Healthy Aging

Astaxanthin: A Gift from Algae

The role of astaxanthin in brain and eye health

Algae may be pond scum (literally), but that doesn’t mean they’re useless. On the contrary, algae produce a substance with major benefits for human and animal health: astaxanthin.[1]

In nature, astaxanthin serves to protect the algal cysts from the sun’s harmful ultraviolet rays,[2] so perhaps it is not surprising it protects our skin from them as well.[3] Numerous studies have shown that astaxanthin can shield the brain, eyes, skin, and many other organs against the oxidative damage associated with aging. Moreover, studies suggest that astaxanthin supports long-term memory, and may even protect the brain against neurodegenerative disorders such as Alzheimer’s disease and Parkinson’s disease.[4]

A single (3.5 ounce) serving of salmon provides up to 3.8 mg of astaxanthin.[5] However, the richest natural source of astaxanthin is the freshwater algae, Haematococcus pluvialis, which contains a whopping 3,800 milligrams (3.8 grams) of astaxanthin per 3.5 ounces (dry weight).[4],[6]

Thankfully, you don’t need to gulp down algae like the salmon does to obtain astaxanthin. Algae are now cleanly farmed to maximize the production of this valuable antioxidant, and the resulting purified natural astaxanthin is available as a supplement ingredient.[4],[7] Importantly, one should seek out a natural astaxanthin product because it has 90 times more intracellular antioxidant activity than synthetic (laboratory-made) astaxanthin, which also is available on the market.[8]

Effects of astaxanthin on the brain

The brain is especially vulnerable to oxidative stress and inflammation, processes that contribute to age-related memory loss and neurodegenerative diseases.[9],[10] Astaxanthin (AST) has a unique chemical structure that allows it to cross the blood-brain barrier and thus to shield brain cells against damage.[11],[12],[13]

The data from preclinical studies are particularly exciting, because they show that AST not only prevents oxidative damage, but also causes a measurable improvement in memory and cognition.

Preclinical studies suggest that AST has an array of beneficial effects within the brain:

  • AST protects the brain against the toxic effects of aluminum,[14] a metal that has been linked to Alzheimer’s disease.[15]
  • AST protects the brain against the toxic effects of environmental tobacco smoke, a pollutant that impairs cognitive function.[16]
  • AST also protects the brain and eyes against damage due to chemotherapy drugs (e.g., “chemobrain”).[17],[18]
  • AST induces the synthesis of nuclear factor erythroid 2 (NF-E2)-related factor (Nrf2), a master regulator of the body’s antioxidant response.[19]
  • AST ameliorates age-related damage in the hippocampus, a brain region essential for long-term memory, spatial processing, and navigation.[20]
  • AST stimulates the proliferation of brain stem cells, which can give rise to new neurons to replace degenerating cells.[21]
  • Consistent with the above, AST boosts the number of mature neurons in the brain.[22]

The data from preclinical studies are particularly exciting, because they show that AST not only prevents oxidative damage, but also causes a measurable improvement in memory and cognition.[11],[21],[23] Beneficial effects of AST have been demonstrated in animals with high blood pressure (hypertension),[24] diabetes,[25] and brain injury or stroke.[26],[27],[28]

Alzheimer’s disease (AD) is associated with the accumulation of amyloid β peptides, which form aggregates (clumps) that lead to neuronal damage, cell death, and memory problems.[29],[30] AST is capable of protecting neurons from the damaging effects of amyloid β peptides.[12],[31] A combination of AST and fish oil (a source of omega-3 polyunsaturated fatty acids) was shown to enhance the beneficial effects of AST in an animal model of AD.[32],[33]

In addition to its direct antioxidant effects, AST helps prevent the accumulation of phospholipid hydroperoxides (PLOOH) in red blood cells.[12],[34] PLOOH are the primary oxidation products of phospholipids, and their accumulation causes a reduction in oxygen transport to the brain, which contributes to the progression of dementia.[35],[36],[37]

In an animal model of Parkinson’s disease, dopaminergic neuron death was reduced by supplementation with AST.

Parkinson’s disease (PD) is associated with the degeneration of dopaminergic neurons in the substantia nigra within the brain, leading to the decline of dopamine that is characteristic of PD.  In an animal model of PD, dopaminergic neuron death was reduced by supplementation with AST.[12],[38],[39] The results were particularly significant in younger versus older animals. Thus AST may provide a valuable nutritional strategy for brain support during aging.

Human clinical trials of AST have begun.  In several studies, AST was shown to support cognitive and memory functions in healthy aging adults.[40],[41],[42] In one randomized double-blind placebo-controlled study, healthy middle-aged and elderly subjects who complained of age-related forgetfulness showed improvements in learning and memory test scores after 12 weeks of supplementation with 6 mg or 12 mg AST daily.[41]

Effects of astaxanthin on the eyes

Aging is associated with conditions such as dry eye, cataracts, glaucoma, and macular degeneration. Many of these effects are a result of ultaviolet (UV) exposure, which causes oxidative damage to the cornea, lens, and retina of the eye.[43],[44],[45] AST may help protect the eyes against UV damage,[46],[47],[48],[49] in a manner similar to that observed for lutein, another member of the carotenoid family.[50]

AST was shown to prevent cataract formation in the lens, and to protect the retina against damage associated with elevated intraocular pressure, a condition associated with glaucoma.

In animal models, supplementation with AST was shown to protect against photokeratitis (a condition in which the cornea, the clear dome on the front surface of the eye, becomes inflamed in response to UV light).[45],[46],[51] AST also was shown to prevent cataract formation in the lens,[52] and to protect the retina against damage associated with elevated intraocular pressure, a condition associated with glaucoma.[53]

Human studies show that natural AST (6 mg daily) can reduce eye soreness, dryness, fatigue, and blurred vision.[54],[55] In addition, AST was shown to support healthy blood flow in the choroid, the vascular layer of the eye.[56] A placebo-controlled clinical trial in healthy adults showed that four weeks of AST supplementation (6 mg daily) improved retinal capillary blood flow, another indicator of eye health.[57]

The carotenoids lutein and zeaxanthin have been shown to protect against age-related macular degeneration (AMD),[58],[59] and AST may have similar or complementary effects. In a study of individuals with AMD, volunteers who took a daily carotenoid and antioxidant supplement containing AST, lutein, and zeaxanthin, were more likely to report clinically meaningful stabilization/improvements in visual function through 24 months compared with non-treated subjects.[60]

Wrapping up

Numerous studies suggest that astaxanthin can support brain function and eye health as we age, and protect against the cumulative effects of environmental toxins and UV exposure.  In sum, astaxanthin is truly a gift from algae (we promise not to call them pond scum anymore!). 

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