Category: Diet and Nutrition

Ultra-processed Foods Linked to Mouth, Throat and Oesophagus Cancer Risk

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Eating more ultra-processed foods (UPFs) may be associated with a higher risk of developing cancers of the upper aerodigestive tract (ie, the mouth, throat and oesophagus), according to a new study in the European Journal of Nutrition. The authors of this study, led by the University of Bristol and the International Agency for Research on Cancer (IARC), say that obesity associated with the consumption of UPFs may not be the only factor to blame.

Several studies have identified an association between UPF consumption and cancer, including a recent study which looked at the association between UPFs and 34 different cancers in the largest cohort study in Europe, the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, which followed 450 111 adults who for approximately 14 years.

As more evidence emerges about the associations between eating UPFs and adverse health outcomes, researchers from the Bristol Medical School and IARC wanted to explore this further.

Since many UPFs have an unhealthy nutritional profile, the team sought to establish whether the association between UPF consumption and head and neck cancer and oesophageal adenocarcinoma in EPIC could be explained by an increase in body fat.

Results from the team’s analyses showed that eating 10% more UPFs is associated with a 23% higher risk of head and neck cancer and a 24% higher risk of oesophageal adenocarcinoma in EPIC.

Increased body fat only explained a small proportion of the statistical association between UPF consumption and the risk of these upper-aerodigestive tract cancers.

Fernanda Morales-Berstein, a Wellcome Trust PhD student at the University of Bristol and the study’s lead author, explained: “UPFs have been associated with excess weight and increased body fat in several observational studies. This makes sense, as they are generally tasty, convenient and cheap, favouring the consumption of large portions and an excessive number of calories. However, it was interesting that in our study the link between eating UPFs and upper-aerodigestive tract cancer didn’t seem to be greatly explained by body mass index and waist-to-hip ratio.”

The authors suggest that other mechanisms could explain the association.

For example, additives including emulsifiers and artificial sweeteners which have been previously associated with disease risk, and contaminants from food packaging and the manufacturing process, may partly explain the link between UPF consumption and upper-aerodigestive tract cancer in this study.

Fernanda Morales-Berstein and colleagues did caution that the associations between UPF consumption and upper-aerodigestive tract cancers found in the study could be affected by certain types of bias.

This would explain why they found evidence of an association between higher UPF consumption and increased risk of accidental deaths, which is highly unlikely to be causal.

Inge Huybrechts, Team head of the Lifestyle exposures and interventions team at IARC, added: “Cohorts with long-term dietary follow-up intake assessments, considering also contemporary consumption habits, are needed to replicate these study’s findings, as the EPIC dietary data were collected in the 1990s, when the consumption of UPFs was still relatively low. As such associations may potentially be stronger in cohorts including recent dietary follow-up assessments.”

Further research is needed to identify other mechanisms, such as food additives and contaminants, which may explain the links observed.

However, based on the finding that body fat did not greatly explain the link between UPF consumption and upper-aerodigestive tract cancer risk in this study, Fernanda Morales-Berstein, suggested: “Focussing solely on weight loss treatment, such as semaglutide, is unlikely to greatly contribute to the prevention of upper-aerodigestive tract cancers related to eating UPFs.”

Source: University of Bristol

Tryptophan-rich Foods might Ease Colitis… and Braai Smoke may Help too

…although braai smoke still isn’t great for your lungs

Irritable bowel syndrome. Credit: Scientific Animations CC4.0

Ulcerative colitis is an inflammatory bowel disease that is prone to flareups, especially around feasts. New research in mice suggests that certain foods – especially those high in tryptophan, like turkey, pork, nuts and seeds – could reduce the risk of a colitis flare. It also helps explain why cigarette smokers are less likely to have colitis. The findings, published in Nature Communications, point to a noninvasive method of improving long-term colitis management, if the results are validated in people.

“Although there are some treatments for ulcerative colitis, not everyone responds to them,” says senior author Sangwon Kim, PhD, an assistant professor of immunology at Thomas Jefferson University.

“This disease has a huge impact on quality of life, and can lead to surgery to remove the colon or cancer.”

Since ulcerative colitis is caused by inflammation of the inner lining of the colon and rectum, Dr Kim and his colleagues looked for ways to calm the inflamed tissue.

They focused on a group of immune cells called T-regulatory (T-reg) cells, which can help break the cycle of inflammation. They reasoned that getting more T-reg cells to the colon might reduce the inflammation that causes colitis.

Dr Kim’s team thought about how to attract the T-reg cells, and found a specific receptor, CPR15, on the surface of T-reg cells that acts like a magnet for the colon. The more CPR15 the T-reg cells have, the more strongly they are attracted to the colon.

So they searched for molecules that could make T-reg cells produce more GPR15 to turn up the power of the magnet. They found tryptophan – specifically, one of the molecules that tryptophan breaks down into in the body – could increase these receptors called GPR15.

To test whether these molecules could control colitis, the researchers supplemented tryptophan in the diet of mice over a period of two weeks.

They saw a doubling in the amount of inflammation-suppressing T-reg cells in the colon tissue compared to mice that weren’t fed extra tryptophan.

Dr. Kim’s team also saw a reduction in colitis symptoms, which seemed to last for at least a week after tryptophan was removed from the diet.

“In human time that might translate to about a month of benefit,” explained Dr Kim.

However, when tryptophan was given to mice during a colitis flare, it provided little benefit, suggesting this dietary change might only be effective at preventing future flares rather than treating them.

In a chance finding, while looking for molecules that could increase GPR15, the researchers also stumbled across a molecule that helps explain why smoking seems to be protective against colitis. Researchers have long observed that people who smoke cigarettes have a lower incidence of ulcerative colitis than the general public.

Dr. Kim’s team found a molecule that is prevalent in smoke – from cigarettes and barbeque alike – that can also increase GPR15 levels on T-reg cells “Although both might help protect against colitis, tryptophan is obviously the much safer and healthier option,” says Dr Kim.

In the future, the researchers plan to test whether these results can be translated to people with colitis. Tryptophan supplement is considered safe, as long as the dose doesn’t exceed 100mg per day. Using the mouse data as a guide, Dr Kim expects that 100mg could be enough to see an effect in humans, and is planning further testing in clinical trials.

Source: Thomas Jefferson University

A Startling Connection between Malnutrition and Antibiotic Resistance

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A study published in Nature Microbiology has uncovered startling connections between micronutrient deficiencies and the composition of gut microbiomes in early life that could help explain why resistance to antibiotics has been rising across the globe.

A University of British Colombia team investigated how deficiencies in crucial micronutrients such as vitamin A, B12, folate, iron, and zinc affected the community of bacteria, viruses, fungi and other microbes that live in the digestive system.

They discovered that these deficiencies led to significant shifts in the gut microbiome of mice – most notably an alarming expansion of bacteria and fungi known to be opportunistic pathogens.

Importantly, mice with micronutrient deficiencies also exhibited a higher enrichment of genes that have been linked to antibiotic resistance.

“Micronutrient deficiency has been an overlooked factor in the conversation about global antibiotic resistance,” said Dr. Paula Littlejohn, a postdoctoral research fellow with UBC’s department of medical genetics and department of pediatrics, and the BC Children’s Hospital Research Institute. “This is a significant discovery, as it suggests that nutrient deficiencies can make the gut environment more conducive to the development of antibiotic resistance, which is a major global health concern.”

Bacteria naturally possess these genes as a defence mechanism. Certain circumstances, such as antibiotic pressure or nutrient stress, cause an increase in these mechanisms. This poses a threat that could render many potent antibiotics ineffective and lead to a future where common infections could become deadly.

Antibiotic resistance is often attributed to overuse and misuse of antibiotics, but the work of Dr. Littlejohn and her UBC colleagues suggests that the ‘hidden hunger’ of micronutrient deficiencies is another important factor.

“Globally, around 340 million children under five suffer from multiple micronutrient deficiencies, which not only affect their growth but also significantly alter their gut microbiomes,” said Dr. Littlejohn. “Our findings are particularly concerning as these children are often prescribed antibiotics for malnutrition-related illnesses. Ironically, their gut microbiome may be primed for antibiotic resistance due to the underlying micronutrient deficiencies.”

The study offers critical insights into the far-reaching consequences of micronutrient deficiencies in early life. It underscores the need for comprehensive strategies to address undernutrition and its ripple effects on health. Addressing micronutrient deficiencies is about more than overcoming malnutrition, it may also be a critical step in fighting the global scourge of antibiotic resistance.

Source: University of British Columbia

Vitamin B12 Plays a Key Role in Cellular Reprogramming and Tissue Regeneration

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Vitamin B12 is a well-known micronutrient that has long been acknowledged for its essential role in maintaining nerve function, supporting red blood cell production, and facilitating DNA synthesis, all vital processes for overall health. Researchers have now discovered that vitamin B12 also plays a pivotal role in cellular reprogramming and tissue regeneration. The findings have been published in the journal Nature Metabolism.

The research was focused on an experimental process known as cellular reprogramming which is thought to mimic the early phases of tissue repair. The IRB team found that cellular reprogramming in mice consumes large amounts of vitamin B12. Indeed, the depletion of vitamin B12 becomes a limiting factor that delays and impairs some aspects of the reprogramming process. Considering the abundance of vitamin B12 in the normal diet of mice, the investigators were surprised to observe that the simple supplementation of vitamin B12 significantly enhanced the efficiency of reprogramming.

Therapeutic potential in ulcerative colitis

The researchers validated their findings in a model of ulcerative colitis, demonstrating that the intestinal cells initiating repair undergo a process similar to cellular reprogramming and also benefit from vitamin B12 supplementation. Patients with intestinal bowel disease could potentially benefit from vitamin B12 supplementation.

“Our research uncovers a critical role of vitamin B12 in cellular reprogramming and tissue repair. These findings hold promise for regenerative medicine, with the potential to benefit patients through an improved nutrition,” says lead researcher Dr Manuel Serrano at IRB.

Understanding the role of vitamin B12 in cellular reprogramming

In this study, the researchers delved into the metabolic requirements of cellular reprogramming and found that vitamin B12 is a limiting factor for a particular branch of metabolism involved in a reaction known as methylation. Precisely, the DNA of the cells initiating reprogramming or tissue repair require very high levels of this methylation reaction and therefore of vitamin B12. The researchers discovered that vitamin B12 insufficiency during reprogramming or tissue repair resulted in significant epigenetic changes, leading to errors in the function of multiple genes.

“Supplementation with vitamin B12 corrected this imbalance, resulting in enhanced gene function fidelity and overall improved reprogramming efficiency,” confirms Dr. Marta Kovatcheva, first author of the study and a postdoctoral researcher in the same laboratory. Dr. Kovatcheva will open a new laboratory in 2024 at the Istituto Fondazione di Oncologia Molecolare ETS (IFOM) in Milan, Italy, which will be focused on the study of partially reprogrammed cells in vivo.

Separate study links vitamin B12 to lower inflammation

The group led by Dr. Serrano has recently published another study, in collaboration with the laboratory of Dr. Rosa Lamuela-Raventós at the University of Barcelona (UB), and Dr. Ramon Estruch at the Hospital Clínic of Barcelona, in which they concluded that people with higher levels of vitamin B12 in blood had lower levels of inflammatory markers (IL-6 and CRP). The researchers also observed a similar relationship in aged mice. These observations suggest that vitamin B12 exerts anti-inflammatory action by reducing these markers in the body and they provide valuable insights into the potential health benefits of vitamin B12.

Source: Institute for Research in Biomedicine (IRB Barcelona)

Cholesterol Discovery could Lead to New Therapies to Prevent Cardiovascular Disease

Source: CC0

Researchers at the University of Leicester have discovered the mechanism by which cholesterol in the diet is absorbed into cells. This discovery, which has just been published in the journal Science opens up new opportunities for therapeutic intervention to control cholesterol uptake that could complement other therapies and potentially save lives.

The research, conducted with colleagues from the USA, China and Australia, has shown that two proteins (called Aster B and Aster C) play a key role in transporting cholesterol from the membrane of the cells lining our intestine to the internal compartment where it is modified prior to circulation.

Funding came from the Leducq Foundation which awarded $6 million to eight laboratories across the USA and Europe for collaborative research into how cholesterol is transported in our bodies.

University of Leicester researchers from the Institute of Structural and Chemical Biology, used their expertise to reveal how Ezetimibe, a cholesterol lowering drug, blocks the ability of Aster B and C to transport cholesterol.

Professor John Schwabe, Director of the Institute for Structural and Chemical Biology, said: “This breakthrough is the result of a long-lasting collaboration and forms part of an international effort to identify ways in which we can combat cardiovascular disease and stroke. A better understanding of important areas of cholesterol absorption and metabolism and, particularly, how cholesterol moves within cells and tissues is essential. This knowledge will allow us to design new drugs and therapies that target specific proteins involved in these pathways to combat most pressing public health problems such as heart attacks and stroke.

Professor Schwabe added: “If we can prevent some cholesterol from being absorbed into our cells, we may ultimately be able to prevent individuals from having high cholesterol and cut down their risks of heart attack and stroke and therefore potentially save lives.

“The Leducq team of experts have different expertise that is used to target the problem at different levels and following different approaches. In addition to target cholesterol absorption, we are trying to identify how cholesterol metabolism and transport affect cholesterol levels and atherosclerotic disease. Cholesterol transporters are essential to regulate blood cholesterol levels therefore we are testing small molecules that influence the function of these transporters in order to develop drugs that ultimately lower the risk for heart attack and stroke.”

Postdoctoral Researcher, Dr Beatriz Romartinez-Alonso, added: “This has been a great project to work on – discovering new science highly relevant to human health.”

Source: University of Leicester

The Seasons Affect Appetite in Unexpected Ways

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Many people may feel that they are healthier in the summer: the sun is shining, they get plenty of vitamin D, and the days are long. However, recent research from the University of Copenhagen suggests that eating habits in winter may be better for metabolic health than eating habits in summer – at least in the case of mice. Researchers have examined the metabolism and weight of mice exposed to both ‘winter light’ and ‘summer light’.

“We found that even in non-seasonal animals, differences in light hours between summer and winter do cause differences in energy metabolism. In this case, body weight, fat mass and liver fat content,” says Lewin Small, who carried out the research while a postdoc at Novo Nordisk Foundation Center for Basic Metabolic Research at the University of Copenhagen. He adds:

“We found this mostly in mice exposed to winter light hours. These mice had less body weight gain and adiposity. They have more rhythmicity in the way they eat over a 24-hour period. And this then led to benefits in metabolic health.”

The study, published in Cell Metabolism, is the first of its kind to examine light hour’s influence on metabolism in mice, that are not considered seasonal animals as like humans they do not only breed in specific seasons. Animals breeding in specific seasons gain weight before the breeding season to save energy supplies.

Light hours impact metabolism

Lewin Small’s inspiration for initiating the study stemmed from the significant variation in daylight hours across various regions of the world.

“We study the influence of the time-of-day on aspects of metabolism such as exercise, obesity and diabetes. However, most studies that investigate this link do so assuming an equal length of day and night all year round,” says Lewin Small.

Therefore, they wanted to find out what the seasonal light differences meant for the metabolism. Most people in the world live with at least a two-hour difference in light between summer and winter.

“I come from Australia, and when I first moved to Denmark, I was not used to the huge difference in light between summer and winter and I was interested in how this might affect both circadian rhythms and metabolism,” says Lewin Small and adds:

“Therefore, we exposed laboratory mice to different light hours representing different seasons and measured markers of metabolic health and the circadian rhythms of these animals.”

Because the research was conducted using mice as the experimental subjects, it is not possible to assume that the same thing goes for humans.

“This is a proof of principle. Do differences in light hours affect energy metabolism? Yes, it does. Further studies in humans may find that altering our exposure to artificial light at night or natural light exposure over the year could be used to improve our metabolic health,” says Juleen Zierath, Professor at the Novo Nordisk Center for Basic Metabolism Research (CBMR) and senior author of the study.

Lewin Small adds that the findings are important to understand how eating patterns are affected by the light and seasons which might help us understand why some people gain more weight or if people gain more weight in a specific time of year.

“Differences in light between summer and winter could affect our hunger pathways and when we get hungry during the day,” he says.

Source: University of Copenhagen – The Faculty of Health and Medical Sciences

Strength Training may Reduce Health Risks of a High-protein Diet

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Progressive strength training using resistance can protect against the detrimental effects of a high-protein diet, according to new research in mice.

The study, published today as a Reviewed Preprint in eLife, presents what the editors describe as a valuable finding on the relationship between a high-protein diet and resistance exercise on fat accumulation and glucose homeostasis, supported by solid evidence. They say the findings will be relevant to dietitians and others trying to understand links between dietary protein, diabetes and exercise.

Dietary protein provides essential nutrients that control a wide variety of processes in the body and can influence health and lifespan. Protein consumption is generally thought of as good, promoting muscle growth and strength, especially when combined with exercise. Yet in people with a sedentary lifestyle, too much protein can increase the risk of heart disease, diabetes and death.

“We know that low-protein diets and diets with reduced levels of specific amino acids promote healthspan and lifespan in animals, and that the short-term restriction of protein improves the health of metabolically unhealthy, adult humans,” explains lead author Michaela Trautman, Research Assistant at the Department of Medicine, School of Medicine and Public Health, University of Wisconsin, US. “But this presents a paradox — if high dietary protein is so harmful, many people with high-protein diets or protein supplements would be overweight and at an increased risk of diabetes, whereas athletes with high-protein diets are among the most metabolically healthy.”

To examine the possibility that exercise can protect against the detrimental effects of a high-protein diet, the researchers used a progressive resistance-based strength training program in mice. The animals pulled a cart carrying an increasing load of weight down a track three times per week for a three-month period, or pulled an identical cart without any load for the same time period. One group of mice were fed a low-protein diet (7% of calories from protein) and a second group were fed a high-protein diet (36% of calories from protein). The team then compared the body composition, weight and metabolic measurements, such as blood glucose, of the different groups.

The results were as the team expected: the high-protein diet impaired metabolic health in sedentary mice pulling no weight; these mice gained excess fat mass compared to the low-protein diet mice. But in the mice pulling the increasing weight, a high-protein diet led to muscle growth especially in the forearm, and protected the animals from gaining fat. However, the exercise did not protect the mice from the effects of high protein on blood sugar control.

Additionally, although the high-protein-fed mice gained strength more quickly than the low-protein-fed mice, there was no difference in the maximum weight each set of mice could pull by the end of the study period, even though the mice fed high-protein diets were bigger and had larger muscles.

Although the evidence supporting the claims of the study was considered to be solid, the editors highlight a couple of limitations. For instance, the use of mice might limit the generalisability of the findings to humans, due to inherent physiological differences. The editors note that the findings would also be strengthened further by the inclusion of a direct investigation into the underlying molecular mechanisms responsible for the observed results.

“We know that many people deliberately consuming high-protein diets or consuming protein supplements to support their exercise regimen are not metabolically unhealthy, despite the body of evidence showing that high-protein levels can have detrimental metabolic effects,” says senior author Dudley Lamming, Associate Professor of Medicine (Endocrinology) at the Department of Medicine, School of Medicine and Public Health, University of Wisconsin. “Our research may explain this conundrum, by showing that resistance exercise protects from high-protein-induced fat gain in mice. This suggests that metabolically unhealthy, sedentary individuals with a high-protein diet or protein supplements might benefit from either reducing their protein intake or more resistance exercise.”

Source: eLife

Study Classifies Four Eating Eating Behaviours of Children

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Children fall broadly into four eating categories, according to new research at Aston University, and parents feed their children differently depending on those categories.

The four categories identified by Dr Abigail Pickard and the team in the School of Psychology are ‘avid’, ‘happy’, ‘typical’, and ‘fussy’. The results, which showed specific temperaments and carer feeding patterns associated with overeating, are published in the journal Appetite.

In the UK, around a fifth of children are overweight or obese when they begin school, rising to around a third by the time they leave primary school at age 11. The team sought to identify eating behaviour patterns and how these are associated with temperament, feeding practices and food insecurity, as a way to predict which children are more at risk of becoming overweight.

Typical eaters made up 44% of the children in the study, while fussy eaters accounted for 16%. But of greatest interest to the team was that around one in five young children in the study were found to show “avid eating,” including greater enjoyment of food, faster eating speed, and weaker sensitivity to internal cues of ‘fullness’. The behaviours that distinguish children with avid eating from those who show ‘happy’ eating (17.7% of children in the study), who have similarly positive responses to food, are wanting to eat (or eating more) in response to the sight, smell or taste of palatable food, and a higher level of emotional overeating. In combination, these eating behaviours can lead to overeating and subsequent weight gain.

Dr Pickard and the team have also shown that there are significant differences in children’s temperament and caregivers’ feeding practices between each of the four eating behaviour patterns. Children with avid eating are more likely to be active and impulsive, and their caregivers are more likely to give them food to regulate their emotions or to restrict food for health reasons. Children with avid eating were also less food secure than children who showed happy or typical eating behaviours.

Principal investigator of the project, Professor Jackie Blissett, said: “Whilst feeding practices are key intervention targets to change children’s eating behaviour and child weight outcomes, there has been little evaluation of how feeding practices interact with children’s food approach behaviours to predict eating behaviour.”

She explained that despite the knowledge of the influence of feeding practices on children’s weight, current public health advice is generic and does not reflect variability in children’s appetites. Parents and caregivers can be left feeling frustrated when trying to manage their child’s food intake. By defining the four eating behaviour profiles, this research project, which is funded by the Economic and Social Research Council and co-developed by Professor Claire Farrow, Dr Clare Llewellyn, Dr Moritz Herle, Professor Emma Haycraft and Dr Helen Croker will make it easier to identify the best feeding practices for each eating pattern and provide tailored, effective advice for parents.

Dr Pickard said: “Parents can use this research to help them understand what type of eating pattern their child presents. Then based on the child’s eating profile the parent can adapt their feeding strategies to the child. For example, children in the avid eating profile may benefit more from covert restriction of food, i.e., not bringing snacks into the home or not having foods on display, to reduce the temptation to eat foods in the absence of hunger. Whereas, if a child shows fussy eating behaviour it would be more beneficial for the child to have a balanced and varied selection of foods on show to promote trying foods without pressure to eat.”

The team has planned further research investigating avid eating behaviour and will invite the caregivers and their children into the specialist eating behaviour lab at Aston University to get a better picture of what avid and typical eating behaviours look like in a real-life setting. All the findings will be integrated and the researchers will work with parents to develop feasible and helpful feeding guidelines to reduce children’s intake of palatable snack foods.

Source: Aston University

Red Meat Consumption Linked to Increased Type 2 Diabetes Risk

“Meat’s back off the menu, boys”

Photo by Jose Ignacio Pompe on Unsplash

People who eat just two servings of red meat per week may have an increased risk of developing type 2 diabetes compared to people who eat fewer servings, and the risk increases with greater consumption, according to a new study in The American Journal of Clinical Nutrition. However, substituting plant or diary protein for red meat was associated with reduced risk of type 2 diabetes.

“Our findings strongly support dietary guidelines that recommend limiting the consumption of red meat, and this applies to both processed and unprocessed red meat,” said first author Xiao Gu, postdoctoral research fellow in the Department of Nutrition at Harvard T.H. Chan School of Public Health.

While previous studies have found a link between red meat consumption and type 2 diabetes risk, this study, which analysed a large number of type 2 diabetes cases among participants being followed for an extended period of years, adds a greater level of certainty about the association.

Type 2 diabetes rates are increasing rapidly in the US and worldwide. This is concerning not only because the disease is a serious burden, but it also is a major risk factor for cardiovascular and kidney disease, cancer, and dementia.

For this study, the researchers analysed health data from 216 695 participants from the Nurses’ Health Study (NHS), NHS II, and Health Professionals Follow-up Study (HPFS). Diet was assessed with food frequency questionnaires every two to four years, for up to 36 years. During this time, more than 22 000 participants developed type 2 diabetes.

The researchers found that consumption of red meat, including processed and unprocessed red meat, was strongly associated with increased risk of type 2 diabetes. Participants who ate the most red meat had a 62% higher risk of developing type 2 diabetes compared to those who ate the least. Every additional daily serving of processed red meat was associated with a 46% greater risk of developing type 2 diabetes and every additional daily serving of unprocessed red meat was associated with a 24% greater risk.

The researchers also estimated the potential effects of substituting one daily serving of red meat for another protein source. They found that substituting a serving of nuts and legumes was associated with a 30% lower risk of type 2 diabetes, and substituting a serving of dairy products was associated with a 22% lower risk.

“Given our findings and previous work by others, a limit of about one serving per week of red meat would be reasonable for people wishing to optimise their health and wellbeing,” said senior author Walter Willett, professor of epidemiology and nutrition.

In addition to health benefits, swapping red meat for healthy plant protein sources would help reduce greenhouse gas emissions and climate change, and provide other environmental benefits, according to the researchers.

Source: Harvard T.H. Chan School of Public Health

In Humans, Reducing Calorie Intake Rejuvenates Muscles and Stimulates Anti-ageing Effects

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Reducing overall calorie intake may rejuvenate muscles and activate biological pathways important for good health, according new study, published in the journal Aging Cell. Calorie restriction, which cuts intake of calories but not essential nutrients, has long been known to delay the progression of age-related diseases in animal models. This finding, by researchers at the National Institutes of Health and their colleagues, suggests the same biological mechanisms may also apply to humans.

Researchers analysed data from participants in the Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE), a study supported by the National Institute on Aging (NIA) that examined whether moderate calorie restriction conveys the same health benefits seen in animal studies. They found that during a two-year span, the goal for participants was to reduce their daily caloric intake by 25%, but the highest the group was able to reach was a 12% reduction. Even so, this slight reduction in calories was enough to activate most of the biological pathways that are important in healthy aging.

“A 12% reduction in calorie intake is very modest,” said corresponding author and NIA Scientific Director Luigi Ferrucci, MD, PhD. “This kind of small reduction in calorie intake is doable and may make a big difference in your health.”

The research team next sought to understand the molecular underpinnings of the benefits seen in limited, previous research of calorie restriction in humans. One study showed that individuals on calorie restriction lost muscle mass and an average of 20 pounds of weight over the first year and maintained their weight for the second year. However, despite losing muscle mass, calorie restriction participants did not lose muscle strength, indicating calorie restriction improved the amount of force generated by each unit of muscle mass, called muscle specific force.

For the current study, scientists used thigh muscle biopsies from CALERIE participants that were collected when individuals joined the study and at one-year and two-year follow ups.

To figure out which human genes were impacted during calorie restriction, the scientists isolated messenger RNA (mRNA), a molecule that contains the code for proteins, from muscle samples. The team determined the protein sequence of each mRNA and used the information to identify which genes originated specific mRNAs. Further analysis helped the scientists establish which genes during calorie restriction were upregulated, meaning the cells made more mRNA; and which were downregulated, meaning the cells produced less mRNA. The researchers confirmed calorie restriction affected the same gene pathways in humans as in mice and non-human primates. For example, a lower caloric intake upregulated genes responsible for energy generation and metabolism, and downregulated inflammatory genes leading to lower inflammation.

“Since inflammation and aging are strongly coupled, calorie restriction represents a powerful approach to preventing the pro-inflammatory state that is developed by many older people,” said Ferrucci.

Source: NIH/National Institute on Aging