Tag: protein intake

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Even Vegans who get Enough Total Protein may Fall Short for Some Essential Amino Acids

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Even vegans who get enough total protein may fall short for some essential amino acids

In New Zealand study, 3 in 4 vegans ate sufficient protein, but half didn’t meet daily lysine and leucine requirements

In a new study of people with long-term vegan diets, most ate an adequate amount of total daily protein, but a significant proportion did not meet required levels of the amino acids lysine and leucine. Bi Xue Patricia Soh and colleagues at Massey University, New Zealand, present these findings in the open-access journal PLOS One on April 16, 2025.

Proteins are made up of various molecular “building blocks” known as amino acids. While the human body can synthesise most of the amino acids we need to live, we completely rely on the food we eat to provide the nine “indispensable amino acids” we cannot make ourselves. Typically, plant-based foods have more varied levels of indispensable amino acids that the body can use, as compared to animal-sourced foods, so they are of particular concern in vegan diets.

However, most prior research on protein in vegan diets has not considered specific amino acids nor the digestibility of different foods, which accounts for the fact that not all of what we eat, including amino acids, is fully utilised by the body.

To help deepen understanding of amino acid intake in vegan diets, Soh and colleagues analysed detailed, four-day food diaries kept by 193 long-term vegans living in New Zealand. They used information from the United States Department of Agriculture and the New Zealand FoodFiles database to calculate participants’ intake of different amino acids from the different foods they ate.

The analysis showed that about three quarters of participants met daily total protein requirements. Accounting for body weight, intake of all indispensable amino acids also met requirements.

However, when considering digestibility, only about half of the participants met daily requirements for lysine and leucine levels, making them the most limiting indispensable amino acids in the study. Among the food types consumed by participants, legumes and pulses were the biggest contributors to overall protein and lysine intake.

These findings underscore that meeting total daily protein requirements does not necessarily mean meeting indispensable amino acid requirements. On the basis of their findings, the researchers call for future research to explore how intake of leucine and lysine could be boosted for vegans in a nutritionally balanced manner.

The authors add: “Vegan diets are the most restrictive form of plant-based eating, relying entirely on plant sources for all nutrients. Achieving high protein quality on a vegan diet requires more than just consuming enough protein – it also depends on the right balance and variety of plant foods to supply all the amino acids in the quantities that our body needs. Prolonged deficiencies in these essential nutrients can negatively affect overall protein balance, muscle maintenance and other physiological functions, especially in more vulnerable populations.”

“In our study, lysine and leucine were the most commonly under-consumed amino acids in our vegan cohort and fall below the daily requirements needed by our body. This is because many plant foods generally contain lower quantities of these amino acids that can be absorbed and utilised by the body. However, the inclusion of legumes, nuts and seeds emerged as valuable plant sources – not only to support overall protein intake but also to specifically increase lysine and leucine quantities in a vegan diet.”

Provided by PLOS

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More Protein and Fibre While Dropping Calories is Key for Weight Loss

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Photo by Andres Ayrton on Pexels

Participants on a self-directed dietary education program who had the greatest success at losing weight across a 25-month period consumed greater amounts of protein and fibre, found a study published in Obesity Science and Practice. Personalisation and flexibility also were key in creating plans that dieters could adhere to over time. 

At the one-year mark, successful dieters (41% of participants) had lost 12.9% of their body weight, compared with the remainder of the study sample, who lost slightly more than 2% of their starting weight. 

The dieters were participants in the Individualised Diet Improvement Program, which uses data visualisation tools and intensive dietary education sessions to increase dieters’ knowledge of key nutrients, enabling them to create a personalised, safe and effective weight-loss plan, said Manabu T. Nakamura, a professor of nutrition at the University of Illinois Urbana-Champaign and the leader of the research.

“Flexibility and personalisation are key in creating programs that optimise dieters’ success at losing weight and keeping it off,” Nakamura said. “Sustainable dietary change, which varies from person to person, must be achieved to maintain a healthy weight. The iDip approach allows participants to experiment with various dietary iterations, and the knowledge and skills they develop while losing weight serve as the foundation for sustainable maintenance.”

The pillars of iDip are increasing protein and fibre consumption along with consuming 1500 calories or less daily. 

Based on the dietary guidelines issued by the Institutes of Medicine, the iDip team created a one-of-a-kind, two-dimensional quantitative data visualisation tool that plots foods’ protein and fibre densities per calorie and provides a target range for each meal. Starting with foods they habitually ate, the dieters created an individualised plan, increasing their protein intake to about 80g and their fibre intake to about 20g daily.

In tracking the participants’ eating habits and their weights with Wi-Fi enabled scales, the team found strong inverse correlations between the percentages of fibre and protein eaten and dieters’ weight loss.    

“The research strongly suggests that increasing protein and fibre intake while simultaneously reducing calories is required to optimise the safety and efficacy of weight loss diets,” said first author and U. of I. alumna Mindy H. Lee, a then-graduate student and registered dietitian-nutritionist for the iDip program. 

Nakamura said the preservation of lean mass is very important while losing weight, especially when using weight-loss drugs.

 “Recently, the popularity of injectable weight loss medications has been increasing,” Nakamura said. “However, using these medications when food intake is strongly limited will cause serious side effects of muscle and bone loss unless protein intake is increased during weight loss.”

A total of 22 people who enrolled in the program completed it, including nine men and 13 women. Most of the dieters were between the ages of 30–64. Participants reported they had made two or more prior attempts to lose weight. They also had a variety of comorbidities – 54% had high cholesterol, 50% had skeletal problems and 36% had hypertension and/or sleep apnoea. Additionally, the dieters reported diagnoses of diabetes, nonalcoholic fatty liver disease, cancer and depression, according to the study.

The seven dieters who reported they had been diagnosed with depression lost significantly less weight: about 2.4% of their starting weight compared with those without depression, who lost 8.39% of their initial weight. The team found that weight loss did not differ significantly among participants with other comorbidities, or between younger and older participants or between men and women.

Body composition analysis indicated that dieters maintained their lean body mass, losing an average of 7.1kg of fat mass and minimal muscle mass at the six-month interval. Among those who lost greater than 5% of their starting weight, 78% of the weight they lost was fat, according to the study.

Overall, the participants reduced their fat mass from an average of 42.6kg at the beginning of the program to 35.7kg at the 15-month mark. Likewise, the dieters reduced their waists by about 7cm at six months and by a total of 9cm at 15 months, the team found. 

In tracking dieters’ protein and fibre intake, the team found a strong correlation between protein and fibre consumption and weight loss at three months and 12 months.

“The strong correlation suggests that participants who were able to develop sustainable dietary changes within the first three months kept losing weight in the subsequent months, whereas those who had difficulty implementing sustainable dietary patterns early on rarely succeeded in changing their diet in the later months,” Nakamura said.

The team hypothesised that this correlation could also have been associated with some dieters’ early weight loss success, which may have bolstered their motivation and adherence to their program.

Source: University of Illinois at Urbana-Champaign

Categories : Cardiovascular Disease Diet and NutritionTags :

Excessive Protein Consumption Increases Atherosclerosis Risk

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Cardiovascular pitfalls to increasing protein intake discovered

Image by Scientific Animations, CC4.0

University of Pittsburgh School of Medicine researchers discovered a molecular mechanism by which excessive dietary protein could increase atherosclerosis risk. The study, published in Nature Metabolism, combined small human trials with in vitro human and mouse cell experiments.

It showed that consuming over 22% of dietary calories from protein can lead to increased activation of immune cells that play a role in atherosclerotic plaque formation, driving the disease risk.

Furthermore, the scientists showed that one amino acid, leucine, seems to have a disproportionate role in driving the pathological pathways linked to atherosclerosis, or stiff, hardened arteries.

“Our study shows that dialling up your protein intake in pursuit of better metabolic health is not a panacea. You could be doing real damage to your arteries,” said senior and co-corresponding author Babak Razani, MD, PhD, professor of cardiology at Pitt.

“Our hope is that this research starts a conversation about ways of modifying diets in a precise manner that can influence body function at a molecular level and dampen disease risks.”

According to a survey of an average American diet over the last decade, Americans generally consume a lot of protein, mostly from animal sources.

Further, nearly a quarter of the population receives over 22% of all daily calories from protein alone.

That trend is likely driven by the popular idea that dietary protein is essential to healthy living, says Razani.

But his and other groups have shown that overreliance on protein may not be such a good thing for long-term health.

Following their 2020 research, in which Razani’s laboratory first showed that excess dietary protein increases atherosclerosis risk in mice, his next study in collaboration with Bettina Mittendorfer, PhD, a metabolism expert at the University of Missouri, Columbia, delved deeper into the potential mechanism and its relevance to the human body.

To arrive at the answer, Razani’s laboratory, led by first-authors Xiangyu Zhang, Ph.D., and Divya Kapoor, M.D., teamed up with Mittendorfer’s group to combine their expertise in cellular biology and metabolism and perform a series of experiments across various models, from cells to mice to humans.

“We have shown in our mechanistic studies that amino acids, which are really the building blocks of the protein, can trigger disease through specific signaling mechanisms and then also alter the metabolism of these cells,” Mittendorfer said.

“For instance, small immune cells in the vasculature called macrophages can trigger the development of atherosclerosis.”

Based on initial experiments in healthy human subjects to determine the timeline of immune cell activation following ingestion of protein-enriched meals, the researchers simulated similar conditions in mice and in human macrophages, immune cells that are shown to be particularly sensitive to amino acids derived from protein.

Their work showed that consuming more than 22% of daily dietary calories through protein can negatively affect macrophages that are responsible for clearing out cellular debris, leading to the accumulation of a “graveyard” of those cells inside the vessel walls and worsening of atherosclerotic plaques overtime.

Interestingly, the analysis of circulating amino acids showed that leucine, an amino acid enriched in animal-derived foods like beef, eggs and milk, is primarily responsible for abnormal macrophage activation and atherosclerosis risk, suggesting a potential avenue for further research on personalized diet modification, or “precision nutrition.”

Razani is careful to note that many questions remain to be answered, mainly: What happens when a person consumes between 15% of daily calories from protein as recommended by the USDA and 22% of daily calories from protein, and if there is a ‘sweet spot’ for maximising the benefits of protein (such as muscle gain) while avoiding kick-starting a molecular cascade of damaging events leading to cardiovascular disease.

The findings are particularly relevant in hospital settings, where nutritionists often recommend protein-rich foods for the sickest patients to preserve muscle mass and strength.

“Perhaps blindly increasing protein load is wrong,” Razani said.

“Instead, it’s important to look at the diet as a whole and suggest balanced meals that won’t inadvertently exacerbate cardiovascular conditions, especially in people at risk of heart disease and vessel disorders.”

Razani also notes that these findings suggest differences in leucine levels between diets enriched in plant and animal protein might explain the differences in their effect on cardiovascular and metabolic health.

“The potential for this type of mechanistic research to inform future dietary guidelines is quite exciting,” he said.

Source: University of Pittsburgh

Categories : Diet and Nutrition TransplantsTags :

Is Protein Restriction the Best Option after Kidney Transplant?

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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