Clarifying krill – what’s the hype?

Nina BaileyBSc MSc PhD ANutr

Krill are shrimp-like crustaceans of the species Euphausia superba, found mostly in the Antarctic and North Pacific oceans

• The DHA content of krill is similar to that of oily fish, but the EPA content is generally higher

• Krill oil also contains the carotenoid astaxanthin, a naturally occurring antioxidant that gives krill oil its red/pink colour and that acts as a natural preservative

• The growing interest in krill as an alternative source of omega-3 is leading to an increase in krill oil products

• The message that krill may provide benefits similar to fish oil has been growing rapidly although there are still relatively few human studies conducted on krill

• Initial indications suggest that krill oil can reduce inflammation and cardiovascular risk factors including cholesterol and triglycerides

• Studies confirming the specific benefits of fish oil currently run into the thousands, compared to only a handful on krill oil

Krill oil – USPs

• The long-chain fatty acids in krill are absorbed and carried to the body’s cells in phospholipid form

• Phospholipids form the structural basis of cell membranes and are more effectively utilised by the body

All fat must be digested before uptake:

Lipase breaks bonds in triglyceridesPhospholipase breaks bonds in phospholipidsCarboxyl ester lipase breaks bonds in ethyl esters

MonoglyceridesFree fatty acidsLysophosphatides

After absorption into enterocytes, the metabolism of long-chain fatty acids involves re-esterification into:

Triglyceride (2-monoglyceride pathway)Phospholipid (a-glycerophosphate pathway)Formation of chylomicrons for further

transport

Much of the marketing of krill oil focuses on its superior bioavailability, with consumer targeted messages such as ‘less is more’

MegaRed Krill oil 300mg ‘one-a-day-capsule’ delivers 36mg EPA and 16.5mg DHA

But are the omega-3 fatty acids in krill oil more bioavailable than those found in standard fish body oil?

Vitabiotics Ultra Krill oil

MegaRed Superba Red

Bioglan Holland & Barrett

CardioRed Healthspan

Krill oil content (mg/capsule) 1000 300 500 500 1500 500 500

EPA/capsule (mg/capsule) 120 36 70 60 120 70 70

DHA/capsule (mg/capsule) 55 16.5 32 27.5

75 32.5 32

Total omega-3/g oil 220 220 250 175 170 240 240

EPA/g oil 120 120 140 120 80 140 140

DHA/g oil 55 55 64 55 50 65 64

NB Average omega-3 = 216 mg/g; average EPA = 123 mg/g; average DHA = 58 mg/g

Krill vs fish oil in ‘like for like’ dosing (Maki et al., 2009)

2g krill oil vs 2g fish oil

Comparing krill with fish oil (Ulven et al., 2011)

3.0g krill oil vs 1.8g fish oil

Comparing krill, rTAG and EE at comparative doses (Schuchardt et al., 2011)

EPA and DHA 1680mg

Krill vs fish oil in ‘like for like omega-3’ dosing (Ramprasath et al., 2013)

600mg of omega-3

Study 1

Study 1• 4-week randomised double-blind intervention in ‘healthy’

but overweight individuals

– Krill oil (2.0 g/day) • 216 mg EPA: 90 mg DHA (omega-3 = 306 mg)• n = 25

– Fish oil (2.0 g/day) • 212 mg EPA: 178 mg DHA (omega-3 = 390mg)• n = 26

– Control group• Olive oil• n = 25

– Krill oil216 mg EPA: 90 mg DHA(omega-3 = 306 mg)

– Fish oil 212 mg EPA: 178 mg DHA (omega-3 = 390mg)

Krill oil delivers 22% less omega-3

Plasma concentrations μmol/L

Main findings

No significant differences in changes in serum lipids, glucose homeostasis, markers of inflammation or oxidative stress

Significant increases from baseline in plasma levels of EPA and DHA were observed in both the krill and fish oil groups but not the control

At the end of the treatment period, the mean plasma EPA concentration was higher in the krill oil group compared with the fish oil group (377 vs 293 μmol/L), whereas the mean plasma DHA concentrations were comparable (476 vs 478 μmol/L)

The authors therefore suggest that the EPA and DHA from krill oil are absorbed at least as well as that from fish oil

Study 2

• 7-week intervention ‘healthy’ individuals

– Krill oil (3.0 g/day) • 543 mg EPA + DHA• n = 36

– Fish oil (1.8 g/day) • 864 mg EPA + DHA• n = 40

– Control group• no supplementation

Main findings

No significant differences in changes in serum lipids or markers of inflammation or oxidative stress

Significant increases in plasma EPA, DPA and DHA were observed in both the krill and fish oil groups but not the control

No significant differences in plasma EPA, DPA and DHA between the krill and fish oil groups

The authors therefore suggest that krill and fish oil represent comparable dietary sources of omega-3 even if the EPA and DHA dose in the krill oil was 62.8% of that in the fish oil

Baseline 7 weeks 40

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Fish oil Krill oil Control

Changes in EPA blood plasma levels (mmol/L) after seven weeks of supplementation with krill oil, fish oil or placebo

EPA

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Ulven SM, Kirkhus B, Lamglait A, Basu S, Elind E, Haider T, Berge K, Vik H, Pedersen JI. Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteers. Lipids. 2011 46:37-46.

Changes in DHA blood plasma levels (mmol/L) after seven weeks of supplementation with krill oil, fish oil or placebo

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Baseline 7 weeks 20

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Fish oilKrill oilControl

Ulven SM, Kirkhus B, Lamglait A, Basu S, Elind E, Haider T, Berge K, Vik H, Pedersen JI. Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteers. Lipids. 2011 46:37-46.

Baseline 7 weeks 175

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Fish oilKrill oilControl

Changes in AA blood plasma levels (mmol/L) after seven weeks of supplementation with krill oil, fish oil or placebo

AA b

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Ulven SM, Kirkhus B, Lamglait A, Basu S, Elind E, Haider T, Berge K, Vik H, Pedersen JI. Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteers. Lipids. 2011 46:37-46.

Study 3

Incorporation of EPA and DHA into plasma phospholipids in response to different omega-3 fatty acid formulations

Double-blinded cross overn = 12 (males)Single dose of:

• 7.0g krill oil (1050 mg EPA: 630mg DHA)• 3.4g fish oil ethyl-ester (1008mg EPA: 672mg) • 3.4g fish oil triglyceride (1008mg EPA: 672mg)

• Main findings– The omega-3 concentrations in plasma phospholipids were at

their highest 24 hours after consumption of all three EPA and DHA containing oils

– EPA and DHA were absorbed in the following orderKrill oil > triglyceride > ethyl ester

– Krill oil contained high amounts of EPA and DHA as free fatty acids rather than as total phospholipid (22% EPA and 21% DHA)

– However, due to high standard deviation values, there were no statistically significant difference in uptake between the three treatments

Study 4

Double-blinded, randomised, placebo-controlled, crossover trialThree treatment phases:

3g krill oil providing 600mg of omega-33g fish oil providing 600mg of omega-33g placebo control (corn oil)

Each treatment lasted 4 weeks with each separated by an 8-week washout phase

Main findings

Consumption of 3g/day krill oil for 4 weeks increased plasma and RBC concentrations of total omega-3, EPA, and the sum of EPA and DHA compared with fish and corn oil

Consumption of 3g/day krill oil for 4 weeks decreased plasma omega-6 fatty acids with a subsequent decrease in the omega-6 to omega-3 ratio

Authors conclude that krill is superior to fish oil in increasing omega-3, decreasing the omega-6 to omega-3 ratio and improving the omega-3 index

However……

Careful examination of the fatty acid profiles of the oils used showed that the fish oil used was not a typical fish oil

To match the concentrations of omega-3 and volumes between krill and fish oil, the fish oil was diluted with corn oil at a ratio of 1.3:1.0

Of the 3g ‘fish oil’ total, only 1.7g was true fish oil, with 1.3g corn oil added to ‘make up the volume’

However…… The omega-6 content of the krill oil was low (1.73g/100g oil)

compared with fish oil (21.95g/100g oil)

Linoleic acid was the dominant fatty acid (32%) in the fish oil giving it an omega-6 to omega-3 of >1

The omega-3 content of the krill oil delivered 17% more omega-3 than the fish oil (778mg vs 664mg)

Due to the fatty acid profile being non-representative of typical commercially marketed fish oil, the conclusions presented were subsequently deemed not justified and misleading (Nichols et al., 2014)

Nichols et al., 2014

2g krill oil vs 2g fish oilComparable uptake of EPA and DHA

3g krill oil vs 1.8g fish oilComparable uptake of EPA and DHA but no significant difference in omega-3 levels with higher intake of krill – doesn’t support the ‘less is more’ claim

Krill vs rTG vs EE Supplementing with 7g krill delivers comparable EPA and DHA to rTAG and EE without significantly increased bioavailability

3g krill oil vs 3g fish oilUptake of EPA and DHA as krill oil superior to fish oil ?? Issue with study bias

Although superior bioavailability of omega-3 in krill oil over fish oil is suggested, none of the studies have managed to show significant improvement in absorption of omega-3 fatty acids from krill oil over fish oil

At the most, data from a bioavailability study in humans showed a tendency for higher bioavailability for EPA after krill oil consumption compared with fish oil (Schuchardt et al., 2013); however, this study tested an acute single dose of omega-3 PUFA over 48h

The study by Ramprasath et al, 2013 must be interpreted with caution because of study bias

• It is likely that EPA and DHA in phospholipid found in krill oil is more bioavailable than EPA found in fish oil as either triglyceride or ethyl-ester form

• EPA and DHA are absorbed in the following order: Krill oil > triglyceride > ethyl ester, which would be expected given that krill oil is in phospholipid

• Ethyl-ester bioavailability can be significantly improved if taken with other fat to provide the glycerol backbone required for re-esterification (Nordov et al., 1991)

Summary

• Krill delivers approx. 123mg EPA per gram and delivers both EPA and DHA

• It is generally accepted that highly concentrated omega-3 oils are required to deliver therapeutic outcomes– 1g EPA required for depression– 2g EPA required for schizophrenia– 2-4g EPA required for hypercholesterolaemia

• Whilst krill oil raises EPA and DHA levels comparative to that of fish oil, high volumes of krill oil would required to achieve the therapeutic levels of omega-3 that can be delivered by oils containing 70-90% omega-3

Summary• There is little evidence to support the bioavailability claims

related to krill oil

• Many of the health benefits attributed to krill oil may arise from its high astaxanthin content

• Given the cost of krill oil compared to standard fish oils, krill oil may not currently offer a cost-effective substitute for highly concentrated omega-3 products

• More human intervention studies are required to investigate the effects of krill oil

References• Maki KC, Reeves MS, Farmer M, Griinari M, Berge K, Vik H, Hubacher R, Rains TM: Krill oil

supplementation increases plasma concentrations of eicosapentaenoic and docosahexaenoic acids in overweight and obese men and women. Nutrition research 2009, 29:609-615.

• Nichols PD, Kitessa SM, Abeywardena M: Commentary on a trial comparing krill oil versus fish oil. Lipids in health and disease 2014, 13:2

• Ramprasath VR, Eyal I, Zchut S, Jones PJ: Enhanced increase of omega-3 index in healthy individuals with response to 4-week n-3 fatty acid supplementation from krill oil versus fish oil. Lipids in health and disease 2013, 12:178.

• Schuchardt JP, Schneider I, Meyer H, Neubronner J, von Schacky C, Hahn A: Incorporation of EPA and DHA into plasma phospholipids in response to different omega-3 fatty acid formulations--a comparative bioavailability study of fish oil vs. krill oil. Lipids in health and disease 2011, 10:145.

• Ulven SM, Kirkhus B, Lamglait A, Basu S, Elind E, Haider T, Berge K, Vik H, Pedersen JI: Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteers. Lipids 2011, 46:37-46.

ninab@igennus.comwww.igennus.comdrninabailey.co.uk

01223 42143407527384229

Vitabiotics Ultra Krill oil

MegaRed Superba Red

Bioglan Holland & Barrett

CardioRed Healthspan

Price £ 14.95 17.99 23.95 21.99 26.99 24.95 15.95

Capsules 30 30 60 30 60 60 60

Recommended dose (daily) 1-2g 300mg 1-1.5g 500mg 3 g 1g 0.5 - 1g

Krill oil content (mg/capsule) 1000 300 500 500 1500 500 500

EPA/capsule (mg/capsule) 120 36 70 60 120 70 70

DHA/capsule (mg/capsule) 55 16.5 32 27.5 75 32.5 32

Total omega-3/g oil 220 220 250 175 170 240 240

EPA/g oil 120 120 140 120 80 140 140

DHA/g oil 55 55 64 55 50 65 64

NB Average omega-3 = 216 mg/g; average EPA = 123 mg/g; average DHA = 58 mg/g