**1. Introduction**

Healthy diet, along with physical and cognitive activity, is a modifiable lifestyle factor that has been associated with overall health in old age. Aging is a collective, multifactorial progression of physiological dysfunctions at cellular and tissue levels, as well as the deregulation of normal cell pathways and lost synchronicity among defense mechanisms in the body, leading to the development of age-related diseases [1].

A number of studies explored the phytochemical composition, bioactivity, and antioxidant potential of nuts [2,3]. Scientific evidence demonstrated the potential benefits of a higher intake of nuts or nut-enriched Mediterranean diets (MDs) against risk factors associated with pathological conditions linked with aging, such as cardiometabolic diseases, cancer, or cognitive disorders [4–8]. This review focused on middle-aged and older adults, a constantly growing group, with particular attention given to how these individuals can benefit from healthy dietary plans enhanced with tree nuts and peanuts, and how the extra bioactive antioxidant compounds may add quality to the increased life expectancy.

The aim of this study was to present up-to-date evidence confirming that nut intake and nut-enriched MDs [9] can be beneficial in delaying aging and can support modern medicine in treating age-related diseases. We investigated human studies that assessed the effects of nut consumption on the health of a middle-aged and elderly population 55 years of age and older. We searched PubMed/MEDLINE and EMBASE databases for peer-reviewed articles published in the decade from 2009 to June 2019. We also examined studies found in the references of meta-analysis that were in accordance with our inclusion criteria: subject age ≥55 years and nuts with antioxidant and anti-inflammatory activities added in the diet. In this review, the word "nuts" includes tree nuts, such as walnuts (*Juglans regia*), almonds (*Prunus dulcis*), hazelnuts (*Corylus avellana*), pistachios (*Pistacia vera*), pecans (*Carya illinoinensis*), cashews (*Anacardium occidentale*), pine nuts (*Pinus pinea*), Brazil nuts (*Bertholletia excelsa*), macadamias (*Macadamia integrifolia*), and also peanuts (*Arachis hypogaea*), botanically classified as legumes but with a nutrient profile comparable to tree nuts.

In addition, we summarized several nut phytochemicals with biological antioxidant activity, their possible mechanisms of actions, as well as the influence of nuts on gut microbiota (GM).
