Vitamin A is a broad span of nutrients that are crucial to maintaining our health. 

In this article I will explore the benefits of Vitamin A and its function in the body – but I’ll also explore the dangers of having a too-high Vitamin A intake.

Importance of Vitamin A in diet

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Vitamin A is involved in immune function, reproduction, and cellular communication, development of a fetus, specifically the heart, ears, eyes, and limbs.

Vitamin A is critical for vision as an essential component of rhodopsin, a protein that absorbs light in the retinal receptors.

Vitamin A also supports cell growth and differentiation, playing a critical role in the maintenance of the heart, lungs, kidneys, and other organs.

Sources of Vitamin A in diet

Vitamin A is considered safe when consumed in recommended dietary allowances (RDAs). There are two forms of vitamin A that are available in the human diet: animal based and plant based.

Adults who eat fortified foods with Vitamin A, such as low-fat dairy products and a lot of fruits and vegetables, generally lack the need for supplements or multivitamins that contain Vitamin A.

Key sources are:

– Liver
– Fish and fish oils
– Milk
– Eggs
– Dark fruits
– Leafy, green vegetables
– Orange and yellow vegetables (sweet potatoes, carrots)
– Tomato products
– Some vegetable oils
– Fortified food (have added vitamins) like cereal

What happens when you take high amounts of Vitamin A?

Vitamin A toxicity is rare in the general population.

Vitamin A toxicity occurs when excess amounts of vitamin A are stored in the liver and it accumulates over time.

Most people develop vitamin A toxicity by taking high-dose of dietary supplements.

This may be because of megavitamin therapy. A megavitamin therapy involves consuming very large doses of certain vitamins in an attempt to prevent or treat diseases.

Chronic and short term toxicity

Vitamin A toxicity can occur with high amounts of Vitamin A are taken over short or long periods of time. Consequently, toxicity can be short or long-term.

Hypervitaminosis A or Vitamin A toxicity occurs when you have too much vitamin A in your body.

Acute toxicity occurs after consuming large amounts of vitamin A over a short period of time, typically within a few hours or days. Chronic toxicity occurs when large amounts of vitamin A build up in the body over a long period of time.

vitamin a toxicity_2Causes and symptoms of Vitamin A toxicity

Symptoms include visual changes, bone pain, and skin changes.

Chronic toxicity can lead to liver damage and increased pressure on the brain.

Symptoms vary based on whether toxicity is acute or chronic. Headaches and rash are common in both forms of the illness. Acute Vitamin A toxicity in children is usually the result of an accident.

Acute Vitamin A toxicity

– Drowsiness
– Irritability
– Abdominal pain
– Nausea
– Vomiting
– Increased pressure on the brain/cerebral edema (swelling in the brain)
– Dry skin
– Headache
– Loss of appetite

Symptoms of chronic vitamin A toxicity include

– Blurry vision or other visual changes
– Swelling of the bones
– Bone pain
– Dry lips
– Hip fractures
– Poor appetite
– Dizziness
– Nausea and vomiting
– Sensitivity to sunlight
– Dry, rough skin
– Itchy or peeling skin
– Cracked fingernails
– Skin cracking at the corners of the mouth
– Mouth ulcers
– Yellowed skin (jaundice)
– Hair loss
– Respiratory infection
– Confusion
– High levels of calcium
– Psychiatric changes

In children, signs of toxicity of Vitamin A include

– Irritability
– Drowsiness
– Dizziness
– Delirium
– Coma
– Vomiting
– Diarrhea
– Increased pressure in the brain with bulging fontanel’s
– Softening of the skull bone
– Double vision
– Inability to gain weight

In infants

– Headache
– Swelling of the optic (eye) disk
– Bulging eyeballs
– Visual disturbances
– Skin redness and peeling
– Inability to gain weight

Diagnosis

This condition can be diagnosed using blood tests to check your vitamin A levels. Most people improve simply by decreasing their intake of Vitamin A.

Recommended dietary allowances

The recommended dietary allowances (RDAs) for vitamin A are given as mcg of retinol activity equivalents (RAE).

The RDAs for Vitamin A are as follows

Males (>14 y) – 900 mcg RAE

Females (>14 y) – 700 mcg RAE

– Pregnancy (14-18 y) – 750 mcg RAE

– Pregnancy (19-50 y) – 770 mcg RAE

– Lactation (14-18 y) – 1200 mcg RAE

– Lactation (19-50 y) – 1300 mcg RAE

The RDAs for children are as follows

0-6 months – 400 mcg RAE

7-12 months – 500 mcg RAE

1-3 years – 300 mcg RAE

4-8 years – 400 mcg RAE

9-13 years – 600 mcg RAE

Supplements are typically 10,000-50,000 international units (IU) per capsule.

Fish-liver oils may contain more than 180,000 IU/g.

The acute toxic dose of vitamin A is 25,000 IU/kg, and the chronic toxic dose is 4000 IU/kg every day for 6-15 months.

(Beta-carotene – i.e, Provitamin A – is converted to retinol but not rapidly enough for acute toxicity.)

Yes, Vitamin A is a necessary component to your diet and crucial for your body to function properly but take care! There is such a thing as ‘too much of a good thing.’

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