Opinion of the Scientific Panel on Additives and Products or Substances used in Animal Feed on the request from the European Commission on the safety of use of colouring agents in animal nutrition. PART I. General Principles and Astaxanthin

Astaxanthin [(3S,3’S)-3,3’-dihydroxy-β,β-carotene-4,4’-dione) is a natural carotenoid with red pigmenting properties occurring in yeasts, algae, crustaceans, and predator fish like salmonids. It is approved at EU level as feed additive for salmon and trout at 100 mg kg-1 complete feed from 6 months of age onwards without time limit (and for ornamental fish). No specifications could be found at EU level, however the FEEDAP Panel recommends the inclusion of specifications. Products on the market are either synthetically or biotechnically produced. Astaxanthin is a vitamin A precursor for fish, and important for growth and survival, specific functions in reproduction and metabolism, and health in salmonids. Astaxanthin is the major carotenoid in supplementing salmonid feed. The absorption capacity is limited, salmon would built a plateau at about 10 mg kg-1 flesh, trout at a higher level of about 10-25 mg kg-1 flesh. Absorption is determined by several factors, the occurrence of free or esterified astaxanthin, and dietary factors (mainly lipid level), excretion of undigested astaxanthin amounts highest to about 40%. Astaxanthin is metabolised in salmonids through reductive pathways, leading to idoxanthin, adonixanthin and zeaxanthin. No cleavage of the polyen chain is observed. Metabolites were mainly excreted via the bile. After astaxanthin application, the pigments deposited in flesh of trout and Chinook salmon are predominantly astaxanthin, in the arctic charr also idoxanthin. Safety assessment was difficult due to the scarceness of fully published toxicity studies. The FEEDAP Panel therefore decided to consider also summaries and abstracts as additional information. Astaxanthin is not mutagenic and not clastogenic. In three subchronic studies on rats performed with astaxanthin rich algae Haematococcus pluvialis or yeast Phaffia rhodozyma, no toxic effects were described at 2 mg, 11 mg kg-1, and about 40 mg asthaxanthin kg-1 bodyweight. In a 37 week rat study a corresponding value of at least 25 mg asthaxanthin kg-1 bodyweight could be seen. A reproductive toxicity study, including developmental toxicity, with astaxanthin up to 400 mg kg-1 bodyweight did not show (statistically) significant adverse effects. Carcinogenicity studies could not be found, but several subchronic studies showed an anticarcinogenic effect of astaxanthin in experimental models with different carcinogens. The FEEDAP Panel could not set a NOEL (no observed effect level) nor an ADI (acceptable daily intake) for different reasons (astaxanthin content of the product not clearly stated, no chronic study available, full toxicological data set not known). Studies on healthy human volunteers showed that a daily intake of 5 and 12 mg astaxanthin for four weeks, and 6 mg for 8 weeks was tolerated without clinical signs. The data available on intake of trout and salmon flesh by the consumer are insufficient. Worst case calculations indicate that the mean astaxanthin uptake of the European consumer would not exceed 2 mg day-1. Supplementing salmonid feed with astaxanthin would not increase flesh astaxanthin of farmed fish essentially compared to wild catches. The FEEDAP Panel considers therefore the use of human consumer. No data is available for a qualified assessment of the environmental impact of asthaxanthin in salmonid feed. Astaxanthin added to the feed of farmed fish is a substitute of natural sources in the habitat of wild living salmon and trout. The FEEDAP Panel concludes mainly based on the oxydative suceptibility of astaxanthin and the large distribution volume in water of fish operations that the use of astaxanthin as feed additive to salmon and trout will not pose a significant risk to the environment.