1. Clarifying krill – what’s the hype?
Nina Bailey
BSc MSc PhD ANutr

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

3. • 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

4. • 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

5. 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

7.  All fat must be digested before uptake:
Lipase breaks bonds in triglycerides
Phospholipase breaks bonds in phospholipids
Carboxyl ester lipase breaks bonds in ethyl esters
Monoglycerides
Free fatty acids
Lysophosphatides

8.  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

10.  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?

11. 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

12.  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

13. Study 1

14. 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

15. – Krill oil
216 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

16. 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

17. Study 2

18. • 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

19. 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

20. Baseline 7 weeks
40
45
50
55
60
65
70
75
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
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.

21. Changes in DHA blood plasma levels (mmol/L) after seven weeks of
supplementation with krill oil, fish oil or placebo
Baseline 7 weeks
20
30
40
50
60
70
80
Fish oil
Krill oil
Control
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.

22. Baseline 7 weeks
175
177
179
181
183
185
187
189
191
193
195
Fish oil
Krill oil
Control
Changes in AA blood plasma levels (mmol/L) after seven weeks of
supplementation with krill oil, fish oil or placebo
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.

23. Study 3

24. Incorporation of EPA and DHA into plasma phospholipids in
response to different omega-3 fatty acid formulations
Double-blinded cross over
n = 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)

26. • 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 order
Krill 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

27. Study 4

28. Double-blinded, randomised, placebo-controlled,
crossover trial
Three treatment phases:
3g krill oil providing 600mg of omega-3
3g fish oil providing 600mg of omega-3
3g placebo control (corn oil)
Each treatment lasted 4 weeks with each separated by
an 8-week washout phase

29. 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

30. 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’

31. 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)

32. 
Nichols et al., 2014

33.  2g krill oil vs 2g fish oil
Comparable uptake of EPA and DHA
 3g krill oil vs 1.8g fish oil
Comparable 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 oil
Uptake of EPA and DHA as krill oil superior to fish oil ?? Issue with study
bias

34.  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

35. • 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

36. • 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

37. 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

38. 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.

39. ninab@igennus.com
www.igennus.com
drninabailey.co.uk
01223 421434
07527384229

41. 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