Vitamins are readily available and sold in many different formulations and a wide variety of retail outlets. The food industry occasionally supplements foods with vitamins. Vitamins can be taken in excess and problems from Hypervitaminosis, although uncommon, do occur.

Vitamin A is present as fatty-acid ester in food sources such as liver, kidney, and milk, and as pro-vitamin A carotenoids in plants, usually as beta-carotene. 

Vitamin A has numerous roles in the body, not only vision. It is also important for bone growth and a role of cellular processes. The immune system requires vitamin A for proper function and the linings and membranes of the body need vitamin A to remain healthy.

High intake of beta-carotene (hypercarotenaemia) can color the skin yellow, sparing the eyes (in contrast to jaundice where the sclera are also yellow).

Hypervitaminosis A occurs after sudden, massive intake of vitamin A which causes acute toxicity.

The body stores excess amounts of vitamin A, primarily in the liver. Although excess preformed vitamin A can have significant toxicity, large amounts of beta-carotene and other pro-vitamin A carotenoids are not associated with major adverse effects. 

More sustained intake of excess vitamin A leads to dizziness, nausea, headaches, skin irritation, pain in joints and bones, coma, and even death.

Although Hypervitaminosis A can be due to excessive dietary intakes, the condition is usually a result of consuming too much preformed vitamin A from supplements. Excess intake of preformed vitamin A can cause congenital birth defects, including malformations of the eye, skull, lungs, and heart. So, Women who might be pregnant should therefore not take high doses of vitamin A supplements.

Pregnant women should not exceed their recommended intake of 600 micrograms/day. High doses of vitamin A can be Teratogenic (malformation or defect of the embryo or fetus). 
Acute Hypervitaminosis A

This occurs after large over dose of the vitamin. This can occur with unusual dietary intake, for example, ingestion of polar bear liver, which has very high vitamin A content.

 Symptoms include:


Abdominal pain


Lethargy (fatigue/drowsiness)

Visual changes

Impaired consciousness
Chronic Hypervitaminosis A

This occurs when vitamin A toxicity is present for more than three months. Symptoms often include:

Bone pain and swelling 

Stomatitis (inflammation of the mouth)

Loss of appetite


Hepatosplenomegaly (enlargement of both the liver and spleen)

Liver failure


Stop the supplements. If there are changes in mental state, admission to hospital is required. Staying under the tolerable limit of 600mcg per day should prevent toxicity.


Vitamin D comes in three isoforms, the most active being calciferol, or Vitamin D3. In the body it is enzymatically altered in the liver and kidneys to form 1,25 dihydroxyvitamin D. This active form functions as a hormone, telling the intestine to increase calcium absorption and also playing a role in the balance of calcium and phosphorus in the blood. Vitamin D is essential for proper bone and tooth mineralization and deficiency can result in Ricketts and osteomalacia. It also has important functions within the body’s individual cells.

Vitamin D is actually quite easy to get, 10-15 minutes of exposure to ultra violet radiation (sunlight) 3 times a week is sufficient to induce the skin to synthesize all your body’s vitamin D.

Vitamin D toxicity can cause nonspecific symptoms such as anorexia (loss of appetite), weight loss and arrhythmias (irregular heartbeat). More serious effects include raised blood calcium (hypercalcaemia) leading to urinary tract stones and also vascular and tissue calcification, causing damage to the heart, blood vessels and kidneys. 

It should be noted that excessive sun exposure does not result in vitamin D toxicity because the sustained heat on the skin is thought to degrade pre-vitamin D3 and vitamin D3 as it is formed.

In children, Hypervitaminosis D can results in dental enamel hypoplasia (underdevelopment of the enamel).

Stop the supplements and treat the cause. Infants should not receive more than 25μg daily; all others can tolerate, but should not exceed 50μg daily.


There are actually 8 different vitamins in the vitamin E family, referred to as tocopherols. Alpha-tocopherol is the most active, but all have some degree of potency in humans.

Vitamin E is best known as an antioxidant. It also appears to function in the immune system, as well as within individual cells.

Vitamin E is present in many foods, particularly vegetable oils, unprocessed cereal grains, nuts and seeds. There is no evidence of any adverse effects from consuming vitamin E in food. However, high doses of alpha-tocopherol (a tocopherol-isomer of component of vitamin E, with high vitamin E potency) supplements can affect blood clotting and cause hemorrhage, same with vitamin K, though Vitamin K toxicity is not common, but is a concern for people with clotting disorders. Some forms of vitamin K can, at high levels, compromise anti-oxidants in the body and may also cause liver damage and hemolytic anemia (anemia caused by excessive destruction of RBC).

Symptoms include:



Gastrointestinal upset

Bleeding problems as blood coagulation is impaired.


Stop the supplements. Staying under the tolerable limit of 0.8mg per day should prevent toxicity.


High intakes of vitamin B6 from food sources have not been reported to cause adverse effects. However, long-term use of supplements can cause severe and progressive sensory neuropathy (diseases of the PNS) with ataxia (lack of coordination while performing voluntary movements). The severity of symptoms is dose-dependent and the symptoms usually stop when the supplements are discontinued.

 Other adverse effects of excessive vitamin B6 intake include painful skin rashes, nausea and heartburn, paresthesia in hands and feet (a sensation of burning, itching or tingling of the skin with no obvious cause).

Stopping the vitamin B6 supplement resolves symptoms unless irreversible nerve damage has already occurred. Also, staying under the tolerable limit of 100mcg per day should prevent toxicity.


Toxicity from excess of vitamins A and D and vitamin E, can occur but it is important not to exaggerate the risk. However, the belief that vitamins are good, therefore lots of vitamins are even better is inaccurate. 

It is important for everyone to be informed and to be able to identify misinformation, harmful diets and potentially harmful misuse of vitamin supplements. Doing this will help saves life through the prevention of Hypervitaminosis. 

_Nwachukwu Rejoice O.

Federal Polytechnic, Ede.


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