title: Effects of diets high in walnuts and flax oil on hemodynamic responses to stress and vascular endothelial function.
abstract: BACKGROUND
  Polyunsaturated fatty acids (PUFA) have beneficial effects on cardiovascular risk, although the mechanisms are incompletely understood. In a previous article, we showed significant reductions in low-density lipoprotein cholesterol and several markers of inflammation with increasing intake of alpha-linolenic acid (ALA) from walnuts and flax.
  
  
  OBJECTIVE
  To examine effects of ALA on cardiovascular responses to acute stress, flow-mediated dilation (FMD) of the brachial artery, and blood concentrations of endothelin-1 and arginine-vasopressin (AVP).
  
  
  METHODS
  Using a randomized, crossover study design, cardiovascular responses to acute stress were assessed in 20 hypercholesterolemic subjects, a subset of whom also underwent FMD testing (n  =  12). Participants were fed an average American diet (AAD) and 2 experimental diets that varied in the amount of ALA and linoleic acid (LA) that they contained. The AAD provided 8.7% energy from PUFA (7.7% LA, 0.8% ALA). On the LA diet, saturated fat was reduced, and PUFA from walnuts and walnut oil provided 16.4% of energy (12.6% LA, 3.6% ALA). On the ALA diet, walnuts, walnut oil, and flax oil provided 17% energy from PUFA (10.5% LA, 6.5% ALA).
  
  
  RESULTS
  The ALA and LA diets significantly reduced diastolic blood pressure (-2 to -3 mm Hg) and total peripheral resistance (-4%), and this effect was evident at rest and during stress (main effect of diet, p < 0.02). FMD increased (+34%) on the diet containing additional ALA. AVP also increased by 20%, and endothelin-1 was unchanged.
  
  
  CONCLUSIONS
  These results suggest novel mechanisms for the cardioprotective effects of walnuts and flax, and further work is needed to identify the bioactives responsible for these effects.
authors.affiliation: Department of Biobehavioral Health, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. sgw2@psu.edu
authors.forename: Sheila G
authors.initials: SG
authors.lastname: West
authors.forename: Andrea Likos
authors.initials: AL
authors.lastname: Krick
authors.forename: Laura Cousino
authors.initials: LC
authors.lastname: Klein
authors.forename: Guixiang
authors.initials: G
authors.lastname: Zhao
authors.forename: Todd F
authors.initials: TF
authors.lastname: Wojtowicz
authors.forename: Matthew
authors.initials: M
authors.lastname: McGuiness
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Bagshaw
authors.forename: Paul
authors.initials: P
authors.lastname: Wagner
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Ceballos
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Holub
authors.forename: Penny M
authors.initials: PM
authors.lastname: Kris-Etherton
mesh_terms: D015415:Biomarkers / Q000097:blood; D001794:Blood Pressure; D002318:Cardiovascular Diseases / Q000517:prevention & control; D008078:Cholesterol, LDL / Q000097:blood; D018592:Cross-Over Studies; D004032:Diet; D019332:Endothelin-1 / Q000097:blood; D019597:Flax / Q000737:chemistry*; D006801:Humans; D006937:Hypercholesterolemia; D031324:Juglans / Q000737:chemistry*; D019787:Linoleic Acid / Q000008:administration & dosage / Q000097:blood; D008875:Middle Aged; D009754:Nuts; D010938:Plant Oils / Q000494:pharmacology*; D012307:Risk Factors; D013315:Stress, Psychological; D014655:Vascular Resistance / Q000187:drug effects*; D017962:alpha-Linolenic Acid / Q000008:administration & dosage / Q000097:blood
chemical_list: D015415:Biomarkers; D008078:Cholesterol, LDL; D019332:Endothelin-1; D010938:Plant Oils; D017962:alpha-Linolenic Acid; D019787:Linoleic Acid