Synthetic astaxanthin is significantly inferior to algal-based astaxanthin as an antioxidant and may not be suitable as a human nutraceutical supplement

Abstract

Synthetic astaxanthin (S-AX) was tested against natural astaxanthin from Haematococcus pluvialis microalgae (N-AX) for antioxidant activity. In vitro studies conducted at Creighton University and Brunswick Laboratories showed N-AX to be over 50 times stronger than S-AX in singlet oxygen quenching and approximately 20 times stronger in free radical elimination. N-AX has been widely used over the last 15 years as a human nutraceutical supplement after extensive safety data and several health benefits were established. S-AX, which is synthesised from petrochemicals, has been used as a feed ingredient, primarily to pigment the flesh of salmonids. S-AX has never been demonstrated to be safe for use as a human nutraceutical supple- ment and has not been tested for health benefits in humans. Due to safety concerns with the use of synthetic forms of other carotenoids such as can- thaxanthin and beta-carotene in humans, the au- thors recommend against the use of S-AX as a hu- man nutraceutical supplement until extensive, long-term safety parameters have been established and human clinical trials have been conducted showing potential health benefits. Additionally, differences in various other properties between S- AX and N-AX such as stereochemistry, esterification and the presence of supporting naturally occurring carotenoids in N-AX are discussed, all of which elicit further questions as to the safety and potential health benefits of S-AX. Ultimately, should S-AX prove safe for direct human consumption, dosage levels roughly 20–30 times greater than N-AX should be used as a result of the extreme difference in antioxidant activity between the two forms.