title: Health effects of protein intake in healthy adults: a systematic literature review.
abstract: The purpose of this systematic review is to assess the evidence behind the dietary requirement of protein and to assess the health effects of varying protein intake in healthy adults. The literature search covered the years 2000-2011. Prospective cohort, case-control, and intervention studies were included. Out of a total of 5,718 abstracts, 412 full papers were identified as potentially relevant, and after careful scrutiny, 64 papers were quality graded as A (highest), B, or C. The grade of evidence was classified as convincing, probable, suggestive or inconclusive. The evidence is assessed as: probable for an estimated average requirement of 0.66 g good-quality protein/kg body weight (BW)/day based on nitrogen balance studies, suggestive for a relationship between increased all-cause mortality risk and long-term low-carbohydrate-high-protein (LCHP) diets; but inconclusive for a relationship between all-cause mortality risk and protein intake per se; suggestive for an inverse relationship between cardiovascular mortality and vegetable protein intake; inconclusive for relationships between cancer mortality and cancer diseases, respectively, and protein intake; inconclusive for a relationship between cardiovascular diseases and total protein intake; suggestive for an inverse relationship between blood pressure (BP) and vegetable protein; probable to convincing for an inverse relationship between soya protein intake and LDL cholesterol; inconclusive for a relationship between protein intake and bone health, energy intake, BW control, body composition, renal function, and risk of kidney stones, respectively; suggestive for a relationship between increased risk of type 2 diabetes (T2D) and long-term LCHP-high-fat diets; inconclusive for impact of physical training on protein requirement; and suggestive for effect of physical training on whole-body protein retention. In conclusion, the evidence is assessed as probable regarding the estimated requirement based on nitrogen balance studies, and suggestive to inconclusive for protein intake and mortality and morbidity. Vegetable protein intake was associated with decreased risk in many studies. Potentially adverse effects of a protein intake exceeding 20-23 E% remain to be investigated.
authors.affiliation: DTU Food, National Food Institute, Lyngby, Denmark.
authors.forename: Agnes N
authors.initials: AN
authors.lastname: Pedersen
authors.forename: Jens
authors.initials: J
authors.lastname: Kondrup
authors.forename: Elisabet
authors.initials: E
authors.lastname: Børsheim
keywords: Nordic nutrition recommendations; animal protein; chronic disease; mortality; nitrogen balance; protein requirement; vegetable protein
references.citation: Arch Intern Med. 2004 Apr 26;164(8):885-91
references.pmid: 15111375
references.citation: Am J Clin Nutr. 2008 Nov;88(5):1322-9
references.pmid: 18996869
references.citation: N Engl J Med. 2006 Nov 9;355(19):1991-2002
references.pmid: 17093250
references.citation: Arch Med Res. 2006 Aug;37(6):778-86
references.pmid: 16824939
references.citation: Eur J Nutr. 2001 Oct;40(5):231-7
references.pmid: 11842948
references.citation: Am J Clin Nutr. 2006 Oct;84(4):789-97
references.pmid: 17023705
references.citation: Int J Obes (Lond). 2011 Aug;35(8):1104-13
references.pmid: 21139559
references.citation: Nutr J. 2011 Apr 30;10:41
references.pmid: 21529374
references.citation: Eur J Cancer. 2010 Feb;46(3):581-7
references.pmid: 19850469
references.citation: Obesity (Silver Spring). 2006 Jan;14(1):106-14
references.pmid: 16493128
references.citation: J Am Soc Nephrol. 2004 Dec;15(12):3225-32
references.pmid: 15579526
references.citation: Med Sci Sports Exerc. 2009 Mar;41(3):709-31
references.pmid: 19225360
references.citation: World Health Organ Tech Rep Ser. 1985;724:1-206
references.pmid: 3937340
references.citation: Am J Med. 1986 Nov;81(5):809-15
references.pmid: 3776988
references.citation: Diabetes Care. 2010 Jan;33(1):43-8
references.pmid: 19825820
references.citation: J Am Coll Health. 2007 May-Jun;55(6):361-5
references.pmid: 17517548
references.citation: Am J Epidemiol. 2005 Feb 1;161(3):239-49
references.pmid: 15671256
references.citation: Am J Clin Nutr. 2005 Jul;82(1):41-8
references.pmid: 16002798
references.citation: Nutr Cancer. 2002;42(1):10-7
references.pmid: 12235640
references.citation: Ann Intern Med. 2010 Sep 7;153(5):289-98
references.pmid: 20820038
references.citation: Am J Clin Nutr. 2008 Feb;87(2):339-46
references.pmid: 18258623
references.citation: J Am Coll Health. 2007 Sep-Oct;56(2):147-52
references.pmid: 17967760
references.citation: Am J Clin Nutr. 2001 Jan;73(1):118-22
references.pmid: 11124760
references.citation: Br J Nutr. 2011 Aug;106(3):317-26
references.pmid: 21342608
references.citation: J Am Geriatr Soc. 2010 Jun;58(6):1063-71
references.pmid: 20487071
references.citation: Appl Physiol Nutr Metab. 2006 Oct;31(5):557-64
references.pmid: 17111010
references.citation: Dig Dis Sci. 2001 Jan;46(1):86-95
references.pmid: 11270799
references.citation: Epidemiology. 2011 Mar;22(2):170-9
references.pmid: 21206366
references.citation: Eur J Clin Nutr. 2007 May;61(5):575-81
references.pmid: 17136037
references.citation: Br J Nutr. 2004 Jan;91(1):41-51
references.pmid: 14748937
references.citation: N Engl J Med. 1997 Apr 17;336(16):1117-24
references.pmid: 9099655
references.citation: Ann Oncol. 2003 Jun;14(6):907-12
references.pmid: 12796029
references.citation: Int J Obes (Lond). 2006 May;30(5):774-81
references.pmid: 16314879
references.citation: Am J Clin Nutr. 2003 Jan;77(1):109-27
references.pmid: 12499330
references.citation: J Am Soc Nephrol. 2009 Aug;20(8):1797-804
references.pmid: 19443643
references.citation: Am J Clin Nutr. 2010 May;91(5):1311-6
references.pmid: 20219968
references.citation: Br J Cancer. 2000 Jul;83(1):121-6
references.pmid: 10883679
references.citation: Am J Clin Nutr. 2010 Jan;91(1):39-45
references.pmid: 19889826
references.citation: Ann Intern Med. 2003 Mar 18;138(6):460-7
references.pmid: 12639078
references.citation: J Intern Med. 2007 Apr;261(4):366-74
references.pmid: 17391111
references.citation: Br J Nutr. 2008 May;99(5):1107-16
references.pmid: 17988431
references.citation: Am J Physiol Endocrinol Metab. 2008 Oct;295(4):E921-8
references.pmid: 18697911
references.citation: Nutr Rev. 2011 Apr;69(4):215-30
references.pmid: 21457266
references.citation: Am J Kidney Dis. 2004 Dec;44(6):950-62
references.pmid: 15558517
references.citation: Cancer Epidemiol Biomarkers Prev. 2001 Oct;10(10):1055-62
references.pmid: 11588131
references.citation: Am J Clin Nutr. 2010 Nov;92(5):1265-72
references.pmid: 20881068
references.citation: Atherosclerosis. 2008 Sep;200(1):13-27
references.pmid: 18534601
references.citation: J Bone Miner Res. 2010 Dec;25(12):2770-6
references.pmid: 20662074
references.citation: Eur J Clin Nutr. 2006 May;60(5):643-9
references.pmid: 16340944
references.citation: Int J Obes Relat Metab Disord. 2000 Sep;24(9):1119-30
references.pmid: 11033980
references.citation: Appl Physiol Nutr Metab. 2009 Aug;34(4):632-9
references.pmid: 19767798
references.citation: J Am Coll Nutr. 2011 Apr;30(2):79-91
references.pmid: 21730216
references.citation: Br J Nutr. 2009 Jan;101(1):108-15
references.pmid: 18466652
references.citation: Clin Nutr. 2011 Jun;30(3):303-11
references.pmid: 21239090
references.citation: Am J Clin Nutr. 2009 Dec;90(6):1509-16
references.pmid: 19812175
references.citation: J Nutr. 2005 May;135(5):1088-92
references.pmid: 15867286
references.citation: J Am Diet Assoc. 2011 Aug;111(8):1150-1155.e1
references.pmid: 21802560
references.citation: Hypertens Res. 2002 Sep;25(5):689-95
references.pmid: 12452320
references.citation: Int J Cancer. 2003 Mar 20;104(2):221-7
references.pmid: 12569578
references.citation: J Bone Miner Res. 2008 Dec;23(12):1915-22
references.pmid: 18665794
references.citation: Am J Clin Nutr. 2009 May;89(5):1357-65
references.pmid: 19279077
references.citation: Fam Pract. 2003 Aug;20(4):401-9
references.pmid: 12876110
references.citation: Kidney Int. 2008 Jun;73(11):1216-9
references.pmid: 18322541
references.citation: Hypertension. 2002 May;39(5):1000-6
references.pmid: 12019283
references.citation: Am J Clin Nutr. 2009 Dec;90(6):1674-92
references.pmid: 19889822
references.citation: Am J Clin Nutr. 2011 Apr;93(4):844-50
references.pmid: 21310828
references.citation: Cancer Epidemiol Biomarkers Prev. 2004 Sep;13(9):1521-7
references.pmid: 15342455
references.citation: Ann Oncol. 2002 Mar;13(3):369-73
references.pmid: 11996466
references.citation: JAMA. 2005 Nov 16;294(19):2455-64
references.pmid: 16287956
references.citation: Int J Obes (Lond). 2009 Jul;33 Suppl 3:S1-92
references.pmid: 19597430
references.citation: Eur J Cancer Prev. 2001 Oct;10(5):395-406
references.pmid: 11711754
references.citation: J Natl Cancer Inst. 2008 Dec 3;100(23):1695-706
references.pmid: 19033572
references.citation: Nutr Cancer. 2010;62(6):710-8
references.pmid: 20661818
references.citation: Am J Epidemiol. 2004 Mar 1;159(5):454-66
references.pmid: 14977641
references.citation: Kidney Int. 1996 Jun;49(6):1598-607
references.pmid: 8743462
references.citation: Circulation. 2001 Feb 13;103(6):856-63
references.pmid: 11171795
references.citation: Am J Clin Nutr. 2009 May;89(5):1402-9
references.pmid: 19261724