Lutein belongs to the carotenoids and, along with beta-carotene, is the most abundant member of this class of natural pigments. It is assigned to the xanthophylls. In plants it occurs together with the carotenoid zeaxanthin. Lutein helps plants to use solar energy effectively in photosynthesis. In flowers and fruits, it is often responsible for their yellow colouration and acts as an attractant. It has colouring effects on some animals that eat lutein-containing plants. This can be seen in bird feathers, the corpus luteum or egg yolk. Other examples are the yellow legs and claws of chickens, whose colouring only becomes so intense with the help of lutein.
Like all carotenoids, lutein is fat-soluble. With this property and its yellow colour, it is suitable as a vegetable colourant for food and approved as a food additive. Processed cheese and jams are examples for the use of lutein. To give the yolk of hens’ eggs a strong yellow colour, it can be added to feed by farmers or their suppliers.
Industrially, lutein is often extracted from the petals of marigolds (botanical name Tagetes).
The animal and human organism can absorb lutein exclusively through the diet. For a natural intake of lutein, vegetables such as spinach, broccoli, peas, peppers and kale are recommended. If you prefer fruit, oranges, apricots, peaches and nectarines are good sources. Chicken egg yolk is also a good source of lutein.
Studies have shown that it is relatively heat stable. After cooking for 15 minutes, sufficient lutein was still detected in the food. Overall, cooking foods improves the body’s ability to use lutein. When preparing food, it should be kept in mind that the usability of lutein depends on the fat content of the dish. The body only absorbs the lutein during fat digestion in the small intestine. Dietary fibres have an inhibiting effect on the absorption.
Storage in the body can be detected long after eating foods containing lutein. Lutein is found in particular in the sheath of nerve tissue and in the brain. In the macula of our eyes, also known as the yellow spot on the retina, only two carotenoids are detectable: lutein and zeaxanthin.
One of the properties of lutein is the development of orange-yellow crystals that are sensitive to oxidation. In scientific studies, it has been observed that it interacts with numerous free radicals due to its antioxidant properties. As a result, these become less reactive and are no longer as harmful.