Phytic acid

Phytic acid
Names
IUPAC name
(1R,2S,3r,4R,5S,6s)-cyclohexane-1,2,3,4,5,6-hexayl hexakis[dihydrogen (phosphate)]
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.001.369
E number E391 (antioxidants, ...)
UNII
Properties
C6H18O24P6
Molar mass 660.03 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Phytic acid (known as inositol hexakisphosphate (IP6), inositol polyphosphate, or phytate when in salt form) is the phosphate ester of inositol. It contains six phosphate groups. At physiological pH, these phosphates are partially ionized. The resulting anion is a colorless species that has significant nutritional role as the principal storage form of phosphorus in many plant tissues, especially bran and seeds.[1] It can be found in cereals and grains.

Catabolites of phytic acid are called lower inositol polyphosphates. Examples are inositol penta- (IP5), tetra- (IP4), and triphosphate (IP3).

Significance in agriculture

Phosphorus and inositol in phytate form are not, in general, bioavailable to nonruminant animals because these animals lack the digestive enzyme phytase required to hydrolyze (break) the inositol-phosphate linkages. Ruminants are readily able to digest phytate because of the phytase produced by rumen microorganisms.[2]

In most commercial agriculture, nonruminant livestock, such as swine, fowl, and fish,[3] are fed mainly grains, such as maize, legumes, and soybeans. Because phytate from these grains and beans is unavailable for absorption, the unabsorbed phytate passes through the gastrointestinal tract, elevating the amount of phosphorus in the manure.[2] Excess phosphorus excretion can lead to environmental problems, such as eutrophication.[4]

Also, viable low-phytic acid mutant lines have been developed in several crop species in which the seeds have drastically reduced levels of phytic acid and concomitant increases in inorganic phosphorus.[5] However, germination problems have reportedly hindered the use of these cultivars thus far. This may be due to phytic acid's critical role in both phosphorus and metal ion storage.

The use of sprouted grains will reduce the quantity of phytic acids in feed, with no significant reduction of nutritional value.[6]

Phytate variants also have the potential to be used in soil remediation, to immobilize uranium, nickel and other inorganic contaminants.[7]

Biological and physiological roles

Although indigestible for many animals, phytic acid and its metabolites as they occur in seeds and grains have several important roles for the seedling plant.

Most notably, phytic acid functions as a phosphorus store, as an energy store, as a source of cations and as a source of myoinositol (a cell wall precursor). Phytic acid is the principal storage form of phosphorus in plant seeds.[8]

In animal cells, myoinositol polyphosphates are ubiquitous, and phytic acid (myoinositol hexakisphosphate) is the most abundant, with its concentration ranging from 10 to 100 µM in mammalian cells, depending on cell type and developmental stage.[9][10]

This compound is not obtained from the animal diet, but must be synthesized inside the cell from phosphate and inositol (which in turn is produced from glucose, usually in the kidneys). The interaction of intracellular phytic acid with specific intracellular proteins has been investigated in vitro, and these interactions have been found to result in the inhibition or potentiation of the physiological activities of those proteins.[11][12] The best evidence from these studies suggests an intracellular role for phytic acid as a cofactor in DNA repair by nonhomologous end-joining.[11] Other studies using yeast mutants have also suggested intracellular phytic acid may be involved in mRNA export from the nucleus to the cytosol.[13][14]

Inositol hexaphosphate facilitates the formation of the six-helix bundle and assembly of the immature HIV-1 Gag lattice. IP6 makes ionic contacts with two rings of lysine residues at the centre of the Gag hexamer. Proteolytic cleavage then unmasks an alternative binding site, where IP6 interaction promotes the assembly of the mature capsid lattice. These studies identify IP6 as a naturally occurring small molecule that promotes both assembly and maturation of HIV-1.[15]

Food science

Phytic acid was discovered in 1903,[16] Phytic acid, mostly as phytate in the form of phytin, is found within the hulls of seeds, including nuts, grains and pulses.[1] In-home food preparation techniques can break down the phytic acid in all of these foods. Simply cooking the food will reduce the phytic acid to some degree. More effective methods are soaking in an acid medium, sprouting and lactic acid fermentation such as in sourdough and pickling.[17] No detectable phytate (less than 0.02 % of wet weight) was observed in vegetables such as scallion and cabbage leaves or in fruits such as apples, oranges, bananas, or pears.[18]

Phytic acid has a strong binding affinity to "minerals," such as calcium, iron, and zinc.[19] The binding of phytic acid with iron is more complex, although there certainly is a strong binding affinity, molecules like phenols and tannins also influence the binding.[20] When iron and zinc bind to phytic acid they form insoluble precipitates and are far less absorbable in the intestines. This process can therefore contribute to iron and zinc deficiencies in people whose diets rely on these foods for their mineral intake, such as those in developing countries[21][22] and vegetarians.[23]

As a food additive, phytic acid is used as the preservative E391.

Food sources of phytic acid (g/100g) [24] [18] [25][26][27][28][29][30]
Food [% minimum dry] [% maximum dry]
Pumpkin seed4.34.3
Linseed2.152.78
Sesame seeds flour5.365.36
Chia seeds0.961.16
Almonds1.353.22
Brazil nuts1.976.34
Coconut0.360.36
Hazelnut0.650.65
Peanut0.951.76
Walnut0.980.98
Maize (Corn)0.752.22
Oat0.421.16
Oat Meal0.892.40
Brown rice0.840.99
Polished rice0.140.60
Wheat0.391.35
Wheat flour0.251.37
Wheat germ0.081.14
Whole wheat bread0.431.05
Beans, pinto2.382.38
Buckwheat1.001.00
Chickpeas0.560.56
Lentils0.440.50
Soybeans1.002.22
Tofu1.462.90
Soy beverage1.241.24
Soy protein concentrate1.242.17
New potato0.180.34
Spinach0.22NR
Avocado fruit0.510.51
Food sources of phytic acid (fresh weight)[26]
Food [% minimum fresh weight] [% maximum fresh weight]
Taro0.1430.195
Cassava0.1140.152

Chestnuts contain 47 mg of phytic acid for 100g.[31]

Oak acorn of Quercus ilex contains 127 mg of phytic acid for 100g.[32]

Effect on human health

Some authors such as Norbdo and Gunnar (1972)[33] describe phytic acid as "cariostatic", or tending to inhibit the formation of caries (cavities). However, older literature contains more nuanced and sophisticated views on this substance. In a 1939 paper[34], Douglas Harrison and Edward Mellanby described how phytic acid can be mildly cariostatic in a diet where the Calcium to Phosphorus ratio is unbalanced. However, phytic acid typically leads to the development of rickets and caries because it binds to calcium (among other minerals) and can therefore cause deficiencies in calcium uptake. The rachitogenic action can be reduced through mineral supplementation, food preparation methods that destroy phytic acid, and/or the use of phytases (enzymes that convert the phosphorus in phytic acid into a usable inorganic form).

Because phytic acid can affect the absorption of iron, Hurrell et al argue that "dephytinization should be considered as a major strategy to improve iron nutrition during the weaning period".[35] Phytic acid's chelating properties have given the acid a reputation as an anti-nutrient with deleterious aspects; some authors argue that this stigmatization ignores its beneficial properties and modern uses.[36][37]

Many modern authors argue that phytic acid can be beneficial to human health because it is an antioxidant[38][39]. In-vitro experiments suggest that phytic acid may have cancer-fighting properties[40]. A pilot study of Inositol Hexaphosphate plus Inositol found that one patient exhibited a reduced tumor growth rate (no figures were provided); however, the researchers noted that controlled randomized clinical trials would be necessary to confirm those observations.[38] The same researchers, Ivana Vucenik and AbulKalam Shamsuddin, also argue that Inositol hexaphosphate is an "essential nutrient" and 'has many characteristics of a vitamin, contrary to the established and, unfortunately, still existing dogma among nutritionist about its “anti-nutrient” role'.[41]

See also

References

  1. 1 2 Phytic acid. phytochemicals.info
  2. 1 2 Klopfenstein TJ, Angel R, Cromwell G, Erickson GE, Fox DG, Parsons C, Satter LD, Sutton AL, Baker DH (July 2002). "Animal Diet Modification to Decrease the Potential for Nitrogen and Phosphorus Pollution". Council for Agricultural Science and Technology. 21.
  3. ↑ Romarheim OH, Zhang C, Penn M, Liu YJ, Tian LX, Skrede A, Krogdahl Å, Storebakken T (2008). "Growth and intestinal morphology in cobia (Rachycentron canadum) fed extruded diets with two types of soybean meal partly replacing fish meal". Aquaculture Nutrition. 14 (2): 174–180. doi:10.1111/j.1365-2095.2007.00517.x.
  4. ↑ Mallin MA (2003). "Industrialized Animal Production—A Major Source of Nutrient and Microbial Pollution to Aquatic Ecosystems". Population and Environment. 24 (5): 369–385. doi:10.1023/A:1023690824045. JSTOR 27503850.
  5. ↑ Guttieri MJ, Peterson KM, Souza EJ. "Milling and Baking Quality of Low Phytic Acid Wheat". Crop Science. 46 (6): 2403–8. doi:10.2135/cropsci2006.03.0137.
  6. ↑ Malleshi, N. G.; Desikachar, H. S. R. (1986). "Nutritive value of malted millet flours". Plant Foods for Human Nutrition. 36 (3): 191–6. doi:10.1007/BF01092036.
  7. ↑ Seaman JC, Hutchison JM, Jackson BP, Vulava VM (2003). "In situ treatment of metals in contaminated soils with phytate". Journal of Environmental Quality. 32 (1): 153–61. doi:10.2134/jeq2003.0153. PMID 12549554. {
  8. ↑ Reddy NR, Sathe SK, Salunkhe DK (1982). "Phytates in legumes and cereals". Advances in Food Research. 28: 1–92. doi:10.1016/s0065-2628(08)60110-x. PMID 6299067.
  9. ↑ Szwergold BS, Graham RA, Brown TR (December 1987). "Observation of inositol pentakis- and hexakis-phosphates in mammalian tissues by 31P NMR". Biochemical and Biophysical Research Communications. 149 (3): 874–81. doi:10.1016/0006-291X(87)90489-X. PMID 3426614.
  10. ↑ Sasakawa N, Sharif M, Hanley MR (July 1995). "Metabolism and biological activities of inositol pentakisphosphate and inositol hexakisphosphate". Biochemical Pharmacology. 50 (2): 137–46. doi:10.1016/0006-2952(95)00059-9. PMID 7543266.
  11. 1 2 Hanakahi LA, Bartlet-Jones M, Chappell C, Pappin D, West SC (September 2000). "Binding of inositol phosphate to DNA-PK and stimulation of double-strand break repair". Cell. 102 (6): 721–9. doi:10.1016/S0092-8674(00)00061-1. PMID 11030616.
  12. ↑ Norris FA, Ungewickell E, Majerus PW (January 1995). "Inositol hexakisphosphate binds to clathrin assembly protein 3 (AP-3/AP180) and inhibits clathrin cage assembly in vitro". The Journal of Biological Chemistry. 270 (1): 214–7. doi:10.1074/jbc.270.1.214. PMID 7814377.
  13. ↑ York JD, Odom AR, Murphy R, Ives EB, Wente SR (July 1999). "A phospholipase C-dependent inositol polyphosphate kinase pathway required for efficient messenger RNA export". Science. 285 (5424): 96–100. doi:10.1126/science.285.5424.96. PMID 10390371.
  14. ↑ Shears SB (March 2001). "Assessing the omnipotence of inositol hexakisphosphate". Cellular Signalling. 13 (3): 151–8. doi:10.1016/S0898-6568(01)00129-2. PMID 11282453.
  15. ↑ Dick RA, Zadrozny KK, Xu C, Schur FK, Lyddon TD, Ricana CL, Wagner JM, Perilla JR, Ganser-Pornillos BK, Johnson MC, Pornillos O, Vogt VM (August 2018). "Inositol phosphates are assembly co-factors for HIV-1". Nature. 560 (7719): 509–512. doi:10.1038/s41586-018-0396-4. PMID 30069050.
  16. ↑ Mullaney EJ, Ullah, Abul H.J. "Phytases: attributes, catalytic mechanisms, and applications" (PDF). United States Department of Agriculture–Agricultural Research Service. Archived from the original (PDF) on 2012-11-07. Retrieved May 18, 2012.
  17. ↑ "Phytates in cereals and legumes". fao.org.
  18. 1 2 Phillippy BQ, Wyatt CJ (May 2001). "Degradation of phytate in foods by phytases in fruit and vegetable extracts". Journal of food science. 66 (4): 53–59.
  19. ↑ Dendougui F, Schwedt G (September 2004). "In vitro analysis of binding capacities of calcium to phytic acid in different food samples". European food research and technology. 219 (4): 409–15. doi:10.1007/s00217-004-0912-7.
  20. ↑ Prom-u-thai C, Huang L, Glahn RP, Welch RM, Fukai S, Rerkasem B (2006). "Iron (Fe) bioavailability and the distribution of anti-Fe nutrition biochemicals in the unpolished, polished grain and bran fraction of five rice genotypes". Journal of the Science of Food and Agriculture. 86 (8): 1209–15. doi:10.1002/jsfa.2471.
  21. ↑ Hurrell RF (September 2003). "Influence of vegetable protein sources on trace element and mineral bioavailability". The Journal of Nutrition. 133 (9): 2973S–7S. doi:10.1093/jn/133.9.2973S. PMID 12949395.
  22. ↑ Committee on Food Protection; Food and Nutrition Board; National Research Council (1973). "Phytates". Toxicants Occurring Naturally in Foods. National Academy of Sciences. pp. 363–371. ISBN 978-0-309-02117-3.
  23. ↑ "Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets". Journal of the American Dietetic Association. 103 (6): 748–65. June 2003. doi:10.1053/jada.2003.50142. PMID 12778049.
  24. ↑ Dephytinisation with Intrinsic Wheat Phytase and Iron Fortification Significantly Increase Iron Absorption from Fonio (Digitaria exilis) Meals in West African Women (2013)
  25. ↑ Reddy NR, Sathe SK (2001). Food Phytates. Boca Raton: CRC. ISBN 1-56676-867-5.
  26. 1 2 Phillippy BQ, Bland JM, Evens TJ (January 2003). "Ion chromatography of phytate in roots and tubers". Journal of Agricultural and Food Chemistry. 51 (2): 350–3. doi:10.1021/jf025827m. PMID 12517094.
  27. ↑ Macfarlane BJ, Bezwoda WR, Bothwell TH, Baynes RD, Bothwell JE, MacPhail AP, Lamparelli RD, Mayet F (February 1988). "Inhibitory effect of nuts on iron absorption". The American Journal of Clinical Nutrition. 47 (2): 270–4. doi:10.1093/ajcn/47.2.270. PMID 3341259.
  28. ↑ Gordon DT, Chao LS (March 1984). "Relationship of components in wheat bran and spinach to iron bioavailability in the anemic rat". The Journal of Nutrition. 114 (3): 526–35. doi:10.1093/jn/114.3.526. PMID 6321704.
  29. ↑ Arendt EK, Zannini E. "Chapter 11: Buckwheat". Cereal grains for the food and beverage industries. Woodhead Publishing. p. 388. ISBN 978-0-85709-892-4.
  30. ↑ Pereira Da Silva B. Concentration of nutrients and bioactive compounds in chia (Salvia Hispanica L.), protein quality and iron bioavailability in wistar rats (Ph.D. thesis). Federal University of Viçosa.
  31. ↑ Scuhlz M. "Paleo Diet Guide: With Recipes in 30 Minutes or Less: Diabetes Heart Disease: Paleo Diet Friendly: Dairy Gluten Nut Soy Free Cookbook". PWPH Publications – via Google Books.
  32. ↑ "First Phytochemiical Analysis of the Anti-Nutritional Aspect of Holm OOak Acorn (Quercus Ilex L)) of Tessala (Algeria NW) befoore and after Cooking (PDF Download Available)". ResearchGate.
  33. ↑ Nordbö H, Rölla G (May 1972). "Desorption of salivary proteins from hydroxyapatite by phytic acid and glycerophosphate and the plaque-inhibiting effect of the two compounds in vivo". Journal of Dental Research. 51 (3): 800–2.
  34. ↑ Harrison DC, Mellanby E (October 1939). "Phytic acid and the rickets-producing action of cereals". The Biochemical Journal. 33 (10): 1660–1680.1. PMC 1264631. PMID 16747083.
  35. ↑ Hurrell RF, Reddy MB, Juillerat MA, Cook JD (May 2003). "Degradation of phytic acid in cereal porridges improves iron absorption by human subjects". The American Journal of Clinical Nutrition. 77 (5): 1213–9. CiteSeerX 10.1.1.333.4941. doi:10.1093/ajcn/77.5.1213. PMID 12716674.
  36. ↑ Graf E (November 1983). "Applications of phytic acid". Journal of the American Oil Chemists' Society. 60 (11): 1861–1867. doi:10.1007/bf02901539.
  37. ↑ Thompson LU (1993-01-01). "Potential health benefits and problems associated with antinutrients in foods". Food Research International. 26 (2): 131–149. doi:10.1016/0963-9969(93)90069-U.
  38. 1 2 Vucenik I, Shamsuddin AM (November 2003). "Cancer inhibition by inositol hexaphosphate (IP6) and inositol: from laboratory to clinic". The Journal of Nutrition. 133 (11 Suppl 1): 3778S–3784S. doi:10.1093/jn/133.11.3778S. PMID 14608114.
  39. ↑ Shamsuddin, Abulkalam M. (2002). "Anti-cancer function of phytic acid". International Journal of Food Science and Technology. 37 (7): 769–782. doi:10.1046/j.1365-2621.2002.00620.x. : Listed as IP-6 Inositol Hexaphosphate
  40. ↑ Tantivejkul K, Vucenik I, Shamsuddin AM (September–October 2003). "Inositol hexaphosphate (IP6) inhibits key events of cancer metastasis: I. In vitro studies of adhesion, migration and invasion of MDA-MB 231 human breast cancer cells". Anticancer Research. 23 (5A): 3671–9. PMID 14666663.
  41. ↑ Vucenik I, Shamsuddin AM (July 2006). "Protection against cancer by dietary IP6 and inositol". Nutrition and Cancer. 55 (2): 109–25.
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