Effects of Walnut Consumption on Anti-MDA-LDL Antibodies and Immunoglobulins in the WAHA Randomized Trial
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Published on: September 20, 2019
Tania Sharma1, Gemma Chiva-Blanch2, Mikhail Caga-Anan3
1Vascular Sciences Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom; Department of Cardiology, Clinical Sciences, Lund University, Lund, Sweden.
Background:
Higher total serum IgG levels have been associated with protection from cardiovascular events in ASCOT (Anglo-Scandinavian Cardiac Outcomes Trial). Antibodies against oxidized low-density lipoprotein (LDL) have also been linked to favorable clinical and vascular imaging outcomes.
Objectives:
The aim of this study was to determine whether regular walnut consumption influences circulating immunoglobulins, malondialdehyde-modified LDL (MDA-LDL), a highly immunogenic form of oxidized LDL, and antibodies against MDA-LDL.
Methods:
The Walnuts and Healthy Aging study was a two-center, randomized controlled trial conducted in Spain and the United States. Adults aged 63 to 79 years were assigned to a walnut-enriched diet or a control diet excluding walnuts for 2 years. Serum total immunoglobulin G (IgG), total immunoglobulin M (IgM), MDA-LDL, and IgG and IgM anti MDA-LDL antibodies were measured by enzyme-linked immunoassays in 474 participants.
Results:
Baseline immunoglobulin concentrations differed substantially by study center. Participants from the United States had 25% lower total IgM and IgG concentrations than participants from Spain. Walnut consumption increased total serum IgG by 11% in the U.S. cohort (95% CI: 0%-24%; P = 0.040), whereas pooled analysis showed a 6% increase across both cohorts (95% CI: 0%-12%; P = 0.041). Over the 2-year study period, total IgM and both IgG and IgM anti-MDA-LDL concentrations declined significantly in both the control and intervention groups.
Conclusions:
Long-term walnut consumption was associated with a modest increase in total serum IgG but had no significant effect on total IgM, MDA-LDL, or antibodies against MDA-LDL. Baseline IgG and IgM concentrations were substantially lower among U.S. participants, suggesting that geographic, environmental, social, or genetic factors may modulate immune biomarkers independently of dietary intervention.