Vitamin A

Deficiency symptoms: A large number of physiological systems may be affected by Vitamin A deficiency. Poor epithelial regeneration can result in skin hyperkeratization, problems with the genitourinary reproductive system (reduced fertility) dysfunction within the gastroenterological/biliary system or the pulmonary system. Patients with Celiac disease, Crohn’s disease and pancreatic disorders are particularly susceptible to Vitamin A deficiency due to malabsorption.

Vitamin A deficiency may result in night blindness and/or epithelial degeneration of the eye. The immune system may also be adversely affected, reducing white blood cell levels and impairing both cell-mediated and humoral defense systems.

Vitamin A is also essential for the developing skeletal system and deficiency can result in growth retardation or abnormal bone formation.

Vitamin A deficiency is most often associated with strict dietary restrictions and excess alcohol intake.

Repletion Information: 

Most plant sources contain provitamin A carotenoids and rich sources include fruits such as cantaloupe, apricots and mango.

Vegetable sources include carrots, spinach, kale and green peas.

RDA’s for Vitamin A are listed in micrograms of Retinol Activity Equivalents (RAE) to account for the different biological activities of retinol (Vitamin A) and provitamin A carotenoids.

- For adult males the RDA is 3000 IU.

- The RDA for non-pregnant females is 1500 IU.

There is no RDA for provitamin a carotenoids.

ADEQUATE ZINC IS REQUIRED to synthesize retinol binding protein (RAP) which transports vitamin A. Therefore a deficiency in zinc limits the body’s ability to mobilize Vitamin A stores from the liver.

EXCESSIVE VITAMIN A INTAKE IS TOXIC AND MUST BE AVOIDED. Liver abnormalities, reduced bone density (osteoporosis) and central nervous system disorders may result from hypervitaminosis A. Early toxicity signs include peeling/itching skin, brittle nails, yellowish skin, alopecia (hair loss), and bone/joint pain. Provitamin A (beta carotene and mixed carotenoids) are much less toxic and not associated with the commonly noted side effects of excess Vitamin A intake.