Substance use disorders (SUDs) involve the compulsive misuse of substances like alcohol, opioids, stimulants, and cannabis, leading to significant health, social, and economic consequences. Affecting millions globally and 7.7% of Americans annually, SUDs severely impair nutritional health by causing deficiencies in essential vitamins like folate and B vitamins, exacerbating both physical and psychological issues. This chapter underscores the vital role of nutrition in SUD recovery, highlighting how addressing nutrient deficiencies supports overall health. Nutritional interventions restore neurotransmitter function, reduce oxidative stress, and stabilize the hypothalamic-pituitary-adrenal (HPA) axis. Amino acids like tyrosine and tryptophan, precursors for dopamine and serotonin, aid in mood regulation and impulse control, while anti-inflammatory nutrients such as polyphenols and omega-3 fatty acids reduce neuroinflammation and promote cognitive and emotional healing. Additionally, probiotics and prebiotics improve gut health, enhancing the gut-brain axis and reducing cravings. A holistic recovery approach, incorporating mindful eating and cognitive-behavioral strategies, fosters physical and emotional well-being. Addressing challenges like nutrient deficiencies, co-occurring disorders, and limited access to healthy foods requires a multidisciplinary approach. By integrating both physiological and psychosocial care, nutritional therapy can improve long-term recovery outcomes and reduce relapse risk in individuals with SUDs.