Substituting Walnuts for Monounsaturated Fat Improves the Serum Lipid Profile of Hypercholesterolemic Men and Women

A Randomized Crossover Trial

  1. Daniel Zambón, MD;
  2. Joan Sabaté, MD, DrPH;
  3. Sonia Muñoz, PhD;
  4. Betina Campero, RD;
  5. Elena Casals, MD;
  6. Manuel Merlos, PhD;
  7. Juan C. Laguna, PhD; and
  8. Emilio Ros, MD
  1. From Hospital Clínic and School of Pharmacy, University of Barcelona, Barcelona, Spain; and Loma Linda University, Loma Linda, California.

    Abstract

    Background: It has been reported that walnuts reduce serum cholesterol levels in normal young men.

    Objective: To assess the acceptability of walnuts and their effects on serum lipid levels and low-density lipoprotein (LDL) oxidizability in free-living hypercholesterolemic persons.

    Design: Randomized, crossover feeding trial.

    Setting: Lipid clinic at a university hospital.

    Patients: 55 men and women (mean age, 56 years) with polygenic hypercholesterolemia.

    Intervention: A cholesterol-lowering Mediterranean diet and a diet of similar energy and fat content in which walnuts replaced approximately 35% of the energy obtained from monounsaturated fat. Patients followed each diet for 6 weeks.

    Measurements: Low-density lipoprotein fatty acids (to assess compliance), serum lipid levels, lipoprotein(a) levels, and LDL resistance to in vitro oxidative stress.

    Results: 49 persons completed the trial. The walnut diet was well tolerated. Planned and observed diets were closely matched. Compared with the Mediterranean diet, the walnut diet produced mean changes of −4.1% in total cholesterol level, −5.9% in LDL cholesterol level, and −6.2% in lipoprotein(a) level. The mean differences in the changes in serum lipid levels were −0.28 mmol/L (95% CI, −0.43 to −0.12 mmol/L) (−10.8 mg/dL [−16.8 to −4.8 mg/dL]) (P < 0.001) for total cholesterol level, −0.29 mmol/L (CI, −0.41 to −0.15 mmol/L) (−11.2 mg/dL [−16.3 to −6.1 mg/dL]) (P < 0.001) for LDL cholesterol level, and −0.021 g/L (CI, −0.042 to −0.001 g/L) (P = 0.042) for lipoprotein(a) level. Lipid changes were similar in men and women except for lipoprotein(a) levels, which decreased only in men. Low-density lipoprotein particles were enriched with polyunsaturated fatty acids from walnuts, but their resistance to oxidation was preserved.

    Conclusion: Substituting walnuts for part of the monounsaturated fat in a cholesterol-lowering Mediterranean diet further reduced total and LDL cholesterol levels in men and women with hypercholesterolemia.

    Article and Author Information

    • Acknowledgments: The authors thank Nahyr Schinca, RD, and Ana Pérez-Heras, RD, for dietary counseling of the participants in the study. Catherine Bouchet, Antonia Codinach, and Ana Asensio provided skillful technical assistance with the laboratory measurements.

    • Grant Support: By the California Walnut Commission, Fundació Privada Catalana de Nutrició i Lípids, Fondo de Investigaciónes Sanitarias de la Seguridad Social (FIS 94/0077), and Comisión Interministerial de Ciencia y Tecnología (CICYT, SAF 97/0215, and OLI 96/2132).

    • Requests for Single Reprints: Emilio Ros, MD, Lipid Clinic, Nutrition & Dietetics Service, Hospital Clínic i Provincial, Villarroel 170, E-08036 Barcelona, Spain.

    • Requests To Purchase Bulk Reprints (minimum, 100 copies): the Reprints Coordinator; phone, 215-351-2657; e-mail, reprints{at}mail.acponline.org.

    • Current Author Addresses: Drs. Zambón and Ros and Ms. Campero: Lipid Clinic, Nutrition & Dietetics Service, Hospital Clínic i Provincial, Villarroel 170, E-08036 Barcelona, Spain.

    • Dr. Sabaté: Department of Nutrition, School of Public Health, Loma Linda University, Loma Linda, CA 92350.

    • Drs. Muñoz, Merlos, and Laguna: Pharmacology Unit, School of Pharmacy, University of Barcelona, E-08028 Barcelona, Spain.

    • Dr. Casals: Department of Clinical Biochemistry, Hospital Clínic i Provincial, Villarroel 170, E-08036 Barcelona, Spain.

    • Author Contributions: Conception and design: D. Zambón, J. Sabaté, E. Ros.

    • Analysis and interpretation of the data: D. Zambón, J. Sabaté, J.C. Laguna, E. Ros.

    • Drafting of the article: D. Zambón, J.C. Laguna, E. Ros.

    • Critical revision of the article for important intellectual content: D. Zambón, J. Sabaté, J.C. Laguna, E. Ros.

    • Final approval of the article: D. Zambón, J. Sabaté, S. Muñoz, B. Campero, E. Casals, M. Merlos, J.C. Laguna, E. Ros.

    • Provision of study materials or patients: D. Zambón, B. Campero.

    • Statistical expertise: D. Zambón, J. Sabaté.

    • Obtaining of funding: D. Zambón, J. Sabaté, J.C. Laguna, E. Ros.

    • Administrative, technical, or logistic support: S. Muñoz, E. Casals.

    • Collection and assembly of data: S. Muñoz, B. Campero, E. Casals, M. Merlos.

    Summary for Patients

    • Summaries for Patients:Eating Walnuts Lowers Cholesterol Levels in People with High Cholesterol Ann Intern Med April 4, 2000 132:538
    « Previous | Next Article »Table of Contents

    This Article

    1. Ann Intern Med April 4, 2000 vol. 132 no. 7 538-546
    1. » Abstract
    2. Figures
    3. Full Text
    4. Full Text (PDF)
      1. Summary for Patients

    Rapid Responses

    1. Submit a response
    2. No responses published

    Current Issue

    1. November 3, 2009, 151 (9)
    1. Alert me to current issues