Ulvan-Na, an Ulvan Subjected to Na+ Cation Exchange, Improves Intestinal Barrier Function in Age-Related Leaky Gut

The global increase in life expectancy underscores the need to promote healthy aging, particularly by addressing age-related leaky gut syndrome, which contributes to systemic inflammation and chronic disease. This study focused on the sustainable production and functional development of <i>Ulva meridionalis</i>, a fast-growing seaweed, to improve gut health and mitigate the effects of aging. Using land-based aquaculture, a scalable cultivation system for <i>U. meridionalis</i> was established, and its polysaccharide, ulvan, was extracted. Ion exchange treatment enhanced the functionality of ulvan to produce ulvan-Na, which contains high levels of Na⁺ and conveys superior anti-aging properties. Ulvan-Na restored intestinal barrier integrity in aged mice by reducing serum LPS levels and increasing claudin-1 expression. Ulvan-Na modulated the gut microbiota, increasing beneficial bacteria such as <i>Clostridiales vadin BB60</i> and suppressing inflammatory bacteria such as <i>Turicibacter</i>. The mechanism was clarified whereby ulvan-Na activates β-catenin to enhance claudin-1 expression. These findings highlight ulvan-Na as a bioactive compound that ameliorates age-related intestinal dysfunction while demonstrating the feasibility of sustainable <i>U. meridionalis</i> production for functional food innovation and environmental conservation.