2. OBJECTIVES
1. Review the definition, diagnostic criteria, and prevalence of metabolic
syndrome
2. Explore n-3 PUFAs and how they relate to metabolic syndrome (MetS)
3. Discuss the findings from early studies
4. Summarize the results, strengths and weaknesses, and recommendations of
the supporting and main articles
5. Give recommendations for future research
6. Provide a take home message
3. Family with Mets
MeMom Dad
GrandM
other
GrandF
ather
Uncle
GrandM
other
Great
Uncle
AuntUncle
Great
Aunt
Cousin
• 6 on my mother’s side • 5 on my father’s side
11 total family members with MetS
4. 10% of children have MetS
34% of American adults have MetS according to the AHA
50% of adults >50 yrs old have MetS
Individuals with MetS are 5x more likely to develop diabetes and 2x more likely to
develop CVD
5. WHAT IS METABOLIC SYNDROME?
Definition: A cluster of biochemical and physiological
abnormalities associated with the development of cardiovascular
disease and type 2 diabetes
Diagnostic Criteria: The patient must present with 3 of the 5
biochemical/physiological complications
o Waist circumference and HDL differ between genders
6. ROLE OF N-3 PUFAS
N-3 PUFAs shown to modulate
- Inflammation
- Oxidative stress
- Obesity
- Endothelial dysfunction
- Hypertriglyceridemia
Exert slight effects on
- Hypertension
- LDL size
- Insulin sensitivity
7. OMEGA-3 FATTY ACIDS
ALA, EPA, & DHA
ALA food sources: Vegetable oils, nuts, seeds
EPA/DHA food sources: marine fish, fish oil
Interconversion is very limited
8. ESSENTIALITY AND N-6/N-3 RATIO
N-3 PUFAs are essential nutrients
Humans lack desaturase enzymes needed to
synthesize N-3’s de novo
N-3 needs depend on N-6 intake
N-3 and N-6 share a similar metabolic pathway and compete for
desaturase and elongase enzymes
The higher the n-6 intake, the more n-3 will be required to see positive
effects of intervention
Baseline levels vary by geographical location
9. DOSAGE AND SIDE EFFECTS
N-3 recommendations depend on disease progression
Most interventional studies use between 1-2g/day
The AI has been set at 1.6g/day for men and 1.1g/day for women
Very few and minimal negative effects: fishy taste, fish burps, GI disturbance,
steatorrhea, slight LDL-C increase, potential for increased bleeding risk, potential
for decreased immunity, possible environmental contamination
FDA ruled that intakes up to 3 g/day are Generally Recognized As Safe (GRAS)
and are unlikely to result in bleeding
10. EARLY STUDIES ON METS ABNORMALITIES
1978: Dyerberg reported that higher EPA levels are protective against thrombosis and atherosclerosis
1979: Dyerberg reported Greenland Eskimos have lower incidence of thrombotic disorders and heart attack due to
substitution of arachidonic acid with EPA
1980: Hirai reported higher EPA/AA ratio in a Japanese fishing village with lower incidence of cardiovascular and
inflammatory diseases
1980: Kromann reported lower incidence of inflammatory disorders in Greenland Eskimos with high fish intake
1983: Prickett reported EPA protected mice from autoimmune nephritis by reducing inflammation
1985: Kromhout et al reported an inverse relation between fish consumption and 20-year mortality from coronary heart
disease
11. EARLY STUDIES CONT.
1987: Joel reported that fish oil supplementation resulted in alleviation of active rheumatoid arthritis
1991: Dolecek reported an inverse relation between dietary PUFA intake and all cardiovascular diseases
1991: Stenson reported fish oil supplementation results in significant improvements in ulcerative colitis
1997: Daviglus et al reported an inverse relation to fish consumption and death from myocardial infarction
2002: Hu et al reported higher consumption of fish and N-3 PUFAs is associated with a lower risk of CHD death
12. N-3/N-6 METABOLISM AND INFLAMMATION
N-6 fatty acids N-3 fatty acids
Arachidonic Acid Eicosapentaenoic Acid
Series 2 Prostaglandins Series 3 Prostaglandins
Series 2 Thromboxanes Series 3 Thromboxanes
Series 4 Leukotrienes Series 5 Leukotrienes
Pro-inflammatory Anti-inflammatory
• Mechanism to reduce inflammation/oxidative stress/endothelial dysfunction
13. PUFA REGULATION OF GENE EXPRESSION
• Mechanism to reduce hypertriglyceridemia & obesity / increase HDL
Protein Effect of n-3 PUFA
SREBP1
(sterol regulatory element
binding protein)
Inhibition
(Decreases lipogenic genes)
Sp1
(Stimulatory protein 1)
Inhibition
(Decreases lipogenic genes)
NF-Y
(Nuclear factor Y)
Inhibition
(Decreases lipogenic genes)
PPAR
(Peroxisome proliferator-
activated receptor response
element)
Activation
(Increases lipolytic genes)
CETP
(Cholesterol ester transfer
protein)
Inhibition
(Increases HDL cholesterol)
14. Supporting Article 1
Metabolic Syndrome: Effects of n-3 PUFAs on
a Model of Dyslipidemia, Insulin Resistance,
and Adiposity
Lombardo, Y. B., Hein, G., & Chicco, A. (2007). Metabolic Syndrome:
Effects of n-3 PUFAs on a Model of Dyslipidemia, Insulin Resistance,
and Adiposity Lipids, 42, 427-437.
15. SUPPORTING ARTICLE 1: LOMBARDO ET AL
Purpose: Investigate the effectiveness of fish oil to reverse dyslipidemia, insulin resistance, and adiposity induced by long term feeding of
a sucrose-rich diet
Methods
1. Wistar rats randomly divided into a control group(N=12) or experimental group (N=12)
o Experimental: Sucrose rich diet (62.5% sucrose, 17% casein, 8% corn oil, 7.5% cellulose, 3.5% salt mixture, 1.5% vitamin mixture)
o Control (CD): Isocaloric diet except sucrose was replaced by starch
2. After 6 months, the experimental group randomly divided into two subgroups.
o Subgroup 1(SRD): Continued the sucrose rick diet up to 8 months
o Subgroup 2 (SRD + FO): Source of fat was replaced with fish oil for the remaining two months
o Control Diet (CD): maintained control diet throughout the 8 month period
- Diets were isoenergetic and provided ad libitum
3. Blood samples were taken to test for FFA and glucose concentrations
Liver, pancreas, gastrocnemius, and adipocyte tissues were assayed for lipogenic and glycogenic enzyme activity
Statistical Analysis: 1-way ANOVA and Newman Keul’s test
16. RESULTS
• Fish oil significantly reduced
plasma triglyceride, FFA, and
glucose concentrations
• Lipogenic enzymes are significantly reduced in the FO group
• Lipolytic enzymes are significantly increased in the FO group
• Triglycerides and triglyceride secretion rate significantly reduced in the
FO group
17. • Insulin sensitivity restored
in FO group
• FO significantly reduced
fat concentration, cell
volume, and relative
weight in both epididymal
and retroperitoneal areas
• LPL levels significantly
higher in SRD group
18. • FO completely normalized glucose stimulated insulin secretion
in SRD fed rats
• In pancreatic islet cells, triglyceride levels were significantly
lower in the FO group which allowed for a normalization of
PDHc activity
19. STRENGTHS/WEAKNESSES
Strengths
• Long study period (8 months)
• Multiple analytical methods (blood samples, tissue
assays from multiple sites, different stimulators for
insulin secretion response)
• Randomization
• Confounding variables tightly controlled for
Weaknesses
• Small sample size (N=12)
• Animal study can’t be generalized to humans
20. Supporting article 2
Omega-3 fatty acid supplements improve the
cardiovascular risk profile of subjects with
metabolic syndrome, including markers of
inflammation and auto-immunity
Ebrahimi, M., Ghayour-Mobarhan, M., Rezaiean, S., Hoseini, M., Parizade,
S.M., Farhoudi, F., & Hosseininezhad, S.J. (2009). Omega-3 fatty acid
supplements improve the cardiovascular risk profile of subjects with
metabolic syndrome, including markers of inflammation and auto-immunity
Acta Cardiologica, 64(3), 321-327.
21. SUPPORTING ARTICLE 2: EBRAHIMI ET AL
Purpose: To investigate the effect of n-3 PUFAs on established cardiovascular risk factors
including anthropometric and biochemical parameters and heat shock protein (Hsp) 27
antibody titers in subjects with metabolic syndrome
Methods: Subjects were randomly assigned to either a control group (N=60)or experimental
group (N=60) for the 6 month test period
o Control group: Maintained normal diet throughout the 6 months
o Experimental group: Normal diet plus daily fish oil capsules (1g/day)
- Fatty acid capsules contained 180mg EPA + 120mg DHA
- Compliance monitored by weekly visits and counting capsules
o Anthropometric and lab data were collected at the end of the trial
Statistical Analysis: Kolmogorov-Smirnov test, ANOVA, Fisher’s exact test, chi square test
22. RESULTS
• Fish oil significantly
reduced weight, BMI,
and systolic blood
pressure
23. • The fish oil group significantly lowered total cholesterol, LDL cholesterol, and
triglycerides
• Significant reduction of inflammatory markers Hsp 27 and CRP
24. STRENGTHS/WEAKNESSES
Strengths
• Length of study (6 months)
• Sample size (120)
• Compliance was monitored
Weaknesses
• Many subjects were taking anti-hypertensive and anti-
diabetic medication
• Effects may have been due to other dietary factors
• Not double-blind or placebo controlled
• Effects in the intervention group may have been due to
25. Main Article
Omega-3 PUFAs improved endothelial
function and arterial stiffness with a parallel
anti-inflammatory effect in adults with
metabolic syndrome
Tousoulis, D., Plastiras, A., Siasos, G., Oikokomou, E., Verveniotis, A.,
Kokkou, E., & Maniatis, K. (2014). Omega-3 PUFAs improved endothelial
function and arterial stiffness with a parallel antiinflammatory effect
inadults with metabolic syndrome. Atherosclerosis, 232, 10-16.
26. MAIN ARTICLE: TOUSOULIS ET AL
• Purpose: Evaluate the effects of n-3 PUFAs on vascular
function and inflammatory processes in subjects with MetS
• Methods: Double-blind, placebo-controlled, crossover
design
Subjects randomly assigned to either a control group (N=14) or
experimental group (N=15) for 12 weeks
o Experimental: Regular diet + daily N-3 PUFA capsule
(2g/day, 46% EPA & 38% DHA)
o Control: Regular diet + daily placebo capsule
Statistical Analysis: ANOVA
- Subjects instructed to avoid changes in diet or exercise
patterns
- Compliance monitored by daily physical activity and diet logs
- Those on cardiovascular or inflammatory medications were
excluded
27. RESULTS
• Significant reductions in total cholesterol, triglycerides, and LDL-C at day 28
• Significant improvements in FMD, PWV, lipid profile, glucose, IL-6, and PAI-1 at day 84
28. • Endothelial function and arterial
stiffness significantly improved
• Inflammation significantly reduced
• Normalization of fibrinolysis
29. STRENGTHS/WEAKNESSES
Strengths
• Double-blind, placebo controlled
• Crossover design
• Strictly controlled for confounding variables (medications,
diet, exercise)
• Length of study (3 months)
• Multiple measurements to test endothelial functionWeaknesses
• Didn’t test other inflammatory markers (CRP, TNF-a, IL-8)
• Small sample size (29)
30. SUMMARY OF FINDINGS
Study Objective Conclusion
Lombardo et al
- Supporting Article 1
Investigate the effectiveness of
fish oil to reverse dyslipidemia,
insulin resistance, and adiposity
induced by long term feeding of
a sucrose-rich diet
Dietary fish oil reverses
dyslipidemia and improves insulin
action and adiposity in SRD fed
rats.
Ebrahimi et al
- Supporting Article 2
To investigate the effect of n-3
PUFAs on established
cardiovascular risk factors
including anthropometric and
biochemical parameters and heat
shock protein (Hsp) 27 antibody
titres in subjects with metabolic
syndrome
Omega-3 supplementation
improves the cardiovascular risk
profile of subjects with MetS,
having positive effects on weight,
BMI, systolic blood pressure, lipid
profile, and markers of
inflammation and immunity.
Tousoulis et al
- Main Article
Evaluate the effects of n-3 PUFAs
on vascular function and
inflammatory processes in
subjects with MetS
Treatment with omega-3 PUFAs
may favorably affect endothelial
function and the elastic
properties of the arterial tree in
MetS subjects, with a parallel
anti-inflammatory effect.
31. FUTURE STUDIES
Defining the optimal N-6/N-3 ratio for metabolic syndrome
Further understanding of the underlying cellular mechanisms used by N-3 PUFAs
Studying N-3 effects on subjects with different genotypes
Differentiating the independent effects of EPA vs. DHA vs. ALA
Long term effects of omega-3 PUFA supplementation
32. TAKE HOME MESSAGE
Reducing the intake of omega-6, and increasing the
intake of omega-3 PUFAs, will be beneficial for reversing
the aberrations of metabolic syndrome including
hypertriglyceridemia, high LDL-C, central obesity,
endothelial dysfunction, and inflammation.
34. REFERENCES
Carpentier, Y. A., Portois, L., & Malaisse W.J. (2006). n-3 Fatty acids and the metabolic syndrome The American Journal of
Clinical Nutrition, 83, 1499-1504.
Clarke, S. D. (2001). Polyunsaturated Fatty Acid Regulation of Gene Transcription: A Molecular Mechanism to Improve the
Metabolic Syndrome. The Journal of Nutrition, 131, 1129-1132.
Daviglus, M. L., Stamler, J., Orencia, A. J., Dyer, A. R., Liu, K., Greenland, P., ... & Shekelle, R. B. (1997). Fish consumption and
the 30-year risk of fatal myocardial infarction. New England Journal of Medicine, 336(15), 1046-1053.
Delarue, J., Guen, V.L., Corporeau, C., & Guillerm, S. . (2007). Can Marine Omega 3 Fatty Acids Prevent and/or Treat
Metabolic Syndrome? . Current Nutrition & Food Science, 3, 151-156.
Dolecek, T. A., & Grandits, G. (1991). Dietary polyunsaturated fatty acids and mortality in the Multiple Risk Factor
Intervention Trial (MRFIT). World review of nutrition and dietetics.
Dyerberg, J., Bang, H. O., Stoffersen, E., Moncada, S., & Vane, J. R. (1978). Eicosapentaenoic acid and prevention of
thrombosis and atherosclerosis?. The Lancet, 312(8081), 117-119.
Dyerberg, J., & Bang, H. O. (1979). Haemostatic function and platelet polyunsaturated fatty acids in Eskimos. The
Lancet, 314(8140), 433-435.
Ebrahimi, M., Ghayour-Mobarhan, M., Rezaiean, S., Hoseini, M., Parizade, S.M., Farhoudi, F., & Hosseininezhad, S.J. (2009).
Omega-3 fatty acid supplements improve the cardiovascular risk profile of subjects with metabolic syndrome, including
markers of inflammation and auto-immunity Acta Cardiologica, 64(3), 321-327.
Flachs, P., Rossmeisl, M., & Kopecky, J. . (2014). The Effect of n-3 Fatty Acids on Glucose Homeostasis and Insulin
Sensitivity Physiological Research, 63, 93-118.
Friend, A., Craig, L., & Turner, S. (2013). The prevalence of metabolic syndrome in children: a systematic review of the
literature. Metabolic syndrome and related disorders, 11(2), 71-80.
35. REFERENCES CONT.
Hirai, A., Hamazaki, T., Terano, T., Nishikawa, T., Tamura, Y., Kumagai, A., & Sajiki, J. (1980). EICOSAPENTAENOIC ACID AND
PLATELET FUNCTION IN TAPANESE. The Lancet, 316(8204), 1132-1133.
Hu, F. B., Bronner, L., Willett, W. C., Stampfer, M. J., Rexrode, K. M., Albert, C. M., ... & Manson, J. E. (2002). Fish and
omega-3 fatty acid intake and risk of coronary heart disease in women. Jama, 287(14), 1815-1821.
Kremer, J. M., JUBIZ, W., MICHALEK, A., RYNES, R. I., BARTHOLOMEW, L. E., BIGAOUETTE, J., ... & LININGER, L. (1987). Fish-
oil fatty acid supplementation in active rheumatoid arthritis: a double-blinded, controlled, crossover study. Annals of
internal medicine, 106(4), 497-503.
Kris-Etherton, P. M., Harris, W.S., & Appel, L.J. (2002). Fish Consumption, Fish Oil, Omega-3 Fatty Acids, and
Cardiovascular Disease. Circulation, 106, 2747-2757.
Kromann, N., & Green, A. (1980). Epidemiological studies in the Upernavik district, Greenland. Acta Medica
Scandinavica, 208(1‐6), 401-406.
Kromhout, Daan, Edward B. Bosschieter, and Cor de Lezenne Coulander. "The inverse relation between fish consumption
and 20-year mortality from coronary heart disease." New England journal of medicine 312.19 (1985): 1205-1209.
Lombardo, Y. B., Hein, G., & Chicco, A. (2007). Metabolic Syndrome: Effects of n-3 PUFAs on a Model of Dyslipidemia,
Insulin Resistance, and Adiposity Lipids, 42, 427-437.
Lopez-Huertas, E. (2012). The effect of EPA and DHA on metabolic syndrome patients: a systematic review of randomised
controlled trials British Journal of Nutrition, 107, 185-194.
Lorenta-Cebrian, S., Costa, A.G., Navas-Carretero, S., Zabala, M., Martinez, J.A., & Moreno-Aliaga, M.J. (2013). Role of
omega-3 fatty acids in obesity, metabolic syndrome, and cardiovascular disease: a review of the evidence Journal of
Physiology and Biochemistry, 69, 633-651.
Poudyal, H., Panchal, S.K., Diwan, V., & Brown, L. . (2011). Omega-3 fatty acids and metabolic syndrome: Effects and
emerging mechanisms of action. Progress in Lipid Research, 50, 372-387.
36. REFERENCES CONT.
Prickett, J. D., Robinson, D. R., & Steinberg, A. D. (1983). Effects of dietary enrichment with eicosapentaenoic acid upon
autoimmune nephritis in female NZBxNZW/F1 mice. Arthritis & Rheumatism, 26(2), 133-139.
Robinson, L. E., Buchholz, A.C., & Mazurak, V.C. (2007). Inflammation, obesity, and fatty acid metabolism: influence of n-3
polyunsaturated fatty acids on factors contributing to metabolic syndrome Applied Physiology, Nutrition, and Metabolism, 32,
1008-1024.
Robinson, L. E., & Mazurak, V.C. (2013). N-3 Polyunsaturated Fatty Acids: Relationship to Inflammation in Healthy Adults
Exhibiting Features of Metabolic Syndrome Lipids, 48, 319-332.
Simopoulos, A. P. (1991). Omega-3 fatty acids in health and disease and in growth and development. The American journal of
clinical nutrition, 54(3), 438-463.
Simopoulos, A. P. (2002). Omega-3 fatty acids in inflammation and autoimmune diseases. Journal of the American College of
Nutrition, 21(6), 495-505.
Tousoulis, D., Plastiras, A., Siasos, G., Oikokomou, E., Verveniotis, A., Kokkou, E., & Maniatis, K. (2014). Omega-3 PUFAs
improved endothelial function and arterial stiffness with a parallel antiinflammatory effect inadults with metabolic syndrome.
Atherosclerosis, 232, 10-16.
