Vitamin B 6

from Wikipedia, the free encyclopedia

Vitamin B 6 is the collective name for three similar chemical compounds that are all precursors of the activated vitamin pyridoxal phosphate . They are pyridoxine , pyridoxal and pyridoxamine ; they are vitamins from the B complex . All three substances can be converted into one another by the metabolism and have the same biological activity. Humans cannot produce the cofactor pyridoxal phosphate entirely themselves and are therefore dependent on the intake of these precursors with food, the content of which is so high that there are usually no deficiency symptoms.

description

Vitamin B 6 is a derivative of pyridine . Vitamin B 6 comes as pyridoxine (an alcohol ), pyridoxamine (an amine ), pyridoxal (an aldehyde ) and their phosphoric acid esters , e.g. B. pyridoxal phosphate (PLP).

  • Pyridoxine (Pyridoxol) CAS No .: 65-23-6

  • Pyridoxal CAS No .: 66-72-8

  • Pyridoxamine CAS No .: 85-87-0

Physiological function

The phosphorylated vitamin B 6 derivatives act as coenzymes in around one hundred enzymatic reactions, almost exclusively in the amino acid metabolism . Pyridoxal phosphate (PLP or PALP, a pyridoxine derivative) takes on another important role as a cofactor in the synthesis of δ-aminolevulinic acid , an intermediate in endogenous heme synthesis. The involvement of pyridoxal phosphate as a cofactor in the breakdown of "animal starch" ( glycogen ) should also be mentioned.

Occurrence

Vitamin B 6 is found in low doses in almost all foods. Good animal sources are dairy products, meat (especially liver, poultry), and fish; Good vegetable sources are cabbage, green beans, lentils, lamb's lettuce, potatoes, whole grains, wheat germ, nuts and seeds, yeast, wheat beer , avocado, and bananas.

requirement

  • Infants (up to 12 months): 0.1-0.3 mg / day
  • Children (1-15 years): 0.4-1.4 mg / day
  • Women: 1.2 mg / day
    • Pregnant women (from the 4th month): 1.9 mg / day
    • Breastfeeding: 1.9 mg / day
  • Men 1.4-1.6 mg / day

Deficiency symptoms (hypovitaminosis)

Because vitamin B 6 is found in almost all foods , deficiency symptoms are rare. They usually appear together with a deficiency in another water-soluble vitamin and have the following signs:

  • Loss of appetite, diarrhea, and vomiting
  • Dermatitis , stunted growth and anemia
  • Degeneration of the peripheral nerves with paralysis and afferent ataxia , that is, perceptions of the body are no longer passed on to the brain, so that it can no longer control the necessary movement sequences of the body properly
  • Convulsive states at irregular intervals
  • Microcytic, hypochromic anemia (disruption of heme biosynthesis )
  • Seborrhea- like damage around the eyes, nose and mouth ( T-Zone )
  • Cheilosis and glossitis
  • Anxiety disorders
  • Sleep disorders (early awakening, difficulty sleeping through the night)
  • Paresthesia, muscle twitching

Vitamin B 6 for histamine intolerance

As a therapy for very high levels of glutamic acid (glutamate) in the blood, as it is e.g. B. can occur in eczema and / or histamine intolerance , Reinhart Jarisch recommends a vitamin B6 dose in the order of 0.5 mg / kg body weight per day. This also promotes the body's own synthesis of diamine oxidase (DAO) and thus combats the causal effects of histamine intolerance. However, this view is controversial and is not shared by all doctors. The reference ranges (normal values) for glutamic acid in blood findings are 20–107 µmol / ml in infants, 18–65 µmol / ml in children and 28–92 µmol / ml in adults.

Consequences of an overdose (hypervitaminosis)

Chronic hypervitaminosis only occurs with a daily intake of more than 50 mg. This dose cannot be achieved through natural intake, only through supplementation . It resulted in neurotoxicity and photosensitivity in a small number of cases . The neurotoxicity results in a peripheral , sensory neuropathy with atactic gait disorders , reflex deficits and disorders of tactile, vibration and temperature sensation. Also, the occurrence of dermatitis such as acne medicamentosa is described. In infants, one gram of pyridoxine per day leads to tachycardia , peripheral circulatory disorders, and areflexia . These complaints largely disappear after the pyridoxine is discontinued, but can also be permanent at particularly high doses. The safe dose for humans is a maximum of 10 mg daily.

Men who consumed more than 20 mg of vitamin B 6 per day over the long term were twice as likely to have lung cancer as men in a comparison group. This effect did not occur in women. In smokers, this risk increases again by a factor of 3, presumably the growth of the precancerous stages could be stimulated by the administration of vitamins.

literature

  • Kleemann, Engel: Pharmaceutical Substances . 3rd Edition, Thieme Verlag 1999.
  • Auterhoff , Knabe, Höltje: Textbook of Pharmaceutical Chemistry . 14th edition, Wissenschaftliche Verlagsgesellschaft mbH, Stuttgart 1999.
  • Eger, Troschütz, Roth: drug analysis . 4th edition, Deutscher Apotheker Verlag, Stuttgart 1999.
  • Kleemann, Roth: Drug Production . Thieme Verlag 1983.

Web links

Wikibooks: Biochemistry and Pathobiochemistry: Pyridoxal Phosphate Metabolism  - Learning and Teaching Materials

Individual evidence

  1. ↑ a b c d e f Recommended intake of vitamin B6 . German Nutrition Society. Retrieved May 20, 2019.
  2. ↑ Reinhart Jarisch: Histamine intolerance, histamine and seasickness . 2nd edition, Thieme Verlag, Stuttgart New York, 2004, ISBN 3-13-105382-8 , p. 151.
  3. ↑ "Information sheet for patients: Histamine intolerance, (HIT) & histamine-reduced diet" ( Memento from September 25, 2014 in the Internet Archive ) Website Dr. Heinz Kofler, accessed December 6, 2013.
  4. ↑ Helmut Greiling, AM Gressner: Textbook of clinical chemistry and pathobiochemistry . Schattauer Verlagsgesellschaft, 1987, ISBN 3-7945-0949-8 .
  5. ↑ a b COMMITTEE ON TOXICITY OF CHEMICALS IN FOOD, CONSUMER PRODUCTS AND THE ENVIRONMENT: STATEMENT ON VITAMIN B6 (PYRIDOXINE) TOXICITY . Ed .: Department of Health. June 1997 ( gov.uk [PDF]).
  6. ^ O. Braun-Falco , H. Lincke: The problem of vitamin B6 / B12 acne. A contribution on acne medicamentosa. In: Munich medical weekly . Vol. 118, pp. 155-160, 1976, PMID 130553 .
  7. ↑ Theodore M. Brasky, Emily White, Chi-Ling Chen: Long-Term, Supplemental, One-Carbon Metabolism-Related Vitamin B Use in Relation to Lung Cancer Risk in the Vitamins and Lifestyle (VITAL) Cohort . In: Journal of Clinical Oncology: Official Journal of the American Society of Clinical Oncology . tape 35 , no. 30 , October 20, 2017, p. 3440–3448 , doi : 10.1200 / JCO.2017.72.7735 , PMID 28829668 , PMC 5648175 (free full text).
  8. ↑ Anja Garms, dpa science editor: Do high-dose B vitamins do more harm than good? In: DAZ.online . August 23, 2017 ( deutsche-apotheker-zeitung.de [accessed July 30, 2018]).