Special Article
`
`February 2007: 63–77
`
`Krill for Human Consumption: Nutritional Value and
`Potential Health Benefits
`Janet C. Tou, PhD, Jacek Jaczynski, PhD, and Yi-Chen Chen, PhD
`
`The marine crustacean krill (order Euphausiacea) has
`not been a traditional food in the human diet. Public
`acceptance of krill for human consumption will de-
`pend partly on its nutritive value. The aim of this
`article is to assess the nutritive value and potential
`health benefits of krill, an abundant food source with
`high nutritional value and a variety of compounds
`relevant to human health. Krill is a rich source of
`high-quality protein, with the advantage over other
`animal proteins of being low in fat and a rich source
`of omega-3 fatty acids. Antioxidant levels in krill are
`higher than in fish, suggesting benefits against oxida-
`tive damage. Finally,
`the waste generated by the
`processing of krill into edible products can be devel-
`oped into value-added products.
`Key words: human health, krill, nutrition
`© 2007 International Life Sciences Institute
`doi: 10.1301/nr.2007.feb.63–77
`
`INTRODUCTION
`
`Human consumption of fish-derived food products
`has been increasing steadily, however, the global capture
`of fish has remained fairly stable for the past 20 years and
`has been forecasted as unlikely to increase in the future.1
`Reports of health benefits has contributed to the rise in
`seafood consumption. For example, the American Heart
`Association recommends eating fish at least twice a week
`as part of their guidelines for reducing heart disease.2
`One way to minimize the gap between the steadily
`
`Drs. Tou and Jaczynski are with West Virginia
`University, Human Nutrition and Foods, Division of
`Animal and Nutritional Sciences, Morgantown, West
`Virginia; Dr. Chen is with Chung Shan Medical Univer-
`sity, School of Nutrition, Jianguo North Road,
`Taichung City, Taiwan, China.
`Please address all correspondence to: Dr. Janet
`Tou, Division of Animal and Nutritional Sciences, West
`Virginia University, P.O. Box 6108, Morgantown, WV
`26506; Phone: 304-293-2631, ext. 4437; Fax: 304-
`293-2232; E-mail: janet.tou@mail.wvu.edu.
`
`increasing consumption and dwindling resources of fish
`is to identify new sources that may be utilized for human
`consumption. Krill is one such resource.
`The Norwegian word “krill” translates into “young
`fry of fish” and has been adopted as the term used to
`describe marine crustaceans belonging to the order Eu-
`phausiacea. Krill is widely known as whale food, but is
`also a source of food for seals, squid, fish, seabirds, and,
`to a much lesser degree, humans. In appearance, krill
`resembles shrimp (Figure 1).3 Similar to other crusta-
`ceans, krill possess a chitinous exoskeleton but are dis-
`tinguishable from other crustaceans by the presence of
`visible external gills, luminous organs, and a cephalo-
`thorax content consisting of extremely active proteolytic
`enzymes. During harvest, these proteolytic enzymes are
`released, resulting in krill meat being rapidly liquefied.4
`A more detailed discussion of the biology of krill is
`available elsewhere.5
`Krill range in size from 0.01 to 2 g wet weight and
`from 8 mm to 6 cm length.6 Despite their small size, krill
`are capable of forming large surface swarms that may
`reach densities of over 1 million animals per cubic meter
`of seawater,7 making them an attractive species for
`harvesting. In addition, krill are found in oceans world-
`wide, making them among the most populous animal
`species. Despite this abundance, the commercial harvest
`of krill has mainly focused on its use as feed in aquari-
`ums, aquaculture, and sport fishing.8 Of the different
`species of krill, only Antarctic krill (Euphausia superba)
`and Pacific krill (Euphausia pacifica) have been har-
`vested to any significant degree for human consumption.
`The underutilization and abundance of krill make it an
`untapped food source for humans that, when coupled
`with a conscientious ecosystem approach to managing
`krill stocks, should result in its long-term sustainability.
`Commercial krill products currently available for
`human consumption consist mainly of frozen raw krill,
`frozen boiled krill, and peeled krill meat.9 However,
`interest in krill as a food source for human consumption
`is expected to increase with the emergence of technolog-
`ical advances and new product development. Still, wide-
`spread acceptance of krill as part of the human diet will
`
`Nutrition Reviews姞, Vol. 65, No. 2
`
`63
`RIMFROST EXHIBIT 1171 Page 0001
`
`

`

`Stomach
`
`Hepatopancreas
`
`Intestine
`
`Heart
`
`Tail Meat
`
`GILLS
`
`Lowest proteolytic activity
`
`Highest proteolytic
`activity
`
`Figure 1. Photograph showing krill body structure. (Adapted with permission from Torres et al.3)
`
`depend on the consumer’s perception of it as a nutritious
`as well as “healthy” food. Therefore, the aims of this
`article are to evaluate the nutritional value of krill as a
`food for human consumption and to review the scientific
`evidence regarding its health benefits.
`
`NUTRIENT COMPOSITION OF KRILL
`
`Seafood is low in calories compared with other
`animal foods. For example, a 100-g serving of shrimp
`provides approximately 106 kcal, whereas the same
`amount of fish provides 110 to 150 kcal, lean beef 250
`kcal, and roasted chicken 200 kcal.10 Proximate analysis
`of whole krill shows a range of 77.9% to 83.1% for
`moisture, 0.5% to 3.6% for total lipids, 11.9% to 15.4%
`for crude protein, 3% for ash, and 2% for chitin and
`glucides.11 To assess the food value of krill, the nutrient
`composition of krill meat was compared with other
`seafoods in the human diet. Shrimp was selected for
`comparison because it is a crustacean familiar to the
`human diet; fish was also selected because it is widely
`regarded to be a “healthy” food.
`As shown in Figure 2, the nutrient composition of
`krill closely resembles that of shrimp. Total protein and
`ash content of krill are comparable to fish, but its total
`lipid content is lower than fatty and lean fish species.
`Overall, krill resembles other seafood in being low in fat
`and a good source of protein. Based on proximate anal-
`ysis, krill offers an attractive food addition to the human
`diet. However, proximate analysis does not provide in-
`formation regarding the type of fat or the quality of the
`protein provided by krill. The next sections of the article
`
`assess individual components of krill for nutritive value
`and potential health benefits.
`
`KRILL OIL
`
`Current dietary recommendations suggest reducing
`fat consumption because high-fat diets have been impli-
`cated in weight gain and in increased risk of various
`diseases, most notably cardiovascular disease (CVD). In
`addition to the amount of fat, the type of fat also has an
`important impact on health. Foods high in saturated fatty
`acids (SFAs) have been linked to increased risk of CVD,
`whereas the omega-3 polyunsaturated fatty acids (␻-3
`PUFAs), particularly eicosapentanoic acids (EPA, 20:
`5␻-3) and decosahexanoic acid (DHA, 22:6␻-3), have
`been linked to reduced risk of CVD.12 Thus, the nutritive
`value of krill oil was evaluated due to the consumer’s
`desire for foods that are low in fat and SFAs and high in
`␻-3 PUFAs.
`
`Nutritional Value
`
`Saether et al.13 analyzed the lipid content of three
`species of krill and reported values ranging from 12% to
`50% on a dry-weight basis. The wide range in lipid
`content was attributed to the sampling occurring during
`different seasons. A reduction in lipid content occurred
`in the spring, when food was scarce, whereas it increased
`in the autumn and early winter, when food was abundant.
`Kolakowska14 reported that
`the lack of reproductive
`activity in the winter raised the lipid content of female
`krill to over 8% of their wet weight. Thus, the lipid
`
`64
`
`Nutrition Reviews姞, Vol. 65, No. 2
`RIMFROST EXHIBIT 1171 Page 0002
`
`

`

`Ash
`Lipids
`Protein
`
` Krill meat
` Euphasia superba
`
`Mixed shrimp species
` Penaeidae and Pandalidae
`
`Wild rainbow trout
`Salmo gairdneri Richardson
`
`Wild coho salmon
`Oncorhynchus kisutch
`
`0
`
`5
`
`10
`
`15
`
`20
`
`25
`
`mg/100g
`
`Figure 2. Proximate analysis of krill, shrimp, and lean (trout) and fatty (salmon) fish. Values for krill are based on Suzuki and
`Shibata9; values for shrimp, trout, and salmon are based on based on USDA.10
`
`content and profile of krill may vary considerably de-
`pending on factors such as season, species, age, and the
`lag time between capture and freezing. These factors
`must be taken into consideration to ensure the consis-
`tency of krill oil. Regardless of this variability, krill is
`similar to other seafood in being low in fat compared
`with other animal foods. The lipid content of krill meat is
`1.5%,9 compared with approximately 26% for lean beef,
`3.6% for chicken, 5.9% for fatty fish, and 3.5% for lean
`fish on a wet-weight basis.10
`
`The lipid content in krill was analyzed for fatty acid
`composition. Table 1 shows that krill provides both of
`the essential fatty acids: ␣-linolenic acid (ALA, 18:3
`␻-3) and linoleic acid (LA, 18:2 ␻-6). In addition, krill is
`low (26.1%) in both SFAs and (24.2%) monounsaturated
`(MUFAs) but high (48.5%) in PUFAs. Palmitic acid
`(16:0) is the predominant SFA, oleic acid (18:1␻-9) is
`the predominant MUFA, and the PUFAs consist mainly
`of ␻-3 fatty acids. Kolakowska et al.15 reported that ␻-3
`PUFAs accounted for approximately 19% of total fatty
`
`Nutrition Reviews姞, Vol. 65, No. 2
`
`65
`RIMFROST EXHIBIT 1171 Page 0003
`
`

`

`acids in Antarctic krill caught during the winter. Of the
`␻-3 PUFAs, EPA and DHA were particularly abundant.
`This was not surprising given that krill feed on marine
`phytoplankton such as single-cell microalgae, which syn-
`thesize large amounts of EPA and DHA.
`The fatty acid composition of krill meat was com-
`pared with that of shrimp, rainbow trout (a lean fish), and
`coho salmon (a fatty fish). As shown in Table 1, the DHA
`content of krill is similar to that of shrimp and fish, but
`its EPA content is higher than either lean or fatty fish.
`Overall, the fatty acid profile of krill resembles that of
`shrimp and fish. However, most of the fatty acids in fish
`are incorporated into triglycerides, whereas 65% of the
`fatty acids in crustaceans are incorporated into phospho-
`lipids.16 Arai et al.17 reported that phospholipids com-
`prise 29.9% of the lipid content of krill, whereas Bot-
`tino18 reported even higher levels of 54% to 58%. The
`variations in krill phospholipid content in these studies
`may be due to differences in krill species, age, season, or
`harvest time.
`Another lipid class of interest is cholesterol. Con-
`sumer perception of krill as a food high in cholesterol
`may reduce its acceptance in the human diet. The cho-
`lesterol level in krill is higher than that of fish but lower
`than that of shrimp (Table 1), and ranges from 62.1 to
`71.6 mg/100 g in tissue and from 17 to 76.3 mg/g in krill
`oil.19 However, it should be noted that two-thirds of the
`sterols in shellfish are non-cholesterol sterols.20 The
`non-cholesterol sterols in shellfish have been reported to
`interfere with cholesterol absorption.21 Rats fed krill
`lipids for 3 weeks22 or 2 months17 failed to show an
`increase in liver or blood cholesterol. Any hypocholes-
`terolemic effects associated with the cholesterol content
`of krill may be negated by its non-cholesterol sterols, low
`fat, low SFA, and high ␻-3 PUFA content. More studies
`on the effects of non-cholesterol sterols and ␻-3 PUFA-
`rich phospholipids derived from krill on CVD risk fac-
`tors are needed before any definitive statements can be
`made regarding the impact of krill on heart disease.
`Consumer interest
`in reducing heart disease through
`dietary modification makes addressing the role of krill on
`CVD risk an important issue in its acceptance for human
`consumption.
`
`Cardiovascular Health Benefits
`
`Although krill oil is being advertised as a supple-
`ment with protective effects against heart disease, few
`published studies exist. Shagaeva et al.23 reported that
`feeding krill meat to patients with type 1 diabetes re-
`duced their incidence of atherosclerosis. However, we
`were unable to critically review this article because it is
`written in Russian. In a recent study, the effect of krill oil
`
`on hyperlipidemia was investigated.24 The study design
`was a double-blind trial comprised of 120 male and
`female subjects (mean age of 51 ⫾ 9.5 years) diagnosed
`with mild to high blood cholesterol and triglycerides.
`Subjects were randomly assigned to one of the following
`treatment groups: 1) low-dose krill oil: 1 g/d if BMI was
`under 30 kg/m2 and 1.5 g/d if BMI was over 30 kg/m2;
`2) high-dose krill oil: 2 g/d if BMI was under 30 kg/m2
`and 3 g/d if BMI was over 30 kg/m2; 3) 3 g/d of fish oil
`containing 180 mg EPA and 120 mg DHA; or 4) placebo
`containing microcrystalline cellulose. Assigned treat-
`ments were given daily for 12 weeks. The primary end
`points measured were total cholesterol,
`triglycerides,
`low-density lipoproteins (LDLs), and high-density li-
`poproteins (HDLs) at baseline and at 90 d.
`The results on blood lipids indicated that placebo,
`fish oil, and low-dose (1.0 –1.5 g/d) krill oil had no
`significant effect on triglycerides, whereas high-dose
`(2–3 g/d) krill oil significantly (P ⬍ 0.05) reduced
`triglycerides by 27% to 28% (Figure 3A). While the
`results of this study showed the absence of a significant
`effect of fish oil on triglycerides, others have reported
`that a similar dose of 3 g/d fish oil lowered triglycerides
`by 30%.25 Total cholesterol was elevated in subjects
`taking a placebo, while both fish oil and krill oil treat-
`ment reduced total cholesterol (P ⬍ 0.05; Figure 3A).
`Krill oil induced higher reductions in cholesterol than
`fish oil, with the low-dose krill oil decreasing total
`cholesterol by of 13% to 14% and the high-dose krill oil
`by 18%.
`The results on circulating lipoproteins indicated in-
`creased (P ⬍ 0.05) LDLs in subjects taking a placebo.
`Fish oil had no significant effect on LDLs, whereas krill
`oil significantly reduced LDLs. Low-dose krill oil re-
`duced LDLs by 32% to 36%, and high-dose krill oil by
`37 to 39% (Figure 3B). In addition, krill oil significantly
`increased HDLs compared with fish oil. Low-dose krill
`oil increased HDLs by 43% to 44%, and high-dose krill
`oil by 55% to 60% (Figure 3B). Based on these findings,
`Bunea et al.24 concluded that krill oil was more effective
`at improving blood lipids and lipoproteins than fish oil.
`Smith and Sahyoun26 reviewed the evidence regarding
`fish oil consumption on CVD and concluded that fish oil
`produced only modest changes on lipoproteins. In some
`cases, high doses (3 g/d) of fish oil have been observed
`to raise LDLs.27 Bunea et al.24 attributed the greater
`lipogenic action of krill oil to the ␻-3 PUFAs in krill
`being associated with phospholipids; the ␻-PUFAs in fish
`are mainly associated with triglycerides. Future research
`should compare the lipogenic effects of providing ␻-3
`PUFAs as phospholipids or triglycerides.
`Limitations of the Bunea et al.24 study include the
`small subject size and the absence of adjustments for
`
`66
`
`Nutrition Reviews姞, Vol. 65, No. 2
`RIMFROST EXHIBIT 1171 Page 0004
`
`

`

`Figure 3. The effect of krill oil, fish oil, or placebo on blood lipids and lipoproteins. Adapted with permission from Bunea et al.24
`P ⬍ 0.05 indicates a significant change from baseline to day 90 of treatment.
`
`other factors such as diet, smoking, gender, and genetics,
`all of which influence blood lipids and lipoproteins.
`Furthermore, the anti-atherosclerotic effects of EPA and
`DHA in fish oil have been attributed to mechanisms
`other than lipogenic actions. Fish oil has been reported to
`reduce CVD risk through diverse mechanisms of reduc-
`ing blood pressure, inflammation, arrhythmia, and ath-
`erosclerotic plaque growth, as well as by promotion of
`endothelial function, anti-thrombosis, and the improve-
`
`ment of insulin sensitivity.28 Whether ␻-3 PUFAs pro-
`vided from food sources other than fish oil exert similar
`effects remains to be determined.
`
`Other Possible Health Benefits
`
`The major focus on ␻-3 PUFAs has been their
`effects on CVD. However, ␻-3 PUFA research has
`expanded into other health issues such as neurological
`
`Nutrition Reviews姞, Vol. 65, No. 2
`
`67
`RIMFROST EXHIBIT 1171 Page 0005
`
`

`

`function, retinal and brain development, cancer, arthritis,
`immunological conditions, diabetes, kidney disease, and
`skin disorders.29 Thus, there are tremendous opportuni-
`ties for research regarding the potential health effects of
`krill. Recently, a role of krill oil in the management of
`premenstrual syndrome was investigated.30 The study
`design was a double-blind trial comprised of 70 women
`of reproductive age who met the diagnostic criteria for
`PMS. Subjects were randomly assigned to take two gel
`capsules containing 1 g of krill oil or 1 g of fish oil (18%
`EPA and 12% DHA) daily at mealtime for a duration of
`3 months. At 45 and 90 d of treatment, the subjects
`completed a self-assessment questionnaire on symptoms
`associated with PMS and also recorded all analgesics
`consumed to alleviate menstrual-related pain.
`The results showed that women taking krill oil
`consumed fewer pain relievers and reported fewer PMS
`symptoms of breast tenderness, joint pain, swelling, and
`bloating compared with women receiving fish oil. The
`decrease in physical symptoms of PMS was attributed to
`the ␻-3 PUFAs in krill oil reducing the production of
`pro-inflammatory 2-series prostaglandins and increasing
`the production of anti-inflammatory 3-series prostaglan-
`dins.30 Women taking krill oil also reported fewer emo-
`tional symptoms associated with PMS, such as feelings
`of being overwhelmed, irritability, stress, and depres-
`sion. Alleviation of emotional symptoms of PMS by krill
`oil has been attributed to the influence of DHA on brain
`function. Based on these findings, Sampalis et al.30
`concluded that krill oil was more effective than fish oil at
`improving both the physical and emotional symptoms of
`PMS. Several limitations of the Sampalis et al.30 study
`are the small subject size, no measurements of blood 2-
`and 3-series eicosanoid concentrations, and problems of
`validity and reliability inherent to self-assessment ques-
`tionnaires. Thus, more studies are needed before any
`
`definitive statement regarding the effect of krill oil on
`PMS can be made.
`Although the consumption of foods high in ␻-3
`PUFAs are recommended for health benefits, there are
`safety issues to consider. Foods rich in PUFAs are highly
`susceptible to lipid peroxidation, which results in oxida-
`tive products that cause deterioration of food quality and
`upon ingestion may cause cellular damage. Increased
`oxidation has been associated with increased risk of
`CVD, cancer, and cataracts, and also accelerates aging.
`Despite its high PUFA content, krill oil is considered
`relatively resistant to oxidation. The stability of krill oil
`has been attributed to its antioxidant content.9 The next
`section of the article assesses the antioxidant and vitamin
`content of krill.
`
`KRILL VITAMIN CONTENT
`
`Antioxidants neutralize free radicals and protect
`against cellular damage. Table 232 shows the level of
`selected antioxidant vitamins in krill, shrimp, and fish,
`along with the Recommended Dietary Allowances
`(RDAs) of these vitamins for adults. The level of vitamin
`A in krill, shrimp, and fish is below the RDA for adults.
`However, the vitamin A content in krill is greater than
`that in shrimp, trout, or salmon. Kinumaki31 reported a
`wide range of 197 to 1446 IU/100 g for the vitamin A
`content in raw or boiled krill. Krill also contains provi-
`tamin A. The principal carotenoid in krill is astaxanthin.
`The reported amount of 1.5 to 2.0 mg astaxanthin in
`100 g of krill tissue indicates that krill is a rich source of
`astaxanthin.8
`Astaxanthin has been used as a colorant added to
`fish feed to give farmed salmon their pink color. The
`discovery of astaxanthin’s powerful antioxidant proper-
`ties has led to research on its potential health benefits. In
`
`68
`
`Nutrition Reviews姞, Vol. 65, No. 2
`RIMFROST EXHIBIT 1171 Page 0006
`
`

`

`a recent review article,33 health benefits attributed to
`astaxanthin included reduced risk of cataracts, diabetes,
`heart disease, neural deterioration, and certain cancers;
`however, most of these studies were conducted using in
`vitro or animal models. In a human trial, young adult
`male volunteers provided astaxanthin in a daily beverage
`for 14 d showed protection against premature LDL oxi-
`dation in the absence of any other dietary changes.34
`Despite the promising results for astaxanthin, research is
`needed regarding the health benefits of astaxanthin de-
`rived from krill.
`One of the most important antioxidants is vitamin E,
`which functions specifically to protect against lipid per-
`oxidation in biological membranes. Due to methodolog-
`ical difficulties, vitamin E has not been determined
`extensively in foods. According to Table 2, krill meets
`the RDA for vitamin E and contains higher amounts of
`vitamin E than either shrimp or fish. Thus, the stability of
`krill may be attributed to its high levels of vitamin E.
`However, other components may also protect krill from
`oxidation. Dunlap et al.35 identified a marine-derived
`tocopherol with enhanced antioxidant effects on cellular
`lipids. Venkatraman et al.36 reported that mice fed a diet
`containing 10% krill oil had higher liver expression of
`endogenous antioxidant enzymes (i.e., catalase, glutathi-
`one peroxidase, and superoxide dismutase) and lower
`peroxide and thiobarbituric acid values compared with
`mice fed a 10% corn oil diet. The high content of vitamin
`E and the presence of other antioxidant components
`suggest that krill may have beneficial effects against
`oxidative damage.
`The water-soluble vitamins play an important role in
`maintaining health by acting as coenzymes in energy
`metabolism. Table 2 shows the levels of selected water-
`soluble vitamins in krill, shrimp, and fish, along with the
`RDA for these vitamins in adults. The levels of thiamin,
`riboflavin, and niacin are higher in fish compared with
`shellfish (i.e., krill and shrimp), but are below the RDA
`for adults, indicating that in general seafood is a poor
`source of these vitamins. Table 2 also shows the levels of
`the B-complex vitamins B12, B6, and folate in krill,
`shrimp, and fish. These vitamins play a role in the
`metabolism of homocysteine, so deficiencies can lead to
`high blood homocysteine. This has important implica-
`tions because a high blood level of homocysteine is an
`independent predictor of heart disease and stroke.37 The
`vitamin B6 content of most seafood is below the RDA,
`and levels in krill are below that of either shrimp or fish.
`Although krill is higher in folate than shrimp and fish,
`levels are still below the RDA. On the other hand,
`vitamin B12 in krill (16 ␮g/100 g) is substantially higher
`than in shrimp (1.16 ␮g/100g) or fish (4.17 to 4.45
`␮g/100g) and exceeds the RDA of 2.4 ␮g/d for adults.
`
`The assessment of the nutritive value of krill based on
`vitamin content indicates that it has considerable appeal
`for human consumption because it provides a good
`source of vitamin B12, vitamin E, and astaxanthin, as
`well as other potential antioxidant compounds.
`
`KRILL PROTEIN QUALITY
`
`Whole Krill
`
`Krill is a high-protein food, having a protein content
`estimated in the range of 60% to 65% dry weight.8
`Similar to other animal foods, the protein derived from
`krill is a complete protein, as indicated by the presence of
`all nine of the indispensable amino acids required by
`adults. As shown in Table 3,38 the level of all of the
`indispensable amino acids in whole krill met the FAO/
`WHO/UNU amino acid requirement for adults39 (with
`the exception of histidine). In contrast, several indispens-
`able amino acids in fish were below the amino acid
`requirement for adults, most notably methionine and
`cysteine. However, it should be noted that the indispens-
`able amino acid levels in whole krill were below the
`reference protein, egg. Tamura40 reported an amino acid
`score in the range of 0.85 to 1.00, indicating that the
`amount of indispensable amino acid provided by krill
`protein met the protein requirement of adults. Although
`considered a high-quality protein, krill is of lower quality
`than whole egg, which has an amino acid score of 1.21.
`In practice, protein quality is determined not only by
`the amino acid composition but also by its digestibility.
`Iwantani et al.41 fed rats a diet containing either egg
`protein or defatted, freeze-dried whole krill for 4 weeks,
`and then determined the weight gain of the animals to
`calculate the protein efficiency ratio. Biological value
`and net protein utilization were also measured to assess
`protein availability and digestibility. Rats fed whole krill
`gained less weight, had a reduced protein efficiency
`ratio, biological value, and net protein utilization com-
`pared with animals fed egg protein. The decreased di-
`gestibility of krill protein may have been due to the
`presence of the exoskeleton. Obatake22 determined the
`nutritive value of the protein in krill meat after removal
`of the exoskeleton, and found that it was still inferior to
`that of egg protein. Findings in the animal studies were
`not always indicative of the findings in humans. In a
`human trial, Tamura42 fed boiled krill or whole egg to
`adult men for 21 days and reported a net protein utiliza-
`tion of 55% for krill and 61% for whole egg, with no
`differences in their digestibility. Based on the evidence,
`krill appears to be a good source of high-quality protein.
`The large biomass and high-quality protein offered by
`krill provides an economical replacement for commer-
`
`Nutrition Reviews姞, Vol. 65, No. 2
`
`69
`RIMFROST EXHIBIT 1171 Page 0007
`
`

`

`cially available protein sources. In addition, commercial
`protein sources available for human consumption such as
`casein, whey, soy protein, lactoalbumin, and wheat glu-
`ten have various limitations. For example, casein is low
`in sulfur amino acids, particularly cysteine, which must
`be added to the diet. Products in which krill protein may
`substitute for other proteins are nutritional supplements,
`sports drinks, infant formulas, and milk replacers. For
`these products, protein concentrates rather than whole
`krill or krill meat are used.
`
`Krill Protein Concentrate
`
`Protein concentrates are produced by technologies
`that concentrate the proteins in food so that levels are
`higher than those in the original food, making them an
`inexpensive source of available protein. Preparation of
`protein concentrate from fish is accomplished by extract-
`ing the lipids, removing the bones, and drying, so that the
`resultant product is 85% to 95% higher in protein than
`the original fish. Lack of proper technology for protein
`recovery from krill has hindered progress in the com-
`mercial development of krill protein concentrates. Some
`research has been carried out that made use of krill’s high
`content of proteolytic enzymes to produce a product with
`protein recovery as high as 80%.43 There is technology
`available for isolating muscle protein in a continuous
`
`mode from whole krill to produce krill protein concen-
`trate. The continuous protein recovery technology is
`based on a principle of isoelectric solubilization followed
`by isolelectric precipitation of the protein. This basic
`biochemical principle has long been used in the dairy
`industry to manufacture cottage cheese, and also in other
`food processing industries such as those for soy protein
`isolates and concentrates. More recently, the principle of
`isoelectric point has been applied to fish muscle44 and
`other animal muscle.45 The protein recovery (dry basis)
`yield from krill using isoelectric solubilization/precipita-
`tion is approximately 90% or greater in a continuous
`mode. A more in-depth discussion of the isoelectrical
`solubilization recovery of krill is available elsewhere.3
`Table 446 shows the amino acid composition of krill
`protein concentrate compared with that of other commer-
`cially available protein concentrates such as casein, whey,
`and soy protein. The indispensable amino acid profiles of
`the protein concentrates were compared with the indispens-
`able amino acid requirements for adults and infants because
`protein concentrates are frequently used in infant formulas.
`As shown in Table 4, krill protein concentrate contains all
`indispensable amino acids in amounts that exceed the re-
`quirements for healthy adults. Krill protein concentrate also
`contains all of the indispensable amino acids in amounts
`that meet the requirements for infants (although leucine,
`tryptophan, and histidine levels were slightly below). Milk-
`
`70
`
`Nutrition Reviews姞, Vol. 65, No. 2
`RIMFROST EXHIBIT 1171 Page 0008
`
`

`

`derived whey protein concentrate, sodium caseinate, and
`soy protein concentrates are more deficient in the indispens-
`able amino acids for infants than are krill protein concen-
`trates.
`The amount of indispensable amino acids in krill
`protein concentrate is higher than that in soy protein
`concentrate and similar to that of the milk protein casein.
`Sidhu et al.29 reported that rats fed krill protein concen-
`trate had similar weight gain and protein efficiency ratio
`as rats fed casein. Although higher than casein, krill
`protein concentrate is low in threonine, leucine, lysine,
`and the sulfur amino acids (methionine and cysteine)
`compared with the whey protein concentrate (Table 4).
`This has important health implications because sulfur
`amino acids are involved in DNA transcription and RNA
`translation and may play a role in reducing the risk of
`CVD, dementia, cirrhosis, and immunomodulation.47
`The health benefits and safety issues regarding the use of
`alternative protein sources need to be investigated in
`more detail.
`
`The Health Benefits and Safety of Krill Protein
`
`Adequate protein intakes are necessary for synthesis
`of structural components of the muscle and of enzymes,
`
`hormones, hemoglobin, and other body tissues. Sidhu et
`al.29 reported that rats fed krill protein concentrate
`showed no difference in organ weights and hemoglobin
`counts than rats fed casein, indicating that krill protein is
`capable of supporting protein synthesis. Too much rather
`than too little protein is typical of the Western diet.
`Consuming protein beyond recommended amounts is
`common among athletes interested in increasing their
`muscle mass. The general population has also recently
`developed an interest in increasing their protein intakes
`due to suggestions that high-protein diets support weight
`loss, and there is some evidence that short-term con-
`sumption of high-protein diets increases satiety and ther-
`mogenesis and reduces energy intake.48 However, de-
`spite growing interest in proteins, the long-term effects
`of high-protein diets on weight loss are unknown and
`there may be harmful effects associated with such diets.
`For example, diets high in protein have been suggested to
`increase the risk for cardiac, renal, bone, and liver
`disease.49
`High-protein diets have also been suggested to in-
`crease the risk of CVD by inducing negative effects on
`blood lipid profiles. However, the negative effects on
`blood lipids are more likely due to the high SFA intakes
`associated with most high-protein diets. Krill, unlike
`
`Nutrition Reviews姞, Vol. 65, No. 2
`
`71
`RIMFROST EXHIBIT 1171 Page 0009
`
`

`

`is low in SFAs.
`other animal sources of proteins,
`Obatake22 reported no difference in serum cholesterol
`levels for rats fed boiled whole krill or krill meat com-
`pared with animals fed casein.
`Another area of concern is the use of alternate
`protein sources in infant formulas. Soy protein has been
`reported to accelerate puberty in female rats compared
`with whey and casein.50 Other concerns regarding alter-
`native protein sources are their ability to support growth
`and their long-term health effects.50 In addition, all food
`proteins have the potential to be allergenic to some
`people. Approximately 1% to 2% of adults and up to 5%
`to 7% of children experience food allergies with symp-
`toms ranging from a mild rash to life-threatening ana-
`phylaxis.51 The Food and Agricultural Organization of
`the United Nations includes crustaceans on its list of the
`eight most significant food allergens.52 According to
`Wild and Lehrer,53 shellfish is the number-one cause of
`food allergies in adult Americans. To our knowledge, no
`studies have examined whether krill protein or krill
`protein concentrate causes food allergies. Determining
`the protein allergens present in krill and the relative
`allergenic activity of krill compared with other major
`protein substitutes is important. For example, soy protein
`used to manage cow’s milk allergies in infants has been
`reported to have less allergenic reactivity compared with
`milk proteins; however, concerns have been raised re-
`garding the isoflavone content in soy infant formulas
`affecting neurobehavioral development, immune, endo-
`crine, and thyroid function.54 Krill protein concentrate,
`which