Walnut components and association with health effects

Walnuts have long been valued not only as a nutritious food but also for their historical use in folk medicine, as well as their applications in cosmetics and pharmaceuticals. The compounds found in walnuts encompass a wide range of categories, including phenolic acids, saponins, quinones, alkaloids, flavonoids, etc. Phenolic compounds, in particular, play a crucial role as antioxidants, offering various health benefits such as anti-carcinogenic, anti-inflammatory, antibacterial, anti-aging, anti-fungal, and neuroprotective properties. For example, phenolic compound treatment has shown promise in enhancing the skin's natural oxidation-relieving system, thereby combating skin aging.
Moreover, walnuts are rich in omega-3 fatty acids, particularly alpha-linolenic acid (ALA), and provide approximately 6–7% of dietary fiber. Traditionally, nuts like walnuts and almonds have been consumed to promote digestion, enhance the immune system, aid in wound healing, and improve circulation. Numerous studies have highlighted the protective effects of walnuts and almonds on human health, with walnut polyphenols, in particular, associated with a reduced risk of cardiovascular diseases through mechanisms such as decreasing low-density lipoprotein (LDL)-cholesterol and increasing high-density lipoprotein (HDL)-cholesterol levels, as well as bolstering the antioxidant defense system. The diverse biological effects of walnut bioactive compounds underscore their potential to enhance human health, with recommendations suggesting their incorporation into diets as a means of mitigating metabolic disorders. The chemical composition of walnuts also holds promise for industrial applications, with various compounds serving as potential sources of natural antioxidants for the development of novel anticancer agents.