VITAMIN A

Retinol, β-carotene

Description

Vitamin A is a fat-soluble vitamin that accumulates within the body’s fat stores. It is necessary to maintain the integrity of the skin, immune function and night vision. It also plays an important role in bone growth, reproduction and lactation.

The body can convert β-carotene into vitamin A as needed.

Sources

Vitamin A is most commonly found in dairy products, margarine, liver, eggs, cheese and fish oil. Orange and dark green fruits and vegetables are good sources of β-carotene.

Vitamin A and β-carotene are expressed as mcg of Retinol Activity Equivalents (RAE).

Approximate Vitamin A Content
 Food  Portion  Content(RAE)
 Beef liver 85 g 6582 mcg
 Broccoli, cooked 250 mL 120 mcg
 Butter 15 mL 97 mcg
 Cantaloupe 69 g 117 mcg
 Carrot, juice 250 mL 2256 mcg
 Carrots, cooked 250 mL 1329 mcg
 Carrots, raw 250 mL 919 mcg
 Chicken liver 20 g 780 mcg
 Cottage cheese 1% 250 mL 25 mcg
 Cottage cheese 2% 250 mL 47 mcg
 Curly kale, cooked 250 mL 885 mcg
 Egg 1 87 mcg
 Green peas, frozen 250 mL 179 mcg
 Instant oatmeal 250 mL 359 mcg
 Lettuce 250 mL 207 mcg
 Food  Portion  Content(RAE)
 Mango 1 79 mcg
 Margarine 15 mL 115 mcg
 Milk 1% 250 mL 142 mcg
 Orange, juice 250 mL 25 mcg
 Papaya 1 167 mcg
 Pumpkin, cooked 250 mL 613 mcg
 Red pepper 1 187 mcg
 Ricotta cheese 250 mL 263 mcg
 Spinach, cooked 250 mL 943 mcg
 Spinach, raw 250 mL 141 mcg
 Sweet potato 1 1228 mcg
 Tomato 1 52 mcg
 Watermelon 286 g 80 mcg
 Winter squash, cooked 250 mL 535 mcg

1 mcg of RAE = 1 mcg of vitamin A = 6 mcg of β-carotene

Recommended Daily Allowance (RDA)

Recommended average daily nutrient intake that is sufficient to meet the nutrient requirements of nearly all (97 to 98%) healthy individuals in each age and gender group. The RDA should only be used as a guide for daily individual intake:

Vitamin A Requirements
 Age  Men   Women 
 1-3 years 300 mcg 300 mcg
 4-8 years 400 mcg 400 mcg
 9-13 years 600 mcg 600 mcg
 14-18 years 900 mcg 700 mcg
 Age  Men   Women 
 19-50 years 900 mcg 700 mcg
 > 50 years 900 mcg 700 mcg
 Pregnancy   +70 mcg
 Breastfeeding   +600 mcg

1 mcg = 3,33 UI

Deficiency

The body can store two years worth of vitamin A in the liver. Deficiencies are virtually nonexistent.

Vitamin A deficiency causes the mucous membranes and skin to dry as well as night blindness and eye lesions.

Toxicity

Unless one ingests large quantities of liver or fish oil, it is practically impossible to have too much vitamin A in one’s diet.

Daily doses of 10 mg of vitamin A may cause headache, hair loss, drying of the mucous membranes and skin, bleeding gums, optic atrophy, bone loss and liver damage. Extremely high doses can also cause nausea, vomiting, fatigue and dizziness. Excessive doses during pregnancy may also increase the risk of birth defects.

β-carotene is not the source of these problems since the body only uses it if there is a vitamin A deficiency.

Supplements

Given that taking too much Vitamin A can be toxic, supplements should not be taken unless indicated by your doctor, furthermore, deficiency is rare. The maximum safe dose is 3 mg (10,000 UI) per day. β-carotene however, does not pose any problem.

Vitamin A supplements are contraindicated when taking isotretinoin (Accutane®) and should be used with caution during pregnancy.

Watch what you eat. Nutrition has a significant impact on health!