Jump to content

Composition of the human body

From Wikipedia, the free encyclopedia

Not to be confused with human anatomy or body composition.
Pie charts of typical human body composition by percent of mass, and by percent of atomic composition (atomic percent)

Body composition may be analyzed in various ways. This can be done in terms of the chemical elements present, or by molecular structure e.g., water, protein, fats (or lipids), hydroxyapatite (in bones), carbohydrates (such as glycogen and glucose) and DNA. In terms of tissue type, the body may be analyzed into water, fat, connective tissue, muscle, bone, etc. In terms of cell type, the body contains hundreds of different types of cells, but notably, the largest number of cells contained in a human body (though not the largest mass of cells) are not human cells, but bacteria residing in the normal human gastrointestinal tract.

Elements

[edit]
The main elements that comprise the human body (including water) can be summarized as CHNOPS.
Element Symbol percent
mass 		percent
atoms
Oxygen O 65.0 24.0
Carbon C 18.5 12.0
Hydrogen H 9.5 62.0
Nitrogen N 2.6 1.1
Calcium Ca 1.3 0.22
Phosphorus P 0.6 0.22
Sulfur S 0.3 0.038
Potassium K 0.2 0.03
Sodium Na 0.2 0.037
Chlorine Cl 0.2 0.024
Magnesium Mg 0.1 0.015
All others < 0.1 < 0.3
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm

About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium. All 11 are necessary for life. The remaining elements are trace elements, of which more than a dozen are thought on the basis of good evidence to be necessary for life.[1] All of the mass of the trace elements put together (less than 10 grams for a human body) do not add up to the body mass of magnesium, the least common of the 11 non-trace elements.

Other elements

[edit]

Not all elements which are found in the human body in trace quantities play a role in life. Some of these elements are thought to be simple common contaminants without function (examples: caesium, titanium), while many others are thought to be active toxins, depending on amount (cadmium, mercury, lead, radioactives). In humans, arsenic is toxic, and its levels in foods and dietary supplements are closely monitored to reduce or eliminate its intake.[2]

Some elements (silicon, boron, nickel, vanadium) are probably needed by mammals also, but in far smaller doses. Bromine is used by some (though not all) bacteria, fungi, diatoms, and seaweeds, and opportunistically in eosinophils in humans. One study has indicated bromine to be necessary to collagen IV synthesis in humans.[3] Fluorine is used by a number of plants to manufacture toxins but in humans its only known function is as a local topical hardening agent in tooth enamel.[4]

Elemental composition list

[edit]
Main article: mineral (nutrient)

The average 70 kg (150 lb) adult human body contains approximately 7×1027 atoms and contains at least detectable traces of 60 chemical elements.[5] About 29 of these elements are thought to play an active positive role in life and health in humans.[6]

The relative amounts of each element vary by individual, mainly due to differences in the proportion of fat, muscle and bone in their body. Persons with more fat will have a higher proportion of carbon and a lower proportion of most other elements (the proportion of hydrogen will be about the same). The numbers in the table are averages of different numbers reported by different references.

The adult human body averages ~53% water.[7] This varies substantially by age, sex, and adiposity. In a large sample of adults of all ages and both sexes, the figure for water fraction by weight was found to be 48 ±6% for females and 58 ±8% water for males.[8] Water is ~11% hydrogen by mass but ~67% hydrogen by atomic percent, and these numbers along with the complementary % numbers for oxygen in water, are the largest contributors to overall mass and atomic composition figures. Because of water content, the human body contains more oxygen by mass than any other element, but more hydrogen by atom-fraction than any element.

The elements listed below as "Essential in humans" are those listed by the US Food and Drug Administration as essential nutrients,[9] as well as six additional elements: oxygen, carbon, hydrogen, and nitrogen (the fundamental building blocks of life on Earth), sulfur (essential to all cells) and cobalt (a necessary component of vitamin B12). Elements listed as "Possibly" or "Probably" essential are those cited by the US National Research Council as beneficial to human health and possibly or probably essential.[10]

Atomic number Element Fraction of mass
[11][12][13][14][15][16]		 Mass (kg)[17] Atomic percent Essential in humans[18] Negative effects of excess Group
8 Oxygen 0.65 45 24 Yes (e.g. water, electron acceptor and DNA)[19] Reactive oxygen species 16
6 Carbon 0.18 13 12 Yes[19] (organic compounds) 14
1 Hydrogen 0.10 7 62 Yes[19] (e.g. water and DNA) Acidosis 1
7 Nitrogen 0.02–0.03 1.8 1.1 Yes[19] (e.g. DNA and amino acids) 15
20 Calcium 0.011–0.015 1.0 0.22 Yes[19][20][21] (e.g. Calmodulin and Hydroxylapatite in bones) Hypercalcaemia 2
15 Phosphorus 5–7×10−3 [22] 0.78 0.22 Yes[19][20][21] (e.g. DNA, Phospholipids and Phosphorylation) Hyperphosphatemia 15
19 Potassium 1.5–2×10−3[23] 0.14 0.033 Yes[19][20] (e.g. Na+/K+-ATPase) Hyperkalemia 1
16 Sulfur 2.5×10−3 0.14 0.038 Yes[19] (e.g. Cysteine, Methionine, Biotin, Thiamine) Sulfhemoglobinemia 16
11 Sodium 1.5×10−3 0.10 0.037 Yes[20] (e.g. Na+/K+-ATPase) Hypernatremia 1
17 Chlorine 1.5×10−3 0.095 0.024 Yes[20][21] (e.g. Cl-transporting ATPase) Hyperchloremia 17
12 Magnesium 500×10−6 0.019 0.0070 Yes[20][21] (e.g. binding to ATP and other nucleotides) Hypermagnesemia 2
26 Iron* 60×10−6 0.0042 0.00067 Yes[20][21] (e.g. Hemoglobin, Cytochromes) Iron overload 8
9 Fluorine 37×10−6 0.0026 0.0012 Yes (AUS, NZ),[24] No (US, EU),[25][26] Maybe (WHO)[27] Fluorine: Highly toxic

Fluoride: Toxic in high amounts

17
30 Zinc 32×10−6 0.0023 0.00031 Yes[20][21] (e.g. Zinc finger proteins) Zinc toxicity 12
14 Silicon 20×10−6 0.0010 0.0058 Probably[28] 14
31 Gallium 4.9×10−6 0.0007 0.00093 No Gallium halide poisoning[29] 13
37 Rubidium 4.6×10−6 0.00068 0.000033 No Potassium replacement 1
38 Strontium 4.6×10−6 0.00032 0.000033 No Calcium replacement 2
35 Bromine 2.9×10−6 0.00026 0.000030 Maybe[30] Bromism 17
82 Lead 1.7×10−6 0.00012 0.0000045 No Lead poisoning 14
29 Copper 1×10−6 0.000072 0.0000104 Yes[20][21] (e.g. copper proteins) Copper toxicity 11
13 Aluminium 870×10−9 0.000060 0.000015 No Aluminium poisoning 13
48 Cadmium 720×10−9 0.000050 0.0000045 No Cadmium poisoning 12
58 Cerium 570×10−9 0.000040 No
56 Barium 310×10−9 0.000022 0.0000012 No toxic in higher amounts 2
50 Tin 240×10−9 0.000020 6.0×10−7 Maybe[1] 14
53 Iodine 160×10−9 0.000020 7.5×10−7 Yes[20][21] (e.g. thyroxine, triiodothyronine) Iodine-induced hyperthyroidism 17
22 Titanium 130×10−9 0.000020 No 4
5 Boron 690×10−9 0.000018 0.0000030 Probably[10][31] 13
34 Selenium 190×10−9 0.000015 4.5×10−8 Yes[20][21] (e.g. selenocysteine) Selenium toxicity 16
28 Nickel 140×10−9 0.000015 0.0000015 Maybe[1] Nickel Toxicity 10
24 Chromium 24×10−9 0.000014 8.9×10−8 Maybe[1][20][21] 6
25 Manganese 170×10−9 0.000012 0.0000015 Yes[20][21] (e.g. Mn-SOD) Manganism 7
33 Arsenic 260×10−9 0.000007 8.9×10−8 Maybe[1][2] Arsenic poisoning 15
3 Lithium 31×10−9 0.000007 0.0000015 Possibly (intercorrelated with the functions of several enzymes, hormones and vitamins) Lithium toxicity 1
80 Mercury 190×10−9 0.000006 8.9×10−8 No Mercury poisoning 12
55 Caesium 21×10−9 0.000006 1.0×10−7 No 1
42 Molybdenum 130×10−9 0.000005 4.5×10−8 Yes[20][21] (e.g. the molybdenum oxotransferases, Xanthine oxidase and Sulfite oxidase) 6
32 Germanium 5×10−6 No 14
27 Cobalt 21×10−9 0.000003 3.0×10−7 Yes (e.g. Cobalamin/Vitamin B12)[32][33] 9
44 Ruthenium 22×10−9 0.000007 No [34] 8
51 Antimony 110×10−9 0.000002 No toxic 15
47 Silver 10×10−9 0.000002 No 11
41 Niobium 1600×10−9 0.0000015 No 5
40 Zirconium 6×10−9 0.000001 3.0×10−7 No 4
57 Lanthanum 1370×10−9 8×10−7 No
52 Tellurium 120×10−9 7×10−7 No 16
39 Yttrium 6×10−7 No 3
83 Bismuth 5×10−7 No 15
81 Thallium 5×10−7 No highly toxic 13
49 Indium 4×10−7 No 13
79 Gold 3×10−9 2×10−7 3.0×10−7 No uncoated nanoparticles possibly genotoxic[35][36][37] 11
21 Scandium 2×10−7 No 3
73 Tantalum 2×10−7 No 5
23 Vanadium 260×10−9 0.000020 1.2×10−8 Possibly[10] (suggested osteo-metabolism (bone) growth factor) 5
90 Thorium 1×10−7 No toxic, radioactive
92 Uranium 1×10−7 3.0×10−9 No toxic, radioactive
62 Samarium 5.0×10−8 No
74 Tungsten 2.0×10−8 No 6
4 Beryllium 3.6×10−8 4.5×10−8 No toxic in higher amounts 2
88 Radium 3×10−14 1×10−17 No toxic, radioactive 2
2 Helium 20.39×10−21 2.4×10−14 1×10−17 No noble gas 18
10 Neon 8.5×10−23 1×10−14 1×10−17 No noble gas 18
18 Argon 4.25×10−23 0.5×10−14 1×10−17 No noble gas 18
36 Krypton 2.125×10−23 0.25×10−14 1×10−17 No noble gas 18

*Iron = ~3 g in males, ~2.3 g in females

Of the 94 naturally occurring chemical elements, 76 are listed in the table above. Of the remaining 18, it is not known how many occur in the human body.

Most of the elements needed for life are relatively common in the Earth's crust. Aluminium, the third most common element in the Earth's crust (after oxygen and silicon), serves no function in living cells, but is toxic in large amounts, depending on its physical and chemical forms and magnitude, duration, frequency of exposure, and how it was absorbed by the human body.[38] Transferrins can bind aluminium.[39]

Periodic table

[edit]
Essential elements for higher organisms (eucarya).[40][41][42][43][44][45]
H   He
Li Be   B C N O F Ne
Na Mg   Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Legend:
  The four basic organic elements
  Quantity elements
  Essential trace elements
  Essentiality or function debated
  Not essential in humans, but essential/beneficial for some non-human eucarya

Composition

[edit]

The composition of the human body can be classified as follows:

The estimated contents of a typical 20-micrometre human cell is as follows:[46]

Compound type Percent of mass Mol. weight (daltons) Compound Percent of molecules
Water 65 18 1.74×1014 98.73
Other inorganics 1.5 N/A 1.31×1012 0.74
Lipids 12 N/A 8.4×1011 0.475
Other organics 0.4 N/A 7.7×1010 0.044
Protein 20 N/A 1.9×1010 0.011
RNA 1.0 N/A 5×107 3×10−5
DNA 0.1 1×1011 46 3×10−11

Tissues

[edit]
The main cellular components of the human body[47][48][49]
Cell type % mass % cell count
Erythrocytes (red blood cells) 4.2 85.0
Muscle cells 28.6 0.001
Adipocytes (fat cells) 18.6 0.2
Other cells 14.3 14.8
Extracellular components 34.3 -

Body composition can also be expressed in terms of various types of material, such as:

Composition by cell type

[edit]
Main article: List of distinct cell types in the adult human body
Main article: Human microbiome § Relative numbers

There are many species of bacteria and other microorganisms that live on or inside the healthy human body. In fact, there are roughly as many microbial as human cells in the human body by number.[47][50][51][52][53] (much less by mass or volume). Some of these symbionts are necessary for our health. Those that neither help nor harm humans are called commensal organisms.

See also

[edit]

References

[edit]
  1. ^ a b c d e Zoroddu MA, Aaseth J, Crisponi G, Medici S, Peana M, Nurchi VM (June 2019). "The essential metals for humans: a brief overview". Journal of Inorganic Biochemistry. 195: 120–129. doi:10.1016/j.jinorgbio.2019.03.013. PMID 30939379. S2CID 92997696.
  2. ^ a b "Arsenic in Food and Dietary Supplements". US Food and Drug Administration. 22 May 2019. Retrieved 20 August 2019.
  3. ^ McCall AS, Cummings CF, Bhave G, Vanacore R, Page-McCaw A, Hudson BG (2014). "Bromine Is an Essential Trace Element for Assembly of Collagen IV Scaffolds in Tissue Development and Architecture". Cell. 157 (6): 1380–92. doi:10.1016/j.cell.2014.05.009. PMC 4144415. PMID 24906154.
  4. ^ Nelson DL, Cox MM (2021). Lehninger Principles of Biochemistry (8th ed.). New York: Macmillan. ISBN 978-1-319-23090-6.
  5. ^ "Questions and Answers - How many atoms are in the human body?". education.jlab.org. Retrieved 4 April 2023.
  6. ^ "Ultratrace minerals". Authors: Nielsen, Forrest H. USDA, ARS Source: Modern nutrition in health and disease / editors, Maurice E. Shils ... et al.. Baltimore : Williams & Wilkins, c. 1999, p. 283-303. Issue Date: 1999 URI: [1]
  7. ^ Use WP:CALC for the mean of means for males and females, since the two groups are of about equal size
  8. ^ See table 1. here
  9. ^ "Guidance for Industry: A Food Labeling Guide 14. Appendix F". US Food and Drug Administration. 1 January 2013. Archived from the original on 4 April 2017.
  10. ^ a b c Institute of Medicine (29 September 2006). Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. National Academies Press. pp. 313–19, 415–22. ISBN 978-0-309-15742-1. Retrieved 21 June 2016.
  11. ^ Chang R (2007). Chemistry, Ninth Edition. McGraw-Hill. p. 52. ISBN 978-0-07-110595-8.
  12. ^ "Elemental Composition of the Human Body" Archived 2018-12-18 at the Wayback Machine by Ed Uthman, MD Retrieved 17 June 2016
  13. ^ Frausto Da Silva JJ, Williams RJ (2001-08-16). The Biological Chemistry of the Elements: The Inorganic Chemistry of Life. OUP Oxford. ISBN 978-0-19-850848-9.
  14. ^ Zumdahl SS (2000). Chemistry, Fifth Edition. Houghton Mifflin Company. p. 894. ISBN 978-0-395-98581-6.)
  15. ^ Cohn S, Vaswani A, Zanzi I, Aloia J, Roginsky M, Ellis K (January 1976). "Changes in body chemical composition with age measured by total-body neutron activation". Metabolism. 25 (1): 85–96. doi:10.1016/0026-0495(76)90163-3. PMID 1246210.
  16. ^ Aloia JF, Vaswani A, Ma R, Flaster E (March 1997). "Comparison of body composition in black and white premenopausal women". Journal of Laboratory and Clinical Medicine. 129 (3): 294–299. doi:10.1016/S0022-2143(97)90177-3. PMID 9042814.
  17. ^ Emsley J (25 August 2011). Nature's Building Blocks: An A-Z Guide to the Elements. OUP Oxford. p. 83. ISBN 978-0-19-960563-7. Retrieved 17 June 2016.
  18. ^ Nielsen FH. "Ultratrace minerals". Modern nutrition in health and disease / editors, Maurice E. Shils ... [et al.] Retrieved 4 April 2023 – via PubAg.
  19. ^ a b c d e f g h Salm S, Allen D, Nester E, Anderson D (9 January 2015). Nester's Microbiology: A Human Perspective. Mcgraw-hill Us Higher Ed. p. 21. ISBN 978-0-07-773093-2. Retrieved 19 June 2016.
  20. ^ a b c d e f g h i j k l m n Subcommittee on the Tenth Edition of the Recommended Dietary Allowances, Food and Nutrition Board, Commission on Life Sciences, National Research Council (1 February 1989). "9-10". Recommended Dietary Allowances: 10th Edition. National Academies Press. ISBN 978-0-309-04633-6. Retrieved 18 June 2016.
  21. ^ a b c d e f g h i j k l "Federal Register :: Request Access". unblock.federalregister.gov. Retrieved 4 April 2023.
  22. ^ Arunabh S, Feuerman M, Ma R, Aloia JF (February 2002). "Total body phosphorus in healthy women and ethnic variations". Metabolism. 51 (2): 180–183. doi:10.1053/meta.2002.29984. PMID 11833045.
  23. ^ Shypailo RJ, Wong WW (2020). "Fat and fat-free mass index references in children and young adults: assessments along racial and ethnic lines". The American Journal of Clinical Nutrition. 112 (3): 566–575. doi:10.1093/ajcn/nqaa128. PMID 32469402.
  24. ^ Australian National Health and Medical Research Council (NHMRC) and New Zealand Ministry of Health (MoH)
  25. ^ "Fluoride in Drinking Water: A Review of Fluoridation and Regulation Issues"
  26. ^ "Scientific Opinion on Dietary Reference Values for fluoride" (PDF). EFSA Journal. 11 (8): 3332. 2013. doi:10.2903/j.efsa.2013.3332. ISSN 1831-4732.
  27. ^ "WHO/SDE/WSH/03.04/96 "Fluoride in Drinking-water"" (PDF). Retrieved 4 April 2023.
  28. ^ Muhammad Ansar Farooq, Karl-Josef Dietz (2015). "Silicon as Versatile Player in Plant and Human Biology: Overlooked and Poorly Understood". Front. Plant Sci. 6 (994): 994. doi:10.3389/fpls.2015.00994. PMC 4641902. PMID 26617630.
  29. ^ Ivanoff CS, Ivanoff AE, Hottel TL (February 2012). "Gallium poisoning: a rare case report". Food Chem. Toxicol. 50 (2): 212–5. doi:10.1016/j.fct.2011.10.041. PMID 22024274.
  30. ^ McCall AS, Cummings CF, Bhave G, Vanacore R, Page-McCaw A, Hudson BG (June 2014). "Bromine is an essential trace element for assembly of collagen IV scaffolds in tissue development and architecture". Cell. 157 (6): 1380–92. doi:10.1016/j.cell.2014.05.009. PMC 4144415. PMID 24906154.
  31. ^ Safe Upper Levels for Vitamins and Mineral (2003), boron p. 164-71, nickel p. 225-31, EVM, Food Standards Agency, UK ISBN 1-904026-11-7
  32. ^ Yamada K (2013). "Cobalt: Its Role in Health and Disease". Interrelations between Essential Metal Ions and Human Diseases. Metal Ions in Life Sciences. Vol. 13. pp. 295–320. doi:10.1007/978-94-007-7500-8_9. ISBN 978-94-007-7499-5. ISSN 1559-0836. PMID 24470095.
  33. ^ Banci L (18 April 2013). Metallomics and the Cell. Springer Science & Business Media. pp. 333–368. ISBN 978-94-007-5561-1. Retrieved 19 June 2016.
  34. ^ Toeniskoetter S (2020). "Ruthenium". Biochemical Periodic Table.
  35. ^ Fratoddi I, Venditti I, Cametti C, Russo MV (2015). "How toxic are gold nanoparticles? The state-of-the-art". Nano Research. 8 (6): 1771–1799. doi:10.1007/s12274-014-0697-3. hdl:11573/780610. ISSN 1998-0124. S2CID 84837060.
  36. ^ "Scientific Opinion on the re-evaluation of gold (E 175) as a food additive". EFSA Journal. 14 (1): 4362. 2016. doi:10.2903/j.efsa.2016.4362. ISSN 1831-4732.
  37. ^ Hillyer JF, Albrecht RM (2001). "Gastrointestinal persorption and tissue distribution of differently sized colloidal gold nanoparticles". Journal of Pharmaceutical Sciences. 90 (12): 1927–1936. doi:10.1002/jps.1143. ISSN 0022-3549. PMID 11745751.
  38. ^ Willhite CC, Karyakina NA, Yokel RA, Yenugadhati N, Wisniewski TM, Arnold IM, et al. (2014-09-18). "Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts". Critical Reviews in Toxicology. 44 (sup4): 1–80. doi:10.3109/10408444.2014.934439. ISSN 1040-8444. PMC 4997813. PMID 25233067.
  39. ^ Mizutani K, Mikami B, Aibara S, Hirose M (2005). "Structure of aluminium-bound ovotransferrin at 2.15 Å resolution". Acta Crystallographica Section D. 61 (12): 1636–42. doi:10.1107/S090744490503266X. PMID 16301797.
  40. ^ Ultratrace minerals. Authors: Nielsen, Forrest H. USDA, ARS Source: Modern nutrition in health and disease / editors, Maurice E. Shils, et al. Baltimore: Williams & Wilkins, c1999.[clarify], p. 283–303. Issue date: 1999.
  41. ^ Szklarska D, Rzymski P (May 2019). "Is Lithium a Micronutrient? From Biological Activity and Epidemiological Observation to Food Fortification". Biol Trace Elem Res. 189 (1): 18–27. doi:10.1007/s12011-018-1455-2. PMC 6443601. PMID 30066063.
  42. ^ Enderle J, Klink U, di Giuseppe R, Koch M, Seidel U, Weber K, et al. (August 2020). "Plasma Lithium Levels in a General Population: A Cross-Sectional Analysis of Metabolic and Dietary Correlates". Nutrients. 12 (8): 2489. doi:10.3390/nu12082489. PMC 7468710. PMID 32824874.
  43. ^ McCall AS, Cummings CF, Bhave G, Vanacore R, Page-McCaw A, Hudson BG (June 2014). "Bromine is an essential trace element for assembly of collagen IV scaffolds in tissue development and architecture". Cell. 157 (6): 1380–1392. doi:10.1016/j.cell.2014.05.009. PMC 4144415. PMID 24906154.
  44. ^ Zoroddu MA, Aaseth J, Crisponi G, Medici S, Peana M, Nurchi VM (2019). "The essential metals for humans: a brief overview". Journal of Inorganic Biochemistry. 195: 120–129. doi:10.1016/j.jinorgbio.2019.03.013.
  45. ^ Remick K, Helmann JD (30 January 2023). "The Elements of Life: A Biocentric Tour of the Periodic Table". Advances in Microbial Physiology. 82. PubMed Central: 1–127. doi:10.1016/bs.ampbs.2022.11.001. ISBN 978-0-443-19334-7. PMC 10727122. PMID 36948652.
  46. ^ Freitas Jr RA (1999). Nanomedicine. Landes Bioscience. Tables 3–1 & 3–2. ISBN 978-1-57059-680-3. Archived from the original on 2018-04-16. Retrieved 2011-04-06.
  47. ^ a b Hatton IA, Galbraith ED, Merleau NS, Miettinen TP, Smith BM, Shander JA (2023-09-26). "The human cell count and size distribution". Proceedings of the National Academy of Sciences. 120 (39): e2303077120. Bibcode:2023PNAS..12003077H. doi:10.1073/pnas.2303077120. ISSN 0027-8424. PMC 10523466. PMID 37722043.
  48. ^ Sender R, Fuchs S, Milo R (2016). "Revised estimates for the number of human and bacteria cells in the body". PLOS Biology. 14 (8): e1002533. bioRxiv 10.1101/036103. doi:10.1371/journal.pbio.1002533. PMC 4991899. PMID 27541692.
  49. ^ Bianconi E, Piovesan A, Facchin F, Beraudi A, Casadei R, Frabetti F, et al. (2013-11-01). "An estimation of the number of cells in the human body". Annals of Human Biology. 40 (6): 463–471. doi:10.3109/03014460.2013.807878. ISSN 0301-4460. PMID 23829164.
  50. ^ American Academy of Microbiology FAQ: Human Microbiome Archived 31 December 2016 at the Wayback Machine January 2014
  51. ^ Judah L. Rosner for Microbe Magazine, February 2014. Ten Times More Microbial Cells than Body Cells in Humans?
  52. ^ Gilbert J, Blaser MJ, Caporaso JG, Jansson J, Lynch SV, Knight R (2018-04-10). "Current understanding of the human microbiome". Nature Medicine. 24 (4): 392–400. doi:10.1038/nm.4517. ISSN 1078-8956. PMC 7043356. PMID 29634682.
  53. ^ Sender R, Fuchs S, Milo R (January 2016). "Are We Really Vastly Outnumbered? Revisiting the Ratio of Bacterial to Host Cells in Humans". Cell. 164 (3): 337–40. doi:10.1016/j.cell.2016.01.013. PMID 26824647.
Retrieved from "http://en.wiki.x.io/w/index.php?title=Composition_of_the_human_body&oldid=1265700799"