Vitamin B-6Caitlyn Beck

Vitamin B-6 Overview B-6 is a family of 3 compounds:

pyridoxal, pyridoxine, and pyridoxamine. All 3 can become active B-6 coenzymes

Pyridoxal Phosphate (PLP) B-6 or Pyridoxine

Vitamin B-6 in Foods Stored in muscle tissues of animals

More readily absorbed Whole-grains Leading sources in US: fortified ready-to-

eat cereals, poultry, beef, potatoes and bananas. Can be lost when foods exposed to heat and other processing

Vitamin B-6 Needs RDA 1.3 mg/day for men and woman up

to age 50 For older adults, RDA increases 1.7

mg/day for men, 1.5 mg/day for momen Daily Value= 2 mg Average daily intake is 2.5 mg in adult

men, and 1.7 mg for women

Vitamin B-6 Upper Level Upper Level for adults 100 mg/day Vitamin B-6 supplements Irreversible nerve damage

Bodybuilders, women attempting to treat for PMS

Painful skin patches, extreme sensitivity to sunlight, nausea, and heartburn

Absorption, Transport, Storage and Excretion of B-6 Absorption is by passive diffusion

Coenzyme form converted to free vitamin form for absorption

Portal vein Liver Blood

Muscle tissue main storage site Excess B-6 generally excreted in urine

phosphorylated Albumin

Functions of B-6:Metabolism Amino acid metabolism Coenzyme for transamination reactions that

transfer amino groups– allows synthesis of nonessential amino acids Without PLP, every amino acid would be essential

PLP helps convert homocysteine to amino acid cysteine

PLP required for release of glucose from glycogen Helps to maintain blood glucose concentration

Functions of B-6:Synthesis of Compounds PLP catalyzes a step in the synthesis of

heme PLP required for synthesis of several

neurotransmitters Serotonin, dopamine, norepinephrine,

gamma-aminobutyric acid, histamine PLP in Vitamin formation

Other Vitamin B-6 Functions Normal immune function Regulation of gene expression Effects on health:

Cancer Cognitive function Carpal tunnel syndrome Premenstrual syndrome Nausea and vomiting in pregnancy

Vitamin B-6 Deficiency Rare in North America Symptoms:

Seborrheic dermatitis, microcytic hypochromic anemia, convulsions, depression, confusion

Elderly, blacks, smokers, users of oral contraceptive agents, alcoholics, underweight or consume poor diets

Medications

Pharmacological Use Supplemental vitamin B-6 has a long

history as a treatment for: Carpal tunnel syndrome Premenstrual syndrome (PMS) Nausea during pregnancy

EAL Study on Vitamin B-6 Does supplemental folate and/or

Vitamins B6 and B12 reduce homocysteine levels and subsequently reduce coronary events? Homocysteine relationship with the

development of brain disorders, bone disorders and cardiovascular disease

553 patients with successful

angioplasty

Homocysteine-lowering therapy

(272 patients)

Placebo(281 patients) 

Result:  Lower serum homocysteine levels in supplemental group vs. control group

Schnyder et al (2002)

98,462 female RNs; 30-55 yrs old

658 incident cases of nonfatal MI

281 cases of fatal CHD

Controlling for CVD risk factors

Risk of CHD lowered with high intake of folate & B-6

Rimm et al (1998)

Result: Intake of folate and vitamin B-6 above the current recommended dietary allowance may be important in the primary prevention of CHD among women.

Risk of CHD reduced w/ folate & B-6 MV

2,954 people with

nondisabling ischemic stroke

Low dose group(200 µg pyridoxine)

High dose group (25 mg

pyridoxine)

Toole et al (2004)

Result: Both decreased total serum homocysteine, however, the high vitamin dose group had a larger decrease at one month, one year, and 2 years.

In Conclusion…Supplemental folate and/or Vitamins B6

and B12 reduced homocysteine levels but there was no significant evidence that it

also subsequently reduced coronary heart events.

QUESTION TIME!

How is the pyridoxal phosphate (PLP) coenzyme

used in amino acid metabolism?

• MAJOR ROLE!• Coenzyme for transamination reactions that

transfer amino groups to allow the synthesis of nonessential amino acids.

• Convert homocysteine to the amino acid cysteine.

• Release of glucose from glycogen– maintain blood glucose concentration

What are some good food sources

of Vitamin B-6?

• Fortified ready-to-eat cereals• Poultry, beef, fish• Potatoes• Bananas

What are some signs of Vitamin B-6

deficiency?

• Seborrheic dermatitis• Microcytic hypochromic anemia• Convulsions• Depression• Confusion

Resources Wardlaw, G. M. (2013). Wardlaw's Perspectives in Nutrition, 9th

edition. New York: McGraw-Hill. Academy of Nutrition and Dietetics. Does supplemental folate

and/or Vitamins B6 and B12 reduce homocysteine levels and subsequently reduce coronary events? Retrieved September 2013, from Evidence Analysis Library: http://andevidencelibrary.com/evidence.cfm?evidence_summar

y_id=98&auth=1  Schnyder. Effect of homocysteine-lowering therapy with folic acid,

vitamin B12, and vitamin B6 on clinical outcome after percutaneous coronary intervention: the Swiss Heart study: a randomized control trial. JAMA 2002; 288: 973-9.

Rimm EB, et al. Folate andvitamin B-6 from diet and supplements in relation to risk of coronary heart disease among women.

JAMA. 1998 Feb 4; 279 (5): 359-364 Toole. Lowering homocysteine in patients with stroke to prevent

recurrent stroke, myocardial infarction, and death: The Vitamin Intervention for Stroke Prevention (VISP)

Randomized Controlled Trial.  JAMA 2004; 291: 565-75. http://ods.od.nih.gov/factsheets/VitaminB6-QuickFacts/