Scientists Discover How Daily Walnut Consumption May Affect Immune Responses in Older Adults

Could eating a handful of walnuts every day influence the immune system and potentially support heart health? A new study suggests that regular walnut consumption may alter certain immune markers linked to cardiovascular health, although researchers caution that the clinical benefits remain uncertain.

Published in JACC: Advances, the study examined whether eating walnuts daily influenced antibodies involved in immune responses associated with atherosclerosis, a condition characterised by plaque buildup and inflammation in blood vessels.

Researchers analysed data from the Walnuts and Healthy Aging (WAHA) randomised controlled trial, which originally enrolled 708 older adults aged 63 to 79 years in Spain and the United States.

The analysis included blood samples from 474 participants, of whom 240 consumed walnuts daily and 234 followed a diet excluding walnuts.

Participants in the intervention group consumed approximately 30–60 grams of walnuts daily for two years, representing around 15% of their total energy intake.

Researchers measured immunoglobulin G (IgG), immunoglobulin M (IgM) and antibodies targeting modified low-density lipoprotein (LDL), which is involved in atherosclerotic processes.

The findings revealed that participants consuming walnuts had approximately 6% higher total IgG concentrations than the control group after two years.

Importantly, the association was more pronounced among American participants, whose IgG concentrations were 11% higher than those of controls. No statistically significant difference was observed among Spanish participants.

However, walnut consumption did not significantly affect total IgM, modified LDL concentrations or antibodies specifically targeting modified LDL.

Researchers suggested that walnuts contain beneficial compounds, including omega-3 fatty acids and polyphenols, which may influence inflammation and immune function.

Nevertheless, the study did not establish whether higher IgG concentrations translated into reduced cardiovascular risk.

The findings suggest that regular walnut consumption may influence certain circulating immune markers, but further research is needed to determine whether these changes provide meaningful protection against cardiovascular disease.

REFERENCE: Sharma, T., Chiva-Blanch, G., Caga-Anan, M., et al. (2026). Effects of Walnut Consumption on Anti-MDA-LDL Antibodies and Immunoglobulins in the WAHA Randomized Trial. JACC Advances, 5(10), 103288. DOI: 10.1016/j.jacadv.2026.103288