Astaxanthin in Pet Foods and Supplements
What is Astaxanthin?
Astaxanthin (3,3'-dihydroxy-β, β'-carotene-4,4'-dione) is a xanthophyll carotenoid synthesized as a secondary metabolite by microalgae as well as a number of bacteria and yeasts. It is a highly potent antioxidant with studies showing far greater antioxidant activity than other carotenoids, such as beta carotene, lycopene, and lutein as well as vitamin C and E (alpha-tocopherol) and plant polyphenols. In fact, it is often considered the most powerful naturally occurring antioxidant, shown to be 6,000 times more potent than vitamin C and 800 times more potent than CoQ10 (Nishida et al., 2007). It is probably one of the best agents for protecting cellular membrane vital for proper health and well-being.
Figure 1. Astaxanthin structure
Numerous studies have shown that astaxanthin has potential health‐promoting effects in the prevention and amelioration of various chronic health issues, such as cancers, chronic inflammatory diseases, metabolic syndrome, diabetes, diabetic nephropathy, and diseases of the cardiovascular, gastrointestinal, liver, neurodegenerative, eye, skin etc. as well as exercise‐induced fatigue, male infertility, and HgCl2‐induced acute renal failure, while also stimulating immunity (Yuan et al., 2011; Ambati et al., 2014; Davinelli et al, 2018). It protects organisms against these wide range of diseases with excellent safety and tolerability (Fakhri et al., 2018). A simple PubMed or Google Scholar search brings hundreds or even thousands of peer reviewed scientific research articles, many of which are clinical trials and several even deal with pet nutrition.
Although it imparts health benefits independent of its antioxidant properties, most of its prominent health boosting effects are associated with its super high antioxidant activity. Capelli (2007) summarizes the beneficial effects of astaxanthin is because of its ability to cross the blood-brain barrier and bring antioxidant and anti-inflammatory protection to the brain, central nervous system, and the eyes, while also being able to travel throughout the body effectively to bring antioxidant and anti-inflammatory protection at a high activity level to all the organs and the skin, to span the cell membranes, bond with muscle tissue, and work as a super-powerful antioxidant to quickly eliminate free radicals and neutralize singlet oxygen.
Evidence shows it is not only people that can benefit from the antioxidant’s powerful way of protecting the body from free radicals, but also dogs and cats. Moreover, certain aspects of the biokinetic uptake of astaxanthin in dogs and cats are similar to that in humans (Park et al., 2010). This super-antioxidant improves mitochondrial function in dogs, both young and old (Park et al., 2013). In the blood, astaxanthin is mainly associated with HDL, and is taken up by blood leukocytes, where it is distributed to all subcellular organelles. In a study, dietary astaxanthin heightened immune response and reduced DNA damage and inflammation in dogs (Chew et al., 2011). In another study, dietary astaxanthin improved mitochondrial function in blood leukocytes, most likely by alleviating oxidative damage to cellular DNA and protein in healthy dogs (Park et al., 2013).
Similarly, supplementation of astaxanthin from Antarctic krill oil led to a significant increase in the Omega-3 Index in comparison to flax seed oil in dogs suggesting that preformed marine EPA and DHA sources were more beneficial in dog feeds, as the dietary requirements proposed by relevant government and industry organizations were not met with conversion from short-chain omega-3 fatty acids from plants (Dominguez et al., 2020). Honda and Takahashi, on the other hand, have received US patents (2007, 2014, 2017) regarding the use of astaxanthin in pet foods in relation to certain aspects of its potential health benefits, including sleep and deodorizing urine and feces.
Availability of Astaxanthin Products
Given the broad effect on overall health, astaxanthin products are used for commercial applications in many different forms, such as powders, capsules, tablets, syrups, oils, soft gels, creams, and granulated powders. Often, astaxanthin is also used as a natural coloring agent in the food, nutraceutical, and cosmetics industry due to its deep crimson red color. While its use in human foods and supplements as well as cosmetics is more common, it is slowly finding its way in pet foods and supplements too. Moreover, astaxanthin patents, both granted as well as pending applications, are available in food, feed, and nutraceutical applications. A few patents have already been granted in pet food applications too.
How Much Astaxanthin
In a comprehensive review in humans, recommended or approved doses varied in different countries and ranged between 2 and 24 mg (Brendler and Williamson, 2019). They reviewed 87 human studies, none of which found safety concerns with natural astaxanthin supplementation, 35 with doses ≥12 mg/day. The acceptable daily intake of 2 mg recently proposed by European Food Safety Authority is based on a toxicological study in rats using synthetic astaxanthin. However, synthetically produced astaxanthin is chemically different from the natural one, so results with synthetic astaxanthin should not be used in assessing natural astaxanthin safety.
In pets, there does not appear to be a recommended or approved dose currently and only a few such related studies seem available. So, it would not be outside the prudency to not exceed the amounts recommended for humans. Its supplementation at relatively higher of 0.3 mg/kg body weight/day for 6 weeks in healthy dogs and 8 weeks in obese dogs induced the elevation of antioxidant function and of liver function by ameliorating lipid metabolism (Murai et al., 2019). Alaskan Huskies were fed diets containing 8% krill meal, which would translate to ~8 mg astaxanthin/kg food, for 6 weeks while undergoing training, whether or not followed by an extreme endurance race (Burri et al., 2018; 2019). Visible deviation from good health was not reported for the krill-fed dogs.
Sources of Astaxanthin
When some algae, such as Haematococcus pluvialis, Chlorella zofingiensis, and Chlorococcum sp. are under stressful conditions, they produce astaxanthin as a secondary metabolite. Phaffia rhodozyma, a type of yeast, also generates substantial amounts of astaxanthin. Similarly, there are many marine bacteria, such as Agrobacterium aurantiacum or the more recently identified Sphingomonas astaxanthinifaciens, that can synthesize this powerful antioxidant. The primary industrial source for natural astaxanthin is the microalgae Haematococcus pluvialis. It seems to accumulate the highest levels of astaxanthin in nature, up to ~4% by dry biomass. Once this microalga reaches maturity, it is harvested, crushed, and dried. The result is a deep-red powder of high purity, containing a high concentration of astaxanthin.
Figure 2. Microalgae Haematococcus pluvialis (left) and yeast Phaffia rhodozyma (right)
However, astaxanthin is not produced by mammals nor by any other animals, so whatever is found in many animal, fish (such as salmon), birds (such as flamingo), or crustaceans (such as krill) is actually derived by the consumption of microalgae. These animals may further be eaten by other animals and the compound reaches humans indirectly. Regardless, it’s the microalgae that remains the primary source of natural astaxanthin used in food and feed applications, while krill is also becoming more commonly available.
It is also synthesized chemically, which is actually considered the more traditional source. It still dominates the astaxanthin commercial market today, with BASF and Hoffman-La Roche as the major producers. Chemical synthesis yields different stereoisomers than what is found naturally (3S, 3’S). However, the recent market interest has generated great interests in producing it naturally via algal (Haematococcus pluvialis) induction or yeast (Phaffia rhodozyma) fermentation. It is believed that natural astaxanthin is much more potent than synthetic ones in eliminating free radicals.
Being a fat-soluble carotenoid, its absorption and retention of supplemental astaxanthin is enhanced when taken with some fat or oils with meals or soon afterward.
Astaxanthin in Pet Food, Treats, and Supplements
Although astaxanthin has been used as an animal feed additive in aquaculture industry for at least a few decades, its use in pet foods, treats, or supplements is a rather recent development. In fact, it hasn’t even entered in any appreciable way. Within the pet food industry, it’s the krill meal (or powder) and krill oil that are used as natural sources of astaxanthin. While krill meal/powder is whole, briefly cooked, dried, and ground krill that is usually processed at sea, on board of factory trawlers, krill oil is just the oil extracted from these creatures.
Krill is one of the most abundant species on earth. Its total biomass is estimated at around 500 million tons. To ensure sustainability of the krill itself as well as the ecosystem around it with no harmful effects on availability for whales, fish, birds, seals, or any other species, harvesting of krill is restricted to 4 million tons by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Currently, krill harvesting is estimated at 200,000 tons annually, which is far below CCAMLR levels.
Figure 3. Antarctic krill (left), krill powder (middle), and krill oil (right)
Astaxanthin is the reason for the characteristic deep, crimson red color found in both krill powder and krill oil. As a result, krill is also used as a natural coloring agent in the industry.
Besides the astaxanthin, another highly beneficial aspect of krill oil and krill powder is the form and type of lipids they contain, viz omega 3 fats. While a vast majority of fat sources used commercially are triglycerides and ethyl esters, lipids in krill are both tri triglycerides and phospholipids, latter being the component of cell membranes. In general, omega 3 EPA and DHA fats in phospholipid form are believed to have greater bioavailability than other forms and thus impart greater cell integrity and health benefits mentioned above.
At Science4Pets, we use krill powder and krill oil as natural sources of astaxanthin in a number of pet supplements, such as PowerPro Raw, Probiotic Pro, Veggie Vigor, Superfood Delight, Krill Oil supplement, etc. For details, please visit our web site at www.science4pets.com and hover the mouse over Shop section. Make sure to also check my blogs and subscribe them for more detailed nutritional science based information and any new releases (https://science4pets.com/blogs/news).
Astaxanthin is probably the best antioxidant used commercially. It is 100s of times better than even the CoQ10. It appears to provide several potential health benefits, which is mostly linked to its super high antioxidant activity. Natural astaxanthin is superior to synthetic ones, but the latter one predominates the industry. Its primary natural sources are micro-algae and krill powder as well as krill oil. Science4Pets uses both krill powder and krill oil in its pet products.
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