Who needs it?

Vitamin A is needed for healthy skin and mucous membranes , for the Prevention of infections. Antioxidant and immune system enhancer. Used to prevent many cancers. Necessary for good vision in the dark.

Signs of deficiency

Ulceration of the oral mucosa, poor vision in the dark, acne, frequent colds and infections , dry , flaky skin , dandruff , Thrush (candidiasis) , cystitis ,diarrhoea.

How much?

RDA (recommended daily intake) 800 mcg
OPN (optimal daily intake) 2500 mcg

Complement range

1000-3000 mcg retinol (do not exceed 3000 mcg retinol if you are pregnant or want to become pregnant) 3000-30000 mcg betakarotene.

Toxicity

May occur if the daily dose exceeds 8000-30000 mcg with long-term use, or a single dose of retinol of 300000 mcg. Betakarotene dosage of about 6 mcg RE per day is not recommended for smokers.

Recommended foods.

Ox liver (10800 mcg), calf liver (8000 mcg),carrots (2100 mcg) ,lettuce (1424 mcg), cabbage ( 900 mcg) , pumpkin (500 mcg), mango (1180 mcg),tomatoes (350 mcg), broccoli (460 mcg), apricots and papaya (610 mcg),mandarins (280 mcg)

Assistants

Works in combination with zinc. Vitamin C and e help preserve vitamin A. It is best to take with food along with multivitamins and antioxidants.

Thieves

Sunbathing, alcohol, coffee and smoking.

Source
Patrick Holford" the new Bible of optimal nutrition " P. 475 book publisher (medical research and Consulting Center)