Introduction

Vitamin A is a name for a group of fat soluble compounds including retinol, retinal and retinyl esters [1]

The two 2 different forms of vitamin-A, preformed vitamin A and provitamin A carotenoids needs to convert to retinol and total body stores of retinol indicates the vitamin-A status in the body.[1,3]

However, to support the important biological functions, retinol further needs to oxidized to retinal and then to retinoic acid. [3]

Of the two vitamin A forms, only provitamin A is found abundantly in plant based diets and beta-carotene is one of the most important provitamin carotenoid followed by alpha-carotene and beta-cryptoxanthin. [1]

Observational studies have found a corelation between excess preformed vitamin-A intake and increased fracture risk as well as irreversible liver damage in some cases.[1,2] However, beta-carotene is not known to be toxic, even with large supplemental doses [1,2].

  • Beta-carotene absorption rate is highly variable (5–65 %) and dependent on food, diet-related factors and health status of the individual.[7]
  • Since vitamin-A is fat-soluble, excess levels are usually stored in the body and can accumulate over a period of time.
  • Approximately 70-90 per cent of vitamin A in the body is stored in the liver and intestine in the form of retinyl esters [1,4].
  • Vitamin A levels in severely deficient individuals decreases to 50 per cent or less. [3,4]
  • The majority of retinol metabolites are excreted in faeces via bile, in urine and to a lesser extent in breath.[3]
  • Also, the catabolic rate for retinol or the total body vitamin-A stores lost per day is expected to be 0.5 % or more for individuals on a vitamin-A free diet. [3,4]

Body Functions

Recommended Daily Intake

Deficiency Symptoms

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Vitamin A Food Sources

foods high in vitamin a vegan

Excessive Intake/ Toxicity Side Effects

Groups At Risk

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Interaction With Other Nutrients

  • Dietary fat – Dietary fat may enhance the absorption of preformed vitamin A and provitamin A carotenoids, hence, it is advisable to eat vitamin A with fatty foods.[7]
  • Iron – Dietary fat may enhance the absorption of preformed vitamin A and provitamin A carotenoids, hence, it is advisable to eat vitamin A with fatty foods.[7][8]
  • Zinc – Zinc deficiency may negatively affect vitamin A status by the mobilization of vitamin A from the liver, however, evidences are not conclusives.[3]

Nutrient Profiles For Food Groups

Fruits

Dried 2.76%
Juice 2.58%
Raw or frozen 2.06%
Canned 2%

Legumes

Legumes 0.1%

Nuts & Seeds

Nuts 0.4%

Veggies

Dried 28%
Cooked 17.5%
Canned 15.52%
Raw or Frozen 14%

Cereal grains & Flour

Cereal grains 0.1%

Oils

Oils 1.86%
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