Vitamin E

Question 1

Vitamin E

Answer 1

• Vitamin E is a generic term for two families of fat soluble compounds with vitamin E activity: Tocopherols & Tocotrienols. Both families contain at least four forms: alpha, beta, gamma & delta. All forms exist within natural foods.
• The only form recognised for human nutrition is α tocopherol . The role and use of other forms is still being investigated.

Question 2

Vitamin E and Food Prep

Answer 2

• Up to 80% of vitamin E is destroyed by freezing, whilst heating destroys around 30% of vitamin E.

Question 3

Vitamin E: Food Sources

Answer 3

• Fresh, raw food sources are best: Sunflower seeds, almonds, pine nuts, olive oil, avocado, sweet potato, spinach.

Question 4

Vitamin E: Absorption

Answer 4

• The liver takes up all forms of vitamin E and preferentially secretes α tocopherol into circulation within lipoproteins.Circulated everywhere, stored to greatest extent in adipose tissue.
• Polyunsaturated Fatty Acid (PUFA) intake increases the requirement for vitamin E, due to its antioxidant properties which protect the fatty acid double bonds from oxidation.

Question 5

Vitamin E: Types

Answer 5

• Naturally sourced vitamin E = d alpha tocopherol. Synthetically produced form = d l alpha tocopherol. L isomers are less active. Synthetic forms of vitamin E are derived from petroleum oil and should be avoided.

Question 6

Vitamin E: Measurement

Answer 6

• Vitamin E is measured in mg of α tocopherol equivalents:

1 mg of natural α tocopherol = 1 α tocopherol equivalent (αTE).

Question 7

Vitamin E: Roles

Answer 7

Anti-Oxidant
Immunity
Anti-Coagulant
Endocrine
Skin Repair

Question 8

Vitamin E: Anti-Oxidant - Functions

Answer 8

• Protects the following from oxidation
- Polyunsaturated Fatty Acids (PUFA) cell membranes
- Nerve sheaths
- Cholesterol (↓ LDL oxidation)
• A vital ‘chain breaking antioxidant’.
•Vitamin C and selenium support the activity of vitamin E by rejuvenating oxidised vitamin E. So, ensure an adequate intake of all antioxidants to optimise the effects of vitamin E.

Question 9

Vitamin E: Anti-Oxidant - Therapeutic Uses

Answer 9

• Atherosclerosis & cardiovascular disease
• Male fertility
• Healthy ageing
• Cataracts
• Alzheimer’s & cognitive decline
• Anti cancer (also stimulates the p53 tumour suppressor gene)

Question 10

Vitamin E: Immunity - Functions

Answer 10

• Increases phagocyte activity
• Differentiation of immature T cells in the thymus
• Antioxidant and mild anti inflammatory properties

Question 11

Vitamin E: Immunity - Therapeutic Uses

Answer 11

• HIV/AIDS
• Healthy immune functioning
• Infections

Question 12

Vitamin E - Anti-coagulant - Functions

Answer 12

• Inhibits platelet aggregation and vitamin K activity (↓clotting factors)

Question 13

Vitamin E: Anti-coagulant - Therapeutic uses

Answer 13

Cardiovascular disease

Question 14

Vitamin E: Endocrine - Functions

Answer 14

• Improves insulin action (& possibly improves insulin resistance)
• Modulates oestrogen receptors and activity

Question 15

Vitamin E: Endocrine - Therpeutic Uses

Answer 15

• Diabetes Mellitus
• Dysmenorrhoea
• Menopause (e.g. vaginal dryness)

Question 16

Vitamin E: Skin Repair - Functions

Answer 16

• Traditional topical use, although mechanism not understood.

Question 17

Vitamin E Deficiency

Answer 17

• A marginal subclinical deficiency is common. Serious deficiencies
are rare unless significantly impaired absorption (i.e. cystic fibrosis).
• Typically presents as:
- Red blood cell destruction (due to erythrocyte oxidation -> haemolytic anaemia) exhaustion after light exercise.
- Easy bruising and slow healing (fewer antioxidants)
- Nerve damage (e.g. neuropathy) due to oxidation.

Question 18

Vitamin E Toxicity

Answer 18

Toxicity (rare):
• High doses with vitamin K deficiency and/or warfarin, can increase bleeding risk. Caution supplements with chemotherapy.
High supplement doses create potential for pro-oxidant effect.