Science Digest – January 29, 2021

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Here’s another stellar issue of the Science Digest, full of the latest scientific research about nutrition, health, and lifestyle – curated exclusively for premium members like you. Read on to learn how…

Sauna use improves heat tolerance during exercise.
Neurological effects of COVID-19 still evident six months post-illness.
Low-carbohydrate diet improves metabolic markers, but a low-fat diet reduces appetite.

And much more!

In other news…
We’ve got another Crowdcast live Q&A coming up Saturday, February 6th, at 9:30 am PDT. The code for this event is genetics. Remember, you can always access the most recent event code and Q&A calendar by visiting your dashboard at

We published a brand-new article about brain-derived neurotrophic factor – better known as BDNF – a protein that plays important roles in brain health and is a fascinating point of convergene for many of the brain benefits of activities we know to be healthful for brain function, like exercise. Be sure to check it out…your brain will love you for it!

Enjoy reading!

Rhonda and team
Science Digest – January 29, 2021
Sauna use improves heat tolerance during exercise.

Exercising in high temperatures stresses the body and reduces performance. Acclimation in a heat chamber improves performance but is costly and time-consuming. A recent study found that supplementing normal endurance training with intermittent post-exercise sauna bathing improves heat tolerance.

The study involved 20 male and female trained middle-distance runners between the ages of 18 and 22 years. Participants completed 30-minute sauna sessions (101° to 108°C; 214° to 226°F) three times a week for three weeks within roughly five minutes of engaging in low-intensity, continuous outdoor exercise. They underwent heat tolerance tests before and after the intervention.

The heat tolerance tests revealed that the sauna users’ peak rectal temperature decreased 0.2°C (0.36°F); skin temperature decreased 0.8°C (1.4°F); and heart rate decreased 11 beats per minute, compared to those who did not use the sauna. Those who used the sauna also saw improvements in VO2max and speed. The improvements appeared to plateau, however, with four weeks of additional sauna exposure eliciting improvements in rectal temperature only (decrease of 0.1°C, 1.8°F).

These findings suggest that sauna bathing after engaging in endurance training improves heat tolerance and boosts performance.

Link to full study.
Learn more about sauna bathing in our overview article.

Neurological effects of COVID-19 still evident six months after recovery.

COVID-19 primarily manifests as a respiratory illness, but cardiovascular, gastrointestinal, and neurological symptoms have been reported in some cases. Although most of these symptoms are acute and resolve within a few weeks, many people experience long-term complications of the illness, a phenomenon referred to as “post-COVID-19 syndrome.” A recent report describes the long-term neurological effects of COVID-19.

Mounting evidence indicates that COVID-19 affects the neurological system. A previous report found that the range of acute neurological symptoms associated with COVID-19 included psychoses, delirium, encephalitis, strokes, and Guillain-Barré syndrome. Other evidence suggests that COVID-19 affects speech. A case report describes a woman who manifested stuttering and word-finding difficulties during her COVID-19 illness. A recent lay article described the occurrence of stutter several weeks after recovering from COVID-19. Neuroscientists posit that the inflammatory response that accompanies COVID-19 perturbs the brain neurocircuitry that controls speech.

The most recent study investigating neurological phenomena associated with COVID-19 involved 165 people (average age, 65 years) who had been hospitalized for the illness and had recovered. Six months after discharge from the hospital, the patients were assessed for long-term neurological symptoms.

The assessments revealed that more than one-third of the patients experienced long-term neurological abnormalities after COVID-19 illness. The most common complaints were fatigue, memory and attention problems, sleep disorders, and muscle pains. Others included depression, anxiety, visual disturbances, impaired sense of smell, and tingling or numbness. The patients who reported having cognitive deficits were more likely to have experienced worse respiratory symptoms and required longer hospitalization than those without cognitive problems.

These findings suggest that COVID-19 is associated with a wide range of neurological disorders and many of these disorders manifest long after the original infection. The authors noted that since their study excluded patients with pre-existing neurological disorders, their findings might underestimate the full burden of neurological symptoms associated with COVID-19.

Link to full study.

Low-carbohydrate diet improves metabolic markers, but low-fat diet reduces appetite.

Obesity affects more than 650 million people worldwide. Although low-carbohydrate and low-fat diets are effective at helping people lose weight, the health benefits and sustainability of the two dietary approaches are matters of controversy. A recent trial weighed the benefits of low-fat versus low-carbohydrate diets.

The causes of obesity and overweight are not fully known. Some scientists have suggested that consuming high-glycemic carbohydrates increases insulin levels, ultimately driving a vicious cycle of body fat accumulation, hunger, and food intake, commonly referred to as the “carbohydrate-insulin” model of obesity. Others have suggested that consuming high-fat foods drives overconsumption of calories due the foods’ high caloric levels, poor ability to provide satisfaction and fullness, and high “pleasure factor.”

The four-week crossover trial involved 20 healthy men and women (average age, 30 years). Half of the participants ate an animal-based, ketogenic, low-carbohydrate diet that provided about 10 percent of its calories from carbohydrates and about 75 percent from fat and high calorie foods. The other half ate a plant-based, low-fat diet that provided about 10 percent of its calories from fat and about 75 percent from carbohydrates and low-calorie foods. After two weeks on their respective diets, participants switched diets and adhered to the new diet for another two weeks. All meals were prepared and served in an in-patient metabolic ward to ensure compliance. The study investigators monitored the participants’ weight, vital signs, blood ketones, energy expenditure, activity, and other measures throughout the study.

Although both diets promoted weight loss, participants on the low-carbohydrate diet lost more weight (1.5 pounds) and faster, but the difference was not statistically or clinically significant. The participants who ate the low-fat diet had higher glucose and insulin levels compared to those who ate the low-carbohydrate diet. They didn’t report any differences in hunger, fullness, or satisfaction with their meals. When eating the low-fat diet, participants ate about 690 fewer calories per day than when eating the low-carbohydrate diet over the two-week period.

These findings suggest that whereas eating a low-carbohydrate diet is beneficial in reducing glucose and insulin levels, the low-fat diet reduces appetite, a finding that contradicts the carbohydrate-insulin model of obesity.

Link to full study.

Moderna COVID-19 vaccine effective against emerging variants of SARS-CoV-2 virus.

On December 18, 2020, the Food and Drug Administration granted emergency use authorization for the Moderna mRNA vaccine against SARS-CoV-2, the virus that causes COVID-19. In recent weeks, however, variants of the SARS-CoV-2 virus have emerged, raising questions about the vaccine’s efficacy. A recent report from Moderna summarizes their findings regarding the two variants.

To be considered a variant, a virus must have sufficient mutations to change a portion of its genetic code. Several variants of the SARS-CoV-2 virus have emerged, but the most notable of these, B.1.1.7, first identified in the United Kingdom, and B.1.351, identified in South Africa, appear to be more transmissible than previous variants. The B.1.1.7 variant has 17 mutations, eight of which are located in the spike protein, the major surface protein that the virus uses to gain access into cells. The B.1.351 variant has 10 mutations located in the spike protein.

The Moderna group tested their vaccine’s capacity to produce neutralizing antibodies against the new variants. They determined that the two-dose vaccine was equally effective against the B.1.1.7 variant in terms of inducing neutralizing antibodies. The level of neutralizing antibodies was sixfold lower against the B.1.351 variant, but this level is still considered sufficient to provide protection against infection. Moderna is investigating whether a third dose (a “booster”) will provide even better immunity against the variants.

The findings presented in this report have not been subjected to peer-review.

Link to report.

Gene therapy slows aging in mice.

Cellular senescence is the condition or process of cellular deterioration that occurs with age. Senescent cells often release inflammatory proteins that can damage neighboring healthy cells. Understanding the genetic and epigenetic bases of cellular senescence is instrumental in developing interventions to slow aging. A recent report identifies a gene therapy strategy to slow aging in mice.

Gene therapy is a technique in which altered (mutated) genes are corrected as a means to prevent or treat disease. One type of gene therapy involves inactivating a mutated gene that is functioning improperly.

The study investigators conducted a genome-wide screen of mesenchymal precursor cells (a descendant of embryonic stem cells) that carried genes for Werner syndrome and Hutchinson-Gilford progeria syndrome – conditions characterized by rapid, accelerated aging. They found that the primary driver of the accelerated aging in both syndromes was KAT7, an enzyme involved in histone modification.

Then the investigators inactivated the KAT7 gene in normally aging mice and prematurely aging mice and found that inactivation of the gene extended the animals’ lifespan. They did not observe any toxicities or adverse events in the animals.

These findings suggest that inactivation of critical genes involved in aging syndromes extends lifespan in mice and shows promise as a strategy to slow aging in humans.

Link to study abstract.

Learn more about aging and cellular senescence in this episode featuring Dr. Judith Campisi.

Taurine facilitates the body’s immune response.

The trillions of microbes that inhabit the human intestine, known collectively as the gut microbiota, play critical roles in health. Research demonstrates that the microbiota provides protection against infections by preventing pathogenic colonization in the gut. Findings from a new study indicate that taurine facilitates the gut microbiota’s immune response to infection.

Maintaining a “friendly” population of gut microbes is essential for good health. An imbalance in the number of harmful versus helpful microbes, a condition known as dysbiosis, drives many disease states, including cardiovascular disease, allergies, asthma, and obesity.

Taurine is an amino acid produced in the body and present in many foods. It plays roles in fat metabolism and many other physiological processes. Taurine breaks down to form hydrogen sulfide, a gas that promotes cardiovascular health and may be useful in treating Alzheimer’s disease. Low taurine levels promote pathogenic colonization of the human gut, but high levels help resist it.

The authors of the study used two groups of mice (normal and germ-free) to better understand how the microbiota influences resistance to colonization. They subjected the normal mice to a mild infection. After the mice recovered, the investigators transferred bacteria from the guts of the recovered mice to the germ-free mice and infected both groups of mice again. They found that the first mild infection primed the gut microbiota to resist colonization associated with a second infection.

Next, they gave the mice either taurine or bismuth subsalicylate (the primary ingredient in many antidiarrheal medicines) in their drinking water for two to three weeks. They subjected the mice to another infection and again measured the response. They found that taurine improved the microbial resistance to pathogenic colonization, but bismuth subsalicylate diminished it due to its capacity to inhibit hydrogen sulfide production.

Link to study abstract.

Sauna bathing ameliorates the harmful effects of high stress occupations.

Stress is essential to human survival. Long-term exposure to stress, however, increases a person’s risk of developing many chronic diseases. A recent review suggests that sauna bathing protects the body from the harmful effects of high stress occupations and describes the mechanisms that drive the protection.

People who work in high-stress occupations, such as firefighters, first responders, and military members, are exposed to both physiological and psychological stressors – often referred to as dual stressors. These dual stressors activate physiological responses to stress that ultimately drive inflammation, the underlying cause of many chronic diseases, including atherosclerosis, diabetes, rheumatoid arthritis, and dementia. Many people in high-stress occupations also work long or irregular hours and may have poor or inconsistent dietary patterns.

Sauna bathing exposes the body to extreme heat. This exposure – a form of stress – increases the body’s core temperature and activates a wide array of protective mechanisms that work together to condition the body for future stressors, a biological phenomenon known as hormesis. Hormesis is a compensatory defense response to a stressor that is disproportionate to the stressor’s magnitude.

The mechanisms that drive the effects of sauna bathing include activation of heat shock proteins and pro- and anti-inflammatory cytokines; decreased blood pressure and arterial stiffness; and multiple improvements in cardiovascular function. Sauna bathing also improves several aspects of metabolic function, primarily via activation of adenosine monophosphate-activated protein kinase (AMPK), a master regulator of cellular energy homeostasis. AMPK activation influences gene expression and inhibits cellular processes that drive oxidative stress.

The findings summarized in this review suggest that sauna bathing shows promise as a strategy to ameliorate the harmful effects of the dual stressors experienced by people working in high-stress occupations. Learn more about sauna bathing in our overview article.

Link to full review.

Designer cytokine restores spinal cord function in mice.

Spinal cord injuries typically cause irreversible loss of sensation and function below the site of injury. Approximately 17,000 people living in the United States will experience traumatic spinal cord injury in any given year. Findings from a new study in mice suggest that a designer cytokine can restore spinal cord function.

Cytokines are a broad category of naturally occurring small proteins that are important in cell signaling. They are released by cells and influence the behavior of other cells. Designer cytokines are genetically engineered proteins that perform specific functions. The authors of the study engineered hyper-interleukin-6, a cytokine that has been shown to regrow neurons of the visual system.

The study involved mice that had sustained a spinal cord injury and were paralyzed. The authors of the study used viral gene therapy to induce hyper-interleukin-6 production in the animals’ damaged neurons.

They found that the hyper-interleukin-6 production caused the axons of various nerve cells in the brain and spinal cord to regenerate within one week of gene therapy. Within two to three weeks post-procedure, the mice began to walk again.

These findings suggest that delivery of a designer cytokine via gene therapy shows promise as a strategy to restore sensory and functional losses after spinal cord injury in mice.

Link to study abstract.

Exercise in middle age improves cardiovascular health later in life.

For optimal health, adults of all ages should engage in at least 150 minutes of moderate intensity physical exercise or at least 75 minutes of vigorous intensity physical exercise each week, or an equivalent combination of both. Findings from a new study show that engaging in moderate-to-vigorous intensity exercise in middle age improves cerebrovascular health later in life.

The study involved an ethnically and racially diverse group of more than 1,600 adults (average age, 54 years). The authors of the study assessed the participants’ moderate-to-vigorous intensity exercise levels based on interviews at the beginning of the study (when they were in middle age) and 25 years later. They classified the participants’ exercise levels as none, low, middle, or high. The participants underwent magnetic resonance imaging studies to assess cerebrovascular health and measure white and gray matter volumes.

Roughly one-third (39 percent) of the participants were classified as having moderate-to-vigorous intensity exercise levels during mid-life, and one-third (34 percent) were classified as having low levels. Those who had high exercise levels (about two-and-a-half hours per week) had greater intact white matter volume but not gray matter in late-life. Those who exercised more were 32 percent less likely to have experienced a lacunar infarct (a type of stroke) compared to those who engaged in no exercise.

These findings suggest that exercise in middle age throughout older age is protective for the brain and underscore public health messaging for people of all ages to engage in more physical activity.

Link to study abstract.

Sleep deprivation mimics many of the symptoms of post-concussion syndrome.

A concussion is a type of brain injury that causes temporary loss of brain function. Concussions are common among student athletes and can affect memory, judgment, reflexes, speech, balance, and coordination. Findings from a recent study suggest that sleep deprivation mimics many of the symptoms of post-concussion syndrome.

Post-concussion syndrome is a condition in which the symptoms of concussion linger far beyond the expected recovery period, lasting months or even years after the original injury. Between 10 and 20 percent of people who experience concussion will have post-concussion syndrome.

The study was part of the NCAA-U.S. Department of Defense Concussion Assessment, Research, and Education Consortium, an ongoing project investigating the effects of concussion and repetitive head impact. More than 30,000 military cadets and university student athletes provided demographic data as well as information on current and previous sport participation, concussion history, and preexisting personal and medical history.

They also completed the Sport Concussion Assessment Tool–3rd Edition (SCAT3) symptom evaluation as part of baseline preseason testing. The SCAT3 is a self-reported inventory of 22 symptoms and includes questions about the number of hours of sleep obtained the night before testing.

The majority of the participants (63 percent of the men and 74 percent of the women) reported having at least one symptom, the most common of which was fatigue or low energy. A subset of the cadets (18 percent of the men and 28 percent of the women) and the university students (11 percent of the men and 20 percent of the women) reported having enough symptoms to meet the diagnostic criteria for post-concussion syndrome. A common denominator among this subset was sleep deprivation (fewer than five hours) the night before the assessment.

These findings suggest that many of the symptoms people report after a concussion are fairly common among cadets and university athletes who have not sustained a recent injury. They also highlight the need to take sleep and other environmental factors into consideration when determining whether athletes are ready to return to activity.

Link to study abstract.

Assay predicts the risk of having a child with a common form of autism.

Autism spectrum disorder is a developmental condition characterized by impaired social interaction, behavioral problems, and poor communication. It typically manifests in early childhood and is slightly more common among boys than girls. Roughly one in 54 people living in the United States has ASD. A team of researchers has developed an assay that predicts the risk of having a child with maternal autoantibody-related autism.

Maternal autoantibody-related autism spectrum disorder is a developmental condition that occurs when proteins (called autoantibodies) that are produced by a pregnant woman’s immune system react with proteins in the developing fetus’s brain. It accounts for approximately 18 percent of all autism cases.

The study involved nearly 800 women enrolled in the Childhood Autism Risks from Genetics and Environment study, which includes mothers of children diagnosed with autism spectrum disorder as well those with normal development. The researchers collected blood from the women and assessed the children’s health and social and cognitive development. They developed an assay to detect and quantify maternal autoantibody reactivity to eight proteins that are highly expressed in the developing brain.

The assay identified four common patterns of reactivity to some of the proteins, and these patterns correlated with having autism spectrum disorder with 100 percent accuracy. The researchers found that reactivity to a protein called CRMP1 increased the odds that a child would have autism spectrum disorder more than twofold.

These findings have relevance for women at high risk of having a child with autism spectrum disorder, such as those with a child previously diagnosed with the disorder or who have health conditions that have been linked with the disorder, such as metabolic syndrome during pregnancy.

Link to full study.

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