Approximately 30% of patients experience "Long-COVID" syndrome presenting with symptomssuch as cognitive difficulties ('brain fog'), fatigue, dyspnea, autonomic dysfunction,depression and anxiety, lasting beyond 12 weeks causing significant disability, andthreaten health and wellbeing of millions around the world. At the current time, there isno effective treatment for long-COVID. Walnuts contain a mixture of nutrients andphytochemicals include monounsaturated fatty acids (MUFA), polyunsaturated fatty acids(PUFA), and alpha-linolenic acid (ALA). Walnut consumption was directly associated withcognitive function. The investigators have shown pomegranate that share the samephytonutrient ellagitannins as walnut and mixed nuts including walnuts could increaseblood microbiome metabolites of tryptophan metabolite indole propionate and serotoninlevels via change of gut microbiota and therefore play an essential role in gut-brainaxis including cognitive function. The proposed pilot study will include 76 adults (ages>40 years) with diagnosis of SARS-CoV2 infection presenting with long-COVID symptomslasting longer than 12 weeks. They will be randomized 1:1 to usual care vs. anintervention group that will include 2 oz (57g) of walnuts daily into their habitual dietfor 12 weeks. The investigators will compare the improvement in symptoms of cognitivecomplains of "brain fog", fatigue and depression of the active intervention group vs.usual care. The outcome of the investigation of the benefit of walnut consumption willprovide important novel information on using dietary sources of polyunsaturated fattyacids and phytochemicals to mitigate the common symptoms of long-COVID. This applicationwas submitted in response to the California Walnut Commission's commodity board topic.