Flaxseed and cardiovascular risk factors: results from a double blind, randomized, controlled clinical trial.
OBJECTIVE
Flaxseed is a rich source of alpha linolenic acid (ALA), fiber and lignans, making it a potentially attractive functional food for modulating cardiovascular risk. We studied the effects of flaxseed on markers of cardiovascular risk in hypercholesterolemic adults.


METHODS
Sixty-two men and post-menopausal women with pre-study low density lipoprotein cholesterol (LDL-C) between 130 and 200 mg/dl were randomized to 40g/day of ground flaxseed-containing baked products or matching wheat bran products for 10 weeks while following a low fat, low cholesterol diet. Fasting lipoproteins, measures of insulin resistance, inflammation, oxidative stress, and safety were assessed at 0, 5 and 10 weeks.


RESULTS
Flaxseed was well-tolerated, and increased serum levels of ALA (p < 0.001). Compared to wheat, flaxseed significantly reduced LDL-C at 5 weeks (-13%, p < 0.005), but not at 10 weeks (-7%, p = 0.07). Flaxseed reduced lipoprotein a (Lp[a]) by a net of 14% (p = 0.02), and reduced the homeostatic model assessment of insulin resistance (HOMA-IR) index by 23.7% (p = 0.03) compared to wheat at 10 weeks, but did not affect markers of inflammation (IL-6, Hs-CRP) or oxidative stress (ox LDL, urinary isoprostanes) at any time points. In men, flaxseed reduced HDL-C concentrations by a net of 16% (p = 0.03) and 9% (p = 0.05) at 5 and 10 weeks, respectively.


CONCLUSIONS
Ground flaxseed has a modest but short lived LDL-C lowering effect, yet reduces Lp(a) and improves insulin sensitivity in hyperlipidemic adults. The HDL-C lowering effect of flaxseed in men warrants additional study.
Bloedon
LeAnne T
LT
Division of General Internal Medicine, University of Pennsylvania Health System, Philadelphia, PA 19104, USA.
Balikai
Shilpa
S
Chittams
Jesse
J
Cunnane
Stephen C
SC
Berlin
Jesse A
JA
Rader
Daniel J
DJ
Szapary
Philippe O
PO
D000368:Aged; D015415:Biomarkers; D002318:Cardiovascular Diseases / Q000097:blood / Q000453:epidemiology / Q000517:prevention & control; D008076:Cholesterol, HDL / Q000097:blood*; D008078:Cholesterol, LDL / Q000097:blood*; D018752:Diet, Fat-Restricted; D004311:Double-Blind Method; D005260:Female; D019597:Flax; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000178:diet therapy*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D013997:Time Factors; D016896:Treatment Outcome; D017962:alpha-Linolenic Acid / Q000008:administration & dosage / Q000097:blood
D015415:Biomarkers; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D017962:alpha-Linolenic Acid