Astaxanthin is a powerful antioxidant produced by microalgae to protect them against ultraviolet light. It has a lovely pink-red colour and when present in the diet of flamingos, gives their feathers their characteristic colour. These microalgae are also consumed by marine wildlife such as Antarctic krill, salmon, rainbow trout, sea bream, shrimp, crayfish and crabs, and is concentrated in their flesh, shells or roe to impart a rich salmon-pink colour. In some crustaceans, such as lobster, the astaxanthin is bound to protein and their shells look blue rather than red. When cooked, the astaxanthin is released and their shells turn red.
The highest concentrations of astaxanthin are found in the tropical algae, Haematococcus pluvialis, which remains green until exposed to strong sunlight. It then rapidly produces astaxanthin and turns red. Haematococcus algae are the source of most natural astaxanthin found in supplements, but astaxanthin can also be produced synthetically, and can also be extracted from red yeasts.
Astaxanthin health benefits
Astaxanthin is fat soluble but, unlike some carotenoids, cannot be converted into vitamin A in the body. It does, however, have an antioxidant potential that is forty times greater than betacarotene, and at least 100 times more potent than vitamin E.
Astaxanthin has several unique properties among antioxidants as it is:
- more powerful than 27 other tested antioxidants, including polyphenols, coenzyme Q10, alpha-lipoic acid and vitamin E
- a ‘pure’ antioxidant that does not possess pro-oxidant properties (compared with vitamin E, for example, which is converted into a free radical after acting as an antioxidant)
- can precisely insert itself into cell membranes and span their entire width, trapping free radicals inside the cell, outside the cell and within the cell membrane itself.
Research suggests that Astaxanthin provides numerous nutritional medicine benefits and can protect against stroke, improve memory and learning, relieve eye fatigue from using visual screens, prevent UV induced skin ageing, boost immune responses to vaccination, inhibit the progression of fatty liver disease, reduce atherosclerosis, decrease blood pressure, improve insulin sensitivity, reduce kidney inflammation, improve male fertility, enhance muscle power and endurance, and reduce unwanted blood clots.
This high biological activity is due to astaxanthin’s ability to link across the entire cell membrane from inside to outside.
Astaxanthin and cholesterol
As an antioxidant, astaxanthin inhibits oxidation of circulating cholesterol and has effects on the liver to improve cholesterol balance. When 61 adults with raised cholesterol took astaxanthin supplements at doses of 0 mg (placebo), 6mg, 12mg or 18mg per day, for 12 weeks, in those taking 6mg or 12 mg per day, levels of ‘good’ HDL-cholesterol significantly increased. In those taking 12mg or 18mg per day, triglyceride levels were also significantly reduced. Another study involving overweight people found that astaxanthin significantly lowered LDL-cholesterol and ApoB (another harmful lipid) within 12 weeks, compared with placebo.
Researchers suggest that astaxanthin could help to preventive atherosclerotic cardiovascular disease (hardening and furring of the arteries) but long-term trials are needed to support this.
Astaxanthin and diabetes
Diabetes is associated with abnormal metabolic reactions which generate high levels of free radicals. These free radicals, caused by raised levels of glucose, can trigger inflammation and damage cells and blood vessel walls, leading to the vascular complications of diabetes. These complications include diabetic retinopathy (eye damage), nephropathy (kidney damage) and neuropathy (nerve damage).
A healthy diet that provides foods high in antioxidants can help prevent these complications, and carotenoids such as lutein, zeaxanthin, lycopene and astaxanthin have all been found to slow the progression of diabetic microvascular complications.
In preclinical studies, astaxanthin was found to lower blood glucose levels, reduce protein losses in urine, and increase levels of protective antioxidant enzymes, to improve cell survival.
Astaxanthin can also improve non-alcoholic fatty liver disease, which is associated with type 2 diabetes and obesity.
Astaxanthin has anti-aging potential
Astaxanthin inserts itself into cell membranes and spans their entire width to protect cells against free radicals both inside and out. In double-blind, randomized controlled trials astaxanthin lowered oxidative stress, blocked oxidative DNA damage, lowered C-reactive protein and other inflammation biomarkers, and boosted immune responses.
Aging is associated with many neurodegenerative diseases that impair cognitive functions (ability to think straight) and memory in older people. Research suggest astaxanthin has neuroprotective effects against Parkinson’s and Alzheimer’s diseases, and age-related cognitive impairment. Studies involving older people with mild cognitive impairment found that taking astaxanthin at a doses of between 6mg and 20mg per day for 12 weeks improved performance in a battery of mental tests. At the end of the studies, volunteers made significantly fewer errors and faster reaction times.
Japanese trials found that astaxanthin improved visual acuity and eye accommodation, possibly through an ability to promote regeneration of retinal nerve cells. It improved fertility in men, and n cell studies was found to enhance energy production in mitochondria.
These findings have positioned astaxanthin as one of the most promising supplements for slowing age-related functional decline.
Astaxanthin in the diet
Wild caught salmon is also an excellent source of astaxanthin.
The astaxanthin content of farmed Atlantic salmon varies between 6mg to 8mg per kilogram flesh in Europe, while in Japan, large trout can provide as much as 25 mg/kg flesh.
While diet should always come first, you would need to eat around 600g salmonid fish to obtain 4mg astaxanthin.
Average daily intakes of dietary astaxanthin are estimated at 0.125 mg/kg body weight – equivalent to around 9.4mg for someone who weighs 75kg.
If you eat no seafood, however, then your intake will approach zero.
Table derived from: Ambati RR et al 2014.
Astaxanthin supplements typically provide between 4mg and 12mg per daily dose.
Taking astaxanthin supplements with food that contains some oil enhances its absorption.
Krill oil is a ready source of both omega-3 fish oil and astaxanthin. One gram of Krill oil typically provides 100 mcg (0.1mg) astaxanthin.
Astaxanthin side effects
As a ‘pure’ antioxidant astaxanthin has a high safety profile, with no serious side effects reported in clinical trials.
Doses of up to 20mg astaxanthin appear to be well tolerated, however the European Food Safety Authority have suggested a conservative acceptable daily intake of 0.034 mg/kg body weight – equivalent to just 2.55mg astaxanthin for a person weighing 75kg.