3 reduced both reactive aggression, which is behavior in response to a provocation, and proactive aggression, which is planned.

The findings also showed that omega-3 may also have benefits for treating heart disease and hypertension, and it is inexpensive and safe to use.

"I think the time has come to implement omega-3 supplementation to reduce aggression. Omega-3 is not a magic bullet that is going to completely solve the problem of violence in society. Based on these findings, we firmly believe it can help, and we should start to act on the new knowledge we have,” said Adrian Raine, Penn neuro-criminologist.

"At the very least, we would argue that omega-3 supplementation should be considered as an adjunct to other interventions, whether they be psychological or pharmacological in nature, and that caregivers are informed of the potential benefits of omega-3 supplementation. We believe the time has come both to execute omega-3 supplementation in practice and also to continue scientifically investigating its longer-term efficacy.”

Reference: Raine, A., & Brodrick, L. (2024). Omega-3 supplementation reduces aggressive behavior: A meta-analytic review of randomized controlled trials. Aggression and Violent Behavior. doi.org/10.1016/j.avb.2024.101956.

Exposure to air pollution during pregnancy is linked to the development of mental health issues in adolescence, according to new research. The University of Bristol-led study, published in JAMA Network Open, investigated the long-term mental health effects of early-life exposure to air and noise pollution.

There is growing evidence indicating that air pollution, consisting of toxic gases and particulate matter, may play a significant role in the onset of mental health issues. Researchers believe that pollution can adversely impact mental health through several mechanisms. These include compromising the blood-brain barrier, promoting neuroinflammation and oxidative stress, and directly entering the brain, causing tissue damage.

The blood-brain barrier is a protective shield that prevents harmful substances in the bloodstream from entering the brain. However, pollutants can weaken this barrier, allowing toxins to penetrate brain tissue and potentially disrupt normal brain function. Neuroinflammation, an inflammatory response within the brain, can be triggered by these pollutants, leading to neuronal damage and contributing to mental health disorders.

In the study, researchers examined the long-term effects of air and noise pollution exposure during pregnancy, early childhood, and adolescence on three common mental health issues: psychotic experiences, depression, and anxiety. Using data from over 9,000 participants in Bristol’s Children of the 90s birth cohort study, which followed over 14,000 pregnant women recruited between 1991 and 1992 and their children, researchers linked early childhood data with mental health reports at ages 13, 18, and 24. This allowed them to map mental health outcomes against outdoor air and noise pollution exposure.

The results showed that small increases in fine particulate matter (PM2.5) during pregnancy and childhood were linked to more psychotic experiences and depression symptoms in teenagers and young adults.

Specifically, every 0.72 micrograms per cubic meter increase in PM2.5 during pregnancy and childhood was linked to an 11% higher chance of psychotic experiences and a 10% higher chance of depression.

"Childhood, adolescence, and early adulthood are key periods for developing psychiatric disorders, with nearly two-thirds of affected individuals becoming unwell by age 25. Our findings contribute to growing evidence that air and noise pollution negatively impact mental health. This is concerning because air pollution is widespread, and mental health issues are increasing globally. Since pollution is preventable, interventions like low emissions zones could improve mental health, particularly for vulnerable groups like pregnant women and children. Although these findings don't prove causation, recent studies show that low emissions zones can positively impact mental health,” said Dr Joanne Newbury, the study’s lead author.

Reference: Newbury JB, Heron J, Kirkbride JB, et al. Air and Noise Pollution Exposure in Early Life and Mental Health From Adolescence to Young Adulthood. JAMA Network Open. 2024;7(5):e2412169. doi:10.1001/jamanetworkopen.2024.12169