Effect of alpha linolenic acid on cardiovascular risk markers: a systematic review.
OBJECTIVE
To determine whether dietary supplementation with alpha linolenic acid (ALA) can modify established and emerging cardiovascular risk markers.


METHODS
Systematic review and meta-analysis of randomised controlled trials identified by a search of Medline, Embase, Cochrane Controlled Trials Register (CENTRAL), and the metaRegister of Controlled Trials (mRCT).


METHODS
All human studies were reviewed.


METHODS
Changes in concentrations of total cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, very low density lipoprotein (VLDL) cholesterol, triglyceride, fibrinogen, and fasting plasma glucose, and changes in body mass index, weight, and systolic and diastolic blood pressure.


RESULTS
14 studies with minimum treatment duration of four weeks were reviewed. ALA had a significant effect on three of the 32 outcomes examined in these studies. Concentrations of fibrinogen (0.17 micromol/l, 95% confidence interval (CI) -0.30 to -0.04, p = 0.01) and fasting plasma glucose (0.20 mmol/l, 95% CI -0.30 to -0.10, p < 0.01) were reduced. There was a small but clinically unimportant decrease in HDL (0.01 mmol/l, 95% CI -0.02 to 0.00, p < 0.01). Treatment with ALA did not significantly modify total cholesterol, triglycerides, weight, body mass index, LDL, diastolic blood pressure, systolic blood pressure, VLDL, and apolipoprotein B.


CONCLUSIONS
Although ALA supplementation may cause small decreases in fibrinogen concentrations and fasting plasma glucose, most cardiovascular risk markers do not appear to be affected. Further trials are needed, but dietary supplementation with ALA to reduce cardiovascular disease cannot be recommended.
Wendland
E
E
Graduate Studies Program in Epidemiology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
Farmer
A
A
Glasziou
P
P
Neil
A
A
D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D002318:Cardiovascular Diseases / Q000097:blood* / Q000178:diet therapy / Q000503:physiopathology; D002784:Cholesterol / Q000097:blood; D019587:Dietary Supplements; D005340:Fibrinogen / Q000032:analysis; D006801:Humans; D012307:Risk Factors; D014280:Triglycerides / Q000097:blood; D017962:alpha-Linolenic Acid / Q000008:administration & dosage*
D001786:Blood Glucose; D014280:Triglycerides; D017962:alpha-Linolenic Acid; D005340:Fibrinogen; D002784:Cholesterol