Dietary protein requirements
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Dietary Protein Requirements: General Population and Methods
For healthy adults, most guidelines recommend a daily protein intake of about 0.8 grams per kilogram of body weight (g/kg/d) as sufficient to meet the needs of nearly all individuals1345+1 MORE. This value is based on nitrogen balance studies, which measure the difference between protein intake and loss, but newer methods suggest these requirements may be underestimated and that intakes above 1.0 g/kg/d could be more appropriate for optimal health, especially in older adults37. The quality of protein, measured by systems like the digestible indispensable amino acid score (DIAAS), is also important for meeting nutritional needs710.
Protein Requirements for Athletes and Physically Active Individuals
Athletes and those with higher physical activity levels may need more protein than the general population. While standard recommendations do not suggest extra protein for active adults, many sports nutrition experts and studies indicate that athletes benefit from higher intakes1256. Endurance athletes are often advised to consume 1.2–1.4 g/kg/d, while strength athletes may require 1.7–1.8 g/kg/d, which is up to 125% higher than sedentary recommendations256. These higher intakes help support muscle repair, growth, and adaptation to training. However, consuming more than 2 g/kg/d does not appear to provide additional benefits and may have risks if sustained long-term256.
Protein Needs in Older Adults
Older adults may require more protein than the standard 0.8 g/kg/d to maintain muscle mass and function, especially when combined with resistance exercise378. Evidence suggests that 1.0–1.3 g/kg/d is beneficial for reducing age-related muscle loss and improving strength. Protein quality and timing, as well as combining protein intake with exercise, are important factors for optimizing muscle health in older age378.
Protein Requirements in Children
Protein requirements for children are typically set at 0.95 g/kg/d for ages 4–13 and 0.85 g/kg/d for ages 14–18, based on nitrogen balance studies49. However, newer research using advanced methods suggests that actual needs may be up to 60% higher, especially for physically active children. More research is needed to refine these recommendations.
Protein Quality, Sources, and Sustainability
Both the quantity and quality of protein are important for health. High-quality proteins, such as those from animal sources, are effective for supporting growth and muscle maintenance, but plant-based proteins can also be effective if consumed in sufficient amounts and variety3510. Sustainable food systems should provide a mix of plant and animal protein sources to meet nutritional needs while considering environmental impacts310.
Safety and Upper Limits
Protein intakes up to twice the recommended intake (about 1.6 g/kg/d) are considered safe for healthy adults, and long-term consumption of up to 2 g/kg/d is generally well tolerated45. The tolerable upper limit is estimated at 3.5 g/kg/d for well-adapted individuals, but chronic intake above 2 g/kg/d may cause health issues and should be avoided. There is little evidence that high protein diets cause kidney or liver problems in healthy people, but excessive use of single amino acid supplements may pose risks25.
Conclusion
Dietary protein requirements vary by age, activity level, and health status. While 0.8 g/kg/d is sufficient for most healthy adults, higher intakes are beneficial for athletes, older adults, and possibly children. Protein quality and source matter, and both animal and plant proteins can support health when consumed appropriately. Most people can safely consume protein at levels up to twice the recommended intake, but extremely high intakes should be avoided. Ongoing research continues to refine these recommendations for different populations and life stages1234+6 MORE.
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