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Astaxanthin: Nature's Potent Pink Carotenoid

By Yousry Naguib, Ph.D.

SIE (September 2002)

Astaxanthin is becoming a popular dietary supplement for its high antioxidant potency. This carotenoid has been marketed in Japan and Europe as a dietary supplement since the late 1990s, and recently gained popularity in the U.S. market.

Astaxanthin is a member of an elite class of carotenoids known as xanthophylls, which also includes lutein, zeaxanthin, and cryptoxanthin. Carotenoids are fat-soluble group of pigments widely distributed in plants and animals. They are potent antioxidants, and play an important role in the prevention of various diseases. Unlike the carotenoid beta carotene, astaxanthin lacks pro-vitamin A activity (1).

Astaxanthin in its synthetic form has been used in the aqua-culture industry to provide the pinkish-red color to salmon, trout and crustaceans such as crabs. krills and shrimps. The worldwide market for astaxanthin in the aquaculture and poultry business is estimated at $185 million and growing steadily.

This nutrient is found in appreciable amounts in the microorganisms yeast Phafaffia rhodozma and the microlagae Haematococcus pluvialis. which have recently been gained considerable interest as potential sources of natural astaxanthin. Among the natural sources H. pluvinlis contains the highest level of astaxanthin, which exists mainly as esters of various fatty acids.


In a recent test-tube experiment, astaxanthin showed an antioxidant activity similar to that of vitamin E, and twice that of alpha-carotene, lutein, and lycopene (2). This antioxidant potency is thought to be important in helping to prevent numerous diseases, including cancer, ultraviolet damage to the skin and macula, as well as cardiovascular conditions.

Oxygen-free radicals are constantly produced in our body as a by-product of aerobic metabolism, and play a vital role in fighting infections and in other essential biochemical processes. However, if these radicals are left unchecked, they could attack and damage cells and DNA, opening the door to the aging process and a host of various degenerative diseases.

Antioxidants, such as carotenoids and bioflavonoids, help cells cope with oxidative stress by neutralizing free radicals, and have been linked to disease prevention. Carotenoids are considered potential membrane antioxidants due to reactivity with singlet oxygen and oxygen-free radicals.

Astaxanthin attaches itself to cell membranes and spans the cell membrane bilayer of fat and water—where free radical attack first occurs—and inhibits the destruction of fatty acids and proteins in cell and mitochondrial membranes caused by lipid peroxidation.

Singlet oxygen, a pro-oxidant found in biological systems, is also capable of damaging proteins, lipids and DNA. Astaxanthin is an excellent quencher of singlet oxygen, with studies showing the singlet oxygen-quenching ability decreasing in the following order: astaxanthin, canthaxanthin, beta-carotene, zeaxanthin. lutein and vitamin E (3).

In one test-tube study, astaxanthin was shown to display antioxidant activity greater than vitamin E and was referred to as the "Super Vitamin E" (4).

In a lab study at Tufts University School of Medicine in Boston, astaxanthin was found to provide more protection than beta-carotene to rat liver microsomes undergoing free radical-initiated lipid peroxidation, and was as effective as vitamin E (5).

More recently, astaxanthin was found to be about two-fold more effective than beta-carotene in trapping free radicals at the surface and inside the membrane. The study suggested that the efficient antioxidant activity of astaxanthin is due to its unique structure, which enhances its activity as compared to other antioxidant nutrients (6).

Astaxanthin has the ability to efficiently trap peroxyl radicals. thus inhibiting lipid peroxidation and suppressing the deleterious effects of peroxyl radicals. In vitamin E-delicient rats, synthetic astaxanthin protected mitochondria from damage caused by lipid peroxidation, and the antioxidant activity was greater than supplemental vitamin E (7). This study, conducted at Kochi Medical School in Japan, also found artificially induced inflammation of rat paws was significantly inhibited by astaxanthin.

Astaxanthin exists in several different forms depending on its structure configuration and its source, including natural versus synthetic. It has been noted that natural astaxanthin provides higher pigmentation to rainbow trout compared to synthetic astaxanthin (8), indicating that the natural astaxanthin is more bioavailable than the synthetic version.


Research demonstrated that astaxanthin protects against pathogens by promoting secondary immune response, in particular humoral immune responses. These responses decline with aging, which can result in autoimmune diseases, frequent infections, and cancer. Enhancement of secondary immune responses by astaxanthin suggests its potential role in restoring antibody responses and maintaining the immune response at optimal levels in older people (9).

Astaxanthin's ability to enhance immune responses was demonstrated in an animal study. Mice fed 40 mg astaxanthin/kg body weight per day three weeks before tumor inoculation had significantly lower tumor size than controls (10).

The chemo-preventive effect of astaxanthin on urinary bladder carcinogenesis was also demonstrated in an animal study. Mice were given a chemical carcinogen in drinking water for 20 weeks, and after a one-week interval, they were given either water containing astaxanthin or water alone (control) for 20 weeks. At the end of the study, the incidence of bladder carcinomas was 42 percent in the control group and 18 percent in the astaxanthin group.

These results indicate that astaxanthin is a possible chemopreventive agent for bladder carcinogenesis, an effect ascribed to its antioxidant activity and ability to suppress cell proliferation (11).

In another study conducted in Japan, mice fed astaxanthin-rich egg yolks developed one-third as many tumors and less cancer incidence compared to controls when stomach tumor was initiated with chemicals (12).


Recently, astaxanthin was shown to provide protection against Helicobacter pylori, which in humans is associated with peptic ulcer disease, and gastric carcinoma. In one study, conducted at the University of Lund in Sweden, mice infected with H. pylori were given daily treatments for 10 days of either algal meal rich in astaxanthin of various potencies (10, 50 and 100 mg/kg body weight), 400 mg/kg vitamin C, or control meals. After 1 and 10 days post-treatment, both the astaxanthin and vitamin C groups showed significantly lower H. pylori colonization levels and lower inflammation scores than controls (13).


In a recent U.S. patent, astaxanthin was shown to ameliorate retinal injury by staving off light-induced oxidation, and to protect photoreceptors from degeneration (14). The patent also suggested that astaxanthin could prevent and treat neuronal damage associated with age-related macular degeneration, and may also treat ischemic reperfusion injury, Alzheimer's disease, Parkinson's disease, and other types of central nervous system diseases.


Cholesterol is a primary indicator of cardiovascular health. It is now established that the gauge of health comes not so much from total cholesterol levels as from the ratio of high-density lipoproteins to low-density lipoproteins. A study at the University of Panama measured cholesterol levels of rats fed diets containing 1,000 parts per million beta-carotene, canthaxanthin, and astaxanthin, respectively, for 30 days. Those on astaxanthin and canthaxanthin showed significant increases in HDL (15).


Carpal tunnel syndrome is the term used to describe a specific group of symptoms (tingling, numbness, weakness, or pain) in the fingers or hands and occasionally in the lower arm and elbow. These symptoms occur when there is pressure on a nerve within the wrist (carpal tunnel). Carpals comprise the eight small bones in the wrist joint.

The most common factor that contributes to carpal tunnel syndrome is doing activities that use the same finger or hand movements repeatedly, such as using computers. It is estimated that three million Americans suffer from Carpal Tunnel Syndrome with total costs to the economy exceeding $15 million billion annually. Non-surgical treatment of carpal tunnel syndrome usually relieves the pressure and pain in the wrist and hands.

In a recent double-blind placebo-controlled clinical study, sponsored by Cyanotech (Kailua-Kona, Hawaii), astaxanthin was shown to improve the condition of patients with Carpal Tunnel Syndrome. Patients who took astaxanthin reported a reduction in both the severity and duration of pain.


A study conducted in Sweden showed that consumption of 2 mg of astaxanthin daily significantly improved (almost three times) the strength and endurance in healthy young male subjects (16).


Research studies conducted thus far have shown astaxanthin to be a powerful antioxidant, and helps to reduce symptoms of H. pylori infections and carpal tunnel syndrome. Astaxanthin is thought to enhance secondary immune responses in humans, and protect against tumor formation ameliorate degeneration of retinal photoreceptors, and protect the central nervous system.


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Information provided by Fuji Chemical Industries USA, inc., Robbinsville, NJ