Meta-analysis of the effects of n-3 polyunsaturated fatty acids on lipoproteins and other emerging lipid cardiovascular risk markers in patients with type 2 diabetes.
OBJECTIVE
To determine the effects of marine-derived n-3 polyunsaturated fatty acids (PUFA) on established and emerging lipid and lipoprotein cardiovascular risk markers in patients with type 2 diabetes.


METHODS
We performed a systematic review and meta-analysis of randomised controlled trials comparing dietary or non-dietary intake of n-3 PUFA with placebo in patients with type 2 diabetes by searching databases from 1966 to December 2006. Changes in the following variables were recorded triacylglycerol; total cholesterol; HDL, LDL and VLDL and their subfractions; lipid ratios; apolipoproteins; and cholesterol particle sizes.


RESULTS
There were 23 trials on non-dietary supplementation, involving 1,075 subjects with a mean treatment duration of 8.9 weeks, with sufficient data to permit pooling. Compared with placebo, n-3 PUFA had a statistically significant effect on four outcomes, reducing levels of (1) triacylglycerol (18 trials, 969 subjects) by 25% (mean 0.45 mmol/l; 95% CI -0.58 to -0.32; p < 0.00001); (2) VLDL-cholesterol (7 trials, 238 subjects) by 36% (0.07 mmol/l; 95% CI -0.13 to 0.00; p = 0.04); and (3) VLDL-triacylglycerol (6 trials, 178 subjects) by 39.7% (0.44 mmol/l; 95% CI -0.83 to -0.05; p = 0.03); while slightly increasing LDL (16 trials, 565 subjects) by 5.7% (0.11 mmol/l; 95% CI 0.00 to 0.22; p = 0.05). There were no significant effects on total cholesterol, apolipoproteins, lipid subfractions or ratios.


CONCLUSIONS
In addition to recognised triacylglycerol-lowering effects, n-3 PUFA supplementation decreases VLDL-cholesterol and VLDL-triacylglycerol, but may have an adverse effect on LDL-cholesterol. Larger and longer term clinical trials are required to conclusively establish the effect of n-3 PUFA on cardiovascular risk markers and outcomes in type 2 diabetic patients.
Hartweg
J
J
Division of Public Health and Primary Health Care, University of Oxford, Old Road Campus, Headington, Oxford, UK. Janine.Hartweg@green.ox.ac.uk
Farmer
A J
AJ
Perera
R
R
Holman
R R
RR
Neil
H A W
HA
D001053:Apolipoproteins / Q000097:blood; D002318:Cardiovascular Diseases / Q000097:blood / Q000517:prevention & control; D002784:Cholesterol / Q000097:blood; D015243:Cholesterol, VLDL / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000188:drug therapy*; D019587:Dietary Supplements; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D008055:Lipids / Q000097:blood*; D008074:Lipoproteins / Q000097:blood*; D008079:Lipoproteins, VLDL / Q000097:blood; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D014280:Triglycerides / Q000097:blood
D001053:Apolipoproteins; D015243:Cholesterol, VLDL; D015525:Fatty Acids, Omega-3; D008055:Lipids; D008074:Lipoproteins; D008079:Lipoproteins, VLDL; D014280:Triglycerides; C030106:very low density lipoprotein triglyceride; D002784:Cholesterol