Tag: sarcopenia

Meat Builds Muscle Proteins Better than Equivalent Vegan Dishes

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Older adults require more protein but eat less than younger people, making it a challenge for them to maintain muscle mass. Eating a meal with meat ensures that muscle proteins are built faster than a vegan meal with the same amount of protein. This study, published in The Journal of Nutrition, was the first to compare the speed at which muscle proteins are being made after eating a complete meal with animal or plant proteins.

Every two to three months the proteins in human muscle are completely renewed. In order to make muscle proteins, we need protein from food, for example from animal sources such as meat, cheese and yoghurt, or from plant products such as beans, nuts and soymilk. Previous research on protein powders showed that animal proteins have better muscle-building properties than plant proteins. “But in reality, we do not get our proteins in powder form, but through complete meals,” says study author and PhD student Philippe Pinckaers. “Those meals contain different types of protein and other nutrients such as fibres, fats and carbohydrates. These nutrients affect how proteins are released from the diet and influences the making of muscle proteins.”

To investigate how muscles respond after eating a complete meal, Pinckaers asked 16 participants aged over 65 to come to the lab twice for a dinner meal.

Dining out in the lab

On one day, the participants sat down to a meal with quinoa with chickpeas, broad beans, soy beans and soy sauce was on the menu, while on the other day the menu consisted of a beef tartlet, potatoes, green beans, apple sauce and herb butter. Both meals had similar amounts of protein, fat, carbohydrates and calories. Prior to the meals, participants were administered an infusion of special amino acids.

“The amino acids administered via the infusion were marked, as it were with a flag,” Pinckaers explains. “We took small pieces of muscle tissue from the participants and were able to measure the amount of ‘flags’ in them. If more flags are measured, it means that muscle proteins are built up faster, which is beneficial for muscles. In this way, we found that after eating a meal with animal protein, muscle protein was built up faster than after eating a vegan meal. This means that a vegan meal does not have the same capacity to make muscle proteins as a meal that includes animal proteins.” This difference arises partly because plant-based foods are harder to digest, and because they naturally contain fewer essential amino acids.

Context is key  

The results do not mean that everyone should eat meat or other animal products, clarifies professor of exercise science and lead researcher Luc van Loon. “Healthy people can very well compensate for the lower quality of plant proteins by eating more of them.” For elderly or frail patients it is a bit more complicated. “Elderly people actually need more protein in order to reach the same level of muscle protein synthesis, when compared to young individuals. However, they actually eat less. Also, patients with reduced appetite or who do not exercise much, for example during hospitalisation, may have trouble consuming a sufficient amount of protein. For them, it is therefore important to choose protein sources that stimulate the making of muscle proteins as much as possible. The best sources in this situation would be proteins from animal products.”

Source: Maastricht University

Cat-borne Toxoplasma Gondii Linked to Frailty in the Elderly

Photo by FOX: https://www.pexels.com/photo/brown-tabby-cat-scratching-head-1265613/

Toxoplasma gondii, a common, cat-borne parasite already associated with risk-taking behaviour and mental illness in humans may also contribute to exhaustion, loss of muscle mass, and other signs of frailty in older adults, suggests a study published in the Journal of Gerontology: Medical Science.

The research, by an international team of scientists including University of Colorado Boulder, University of Maryland School of Medicine and the University of A Coruña in Spain, is the latest to explore how the tiny, single-celled organism T. gondii could have big impacts on human health.

“We often think of T. gondii infection as relatively asymptomatic, but this study highlights that for some people it may have significant health consequences later on,” said co-author Christopher Lowry, a professor at CU Boulder.

Some 11%–15% of people in the US have been infected with T. gondii at some point and rates tend to be far higher in older individuals. In some countries, more than 65% have been infected. Once infected, people can unknowingly harbour the parasite for life.

For the study, the team examined the blood of 601 Spanish and Portuguese adults over 65, along with measures of a common geriatric syndrome known as frailty – which includes unintentional weight loss, tiredeness, loss of cognitive sharpness and other indications of declining health.

A whopping 67% of study subjects were “seropositive” showing markers in their blood of a latent infection.

The researchers did not, as they originally hypothesized, find an association between any infection to T. gondii and frailty. But they did find that, among those infected, those with higher “serointensity” or a higher concentration of antibodies to the parasite, were significantly more likely to be frail.

Higher serointensity could reflect a more virulent or widespread infection, multiple infections or recent reactivation of a latent infection, the authors said.

“This paper is important because it provides, for the first time, evidence of the existence of a link between frailty in older adults and intensity of the response to T. gondii infection,” said co-author Blanca Laffon, a professor of psychobiology at the Interdisciplinary Centre of Chemistry and Biology at University of A Coruña.

How cats spread T. gondii

Wild and domestic felines are considered the definitive host of the parasite, while warm-blooded animals like birds and rodents serve as secondary hosts: When cats eat infected animals, T. gondii takes up residence and multiplies in their intestines, shedding eggs in their faeces.

People are typically infected via exposure to those eggs (via litter boxes, contaminated water or dirty vegetables) or by eating undercooked pork, lamb or other meat that’s infested.

Most people never know they’ve been infected, with only about 10% initially having brief flu-like symptoms. But T. gondii tends to linger dormant for decades, cloaked in cysts in muscle and brain tissue (specifically the emotion-processing region known as the amygdala) with some insidious impacts, mounting research suggests.

In a creepy evolutionary trick seemingly designed to benefit the parasite’s favourite host, rodents infected with T. gondii tend to lose their fear of felines, making it easier for cats to catch rats and mice. In the wild, infected chimpanzees have been shown to actually grow attracted to the smell of the urine of their feline predator, the leopard.

People who have been infected also tend to engage in risky behaviour, with research showing they tend to be more impulsive, more entrepreneurial and more likely to get in a car accident. They also have higher rates of schizophrenia, certain mood disorders, cognitive problems and are more likely to attempt suicide, according to research by Lowry and Dr Teodor Postolache, a professor in the Department of Psychiatry at University of Maryland School of Medicine and senior author on the new study.

A declining immune response?

The authors caution that the new study does not prove causation, but suggests the association should be researched.

They found that frail people with high T. gondii seropositivity also had higher levels of certain inflammatory markers, suggesting that infection with the parasite could exacerbate inflammation that already occurs with aging – aka. “inflammaging.”

Because latent T. gondii tends to hide out in muscle tissue, Postolache suspects it could also play a role in hastening sarcopenia.

Lowry’s research focuses on the impact microorganisms have on the immune system and, thus, mental health. He notes that many microbes that humans have evolved with impact health in a positive way – a theory known as the ‘Old Friends’ hypothesis. Even T. gondii may have health benefits we aren’t yet aware of, he said. But in some cases, a switch flips, and friends become enemies.

In the case of T. gondii, certain medications or immune compromising diseases like HIV or cancer can enable a latent infection to escape suppression and reactivate, with adverse effects. Even in people with healthy immune systems, Lowry notes, immune function can decline with age, potentially wakening dormant dormant T. gondii.

The researchers hope their study will inspire more research into the relationship between T. gondii and frailty, and ultimately lead to new ways of keeping the parasite from doing harm.

For now, they encourage people – especially pregnant and immunocompromised people – to take steps to avoid infection.

Tips for preventing infection:

Change litter box daily, and wash hands afterward.

Avoid eating undercooked meat.

Rinse fruits and vegetables.

If pregnant or immunocompromised:

Avoid changing the litter box if possible (T. gondii infection during pregnancy can cause serious problems to a developing foetus).

Keep cats indoors.

Avoid stray cats.

Source: University of Colorado at Boulder

Is Protein Restriction the Best Option after Kidney Transplant?

Anatomic model of a kidney
Photo by Robina Weermeijer on Unsplash

Scientists at Osaka Metropolitan University have challenged the conventional wisdom that low protein intake is essential for kidney disease patients with their recent study on the relationship between protein intake and skeletal muscle mass in kidney transplant recipients. Their findings were published in Clinical Nutrition.

Chronic kidney disease patients are known to have induced sarcopenia due to chronic inflammation, hypercatabolism, decreased nutrient intake, and decreased physical activity associated with impaired kidney function. A successful kidney transplantation is able to correct or improve many of those physiological and metabolic abnormalities, with the transplant recipients increasing skeletal muscle mass after receiving their new kidney. Since excessive protein intake worsens kidney function, it is commonly believed that patients with chronic kidney disease, including kidney transplant recipients, should limit protein intake to protect their kidneys. On the other hand, it has been suggested that severe protein restriction may worsen sarcopenia and adversely affect prognosis.

Since nutrition and exercise therapy are recommended to improve sarcopenia, protein intake is suspected to relate to recovery of skeletal muscle mass after kidney transplantation. However, few studies have examined the relationship between skeletal muscle mass and protein intake in kidney transplant recipients.

In order to fill this knowledge gap, a research group led by Drs Akihiro Kosoku and Tomoaki Iwai, and Professor Junji Uchida at Osaka Metropolitan University followed 64 kidney transplant recipients for 12 months after their procedure. They investigated the relationship between changes in skeletal muscle mass, as measured by bioelectrical impedance analysis, and protein intake from urine sample. The results showed that changes in skeletal muscle mass during this period were positively correlated with protein intake, and that insufficient protein intake resulted in decreased muscle mass.

Drs Iwai and Kosoku commented, “To improve the life expectancy of kidney transplant recipients, further research is needed to clarify the optimal protein intake to prevent either deterioration in kidney function or sarcopenia. We hope that nutritional guidance, including protein intake, will lead to improved life expectancy and prognosis.”

Source: Osaka Metropolitan University

Low Serum Urate Increases Sarcopenia Risk

Blood sample being drawn
Photo by Hush Naidoo Jade Photography on Unsplash

Adults with low blood levels of urate, the end-product of the purine metabolism in humans, may be at higher risk of sarcopenia and may face a higher risk of early death, according to a new study published in Arthritis & Rheumatology.

Whether or nor low serum urate (SU) levels contribute to adverse outcomes has been the subject of controversy.  The study involved 13 979 participants aged 20 years and older, sourced from the National Health and Nutrition Examination Survey from 1999–2006.

Low serum urate concentrations (<2.5 mg/dL in women; <3.5 mg/dL in men) were associated with low lean mass, underweight BMI (<18.5 kg/m2), and higher rates of weight loss. While low SU was associated with increased mortality (61%) before adjusting for body composition, its effect was reduced and non-significant after adjustment for body composition and weight loss.

“These observations support what many have intuited, namely that people with low serum urate levels have higher mortality and worse outcomes not because low urate is bad for health, but rather that low urate levels tend to occur among sicker people, who have lost weight and have adverse body composition,” explained lead author Joshua F. Baker, MD, MSCE, of the University of Pennsylvania. “While this observational study doesn’t disprove a causal association, it does suggest that great care is needed in interpreting epidemiologic associations between urate levels and health outcomes.”

Source: Wiley

Timely Interventions Could Counteract Sarcopenia

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A new study from Karolinska Institutet in Sweden suggests that the early stages of sarcopenia, where muscles weaken with age faster than expected, could be counteracted with timely interventions designed to preserve physical and cognitive function and manage chronic conditions. The study’s findings are published in the Journal of Cachexia, Sarcopenia and Muscle.

Muscle mass and function is lost with ageing. When this decline is more extensive or rapid than expected, it is categorised as sarcopenia, a common condition in the elderly that often lowers quality of life and increases fall and fracture risks.

Researchers examined how different factors such as sex, age, educational level, living arrangement, lifestyle and chronic conditions affected the development of sarcopenia in people aged 60 and above across a 12-year period.

When the study began, almost 10% of the nearly 3200 participants had sarcopenia, 27% had probable sarcopenia and just over 63% no sarcopenia. Measurements such as grip strength, walking speed, speed of rising from a chair five times and calf circumference were used to assess muscle strength and mass and physical performance.

“Perhaps the most interesting result was that after five years, a roughly equal proportion (just over 10 percent) of the individuals with probable sarcopenia had either improved or deteriorated. This suggests that sarcopenia is a dynamic condition that is modifiable especially in the initial stages, which is a hopeful message,” said corresponding author Caterina Trevisan, affiliated researcher at the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet.

Physical activity and higher results on cognitive tests improved odds of improvement and lowered mortality risk, while a higher number of chronic conditions, male sex and older age had the opposite correlation. For individuals initially diagnosed with severe sarcopenia, there was little chance of improvement, and many of them (almost 71%) died during the follow-up period.

“Our results support the need of early interventions to preserve physical and cognitive functions and manage chronic conditions in older individuals,” says the study’s last author Anna-Karin Welmer, senior lecturer at the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet. “With these tools, we could probably counteract muscle deterioration and the impairment in quality of life this entails. We now need intervention studies to find ways to use these tools to counteract sarcopenia.”

Source: Karolinska Institutet