Occurs with excessive consumption of the fat-soluble vitamins A and D found in fish oils and nuts, amongst other foods. Other vitamins are water-soluble and are excreted in the urine if consumed in excess of the body's needs. The pigment carotin can also accumulate to harmful concentrations if carrots are eaten to excess.
Consuming 4 or more times the recommended amount of vitamin A during pregnancy causes malformation of the foetal head, heart brain and spinal cord.
One baby in 57 born to women taking more than 10,000 IU of vitamin A per day has a birth defect.