More to offer: benefits of astaxanthin14 November 2018
In science, astaxanthin is primarily known for bestowing the pink and red colour to salmon skin and flamingo feathers; however, its potential benefits as a health supplement are slowly being explored. Michael Shaw explores the extent to which astaxanthin may be a useful stay on the progress of vision loss, carpal tunnel syndrome and muscle damage.
‘You are what you eat’ is a phrase best applied to the flamingo. Their name comes from the Spanish and Portuguese-shared word flamengo – literally flame-coloured – for their bright pink feathers. This designation, however, only applies to the adults. Flamingos are born white, emerging from the egg with pink eyes and long, rosey, tottering legs, but without the flushed feathers of their parents – that comes in time. As their mothers regurgitate the shrimp that comprises the main part of the flamingo’s diet, the compound astaxanthin – a type of carotenoid or fat-soluble pigment – slowly passes from the supple flesh of the crustacean into the plumage of the juvenile; there it accumulates, until the offspring becomes indistinguishable from its forebears.
Astaxanthin was first discovered by the Austrian-German biochemist Richard Kuhn in 1938. For his part, he was puzzled about why lobsters turned so dramatically red when boiled. Well, these decapods also contain astaxanthin in their shells, which is bonded closely to another protein, crustacyanin.
For flamingos, the presence of astaxanthin in the feathers changes their light absorption properties, making them appear pink to the human eye; whereas, in lobster shells, it bonds with crustacyanin to create a bluegreen tint. The act of boiling a lobster breaks those bonds loose, allowing the astaxanthin to dominate. In 1938, Kuhn was rewarded for his discovery with the Nobel Prize in Chemistry, but he immediately rejected it in deference to his patron Adolf Hitler’s sworn hatred of the accolade.
Multifaceted food dye
Since then, astaxanthin has primarily been used as a food colouring for salmon, crab and shrimp – which are deemed not pink enough – or as a supplement for battery hens.
The compound is increasingly being recognised as more than one of nature’s many dyes. While also being marketed as a food supplement for decades, its benefits as a powerful antioxidant – up to 550 times stronger than vitamin E – are well known.
According to a study in the Journal of Clinical Biochemistry and Nutrition, astaxanthin was found to reduce systolic and diastolic blood pressure in postmenopausal women by 7% and 4%, respectively. Another set of studies conducted on rats in the late 1990s and early 2000s discovered that the compound could also protect against DNA damage caused by UV radiation.
There are promising signs that these properties automatically lend the intake of astaxanthin to the treatment of more serious medical conditions.
The National Algae Astaxanthin Association (NAXA) claims it has been “shown to decrease the risks of certain chronic diseases related to oxidative stress, supports healthy cardiovascular activity, improves muscle strength and endurance, prevents skin ageing and joint health”. Moreover, astaxanthin’s propensity in crossing the blood-retinal barriers means that it could “positively impact disorders related to [the] eye, brain and central nervous system [CNS]”. In short, this compound – found in abundance throughout the natural world – may turn out to be a miracle health supplement.
One major potential application for astaxanthin lies in ameliorating the long-term symptoms of inflammation with the CNS. According to a review study on the neuroprotective role of the compound published in the journal Marine Drugs, the “CNS is considered highly vulnerable to oxidative stress and inflammation due to its low cell renewal potential and high cellular metabolism, since this organ requires around 25% of total body energy”. An imbalance between the reactive-oxygen species released by glia cells – an important cellular component of the CNS – and mechanisms that detoxify reactive oxygen intermediates will lead to neurodegeneration. This balance is normally maintained through autophagy, a physiological process that removes errant intracellular materials, but the effectiveness of this process slows as one ages.
Several studies suggest that astaxanthin could play a role in reducing neuroinflammation, as well as retinal and hippocampic inflammation in diabetic rats. Meanwhile, the neuroprotective research added that “a number of epidemiological studies have linked the consumption of a carotenoidrich diet with a decreased risk of neurodegenerative diseases in humans”. The 2013 study, ‘Astaxanthin alleviates brain aging in rats’, published in Food & Function, showed that the intake of astaxanthin “could alleviate brain ageing” after similar results were observed in rats. This could – potentially – bear sizeable fruit in the fight against Alzheimer’s disease and other forms of dementia in older patients. Successful human trials demonstrating this, however, are relatively thin on the ground.
The compound still needs to prove its effectiveness
The antioxidant properties of astaxanthin have also led to speculation that it could have widespread benefits in combatting cardiovascular disease, after studies in the mid-1990s found that people with higher levels of carotenoids were less likely to experience heart disease. In another article in Food & Function, Francesco Visioli and Christian Artaria said the evidence is clear that “natural astaxanthin shows a higher quenching and scavenging efficacy than synthetic astaxanthin”, as well as other antioxidants such as vitamins C and E. These results, moreover, do seem to have been reached in separate animal studies.
However, human trials are ongoing. In October, astaxanthin producer Cardax announced that it has initiated its own clinical trial into the compound’s effect on cardiovascular health using high and low doses of its supplement, ZanthoSyn, with 130 subjects participating in a double-blind placebo-controlled clinical study in Hawaii, under the supervision of Dr Scott Miscovich.
“This study is an important example of our commitment to the science underlying our products,” said David G Watamull, the director, president and CEO of Cardax. “If the results are positive, its well-controlled, scientifically credible design should provide a strong foundation for our future growth.”
The results may not be earthshattering and the jury is still out on what effect astaxanthin has on treating oxidative stress in patients with cardiovascular disease or atherosclerosis. “This review and those published by other authors reveal a similar picture for illnesses closely related to CVD [cardiovascular disease] DM [diabetes mellitus], hypertension, CKD [chronic kidney disease], dyslipidemia, chronic inflammation): a steep decline in the number of positive (i.e. health-claim supporting) results from in-vitro experiments to animal studies to human trials,” concluded Visioli and Artaria.
This remains largely the case with most ailments reported as being alleviated with the intake of astaxanthin. While studies on laboratory mice or rats have shown positive results, the benefits do not seem to be carrying over from the rodent body into the human. It has also been suggested that the importance of oxidative stress in accelerating the ageing process may have been overestimated.
“Consequently, antioxidant treatments (especially when untargeted) may not show the desired effects in terms of disease prevention, deceleration and reversal,” stated Visioli and Artaria.
It is unlikely that the number of investigations into the potential health benefits of astaxanthin will diminish in the near future; in fact, the value of the global trade in carotenoids has been estimated by B2B researcher MarketsAndMarkets to reach $1.53 billion by 2020. That growth will hinge on successful applications, based on positive results accrued from human trials. Only that will guarantee astaxanthin’s graduation from food colouring into a dietary requirement with serious – and proven – medical benefits.