Many of those additives are synthetic - adding to the chemical cocktail mix in food. But even those which are claimed to be 'natural' are manufactured in factories – often in China. What the manufacturers mean by using the word 'natural' is that the additives may be derived from natural products but are processed and concentrated into a powder or liquid.
Three of the most widely used egg yolk pigmenters are:
Canthaxanin or Canthaxanthin which appears to be an unsafe additive. It can cause diarrhoea, nausea, stomach cramps, dry and itchy skin, hives, orange or red body secretions, and other side effects.
Do not use canthaxanthin if you experience breathing problems; tightness in the chest; swelling of the mouth, tongue or throat; a skin rash or hives; you are pregnant or breast-feeding or you are allergic to vitamin A or carotenoids.
Capsicum Allergic reactions to capsicum may occur. Stop eating eggs with capsicum-based colouring and seek emergency medical attention if you experience symptoms of a serious allergic reaction including difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives.
Other less serious side effects have also been reported. Talk to your doctor, pharmacist, or health care provider if you experience upset stomach; heartburn; diarrhoea; migraine attacks or burning sensation in the mouth or throat.
Use of Capsicum is not recommended if you are pregnant. If you are or will be breast-feeding while eating food containing Capsicum, check with your doctor or pharmacist to discuss the risks to your baby.
Capsicum colourings can bring on anaphylactic shock. See details from the University of Maryland:
Marigold Some people experience breathing problems, tightness in the chest, swelling of the mouth, tongue or throat. A skin rash or hives may occur.
Article written: September 2001
Of the nearly 4000 different additives currently in use, over 3640 are used purely for cosmetic reasons and as colouring agents.