#224 ‒ Dietary protein: amount needed, ideal timing, quality, and more | Don Layman, Ph.D.
Sep 26, 2022
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Don Layman, a Professor emeritus at the University of Illinois, shares his expertise on dietary protein and muscle synthesis. He breaks down the RDA for protein, emphasizing it as a minimum guideline rather than optimal intake. Discussing protein quality, he explains the differences between animal and plant proteins and their absorption rates. Layman highlights the importance of protein timing, particularly around workouts, and reveals insights from his clinical trials on high-protein diets and their effects on fat loss, especially in different age groups.
The Recommended Dietary Allowance (RDA) for protein should be seen as a minimum for survival, not an optimal level of intake.
Animal proteins are considered higher quality than plant proteins due to their balanced profile of essential amino acids and higher digestibility.
Specific amino acids like leucine play a crucial role in triggering muscle protein synthesis, so protein-rich meals with adequate leucine should be prioritized.
Increasing protein intake and distributing it throughout the day, especially in the morning and evening, can help combat the effects of anabolic resistance and optimize muscle protein synthesis.
Deep dives
The importance of understanding protein and amino acids in muscle-centric nutrition
This podcast episode delves into the concept of muscle-centric nutrition and how it is crucial to consider nutrition, protein, and amino acids from the perspective of maintaining and maximizing muscle, especially as we age. The host, Peter Atia, interviews Don Lehman, an expert in food science and human nutrition, who shares insights on protein requirements, protein quality, and amino acid metabolism. They discuss the misconceptions around protein needs, the differences between animal and plant proteins, and the role of specific amino acids like leucine, methionine, and lysine. The conversation emphasizes the importance of balancing essential amino acids for muscle protein synthesis and the implications for overall health and performance.
The limitations of the RDA in determining protein requirements
The podcast highlights the flaws in using the Recommended Dietary Allowance (RDA) as a measure of protein requirements. Don Lehman explains that the RDA is based on nitrogen balance, which measures the intake and loss of nitrogen, but it underestimates requirements and does not consider other important factors like amino acid composition and bioavailability. The conversation emphasizes the need to focus on specific amino acids like leucine, methionine, and lysine to ensure adequate protein intake and synthesis.
The significance of protein quality and bioavailability
Don Lehman discusses protein quality and bioavailability, focusing on the difference between animal and plant proteins. Animal proteins, such as meat, eggs, and dairy, are considered higher quality because they contain a balanced profile of essential amino acids and have high digestibility. In contrast, plant proteins may be incomplete in terms of essential amino acids and have lower bioavailability due to the presence of fibers and other structures. The conversation emphasizes the importance of considering protein quality and digestibility when evaluating protein sources.
Understanding the role of specific amino acids in muscle protein synthesis
The podcast explores the role of specific amino acids, including leucine, methionine, and lysine, in muscle protein synthesis. These amino acids play a crucial role in signaling muscle growth and repair. Leucine, in particular, is highlighted as a key trigger for the mTOR pathway, which regulates muscle protein synthesis. The conversation emphasizes the importance of consuming protein-rich meals that provide adequate amounts of essential amino acids, particularly leucine, to maximize muscle protein synthesis.
The Importance of Protein Turnover in the Body
Protein turnover is a crucial process in the body, with collagen turnover occurring every 100 days and the body replacing every protein about four times a year. This emphasizes the importance of getting enough protein in our diets, especially as we age and the efficiency of protein turnover decreases. Research has shown that older adults can still respond to protein intake by increasing muscle protein synthesis if given an enriched source of essential amino acids. Therefore, it is recommended that adults consume around 1.6 grams of protein per kilogram of body weight per day to maintain muscle protein synthesis and overall health.
The Impact of Diet on Protein Requirements
Diet plays a significant role in meeting our protein requirements. The average American intake of protein is around 80 grams, which is lower than the recommended intake of 1.6 grams per kilogram of body weight. This means that there is a recycling process going on in the body, where amino acids are reused. For individuals following a plant-based diet, it is important to increase protein intake and overall calories to meet protein requirements. The recommendation is to have around 125 grams of protein per day for plant-based diets, while being cautious of protein quality and ensuring a balance between animal and plant protein sources.
Exploring Anabolic Resistance and Strategies to Overcome it
Anabolic resistance, the reduced efficiency of muscle protein turnover as we age, can be overcome by increasing protein intake and adopting resistance exercise. While hormonal changes play a significant role in anabolic resistance, studies have shown that providing an enriched source of essential amino acids can help older adults respond to protein intake and increase muscle protein synthesis, similar to younger individuals. This highlights the importance of protein distribution throughout the day, with emphasis on consuming higher protein meals in the morning and evening to optimize muscle protein synthesis and combat the effects of anabolic resistance.
Considering Protein Quality and Timing for Optimal Muscle Health
Protein quality and timing are crucial for maintaining muscle health. Research suggests that muscle is most responsive to protein intake in the range of 25 to 60 grams, with leucine being a key amino acid for triggering muscle protein synthesis. It is recommended to have meals with at least 30 grams of protein, containing around 3 grams of leucine, in order to stimulate muscle protein synthesis effectively. Furthermore, distributing protein intake throughout the day, particularly by front-loading protein in the first meal after an overnight fast, can enhance muscle protein synthesis and contribute to better overall muscle health.
Don Layman is a Professor of Food Science and Human Nutrition at the University of Illinois Urbana-Champaign. He has spent the past 40 years investigating the role of dietary protein in muscle protein synthesis. In this episode, Don describes how his decades of research have shaped his thinking around protein, muscle, anabolic factors, metabolism, and more. He explains the recommended dietary allowance (RDA) for protein: what it is, how it came about, and how it should serve only as a guide for the minimum protein necessary for survival rather than as an optimal level of protein intake. He provides an overview of the essential amino acids, explains the nuances of animal versus plant protein, and provides insights for determining protein quality, absorption rates, and how to best track your intake. He discusses the ideal timing of protein intake in relation to resistance exercise, how protein should be distributed among meals, and how limitations in protein utilization per sitting can impact those practicing time-restricted eating. Additionally, Don shares results from his clinical trials, including how a high-protein diet fared in terms of fat loss, and explains the differences in protein utilization between adolescents and adults and how the problem of reduced efficiency of protein utilization in older adults can be overcome.
We discuss:
Don’s background: from growing up on a farm to studying nutritional biochemistry [2:30];
Don’s philosophy on nutrition, muscle, and metabolism [6:30];
The controversial relationship between saturated fat and atherosclerosis [18:15];
The basics of protein and amino acids [25:45];
Origin and limitations of the current recommended dietary allowance (RDA) for protein intake [32:15];
Protein sources: determining quality, absorption rates, and how to track intake [41:15];
Leucine, lysine, and methionine: three important essential amino acids [48:00];
The vital role of ruminant animals in the production of quality protein [53:15];
The differing needs and impacts of dietary protein for a 16-year old compared to a 65-year old [59:30];
Consequences of protein deficiency in childhood [1:06:30];
Muscle protein synthesis: ideal timing, small meals vs. big meals, and more [1:12:45];
Protein needs of children [1:19:45];
How important is timing protein intake around training? [1:24:15];
The role of leucine in fatty acid oxidation by muscle [1:28:15];
High protein diets for fat loss: Results from Don’s clinical trials [1:31:30];
Influence of industry funding on nutrition studies [1:43:45];
Don’s thoughts on plant-based and synthetic “meats” [1:48:45];
Problems with epidemiological studies of dietary protein [1:56:30];
