Is There Such a Thing as Too Much Protein?

by Reed Mangels, PhD, RD

Most people in the United States meet (and usually exceed) their protein needs. With the current emphasis on protein and a proliferation of foods pumped full of protein, you may be wondering if it’s possible to get too much protein. As is true for many issues in nutrition, high protein diets are a controversial topic.

Generally speaking, most people can safely consume more than the Recommended Dietary Allowance (RDA) for protein. In the past, excessive protein was associated with an increased risk of osteoporosis and of kidney disease.

More recent research has failed to find a connection between higher protein intake and poor bone health provided calcium intake is adequate (1-3). There is some evidence of higher protein intakes being associated in an increased risk of fractures in those with very low calcium intakes (4, 5). A diet high in animal protein from meat is likely to be low in calcium.

People without underlying disease do not appear to be at higher risk for kidney disease due to a high protein diet (6, 7). Of course, many people are not aware that they have a disease or condition that may be worsened by a high protein diet. For example, a study of older women found that in those with a mild loss of kidney function, high total protein intake, particularly high intake of nondairy animal protein was associated with a more rapid decline in kidney function (8). Another study found that older adults with a history of heart disease had a decline in kidney function with regular use of a higher protein diet (9).

High protein diets often are based on a lot of animal products including meat, dairy products, and eggs. These foods represent a significant source of saturated fat, a type of fat associated with an increased risk of heart disease and stroke. Additionally, high protein diets based on animal products contain little dietary fiber and may be low in vitamin C and other nutrients, as well as phytochemicals.

Diets higher in animal protein are associated with increased risk of overall mortality and of death from cardiovascular disease (10, 11). Replacing animal foods with plant foods may contribute to reducing the risk of breast and colorectal cancer, cancer mortality, cardiovascular disease mortality, total mortality, and the incidence of type 2 diabetes (12, 13)

There are health concerns associated with use of a high protein diet, especially one based on animal products. That’s not to say that higher protein intakes aren’t beneficial in some situations.

If you eat a varied diet vegan based on whole foods that includes generous amounts of beans and whole grains, vegetables, nuts and seeds, it’s likely you will meet protein needs

If you have questions or concerns about how much protein is right for you, consult a registered dietitian with expertise in vegan nutrition.

To read more about protein for vegans see:

Protein in the Vegan Diet

Protein for Vegans & Vegetarians

Protein for Vegan Children

References

1. Shams-White MM, Chung M, Du M, et al Dietary protein and bone health: a systematic review and meta-analysis from the National Osteoporosis Foundation. Am J Clin Nutr. 2017;105:1528-1543.
2. Darling AL, Manders RJF, Sahni S, et al. Dietary protein and bone health across the life-course: an updated systematic review and meta-analysis over 40 years. Osteoporos Int. 2019;30:741-761.
3. Rizzoli R, Biver E, Bonjour JP, et al. Benefits and safety of dietary protein for bone health-an expert consensus paper endorsed by the European Society for Clinical and Economical Aspects of Osteopororosis, Osteoarthritis, and Musculoskeletal Diseases and by the International Osteoporosis Foundation. Osteoporos Int. 2018;29:1933-1948.
4. Meyer HE, Pedersen JI, Løken EB, et al. Dietary factors and the incidence of hip fracture in middle-aged Norwegians. A prospective study. Am J Epidemiol. 1997;145:117-123.
5. Dargent-Molina P, Sabia S, Touvier M, et al. Proteins, dietary acid load, and calcium and risk of postmenopausal fractures in the E3N French women prospective study. J Bone Miner Res. 2008;23:1915-1922.
6. Devries MC, Sithamparapillai A, Brimble KS, et al. 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. J Nutr. 2018;148:1760-1775.
7. Van Elswyk ME, Weatherford CA, McNeill SH. A systematic review of renal health in healthy individuals associated with protein intake above the US Recommended Daily Allowance in randomized controlled trials and observational studies. Adv Nutr. 2018;9:404-418.
8. Knight EL, Stampfer MJ, Hankinson SE, et al. The impact of protein intake on renal function decline in women with normal renal function or mild renal insufficiency. Ann Intern Med. 2003;138:460-467.
9. Esmeijer K, Geleijnse JM, de Fijter JW, et al. Dietary protein intake and kidney function decline after myocardial infarction: the Alpha Omega Cohort. Nephrol Dial Transplant. 2020;35:106-115.
10. Chen Z, Glisic M, Song M, et al. Dietary protein intake and all-cause and cause-specific mortality: results from the Rotterdam Study and a meta-analysis of prospective cohort studies. Eur J Epidemiol. 2020;35:411-429.
11. Song M, Fung TT, Hu FB, et al. Association of animal and plant protein intake with all-cause and cause-specific mortality. JAMA Intern Med. 2016;176:1453-1463.
12. Fernández-Fígares Jiménez MDC, Storz MA. Cancer risk and mortality following substitution of animal foods with plant foods: A systematic review. Curr Nutr Rep. 2025;14:99.
13. Lamberg-Allardt C, Bärebring L, Arnesen EK, et al. Animal versus plant-based protein and risk of cardiovascular disease and type 2 diabetes: A systematic review of randomized controlled trials and prospective cohort studies. Food Nutr Res. 2023;67.

The contents of this website and our other publications, including The Vegan Journal, are not intended to provide personal medical advice. Medical advice should be obtained from a qualified health professional. We often depend on product and ingredient information from company statements. It is impossible to be 100% sure about a statement, info can change, people have different views, and mistakes can be made. Please use your best judgment about whether a product is suitable for you. To be sure, do further research or confirmation on your own.