Tag: obesity

Chewing Food Thoroughly Helps in Weight Management

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Previous research has shown that the age-old advice of chewing food thoroughly helps protect against weight again obesity, and now a study has revealed why this is so.

Typically, the chewing process reportedly enhances the energy expenditure associated with the metabolism of food and increases intestinal motility all add up to an increased heat generation in the body, known as diet-induced thermogenesis (DIT). However, how prolonged chewing induces DIT in the body remains unclear. A study published in the journal Scientific Reports answers these questions.

DIT increases energy expenditure above the basal fasting level – a factor known to prevent weight gain. The team previously found that slow eating and thorough chewing not only increased DIT but also enhanced blood circulation in the splanchnic region of the abdomen. Although these studies linked chewing-induced-DIT with increased digestion and absorption-related activity in the abdomen, they left scopes for further exploring a few crucial points.

Senior author Prof Hayashi Naoyuki Hayashi from Waseda University explained: “We were unsure whether the size of the food bolus that entered the digestive tract contributed to the increase in DIT observed after slow eating. Also, do oral stimuli generated during prolonged chewing of food play any role in increasing DIT? To define slow chewing as an effective and scientific weight management strategy, we needed to look deeper into these aspects.”

To find the answers, the researchers designed their new study to exclude the effect of the food bolus by involving liquid food. The entire study included three trials conducted on different days. Volunteers swallow 20mL liquid test food normally every 30 seconds as a control trial. In the second trial, the volunteers kept the same test food in their mouth for 30 seconds without chewing, allowing longer tasting before swallowing. In the third trial they studied the effect of both chewing and tasting; the volunteers chewed the 20mL test food for 30 seconds at a frequency of once per second and then swallowed it. The variables such as hunger and fullness, gas-exchange variables, DIT, and splanchnic circulation were duly measured before and after the test-drink consumption.

While there was no difference in hunger and fullness scores among the trials, as Prof Hayashi describes: “We found DIT or energy production increased after consuming a meal, and it increased with the duration of each taste stimulation and the duration of chewing. This means irrespective of the influence of the food bolus, oral stimuli, corresponding to the duration of tasting food in the mouth and the duration of chewing, increased DIT.” Gas exchange and protein oxidation too increased with the duration of taste stimulation and chewing, and so did blood flow in the splanchnic celiac artery. Since this artery supplies blood to the digestive organs, upper gastrointestinal tract motility also increased in responsivense to chewing.

The study demonstrated that energy expenditure through thorough chewing, though small, could help reduce obesity and metabolic syndrome.

With robust evidence behind it, slow eating and thorough chewing could be the latest recommendations for managing weight.

Source: Waseda University

Obesity Found to Fuel Periodontal Disease

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Chronic inflammation resulting from obesity may trigger osteoclast production and bone tissue breakdown, including the alveolar bone that holds teeth in place, according to a new animal model study.

The study, reported in the Journal of Dental Research, found that excessive inflammation caused by obesity raises the number of myeloid-derived suppressor cells (MDSC), a group of immune cells that increase during illness to regulate immune function. MDSCs, which originate in the bone marrow, develop into a range of different cell types, including osteoclasts.

Bone loss is a major symptom of periodontal disease which may ultimately lead to tooth loss. Periodontal disease affects more than 47% of adults 30 years and older, according to the Centers for Disease Control and Prevention.

“Although there is a clear relationship between the degree of obesity and periodontal disease, the mechanisms that underpin the links between these conditions were not completely understood,” said Keith Kirkwood, DDS, PhD, professor of oral biology in the UB School of Dental Medicine.

“This research promotes the concept that MDSC expansion during obesity to become osteoclasts during periodontitis is tied to increased alveolar bone destruction. Taken together, this data supports the view that obesity raises the risk of periodontal bone loss,” said Kyuhwan Kwack, PhD, postdoctoral associate in the UB Department of Oral Biology.

In the study, two groups of mice were fed different diets over the course of 16 weeks: one group a low-fat diet that derived 10% of energy from fat, the other group a high-fat diet getting 45% of energy from fat.

The high-fat diet group developed obesity, had more inflammation and a greater increase of MDSCs in the bone marrow and spleen compared to the low-fat diet group. The high-fat diet group also developed a significantly larger number of osteoclasts and lost more alveolar bone, which holds teeth in place.

Additionally, in the group fed a high-fat diet, the expression was significantly elevated for 27 genes tied to osteoclast formation.
The findings may help reveal the mechanisms behind other chronic inflammatory, bone-related diseases that develop concurrently with obesity, such as arthritis and osteoporosis, Prof Kirkwood said.

Source: University at Buffalo

Nearly 4 in 10 Swedish COVID Patients in ICUs had Obesity

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People with obesity were overrepresented among adults in Sweden in intensive care for COVID during the first wave of the pandemic, with over twice the proportion as compared to the general population. 

The study, appearing in PLOS One, used  the Swedish Intensive Care Registry (SIR) tp the researchers identified all patients with COVID who were admitted to ICUs in Sweden during the initial wave of the pandemic, in spring and summer 2020. Where height and weight data were missing from SIR, this was supplemented directly from the ICUs and also through the Nationwide Passport Register.

Though people with obesity were identified early on as a risk group that was affected especially severely by COVID, this study contributes to a new, more detailed picture.

A total of 1649 individuals with COVID from ICUs around Sweden were included. All the participants were aged 18 and over; three-quarters were men; and pregnant women were excluded.

The results show that patients with obesity (BMI of 30 kg/m2 or more) were overrepresented among those with COVID receiving intensive care in Sweden, which was 39.4 %, compared to 16% in the general population .

A high BMI increased the risk of both serious illness with long stays in intensive care and of death. A link was found between BMI over 30 and a 50% increase in mortality risk, compared with the normal-weight group. Among those who survived, a BMI over 35 was associated with a more than doubled risk of intensive care for over 14 days. These analyses have been adjusted for age, gender, comorbidity, and state of health at ICU arrival.

“For individuals with COVID who are in intensive care, obesity means an increased risk of death, and among those who survive, obesity boosts the risk of intensive care lasting more than 14 days,” explained first author Lovisa Sjögren, researcher at Sahlgrenska Academy, University of Gothenburg. “Based on our results, obesity should be included as an important risk factor in COVID. Patients with obesity who suffer from COVID should be monitored closely.”

The study is based on the Swedish Intensive Care Register, and Dr Sjögren points out that high-quality registers are a basic precondition for studies of this type to be feasible.

Senior author Jenny M Kindblom, Associate Professor at University of Gothenburg added: “Some international studies have shown a connection between high BMI and the risk of becoming severely ill with COVID. We can now show this in a Swedish context, and with the advantage of having a fully up-to-date BMI value for every patient,” said.

At an early stage during the pandemic, the researchers who conducted the study were in touch with HOBS, a Swedish patient organisation for people living with overweight and obesity. Many members were concerned that a high BMI would elevate the risk of serious illness in COVID.

“At the time, there were no publications in the field, and the study was initiated to enable us to answer patients’ questions. We now hope as many people as possible will take the opportunity to get vaccinated, and that health services include BMI – as a risk factor and perhaps choose to exercise special vigilance in monitoring patients with obesity who are suffering from COVID,” said Prof Kindblom.

Source: University of Gothenburg

Hair Loss Tied to High-fat Diets or Genetic Obesity

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A mouse study by Japanese researchers found that high-fat diets or genetically induced obesity can cause loss of hair follicles.

Obesity is linked to the development of numerous diseases in humans, such as heart disease and diabetes. However, it’s not fully clear how body organs specifically deteriorate and lose functionality from chronic obesity. Using mice, researchers from Tokyo Medical and Dental University (TMDU) examined how a high-fat diet or genetically induced obesity can affect hair thinning and loss. The findings, published in Nature, indicated that obesity can lead to depletion of hair follicle stem cells (HFSCs) by inducing certain inflammatory signals, blocking hair follicle regeneration and ultimately resulting in loss of hair follicles.

HFSCs normally renew themselves every hair follicle cycle. With progressing age, HFSCs fail to renew themselves leading to fewer HFSCs and therefore hair thinning. Although overweight people have a higher risk of male pattern balding, whether obesity accelerates hair thinning, how it does this and the molecular mechanisms behind it have remained largely a mystery. The TMDU group aimed to address those questions and identified some of the mechanisms.

Explaining the study, study lead author Hironobu Morinaga said: “High-fat diet feeding accelerates hair thinning by depleting HFSCs that replenish mature cells that grow hair, especially in old mice. We compared the gene expression in HFSCs between HFD-fed mice and standard diet-fed mice and traced the fate of those HFSCs after their activation.

“We found that those HFSCs in HFD-fed obesed mice change their fate into the skin surface corneocytes or sebocytes that secrete sebum upon their activation. Those mice show faster hair loss and smaller hair follicles along with depletion of HFSCs.

“Even with HFD feeding in four consecutive days, HFSCs show increased oxidative stress and the signs of epidermal differentiation.”

“The gene expression in HFSCs from the high-fat–fed mice indicated the activation of inflammatory cytokine signaling within HFSCs,” said senior author Emi Nishimura. “The inflammatory signals in HFSCs strikingly repress the Sonic hedgehog signaling that plays a crucial role in hair follicle regeneration in HFSCs.

However, the researchers noted that activating the Sonic hedgehog signaling pathway in this process can rescue the depletion of HFSCs. “This could prevent the hair loss brought on by the high-fat diet,” said Nishimura.

This study shines a light on cellular and tissue dysfunction from a high-fat diet or genetically induced obesity, and could lead to prevention and treatment of hair thinning along with greater understanding of obesity-related diseases.

Source: Tokyo Medical and Dental University

Obesity Connection to Commonly-used Pesticide

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A commonly-used pesticide could be contributing to the global obesity epidemic, according to a new study.

Researchers discovered that chlorpyrifos slows down the burning of calories in the brown adipose tissue of mice. Reducing this burning of calories, a process known as diet-induced thermogenesis, causes the body to store these extra calories, promoting obesity. Chlorpyrifos is banned for use on foods in Canada, and also now banned in the US and, as of last year, the EU, but widely sprayed on fruits and vegetables in many other parts of the world. In South Africa it is banned for residential use but is still used in agriculture.

Scientists made the discovery after studying 34 commonly used pesticides and herbicides in brown fat cells and testing the effects of chlorpyrifos in mice fed high calorie diets. Their findings were published in Nature Communications and could have important implications for public health.

“Brown fat is the metabolic furnace in our body, burning calories, unlike normal fat that is used to store them. This generates heat and prevents calories from being deposited on our bodies as normal white fat. We know brown fat is activated during cold and when we eat,” said senior author Gregory Steinberg, professor of medicine and co-director of the Centre for Metabolism, Obesity, and Diabetes Research at McMaster.

“Lifestyle changes around diet and exercise rarely lead to sustained weight loss. We think part of the problem may be this intrinsic dialling back of the metabolic furnace by chlorpyrifos.”

Steinberg said chlorpyrifos would only need to inhibit energy use in brown fat by 40 calories every day to trigger obesity in adults, which would translate to an extra 2kg of weight gain per year.

He said that while several environmental toxins including chlorpyrifos have been associated with increasing obesity rates in both humans and animals, these studies have mostly attributed weight gain to increases in food intake and not calorie burning.

“Although the findings have yet to be confirmed in humans, an important consideration, is that whenever possible consume fruits and vegetables from local Canadian sources and if consuming imported produce, make sure it is thoroughly washed,” said Steinberg.

Source: Medical Xpress

Parental History Not The Only Premature Heart Attack Risk

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A new study has shown that, while parental history is a contributing factor, young heart attack victims are more likely to be smokers, obese, and have high blood pressure or diabetes compared to their peers.

“The findings underline the importance of preventing smoking and overweight in children and adolescents in order to reduce the likelihood of heart disease later in life,” said study author Professor Harm Wienbergen of the Bremen Institute for Heart and Circulation Research.

“Understanding the reasons for heart attacks in young adults is important from a societal perspective due to their employment and family responsibilities,” he continued. “However, there are limited data on the predictors of heart events in this group.”

The researchers compared the clinical characteristics of consecutive patients admitted to hospital with acute myocardial infarction at 45 years of age or younger against randomly selected individuals from the German population. Cases and controls were matched according to age and gender. The case-control study enrolled a total of 522 patients with 1191 matched controls from a national database.

The researchers found that the proportion of active smokers was more than three-fold higher in the young heart attack group compared to the general population (82.4% vs 24.1%). Patients were more likely to have high blood pressure (25.1% vs 0.5%), diabetes (11.7% vs 1.7%) and a parental history of premature heart attack (27.6% vs 8.1%) compared to their peers. Patients were more often obese, with a median body mass index (BMI) of 28.4 kg/m2 compared to 25.5 kg/m2 for controls. In contrast, the proportion consuming alcohol at least four times a week was higher in the general population (11.2%) compared to heart patients (7.1%).

The researchers analysed the independent risk factors for the occurrence of acute myocardial infarction at 45 years of age or younger. The analysis was adjusted for age, sex, high blood pressure, diabetes, active smoking, body mass index, alcohol consumption, years of school education, and birth in Germany.

Hypertension was associated with an 85-fold odds of a heart attack aged 45 or under. The corresponding odds of a premature heart attack associated with active smoking, diabetes mellitus, parental history and obesity (BMI 30 kg/m2 or above) were 12, 5, 3 and 2. Alcohol consumption was associated with a lower odds of heart attack at a young age with an odds ratio of 0.3.

Prof Wienbergen said: “Our study shows that smoking and metabolic factors, such as hypertension, diabetes and obesity, are strongly associated with an increased likelihood of premature acute myocardial infarction. A protective effect of moderate alcohol consumption has been described by other studies and is confirmed in the present analysis of young patients.”

He concluded: “Our study suggests that family history is not the only predisposing factor for early heart attacks. The findings add impetus to the argument that young people should be educated about why it is important to avoid smoking and have a healthy body weight.”

Source: European Society of Cardiology

Stress Signal From Fat Cells Induces Protective Effect in Heart

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A stress signal sent from fat cells to the heart could be protective against obesity-induced cardiac damage, according to new research. 

This might help explain the ‘obesity paradox’, where obese individuals have better short- and medium-term cardiovascular disease prognoses compared with those who are normal weight, but have worse long-term outcomes.

“The mechanism we have identified here could be one of many that protects the heart in obesity,” said study leader Philipp E. Scherer, PhD, Professor of Internal Medicine and Cell Biology at UTSW who has long studied fat metabolism.

Study co-leader Clair Crewe, PhD, Assistant Instructor of Internal Medicine at UTSW, explained that the metabolic stress of obesity gradually makes fat tissue dysfunctional, causing shrinkage and death of its mitochondria. This unhealthy fat loses the ability to store lipids generated by excess calories in food, causing lipotoxicity and poisoning other organs. However some organs, including the heart, preemptively defend against lipotoxicity. How the heart actually senses fat’s dysfunctional state has been unknown so far.

The researchers used a genetic technique to speed the loss of mitochondrial mass and function in mice. The mice were fed a high-fat diet and became obese, and their fat cells began sending out extracellular vesicles filled with small pieces of dying mitochondria. Some of these mitochondrial snippets travelled through the bloodstream to the heart and triggered oxidative stress.

Cardiaccells produce a flood of protective antioxidant molecules to counteract this stress, and this protective backlash was so strong that when the scientists injected mice with extracellular vesicles filled with mitochondrial snippets and then induced a heart attack, the animals had significantly less damage to their hearts compared with mice that didn’t receive an injection.

Fat tissue from obese human patients showed that these cells also release mitochondria-filled extracellular vesicles.

The heart and other organs in obese individuals are eventually overwhelmed by lipotoxic effects, resulting in a number of obesity’s comorbidities. If the protective mechanism identified in this study could be artificially generated, it could result in new ways of treating obesity’s negative consequences. This might even be adapted to treat normal weight individuals.

“By better understanding the distress signal from fat,” Dr Crewe said, “we may be able to harness the mechanism to improve heart health in obese and non-obese individuals alike.”

The team’s findings were published in Cell Metabolism.

Source: UT Southwestern Medical Center

Weight Loss Not Prioritised in Heart Patient Care

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Weight loss is given insufficient priority in the management of heart patients despite the benefits, according to a new study of over 10 000 European patients.

In overweight and obese patients with coronary heart disease, weight loss is strongly recommended to reduce the risk of another heart event by improving blood pressure and lipids levels and reducing diabetes risk. This study investigated the management of patients who were overweight or obese at the time of hospitalisation for a first or recurrent heart event such as heart attack. The researchers examined lifestyle advice received, actions taken, and the relationship between weight changes and health status.

The researchers pooled data from the EUROASPIRE IV (2012 to 2013) and EUROASPIRE V (2016 to 2017) studies, which included 10 507 patients with coronary heart disease. Patients were visited 6 to 24 months after hospitalisation for their heart event (the average gap was 16 months). The visit consisted of an interview, questionnaires and a clinical examination including weight, height and blood tests.

The study found that less than 20% had a healthy body mass index (BMI) at the time of hospitalisation for a heart event. Some 16 months later, 86% of patients who were obese during hospitalisation were still obese while 14% of overweight patients had become obese. Young women were particularly affected, with nearly half of those under 55 years being obese. Yet more than a third of obese patients reported they had not received advice on physical activity or nutrition and nearly one in five said they had not been informed that they were overweight. Half of all patients reported not receiving such advice.

Weight management proved effective, with overweight or obese patients who lost 5% or more of their body weight having significantly lower levels of hypertension, dyslipidaemia, and previously unrecognised diabetes compared to those who gained 5% or more of their body weight. However, quitting smoking was observed to result in a 1.8kg average weight gain compared to an 0.4kg average weight gain in persistent smokers.

Study author Professor Catriona Jennings of the National University of Ireland – Galway said cardiac rehabilitation programmes, which typically emphasise exercise, should give equal priority to dietary management. She said: “Weight loss is best achieved by adopting healthy eating patterns and increasing levels of physical activity and exercise. Whilst actively trying to lose weight at the same time as trying to quit smoking is not advised, adopting a cardio-protective diet and becoming more physically active has the potential to mitigate the effects of smoking cessation on weight gain in patients trying to quit. Their aim is to maintain their weight and to avoid gaining even more weight following their quit.”

“Uptake and access to cardiac rehabilitation programmes is poor with less than half of patients across Europe reporting that they completed a programme,” added Professor Jennings. “Such programmes would provide a good opportunity to support patients in addressing overweight and obesity, especially for female patients who were found to have the biggest problem with overweight and obesity in the study. Uptake and access could be improved with the use of digital technology, especially for women, who possibly are less likely to attend a programme because they have many other competing priorities, such as caring for others. There are good reasons for people to address their weight after a cardiac event – but it’s not easy and they do need help.”

The study was published in European Heart Journal – Quality of Care and Clinical Outcomes, a journal of the European Society of Cardiology (ESC).

Source: European Society of Cardiology (ESC)

Journal information: Harrison, S.L., et al. (2021) Cardiovascular risk factors, cardiovascular disease, and COVID-19: an umbrella review of systematic reviews. European Heart Journal – Quality of Care and Clinical Outcomes. doi.org/10.1093/ehjqcco/qcab029.

Excess Body Fat Associated with Dementia Risk

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Photo by Siora Photography on Unsplash

Researchers at the University of South Australia are warning that high levels of body fat can add to the risk of dementia and stroke.

Having examined grey brain matter from about 28 000 people, the reseachers’ study demonstrated that increased body fat incrementally leads to increased atrophy of grey matter in the brain, resulting in greater risk of declining brain health. Obesity is a major and growing issue worldwide; World Health Organization data shows that more than 1.9 billion adults are overweight, with 650 million being obese. 

The lead researcher, Dr Anwar Mulugeta of UniSA, said the findings add to the growing number of issues known to be associated with being overweight or obese.

“Obesity is a genetically complex condition characterised by the excessive body fat,” Dr Mulugeta said. “Commonly linked to cardiovascular disease, type 2 diabetes, and chronic inflammation (a marker of dementia), obesity currently costs Australia’s economy about $8.6 billion dollars each year.

“While the disease burden of obesity has increased over the past five decades, the complex nature of the disease means that not all obese individuals are metabolically unhealthy, which makes it difficult to pinpoint who is at risk of associated diseases, and who is not.

“Certainly, being overweight generally increases your risk for cardiovascular disease, type 2 diabetes, and low-grade inflammation, but understanding the level of risk is important to better direct supports.

“In this study, we investigated the causal relationships of individuals within three metabolically different obesity types* ­– unfavourable, neutral and favourable – to establish whether specific weight groups were more at risk than others.”

These three obesity subtypes are:

  • ‘unfavourable’ – people who tend to have fat around their lower torso and abdominal area. These people have a higher risk of type 2 diabetes and heart diseases.
  • ‘favourable’ – people who have have wider hips but a lower risk of type 2 diabetes and heart diseases.
  • ‘neutral’ – people who have relatively low or very low risk of the cardiometabolic diseases.

Dr Mulugeta continued, “Generally, the three obesity subtypes have a characteristic of higher body mass index, yet, each type varies in terms of body fat and visceral fat distribution, with a different risk of cardiometabolic diseases.

“We found that people with higher levels of obesity especially those with metabolically unfavourable and neutral adiposity subtypes had much lower levels of grey brain matter, indicating that these people may have compromised brain function which needed further investigation.

“However, we did not find conclusive evidence to link a specific obesity subtype with dementia or stroke. Instead, our study suggests the possible role of inflammation and metabolic abnormalities and how they can contribute to obesity and grey matter volume reduction.”

The study analysed the genetic data of up to 336 000 individual records in the UK Biobank, along with self-reported information and linked hospital and death register records to connect dementia and stroke.

It found that, in middle to elderly age groups (37-73), grey brain matter decreased by 0.3 percent for every extra 1 kg/m2, which is equivalent of an extra 3 kg of weight for persons of average height (173 cm).

Senior investigator Professor Elina Hyppönen, Director of UniSA’s Australian Centre for Precision Health based at SAHMRI, said keeping to a healthy weight is important for general public health.

“It is increasingly appreciated that obesity is a complex condition, and that especially excess fat which is located around the internal organs have particularly harmful effects on health,” Prof Hyppönen said.

“Here, we used the individuals’ genetic and metabolic profiles to confirm different types of obesity. In practice, our findings very much support the need to look at the type of obesity when assessing the type of likely health impact.

“Even in a relatively normal weight individual, excess weight around the abdominal area may be a cause of concern.”

Source: University of South Australia

Male and High BMI not Linked to COVID ICU Mortality

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A new meta-analysis shows that, contrary to some previous research, being male and increasing body mass index (BMI) are not associated with increased mortality in COVID patients in intensive care units (ICU).

However, the study by Dr Bruce Biccard (Groote Schuur Hospital and University of Cape Town) and colleagues found that there were a wide range of factors linked to death from COVID in ICU. An August 2020 study of ICU COVID patients in Europe showed an association for age but not male sex.

The meta-analysis, which includes 58 studies and 44 305 patients published in the journal Anaesthesia, showed that, compared to patients without these risk factors, ICU COVID patients had a 40% greater mortality risk with smoking history, 54% higher with hypertension, 41% higher with diabetes, 75% higher with respiratory disease, around twice as high with cardiovascular disease or cancer, and 2.4 times higher with kidney disease. Other factors associated with an increased risk of death were the severity of organ failure, needing mechanical ventilation (a factor of 2.5 over non-ICU), as well as increased white blood cell counts and other inflammation markers.

The authors believe that age may effectively represent frailty in COVID patients which impacts on a person’s physiological reserve to overcome a critical illness. Hypertension, smoking and respiratory disease may be linked by their association with angiotensin-converting enzyme (ACE) receptors in the body, since there is increased expression of ACE-2 receptors amongst smokers and patients with chronic obstructive pulmonary disease. The link between hypertension and cardiovascular disease and increased mortality may be associated with the risk of cardiac injury which occurs with the systemic inflammatory response to COVID infection.

The authors said: “The findings confirm the association between diabetes, cardiovascular and respiratory comorbidities with mortality in COVID patients. However, the reported associations between male sex and increasing BMI worsening outcomes are not supported by this meta-analysis of patients admitted to ICU. This meta-analysis provides a large sample size with respect to these risk factors and is a robust estimate of risk associated with male sex and BMI.”

Source: EurekAlert!

Journal information: Anaesthesiadoi.org/10.1111/anae.15532