Vitamins: Vitamin B6 - Pyridoxine

Question 1

Vitamin B6 – Pyridoxine

Answer 1

• Vitamin B6 (Pyridoxine) is made up of a group of six related vitamers.
• Active B6 is involved in over 100 enzymatic reactions.
• The active forms are pyridoxal 5’-phosphate (PLP) and pyridoxamine 5’-phosphate (P5P)
• Alcohol excess, the OCP and GIT issues increase requirements

Question 2

Food sources

Answer 2

Widely distributed:
* Whole grains
* Green vegetables
* Sunflower seeds
* Pistachios
* Walnuts
* Bananas
* Lentils
* Avocados
* Meat
* Fish

Question 3

Bio availability and absorption

Answer 3

• Vitamin B6 in a varied diet is approximately 75% bio-available.
• Intestinal flora synthesises large amounts that absorption is unknown

Question 4

Food prep

Answer 4

Processing, preserving, heating and light exposure reduces B6.

Question 5

Neurotransmitter production: functions and therapeutic uses

Answer 5

• Functions:
  o Synthesis of:
   GABA
   Dopamine
   Noradrenaline
   Serotonin
• Therapeutic uses:
  o GIT Motility (digestion)
  o Carpal tunnel syndrome
  o Morning sickness
  o Lactation
  o PMS

Question 6

Red blood cell formation: functions and therapeutic uses

Answer 6

• Functions:
  o Used for haem production
• Therapeutic uses:
  o Anaemia

Question 7

Methylation: functions and therapeutic uses

Answer 7

• Functions:
  o Lowers homocysteine
• Therapeutic uses:
  o Cardiovascular disease

Question 8

Energy production: functions and therapeutic uses

Answer 8

• Function:
  o Amino acid metabolism, releases stored glucose
• Therapeutic uses:
  o Fatigue

Question 9

Increased need

Answer 9

• Increased need of vitamin B6 occurs in:
• Alcohol dependent
• Long periods of high stress
• Pregnancy – Particularly in third trimester
• Hormonal imbalances
• Hyperhomocysteinemia (with folate/folic acid and vitamin B12)

Question 10

Deficiency

Answer 10

• Deficiency is rare, and occurs alongside other deficiencies

Question 11

Symptoms

Answer 11

• Low B6 affects the metabolism of fatty acids leading to skin lesions and dermatitis
• Tongue inflammation, recurrent mouth ulcers and sores on the corners of the mouth
• Hormonal imbalance e.g. PMS
• Anaemia (fatigue, pallor, etc.)
• Depression

Question 12

Drug interactions

Answer 12

• Many drugs deplete B6 levels and so intake should be increased. This includes anticonvulsants, antibiotics, alcohol, chemotherapy drug ‘docetaxel’ and the oral contraceptive pill (OCP)
• Levodopa (Parkinson’s medication): The combination of carbidopa and levodopa do not have the B6 depletion problem. However, levodopa (on its own) is broken down by B6 so it should not be supplemented (beyond 5-10 mg / day)

Question 13

Toxicity

Answer 13

• 100-200 mg / day supplements long-term can lead to toxicity symptoms including neuropathy, acne, headache, nausea

Question 14

Vitamin B6 pyridoxine functions

Answer 14

Neurotransmitter production
Red blood cell formation
Methylation
Energy production