Effects of diets high in walnuts and flax oil on hemodynamic responses to stress and vascular endothelial function

J Am Coll Nutr. 2010 Dec;29(6):595-603. doi: 10.1080/07315724.2010.10719898.


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).

Design: 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.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomarkers / blood
  • Blood Pressure
  • Cardiovascular Diseases / prevention & control
  • Cholesterol, LDL / blood
  • Cross-Over Studies
  • Diet*
  • Endothelin-1 / blood
  • Flax / chemistry*
  • Humans
  • Hypercholesterolemia
  • Juglans / chemistry*
  • Linoleic Acid / administration & dosage
  • Linoleic Acid / blood
  • Middle Aged
  • Nuts*
  • Plant Oils / pharmacology*
  • Risk Factors
  • Stress, Psychological
  • Vascular Resistance / drug effects*
  • alpha-Linolenic Acid / administration & dosage
  • alpha-Linolenic Acid / blood


  • Biomarkers
  • Cholesterol, LDL
  • Endothelin-1
  • Plant Oils
  • alpha-Linolenic Acid
  • Linoleic Acid