Astaxanthin

What is astaxanthin?

Astaxanthin - even though this name is difficult to pronounce, this compound is enjoying increasing interest in the world of health and sports nutrition. Astaxanthin, which occurs naturally in algae, salmon, krill, trout, shrimp and some other crustaceans, is a pigment that is responsible for the characteristic pink color of these creatures. It is part of a group of compounds called carotenoids, which are usually found in brightly colored fruits and vegetables such as carrots, apricots and tomatoes. Astaxanthin has strong antioxidant properties similar to other carotenoids such as beta-carotene and lycopene. In fact, some studies have shown that astaxanthin has a 40-1000 times higher antioxidant capacity compared to other carotenoids and vitamin E. Even though astaxanthin is a carotenoid, it is not converted into vitamin A in the human body. Like other carotenoids, astaxanthin has limited oral absorption. Very high doses (up to 465 mg/kg/day in males and up to 557 mg/kg/day in females) have shown no signs of toxicity in rats (8, 9).

Pharmacokinetics

Astaxanthin is a fat-soluble substance, which means that it is better absorbed when consumed in combination with fat (10).

When astaxanthin is consumed, it is digested and absorbed in a similar way to fat (it is broken down into chylomicrons). The chylomicrons are absorbed into the lymphatic circulation before the remaining astaxanthin is digested by lipoprotein lipases. Astaxanthin is then assimilated by lipoprotein particles to be transported into tissues (11). Astaxanthin can affect the metabolism of fat and cholesterol, which is especially true when it comes to cardiovascular health (12). Astaxanthin has been identified in most tissue types in the body, but not in the heart (12).

Applications for astaxanthin

Astaxanthin is most commonly used as an additive due to its strong coloring properties. As such, it is usually added to animal feed to intensify the color of farmed salmon and egg yolks, for example. In addition to this, it is also used as a food colorant. Recently, astaxanthin has also been added to nutritional supplements as there is strong evidence that this compound is a powerful antioxidant capable of helping with a variety of problems including muscle soreness, joint pain, back pain, osteoarthritis, high cholesterol, menstrual cramps and sunburn (1). In addition, astaxanthin promotes cardiovascular health and prostate health.

Astaxanthin sources

There are two ways to obtain astaxanthin: synthetic manufacturing processes or extraction from natural sources such as animals and plants. Synthetic astaxanthin costs around 2000 dollars per kilo, but is considered to be of inferior quality compared to naturally derived astaxanthin due to the presence of steroisomers. Even though synthetically produced astaxanthin is astaxanthin from a chemical point of view, it is structurally different from natural astaxanthin, which could affect its function.

Naturally derived astaxanthin is the preferred compound for use in supplements and costs around 7000 dollars per kilo. Astaxanthin supplements are generally offered in capsule form and usually contain either krill or algae meal derived from microalgae. It is important to note that algae have the highest astaxanthin concentrations relative to their weight and can be farmed more sustainably than krill.

Astaxanthin in the field of sports nutrition

In addition to the above-mentioned health benefits due to its antioxidant effects, astaxanthin has attracted interest in the world of sports nutrition due to several studies showing that it can have performance-enhancing effects. In a recent animal study (2), mice were divided into a training group and a control group and both groups were then further split into an astaxanthin and a placebo group. Each of the two astaxanthin groups received an amount of astaxanthin equivalent to 0.02% of total body weight. This study concluded that mice treated with astaxanthin benefited from the following performance-enhancing effects:

• Shift in respiratory exchange ratio: during exercise, the mice that received astaxanthin had a lower respiratory exchange ratio. This means that they used more fat as an energy source compared to the control groups.
• Reduced glucose utilization: Post-exercise muscle biopsies showed that the glycogen stores of the mice that received astaxanthin had higher levels than the glycogen stores of the mice in the control groups. More available glycogen means
• Improved carnitine palmitoyltransferase (CPT 1) activity: CPT 1 is an essential transporter of fat into the mitochondria, where this fat is burned as an energy source. The authors of the study hypothesized that oxidation by reactive oxygen species produced during exercise reduces the functionality of CPT 1 and that the strong antioxidant properties of astaxanthin could reduce this oxidation of CPT 1. This mechanism could provide an explanation for the first two performance-enhancing qualities observed.
• a reduced dependence on carbohydrates as an energy source and
• a longer time to the onset of exhaustion.

Another animal study (3) examined three concentrations of astaxanthin supplementation in mice (1.2mg, 6mg or 30 mg astaxanthin per kilogram of body weight). This study was able to show that fat utilization during exercise was increased by astaxanthin supplementation, which also applied to the time to exhaustion during swimming training. A follow-up study (4) examined astaxanthin and its effects on body composition in mice. In this study, the same three different astaxanthin concentrations were used and it was observed that mice fed a high-fat diet showed reduced body weight gain at astaxanthin doses of 6 and 30 mg per kilogram of body weight. The amount of adipose tissue was lower in all astaxanthin-treated mice than in a control group, although these differences were only significant in the mice receiving the highest astaxanthin doses.

Astaxanthin and athletic performance

Unfortunately, very few human studies have investigated the effect of astaxanthin on athletic performance. The three studies that can be found include an unpublished Swedish study, a Japanese study and an American study. The Swedish study has a rather poor experimental protocol, which was responsible for this study not being published. However, preliminary results of this study show that supplementation with an astaxanthin capsule at an undisclosed concentration over an unspecified period of time led to a significant improvement in endurance during a squat program.

Another team of scientists conducted two studies with astaxanthin and 34 healthy volunteers (6). This study investigated the ability of astaxanthin to affect visual acuity and lactate production during a 1200 meter run. This study was able to show three strong associations with a daily 6mg dose of astaxanthin:

• Improved depth perception: depth perception is important in many sports. Improved depth perception means that you are able to monitor the world in three dimensions and also better judge distances. An example of this would be estimating the distance between a ball and a club in order to hit the ball correctly.
• Reduced critical flicker fusion frequency stimulus threshold: The critical flicker fusion frequency stimulus threshold is a commonly used vision test to assess the degree of central fatigue or fatigue associated with the central nervous system.
• Reduced lactic acid concentration: Muscle biopsies showed a reduced amount of lactic acid (lactate) in subjects supplementing with astaxanthin. Lactate was previously thought to be the primary cause of muscle fatigue, but more recent studies have refuted this view. Whether the reduced lactic acid levels observed with astaxanthin supplementation have performance-enhancing effects has not yet been conclusively determined.

Possible health benefits

As an antioxidant, astaxanthin is 10 times more powerful than zeaxanthin, lutein and beta-carotene and 100 times more powerful than vitamin E (13, 14). The structure of astaxanthin allows this compound to penetrate the cell membrane, which means that it can protect the cell membrane from inside and outside the cell (15).

Astaxanthin could slow down skin ageing

In a small study of 30 women and 36 men, a combination of oral intake and use directly on the skin reduced wrinkles and age spots while improving skin elasticity, texture and moisture. In another study of 34 middle-aged individuals, oral use of astaxanthin alone had similar effects (16, 17).

Supplementation with astaxanthin and collagen hydrolysate improved skin elasticity and integrity in a clinical study of 44 healthy volunteers, while reducing the production of 2 proteins that degrade collagen in response to UV radiation (MMP-1 and MMP-12). In another study of 23 people, oral astaxanthin reduced skin redness and moisture loss after UV exposure while improving skin texture (18, 19). In mice, astaxanthin prevented skin thickening, collagen reduction and melanin production in response to UV radiation (20). In skin cells exposed to UVA radiation, astaxanthin reduced the radiation-induced production of two proteins that degrade collagen (MMP-1 and SFE/NEP) and the production of a pro-inflammatory cytokine (IL-6). This suggests that astaxanthin may protect against UVA-induced skin aging, including wrinkles and sagging skin (21). Summary: Limited evidence suggests that astaxanthin may protect the skin from aging and UV radiation:

Astaxanthin could reduce fatigue during exercise

In a small study of 21 cyclists, astaxanthin improved power release and power release in timed tests (23).

In a clinical study of 40 male soccer players, oral astaxanthin improved antioxidant status by increasing the activity of an antioxidant enzyme (PON1). Another study of 32 male soccer players found that astaxanthin supplementation improved antioxidant status and reduced muscle damage after exercise (23, 24).

However, two studies of 64 well-trained male cyclists did not observe any improvement in antioxidant status, fat utilization or exercise performance with astaxanthin supplementation. Additionally, in another study of 20 well-trained subjects, astaxanthin did not reduce muscle damage after exercise (25, 26, 27). The antioxidant effects of astaxanthin significantly delayed the onset of exhaustion in a study with rats in a swimming test (28). In dogs, consuming a protein bar containing astaxanthin immediately after exercise increased glycogen and protein production, helping to replenish energy stores (29).

Summary: A few small clinical trials (with mixed results) and some animal studies suggest that astaxanthin may reduce exercise fatigue. However, more large-scale human studies are needed to draw definitive conclusions.

Astaxanthin could reduce the risk of heart disease

In a clinical study of 27 overweight subjects, astaxanthin supplementation reduced levels of "bad" cholesterol (LDL and apoB) and the amount of oxidative damage, which could potentially reduce the risk of arterial blockage. In another clinical trial involving 20 subjects, astaxanthin was also found to reduce LDL oxidation (30, 31). In another study of 61 people with slightly elevated blood lipid levels, astaxanthin reduced triglyceride levels while increasing levels of good HDL cholesterol and a protein that promotes fat breakdown (adiponectin) (32). In mice, astaxanthin delayed and reduced the formation of blood clots in blood vessels while increasing blood flow (33). In rats, rabbits and dogs, pretreatment with synthetic astaxanthin reduced the damage caused by myocardial infarction in heart tissue (34, 35, 36). Blood taken from 20 subjects given astaxanthin showed reduced markers of blood clots, suggesting that astaxanthin may help prevent heart disease caused by blood clots (37).

Summary: Although the study results are promising, further clinical studies are needed before definitive conclusions can be made about whether and to what extent astaxanthin could prevent heart disease.

Astaxanthin could improve cognitive function

In two clinical trials, supplementation with astaxanthin and sesamin reduced mental fatigue and improved cognitive function in terms of the ability to quickly understand and accurately perform complex tasks (psychomotor skills and speed of information processing) (38, 39). Astaxanthin improved the antioxidant status of red blood cells in a small study of 30 middle-aged and elderly people. This resulted in a reduced accumulation of oxidized fats in their cell membranes, which is a risk factor for the development of dementia (40). In rats, astaxanthin delayed brain aging by reducing oxidative damage and increasing levels of a protein that promotes the formation of new brain cells (BDNF) (41). Pretreatment with high doses of astaxanthin (80 mg per kilogram of body weight) was able to significantly reduce brain damage due to strokes in rats (42). Mice pretreated with astaxanthin performed better on learning performance tests after a stroke. In addition, astaxanthin reduced swelling in mice after traumatic brain injury and accelerated recovery (43, 44, 45). Astaxanthin has been shown to protect brain cells from beta-amyloid-induced toxicity, suggesting that astaxanthin may protect against Alzheimer's disease (46, 47).

Summary: Initial evidence of protective effects on the brain and its function is promising, but further research is needed to draw definitive conclusions.

Astaxanthin could be helpful for diabetes

In a clinical study of 44 people with type 2 diabetes, astaxanthin supplementation for 8 weeks improved glycemic control (reduced fructosamine and glucose levels and blood lipid profile) and lowered blood pressure (48). In rats and mice fed a high-fat, high-sugar diet, astaxanthin improved insulin sensitivity (49, 50). In general, high blood glucose levels in diabetic patients cause high levels of oxidative stress. Astaxanthin can protect pancreatic beta cells, which produce insulin, from oxidative stress caused by high blood glucose levels. This has been observed in diabetic mice (51). Astaxanthin also reduced cell damage caused by glucose-induced oxidative stress in brain and kidney cells, suggesting that it could prevent diabetic neuropathy and nephropathy (52, 53, 54). Here too, further clinical studies are needed.

Astaxanthin could be helpful for fatty liver disease

In a pilot study of 12 people with non-alcoholic fatty liver disease, astaxanthin had no effect on liver function or sugar and fat metabolism, but it did reduce the build-up of fat in the liver (55). In the same study, astaxanthin was more effective than vitamin E in preventing or improving fatty liver in mice fed a high-fat diet. It reduced the build-up of fat, liver inflammation and scar tissue (55). As this is only a pilot study, further research is needed to fully understand the effects of astaxanthin on fatty liver.

Astaxanthin could improve the body's immune response

Supplementation with 2 mg astaxanthin for 8 weeks increased the immune response and reduced the production of an inflammatory marker (CRP) in a clinical study of 42 healthy young women (56). In another study, it was observed that astaxanthin supplementation in older animals increased antibody production and reduced the immune response (52). In rats, combined astaxanthin and fish oil supplementation modulated the lymphocyte response (57).

Astaxanthin could help against stomach ulcers

Cell extracts of Haematococcus and Chlorococcum (microalgae containing astaxanthin) reduced the number of H. pylori and gastric inflammation in mice infected with H. pylori bacteria (58, 59). Mice pretreated with astaxanthin developed significantly fewer gastric ulcers (60).

Astaxanthin could have anti-cancer effects

In rats and mice with chemically induced oral cancer, bladder cancer, colon cancer, breast cancer and soft tissue cancer, astaxanthin inhibited tumor formation and tumor growth (61, 62, 63, 64, 65). In cell-based studies, astaxanthin inhibited the growth of various cancer cells and embryonic fibroblasts by activating tumor-suppressive genes such as p53 (52). These are only preliminary results. Under no circumstances should existing cancer treatment be replaced by supplementation with astaxanthin.

Side effects

Astaxanthin is considered probably safe and harmless when consumed in doses that occur naturally in foods and possibly safe when taken as a supplement. Some side effects such as colds, diarrhea and drowsiness have been observed in clinical trials. However, these side effects occurred to the same extent in the astaxanthin and placebo groups (39).

Dosage

In terms of dosage, it is difficult to establish a therapeutic dose that provides the benefits described above. However, if the doses used in the studies mentioned above are converted to humans, the possible recommendations range from 6mg to 1800 mg of astaxanthin per day. One study (7) investigating the toxicity of astaxanthin concluded that no adverse side effects were observed in male and female rats at doses of up to 557mg of astaxanthin per kilogram of body weight per day. However, it is important to note that these are only rough values and it is recommended to follow the dosage recommendation on the packaging in case of doubt. Positive results have been observed in humans at doses as low as 2 mg, with dose-dependent effects at 8 mg (56). Even at very high doses (over 500 mg per kilogram of body weight), no signs of astaxanthin toxicity were observed in mice (8, 9).

Astaxanthin - the super nutrient

Astaxanthin has great potential to become the latest super nutrient. To date, there is strong evidence of antioxidant, anti-inflammatory and anti-cancer effects. In addition to this, recent studies have shown that astaxanthin also has performance-enhancing effects, which include the following:

• Reduction in physical fatigue
• Increased fat utilization
• Improvement of body composition
• Improvement of depth perception
• Reduction of visual fatigue

However, as with all supplements, it is important to remember that these are designed to support a healthy lifestyle with a suitable diet and training and cannot replace it.

References

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