Science Digest – July 30, 2021 External

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We’ve lined up another great collection of stories about the latest research on health, nutrition, and fitness, delivered right to your inbox. Read on to learn how…

A recent study suggesting certain COVID-19 vaccines remain effective against the delta variant.
Eating processed meat increases risk for dementia, but eating unprocessed meat might be protective.
Some evidence that suggests that human lifespan may not have a fundamental limit, in contrast to some recent growing sentiment within the aging community.

And more!

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Science Digest – July 30, 2021
The Pfizer-BioNTech and AstraZeneca COVID-19 vaccines are highly effective against the delta variant.

The delta variant of SARS-CoV-2, the virus that causes COVID-19, first emerged in India and has since become a global concern. To be considered a variant, a virus must have sufficient mutations to change a portion of its genetic code. The delta variant carries seven mutations. A recent report describes the effectiveness of the Pfizer-BioNTech and AstraZeneca vaccines against the delta variant.

The Pfizer-BioNTech vaccine is mRNA-based. It contains the genetic instructions for synthesis of a single viral protein that stimulates the immune system to make antibodies against the SARS-CoV-2 spike protein. mRNA vaccine technology allows rapid scaling of vaccine production and facilitates modification if the virus mutates significantly. The AstraZeneca vaccine is adenoviral vector-based. It uses a modified version of the chimpanzee adenovirus (ChAdOx1) to deliver the genetic information that codes for the SARS CoV-2 spike protein. Adenovirus vector vaccines are currently being tested for numerous infectious agents, ranging from malaria to HIV. Both the Pfizer-BioNTech and AstraZeneca vaccines require two doses for optimal immunity.

The authors of the report took two approaches to gauge vaccine effectiveness against the delta variant versus the alpha variant (the first SARS-CoV-2 form). First, they compared vaccination status in people who had symptomatic COVID-19 with vaccination status in people who reported symptoms but had a negative test. Next, they estimated the proportion of people with cases caused by the delta variant relative to those caused by the alpha variant, based on vaccination status. Nearly 80,000 people were included in the analysis.

The authors found that the effectiveness of both vaccines was lower against the delta variant than against the alpha variant, but the Pfizer-BioNTech vaccine was at least 88 percent effective against delta after two doses, and the AstraZeneca vaccine was 67 percent effective after two doses. Notably, both vaccines were only 30 percent effective against the delta variant after only one dose.

These findings indicate that the Pfizer-BioNTech and AstraZeneca vaccines against COVID-19 are highly effective against the delta variant and underscore the importance of obtaining both doses for optimal immunity. Learn more about COVID-19 vaccines in this clip featuring Dr. Roger Seheult.

Link to full article.

Eating processed meat increases risk for dementia, but eating unprocessed meat might be protective.

Dementia is a broad term that includes Alzheimer’s disease, vascular dementia, and other forms of the condition. It is characterized by the loss of memory, language, problem-solving skills, and/or other aspects of cognitive function. Approximately 50 million people worldwide have dementia. A recent study investigated links between meat consumption and dementia risk.

Meat is rich in several essential nutrients, including protein, iron, zinc, and vitamin B12. Findings from epidemiological studies suggest that diets high in red and processed meats increase a person’s risk for type 2 diabetes, cardiovascular disease, cancer (particularly colorectal cancer), and all causes of premature death.

The present study involved more than 493,000 adults enrolled in the UK Biobank, a biomedical database containing health information about people living in the United Kingdom. The participants completed a food frequency questionnaire in which they provided answers about their meat consumption, to include processed meat, unprocessed poultry, and unprocessed red meat (beef, lamb, and pork). The authors of the study defined “processed meat” as bacon, ham, sausages, meat pies, kebabs, burgers, and chicken nuggets.

They found that eating unprocessed red meat was linked with a lower risk of dementia and Alzheimer’s disease, whereas eating processed meat was linked with higher risk. They did not identify any associations between poultry consumption and dementia risk. Each additional 50-gram per day increment in unprocessed red meat intake decreased their risk for all causes of dementia by 19 percent and decreased their risk for Alzheimer’s disease by 30 percent. In contrast, each additional 25-gram per day increment in processed meat intake increased a person’s risk for all types of dementia by 44 percent and increased their risk for Alzheimer’s disease by 52 percent.

High levels of protein and iron in unprocessed red meat may partially explain the link between unprocessed meat intake and lower risk of dementia. Adequate protein intake has been linked with lower dementia risk in older adults, and iron is necessary for many aspect of brain health, including the production of neurotransmitters and myelin. On the other hand, processed meat contains nitrites and N-nitroso compounds, which may promote oxidative stress, lipid peroxidation, and activation of proinflammatory cytokines or other mechanisms potentially involved in the development of dementia.

These findings suggest that eating processed meat increases a person’s risk for developing dementia but eating unprocessed meat does not. They also underscore the importance of distinguishing between processed and unprocessed meat in nutrition studies. This was a large, well-designed prospective study that accounted for multiple confounding factors, including age, gender, ethnicity, socioeconomic status, educational level, BMI, physical activity level, smoking status, typical sleep duration, stroke history, family history of dementia, and dietary factors (including consumption of vegetables, fruits, fish, tea, coffee, and alcohol).

Link to full article.

Human lifespan may not have a limit.

Since the 1990s, longevity researchers have attempted to estimate the maximum human lifespan; however, supercentenarians (i.e., people who live beyond 110 years) routinely break these estimates. Additional research is needed to provide more accurate models of aging for use in planning government programs and economic policy. Authors of a paper released this year report their updated estimates for the maximum age at death in the year 2100.

The existence of a fixed age limit for humans is an area of debate, with some scientists theorizing that biological processes like the shortening of telomeres are irreversible, determined by genetics, and a strong predictor of death. However, others argue that there is no limit to human lifespan and that age-related risk of death plateaus around 110 years of age. This uncertainty is partly due to a lack of consistent record keeping with verified age information. Research institutions have recently created systems such as the International Database on Longevity, a database containing validated supercentenarian life lengths from 15 countries, to aid in future research.

The investigators used a statistical model created by the authors of a 2017 report on maximum lifespan. This model estimates the survival probability of supercentenarians, meaning the likelihood of surviving each year beyond age 110 years. For the current report, the researchers used updated data from the International Database on Longevity, which currently includes records from more than 1,100 supercentenarians and almost 14,000 semi-supercentenarians (people who live between 105 and 109 years). They also added additional projections to the model regarding future levels of fertility and life expectancy across multiple countries and extended the projection window to the year 2100.

The authors found that the probability of breaking the current maximum reported age at death (122 years and 164 days, set by Jeanne Calment of France) this century is nearly 100 percent; the probability of a person reaching age 126 is approximately 89 percent; and the probability of a person reaching age 130 is nearly 13 percent. While the model did not exclude the possibility of a person living to 135 or 140 years this century, it is extremely unlikely. These estimates are in line with most other projections.

The authors concluded that these data do not support the existence of a maximum human age and forecast substantial increases in the number of supercentenarians in the coming decades.

Link to full report.

Less blue-light exposure at night improves metabolism.

Inorganic light-emitting diodes – better known as LEDs – are ubiquitous in the modern era. Found in cell phones, televisions, computer screens, and a host of other electronic devices, LEDs emit short-wave, high-energy blue light, which has been linked to a wide range of harmful effects on health and sleep. Findings from a recent study suggest that organic LEDs (OLEDs), which produce less light in the blue-wave spectrum, have fewer harmful effects on human metabolism.

Light exposure is one of the primary regulators of the body’s circadian rhythms and plays key roles in sleep quantity and quality. For example, evidence indicates that afternoon exposure to blue light impairs the release of melatonin – the “sleepiness hormone” – in a dose-dependent manner. Similarly, use of LED-lit devices in the evening interferes with sleep by promoting alertness.

The cross-over study involved ten healthy males (average age, 25 years) who did not have sleep disorders. The participants were exposed to either LED, OLED, or dim light for four hours prior to going to sleep. The study investigators assessed the participants’ sleep quality via polysomnography as well as the participants’ self-assessment. The participants ate breakfast one hour after waking up, and the authors measured the participants’ energy expenditure, fat oxidation, core body temperature, and melatonin levels for four hours (continuously) in a room with regular lighting. Each of the participants underwent all three lighting scenarios.

The investigators found that after OLED exposure, the participants’ energy expenditure and core body temperature during sleep were lower than after LED exposure, but their fat oxidation was higher. In addition, the increase in fat oxidation following OLED exposure was associated with higher melatonin levels. Sleep quality did not differ markedly between the different lighting scenarios.

These findings suggest that evening OLED exposure elicits fewer harmful health effects than LED exposure, likely because OLEDs emit less blue light. Learn more about the effects of blue light in this clip featuring sleep expert Dr. Matthew Walker.

Link to full article.

Coffee consumption is associated with a reduced risk of irregular heartbeats.

Coffee consumption is popular worldwide and is associated with reduced risk of cancer, diabetes, and Parkinson’s disease. However, the American College of Cardiology and American Heart Association recommend avoiding caffeine to reduce the risk of cardiac arrhythmias. Findings from a recent observational report suggest coffee consumption may reduce, not increase, the risk of cardiac arrhythmias.

Cardiac arrhythmias occur when the electrical impulses that control heart rate pulse too quickly, called tachycardia, or too slowly, called bradycardia. Coffee is the primary source of caffeine for most people. Because caffeine increases serum levels of catecholamines (e.g., adrenaline), it is plausible that coffee may increase the risk of cardiac arrhythmias. Although results from one observational study from 1980 support an increased risk of arrhythmias with increased coffee consumption, newer and more comprehensive evidence is needed.

The authors collected data regarding habitual coffee consumption and the incidence of cardiac arrhythmias from over 380,000 participants of the United Kingdom Biobank, a long-term registry study of United Kingdom citizens. The researchers assigned participants to one of eight categories of coffee consumption: zero, less than one, one, two, three, four, five, or six or more cups daily. Participants also provided a DNA sample for the sequencing of genes related to coffee metabolism.

Coffee consumption was associated with a reduced risk of cardiac arrhythmia. For each cup of coffee consumed daily, the risk of arrhythmia was reduced by three percent. This means an individual consuming three cups of coffee would have a nine percent risk reduction. This relationship was significant even after taking age, sex, race, metabolic health, smoking, alcohol and tea consumption, and exercise into account. Participants with genetic variants associated with slower caffeine metabolism drank less coffee, but did not have an increased risk of arrhythmia.

Greater coffee consumption was associated with a reduced risk of cardiac arrhythmias, a result that contradicts earlier evidence. Learn how coffee consumption may induce autophagy to improve other aspects of health in this clip featuring Dr. Guido Kroemer.

Link to full report.

Omega-3s reduce risk of death from cardiovascular disease.

The American Heart Association recommends that adults consume at least eight ounces of fish and shellfish each week, especially those that are rich in omega-3 fatty acids. Previous research supports the benefits of omega-3 consumption in preventing coronary heart disease and sudden cardiac death; however, additional research is needed to support the benefits of omega-3s for other cardiovascular disorders. Investigators reviewed the molecular, clinical, and epidemiological evidence for the effects of omega-3s on cardiovascular disease.

Omega-3 fatty acids cannot be produced by the body and must be consumed in the diet. Major food sources of omega-3s include fatty fish, which are rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Plant sources of omega-3s include flax seeds, chia seeds, and walnuts, but the predominant omega-3 fat in these foods is alpha-linolenic acid, which must be converted to EPA before it can be used by the body. Omega-3s and their metabolites improve cardiovascular health through altering the composition of cell membranes and regulating gene expression, among other functions.

The authors searched the literature for randomized controlled trials, in which researchers randomly assign participants to an intervention or a comparable control treatment, and observational studies, which observe a group of participants at a single time point. Randomized controlled trials are suitable for identifying cause-and-effect relationships, but because observational studies measure associations between behavior and health, they are not. Review papers aggregate data from previous research and compare results, a process that can be difficult because dose, sample size, and participant characteristics vary among studies.

The analysis revealed that the dose of omega-3s utilized in the randomized controlled trials ranged from 376 milligrams to 1,800 milligrams. Some of these trials instructed participants to consume the recommended two servings of fish per week. Data from these trials showed that omega-3 consumption decreased cardiovascular disease, with risk reductions ranging from two to 32 percent among trials; however, some trials did not find a benefit of omega-3 consumption for reducing the risk of death from cardiovascular disease. In observational studies, the benefits of omega-3 consumption were strongest for coronary heart disease and sudden cardiac death, confirming previous reports. Evidence from the randomized controlled trials and observational studies was inadequate to support assertions that consumption of omega-3 fatty acids reduce the risk of heart attack, stroke, atrial fibrillation, arrhythmias, and heart failure.

Current data support the consumption of omega-3s for reduced risk of death from cardiovascular disease. The authors concluded that future research should explore the effects of dose, source (i.e., seafood or supplements; plant or animal), and other molecular, physiological, and clinical effects.

Link to full report.
Learn how to make a tasty omega-3 rich salmon roe snack in this recipe video featuring Dr. Rhonda Patrick.

Resistance breathing technique lowers blood pressure.

Nearly two-thirds of adults living in the United States have high blood pressure, defined as having a systolic pressure of 130 mm Hg or higher or a diastolic pressure of 80 mm Hg or higher. Aerobic exercise is one of the most effective strategies for maintaining healthy blood pressure, but fewer than 40 percent of adults meet current exercise guidelines. Findings from a new study suggest that high-resistance inspiratory muscle strength training improves blood pressure.

High-resistance inspiratory muscle strength training is a form of resistance exercise that strengthens the muscles involved in breathing. The technique involves inhaling forcefully via the mouth through a portable, hand-held device that provides resistance against the inhalation. The frequency of training, number of repetitions, and amount of resistance vary based on the participant’s needs and respiratory health.

The study involved 36 healthy adults (ages 50 to 79 years) who had high systolic blood pressure. Half of the participants performed high-resistance inspiratory muscle strength training (five sets of six breaths, with one minute of rest between sets) for six weeks. The other half performed sham breathing exercises against very little resistance. The study investigators measured various biomarkers associated with stress and cardiovascular health in the participants’ blood. They measured the participants’ resting blood pressure at four time points (screening, baseline, end‐intervention, and follow‐up) and measured ambulatory pressure via a portable monitoring device every 20 minutes during the day and every 60 minutes at night over a 24-hour period. They also measured flow‐mediated dilation, an indicator of vascular endothelial function. They treated endothelial cells with plasma drawn from the participants before and after the intervention to assess the bioavailability of nitric oxide, a key signaling molecule in the cardiovascular system.

When participants performed with high-resistance inspiratory muscle strength training, their resting systolic blood pressure decreased from an average of 135 mm Hg to an average of 126 mm Hg. Similarly, their diastolic blood pressure decreased from an average of 79 mm Hg to an average of 77 mm Hg. Their 24-hour systolic blood pressure decreased, and their arterial flow‐mediated dilation improved by approximately 45 percent. The sham training had no effects on blood pressure or flow-mediated dilation. Participants who performed high-resistance inspiratory muscle strength training exhibited decreases in C‐reactive protein (a biomarker of inflammation) and improvements in other markers associated with cardiovascular function. Nitric oxide bioavailability increased in both groups but was 10 percent higher among those who performed high-resistance inspiratory muscle strength training.

These findings suggest that high-resistance inspiratory muscle strength training demonstrates promise as a lifestyle strategy to lower blood pressure. Another lifestyle behavior that reduces blood pressure is sauna use. Learn more about sauna use in our overview article.

Link to full article.

Depression is associated with muscle loss in older adults.

Sarcopenia, the loss of muscle mass with age, is related to falling, poor oral health, and chronic disease. Sarcopenia is a progressive disorder, but early interventions with diet and exercise may improve health outcomes. Authors of a new report investigated the relationship between sarcopenia progression, depression, dementia, and hypertension.

Body composition shifts across the lifespan, with a progression toward lower muscle mass and increased fat mass after age of 60. Because fat and muscle participate in whole-body metabolism and hormone signaling, this shift in body composition contributes to the development of age-related diseases. Previous research has reported a link between sarcopenia, cognitive impairment, and depressive symptoms in older Korean men, but research is needed in additional demographic groups.

The authors collected data from more than 750 adults aged 60 years and older living in Japan. Participants completed surveys to measure depression and dementia status and underwent a physical examination that included the measurement of blood pressure, height, muscle mass, grip strength, and walking speed. The investigators classified participants as having sarcopenia if they had low skeletal muscle index (i.e., the ratio of the muscle in a person’s arms and legs to their height), poor grip strength, and slower walking speed. They defined pre-sarcopenia as having a low skeletal muscle index with normal grip strength and walking speed. Finally, they classified participants with a normal skeletal muscle index as robust.

Sarcopenia was associated with increased age and depression severity, but reduced hypertension. Compared to robust participants, those with pre-sarcopenia were more likely to have depression and hypertension. However, sarcopenia was not associated with dementia, which the authors noted may have been due to the small number of participants (only 49) with dementia.

The authors suggested that future research should explore strategies for management of depression, dementia, and hypertension in the prevention of sarcopenia.

Link to full report.
Watch Dr. Michael Snyder discuss his habits for healthy aging and the prevention of sarcopenia in this clip with Dr. Rhonda Patrick.

Lean people may still have metabolic dysfunction.

The body mass index (BMI) is a ratio of weight to height and is one tool for measuring body size in health care and research. Epidemiological research indicates that individuals with a healthy BMI (between 20 and 25) have the lowest risk of cardiovascular disease and death compared to individuals with underweight (BMI less than 18.5), overweight (BMI between 25 and 30), and obesity (BMI greater than 30); however, some people with a healthy BMI experience metabolic dysfunction and an increased risk of death. Authors of the following report explore the condition lipodystrophy, its physiological causes, and its prevalence in the general population.

Lipodystrophy is a condition in which the amount and/or distribution of fat tissue in the body is abnormal. Visceral fat is fat stored in the abdomen and is associated with insulin resistance, elevated triglycerides, and fatty liver. This is in contrast to fat stored in the lower body, called subcutaneous fat, which is not associated with metabolic dysfunction. In short-term studies, people with a healthy BMI and an increased waist-to-hip ratio (i.e., ratio of visceral to subcutaneous fat) are at a three times greater risk of death than people with obesity and no metabolic dysfunction, a condition referred to as metabolically healthy obesity. However, long-term studies (those with greater than 10 years’ follow-up) show that people with metabolically healthy obesity have a 24 percent increased risk of death, suggesting metabolically healthy obesity is a transient stage between metabolic health and metabolic disease.

The authors recruited almost 1,000 Caucasian/white participants of varying weight status who were at an increased risk of cardiometabolic disease based on weight, family and personal history of diabetes, and elevated glucose levels. The researchers used magnetic resonance imaging (MRI) to precisely measure body fat amount and distribution. They also measured blood pressure, fasting triglyceride levels, fasting glucose, the inflammatory marker C-reactive protein, insulin resistance, and carotid intima thickness (a measure of atherosclerosis). They defined good metabolic health as having two or fewer of the following criteria: blood pressure greater than 130/85 millimeters of mercury or the use of blood pressure medication; fasting triglycerides greater than 150 milligrams per deciliter; fasting HDL cholesterol (i.e., good cholesterol) less than 40 milligrams per deciliter in males or less than 50 milligrams per deciliter for females; fasting glucose greater than 100 milligrams per deciliter or the use of diabetic medication; C-reactive protein level in the 90th percentile or above; or insulin resistance in the 90th percentile or above.

Compared to people with a healthy BMI and good metabolic health, those with a healthy BMI and more than two metabolic risk factors had more insulin resistance, nonalcoholic fatty liver disease, visceral obesity, less lower body subcutaneous fat, and increased atherosclerosis. However, they did not have an increased prevalence of high blood pressure, high triglycerides, low good cholesterol, or increased inflammation. Compared to people with a healthy BMI and metabolic dysfunction, people with overweight or obesity and metabolic dysfunction had a gradual increase in the prevalence of visceral adiposity, fatty liver, insulin resistance, atherosclerosis, and low subcutaneous fat volume in the lower body as BMI increased. This means that metabolic dysfunction in people with a healthy BMI is most characterized by insulin resistance and atherosclerosis and is most strongly associated with lower subcutaneous fat in the lower body than visceral adiposity in the abdomen. The authors used this to support the existence of a lipodystrophy phenotype in people with a healthy BMI.

The authors conclude that some people with a healthy BMI may still have lipodystrophy that puts them at an increased disease risk compared to individuals with a healthy BMI and normal fat distribution. They recommend early testing of insulin sensitivity and use of medications that increase insulin sensitivity in people with lipodystrophy to lower disease risk.

Link to full report.

A ketogenic diet may be beneficial for people with brain tumors.

Glioma is a collective term for tumors that arise from the glial cells in the brain. Astrocytoma, the most common form of glioma, arises from star-shaped cells in the brain called astrocytes. The the survival rate for glioma, including astrocytoma, is low. Findings from a recent study suggest that a ketogenic diet is beneficial for people with astrocytoma.

Ketogenic diets are low in carbohydrates and high in proteins and fats. They cause the body to oxidize fats to produce ketones for energy. For many years, ketogenic diets have been used in the clinical setting to reduce seizures in children. They are currently being investigated for the treatment of cancer because evidence suggests that cancer cells cannot use ketones for energy.

The eight-week intervention study involved 25 people with astrocytoma whose disease was stable following chemotherapy. Participants followed a weekly dietary protocol consisting of five days of a ketogenic diet (consuming 20 grams or less of carbohydrates per day) and two non-consecutive days of fasting (consuming less than 20 percent of their estimated caloric needs). Participants kept food diaries and provided weekly blood and urine for measuring ketones, insulin, glucose, hemoglobin A1c (a measure of long-term blood glucose control), and IGF-1. They underwent brain scans at the beginning and end of the intervention.

About half of the participants adhered to the dietary intervention, which was well-tolerated and elicited few adverse events. Despite the relatively low compliance, all the participants had ketones in their urine, with 80 percent achieving moderate levels. Participants’ hemoglobin A1c, insulin, and fat body mass decreased, but their lean body mass increased. No changes were noted in glucose or IGF-1 levels. The brain scans showed that ketone concentrations increased in the brain (including the tumor tissue) and correlated with ketone levels in the urine.

These findings demonstrate that a ketogenic diet is safe for people with astrocytoma and may be beneficial as adjunctive therapy. Learn more about how a ketogenic diet, combined with fasting and the standard of care treatment, may help treat aggressive cancers in this clip featuring Dr. Valter Longo.

Link to study abstract.

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