--- topic: "Protein Intake" title: "How Much Protein Do You Need?" order: 1 description: "How much protein adults, older people and lifters need, plant versus animal sources, whether high intakes harm kidneys or bones, and how to spread it." question: "How much protein do you really need, and from which sources?" answer: "Most adults need at least 0.8 g per kg of body weight; older adults and lifters likely do better at 1.0 to 1.6 g/kg." actions: - "Baseline: 0.8 g/kg of body weight is the minimum (56 g for a 70 kg adult); aim for 1.0–1.2+ g/kg if over 65, training regularly or recovering from illness [1][2]." - "Spread protein over the day: about 30 g at each of three meals raised muscle protein synthesis more than a lopsided day, and older adults need more per meal [5][6]." - "Lean toward plant proteins (beans, lentils, tofu, nuts, grains), with fish, eggs, dairy and poultry in support: swapping red and processed meat for plant protein goes with lower mortality [7][8]." cautions: - "If you have kidney disease, especially an eGFR below 30 and not on dialysis, you may need to limit protein. Follow your nephrologist's plan rather than these general numbers [2]." - "This article covers healthy adults. Needs differ in pregnancy, childhood, liver disease and other illnesses, so ask a clinician or dietitian." confidence: 3 confidenceNote: "Trial meta-analyses support the muscle and kidney-safety points, but the targets for older adults and the plant versus animal comparison rest mostly on observational data." evidenceSummary: rctCount: 1 observationalCount: 3 metaAnalysisCount: 4 totalParticipants: "715,128 (pooled cohorts)" replicated: true newestStudyYear: 2020 references: - id: "1" pmid: "28298271" title: "Optimizing Protein Intake in Adults: Interpretation and Application of the Recommended Dietary Allowance Compared with the Acceptable Macronutrient Distribution Range" authors: "Wolfe RR, Cifelli AM, Kostas G, et al." year: 2017 journal: "Adv Nutr" - id: "2" pmid: "23867520" title: "Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group" authors: "Bauer J, Biolo G, Cederholm T, et al." year: 2013 journal: "J Am Med Dir Assoc" - id: "3" pmid: "28698222" title: "A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults" authors: "Morton RW, Murphy KT, McKellar SR, et al." year: 2018 journal: "Br J Sports Med" - id: "4" pmid: "30383278" title: "Changes in Kidney Function Do Not Differ between Healthy Adults Consuming Higher- Compared with Lower- or Normal-Protein Diets: A Systematic Review and Meta-Analysis" authors: "Devries MC, Sithamparapillai A, Brimble KS, et al." year: 2018 journal: "J Nutr" - id: "5" pmid: "24477298" title: "Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults" authors: "Mamerow MM, Mettler JA, English KL, et al." year: 2014 journal: "J Nutr" - id: "6" pmid: "25056502" title: "Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men" authors: "Moore DR, Churchward-Venne TA, Witard O, et al." year: 2015 journal: "J Gerontol A Biol Sci Med Sci" - id: "7" pmid: "32699048" title: "Dietary intake of total, animal, and plant proteins and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of prospective cohort studies" authors: "Naghshi S, Sadeghi O, Willett WC, et al." year: 2020 journal: "BMJ" - id: "8" pmid: "27479196" title: "Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality" authors: "Song M, Fung TT, Hu FB, et al." year: 2016 journal: "JAMA Intern Med" - id: "9" pmid: "18175749" title: "Dietary protein intake is associated with lean mass change in older, community-dwelling adults: the Health, Aging, and Body Composition (Health ABC) Study" authors: "Houston DK, Nicklas BJ, Ding J, et al." year: 2008 journal: "Am J Clin Nutr" - id: "10" url: "https://fdc.nal.usda.gov/" title: "FoodData Central (SR Legacy): protein content of common foods" authors: "U.S. Department of Agriculture, Agricultural Research Service" year: 2019 journal: "FoodData Central" - id: "11" pmid: "28404575" title: "Dietary protein and bone health: a systematic review and meta-analysis from the National Osteoporosis Foundation" authors: "Shams-White MM, Chung M, Du M, et al." year: 2017 journal: "Am J Clin Nutr" - id: "12" pmid: "24606898" title: "Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population" authors: "Levine ME, Suarez JA, Brandhorst S, et al." year: 2014 journal: "Cell Metab" --- Most adults need at least 0.8 g of protein per kg of body weight a day (56 g for a 70 kg adult), but that is a floor, not a target [1]. Older adults and people who lift weights probably do better at 1.0 to 1.6 g/kg [2][3]. In healthy people, higher intakes did not harm kidney function in trials [4]. Favor plant proteins and spread protein across your meals. ## How it works **Where 0.8 comes from.** The official recommended allowance was set as the smallest amount that prevents a loss of body nitrogen, not as the best amount. The accepted range for protein is 10% to 35% of calories, and even the bottom of that range sits above the allowance [1]. **Older adults.** An expert group recommends at least 1.0 to 1.2 g/kg a day for people over 65, at least 1.2 g/kg if they exercise, and 1.2 to 1.5 g/kg for those with acute or chronic illness [2]. Among 2,066 adults aged 70 to 79, those in the top fifth for protein lost about 40% less lean mass over 3 years than those in the bottom fifth [9]. **Lifters.** In 49 trials of resistance training, protein supplements added a little muscle and strength. Gains leveled off at about 1.6 g/kg of total daily protein, with the upper end of the estimate at 2.2 g/kg [3]. **Spreading it out.** Eating about 30 g at each of three meals raised 24-hour muscle protein synthesis by 25% compared with a day that put 63 g at dinner [5]. Older men needed about 0.40 g/kg in one meal to get the maximum response, versus 0.24 g/kg for young men [6]. For a 70 kg older adult, that is about 28 g. **Which protein.** Pooling 31 cohorts, plant protein went with lower all-cause and cardiovascular mortality, and an extra 3% of calories from plant protein with 5% lower death risk [7]. In two big US cohorts, replacing 3% of calories from processed red meat with plant protein was linked to 34% lower mortality [8]. **What it looks like.** Per 100 g cooked, lentils and black beans give about 9 g of protein, a hard-boiled egg 12.6 g, salmon 22 to 25 g and ground beef 26 g. A cup of cooked lentils (198 g) provides about 18 g [10]. **Safety.** In 28 trials, higher-protein diets did not reduce kidney filtration in healthy adults [4]. Higher intakes also showed no harm to bone and a small gain at the lumbar spine [11]. Related reading: [sarcopenia](/sarcopenia/natural-prevention-and-reversal), [whey protein](/whey-protein/muscle-recovery-and-metabolic-health), [pea protein](/pea-protein/plant-based-muscle-and-cardiovascular-health) and [beans and legumes](/beans-and-legumes/beans-digestion-and-health). ## The evidence in detail **Muscle and strength.** Morton and colleagues pooled 49 trials (1,863 participants) of resistance training lasting at least six weeks. Protein supplementation increased one-repetition-maximum strength by 2.49 kg (95% CI 0.64 to 4.33), fat-free mass by 0.30 kg (0.09 to 0.52) and muscle fiber area by 310 square micrometers. The benefit shrank with age and was larger in trained people. A break-point analysis put the plateau at 1.62 g/kg a day (95% CI 1.03 to 2.20). Authors reported ties to the US National Dairy Council and a sports-supplement maker [3]. **Older adults.** The PROT-AGE group's recommendations are a consensus statement, not a trial; it notes evidence on quality and timing is insufficient for firm advice [2]. The Health ABC cohort tracked 2,066 adults aged 70 to 79 with DXA scans: the top quintile of protein lost 0.50 kg of lean mass versus 0.88 kg in the bottom quintile, a pattern that held after adjusting for fat mass change but is observational [9]. Moore and colleagues re-analyzed lab studies of healthy men (about 71 and 22 years old): muscle protein synthesis plateaued at 0.40 g/kg per meal in older men versus 0.24 in younger (p = 0.055), and these were single-meal measures, not long-term outcomes [6]. Mamerow's crossover trial in 8 adults compared 7 days of even protein (about 30 g per meal) with a skewed pattern (11, 16 and 63 g); even eating gave 25% higher 24-hour muscle protein synthesis. It was tiny, short, measured synthesis rather than muscle size, and the authors reported ties to beef-industry groups [5]. **Source and mortality.** Naghshi's meta-analysis of 31 cohorts (715,128 people, 113,039 deaths) found total protein was linked to lower all-cause mortality (pooled effect 0.94), plant protein to lower all-cause (0.92) and cardiovascular mortality (0.88), and animal protein was not clearly related to cardiovascular or cancer mortality [7]. In the Nurses' Health Study and Health Professionals Follow-up Study (131,342 people), animal protein was associated with higher cardiovascular mortality (hazard ratio 1.08 per 10% of energy) and plant protein with lower all-cause mortality (0.90 per 3% of energy), mostly in people with at least one unhealthy lifestyle factor; substituting plant protein for processed red meat gave 0.66 [8]. **Conflicting evidence.** Levine and colleagues found that adults aged 50 to 65 reporting high protein intake had 75% higher mortality and a fourfold higher cancer death risk over 18 years, attenuated if the protein was plant-derived, whereas in those over 65 high intake went with lower mortality. Mouse experiments supported a growth-factor mechanism. The senior author holds equity in a company that develops medical foods [12]. These results oppose Naghshi's pooled finding and illustrate how much the answer depends on age and source. **Kidneys and bones.** Devries and colleagues pooled 28 trials (1,358 healthy adults) comparing high protein (at least 1.5 g/kg or 20% of energy) with lower protein. Post-intervention filtration rate was trivially higher with more protein (standardized difference 0.19), and its change did not differ (0.11, 95% CI -0.05 to 0.27). Risk of selection bias was unclear and the data do not cover people with kidney disease [4]. A review of 16 trials and 20 cohorts found moderate evidence for a small lumbar-spine bone density gain (0.52%) with more protein and no effect at hip or whole body, with no adverse effects [11]. **Bottom line (confidence 3 of 5).** The floor is 0.8 g/kg. For lifters and older adults, 1.0 to 1.6 g/kg is better supported than the floor, and in healthy people higher intakes appear safe for kidneys and bones. Plant-leaning sources look best in cohorts, but the evidence is observational.