Excessive intakes of vitamin A compounds result in permanent liver damage and stunted growth. Usually, toxic symptoms are reversed when excessive intakes are ceased. Common foods do not present a problem; uncommon items such as polar bear liver, or shark, halibut, and cod liver oils, which may have up to 30,000 mg/g compared to the normal daily recommendation of 1000 mg/g, may cause problems.
Acute toxicities in adult humans may not be easily achieved with common supplements; however, children can be at risk. Acute toxicity can appear in matter of hours. Symptoms include anorexia, bulging fontanelles, hyperirritability, vomiting, headaches, dizziness, drowsiness, and erythematous swelling. Chronic toxicity may take a few to several months to express clinical symptoms such as anorexia, headache, sore muscles, bleeding lips, hair loss, cracking and peeling skin, nose bleed, liver and spleen enlargement, and anemia.
Excessive vitamin D intakes have resulted in a variety of toxic effects, including death. Excessive ingestion of fish liver oils or supplements can lead to hypercalcemia, membrane damage, hypertension, cardiac insufficiency, renal failure, and hypochromic anemia. Often, withdrawing the vitamin can reverse the symptoms. Levels five times the recommended daily intake can be toxic, especially to children. Concentrations not more than 10 to 20 mg/d can be considered safe. Acute toxicity symptoms include anorexia, nausea, vomiting, diarrhea, headache, polyuria, and polydipsia, usually 2 to 8 d following ingestion. Chronic symptoms include weight loss, pallor, constipation, fever, hypercalcemia, and calcium deposition in soft tissues.
Excess amounts of vitamin E can antagonize vitamin K’s role in the clotting mechanism. Although vitamin K is fat soluble, it is readily excreted from the body, making toxicity unlikely. However, one form of vitamin K known as menadione, which is water soluble, is extremely toxic at high concentrations, leading to jaundice and hemolytic anemia.