Evaluation of the Effect of a Seaweed Flour- and Leucine-Enriched Food on Metabolic and Inflammatory Status in Older Adults With Probable Sarcopenia or Sarcopenia

Overview

Sarcopenia and probable sarcopenia are associated with loss of muscle strength, functional impairment, frailty, and an increased risk of adverse outcomes in older adults. In short-term interventions, structural or functional changes may be modest, whereas certain serum biomarkers of metabolic-nutritional response may be more sensitive. In this protocol version, serum transthyretin (TTR) has been selected as the primary outcome, without assuming that it represents, by itself, a direct measure of muscle mass or overall clinical efficacy.

Sarcopenia is a progressive skeletal muscle disorder associated with aging and an increased risk of disability, hospitalization, dependency, and mortality. Contemporary consensus definitions identify low muscle strength as the primary characteristic of the condition, while muscle quantity or quality and physical performance are used to support the diagnosis and determine its severity. In older adults, anabolic resistance reduces the muscle's responsiveness to habitual dietary protein intake. Leucine has been proposed as an amino acid capable of stimulating key anabolic pathways and therefore represents a plausible candidate for short-term nutritional interventions. In turn, Durvillaea incurvata flour provides bioactive compounds and dietary fiber with potential antioxidant and anti-inflammatory properties, although clinical evidence supporting its use in sarcopenia remains limited. From a methodological perspective, a 28-day follow-up period may be sufficient to detect early metabolic and nutritional responses, but it may be insufficient to demonstrate robust clinical changes in muscle strength, muscle mass, or physical performance. For this reason, serum TTR has been selected as the primary short-term response outcome in the present protocol. The selection of serum TTR as the primary outcome requires careful interpretation. Serum TTR levels may be influenced by protein-energy intake, liver function, inflammatory status, and intercurrent clinical conditions. Accordingly, in this protocol, serum TTR will not be interpreted as a direct surrogate of muscle mass or as a stand-alone measure of clinical efficacy. Rather, it will be considered a serum marker of early metabolic and nutritional response, whose interpretation will be complemented by functional, body composition, inflammatory, and safety-related outcomes. This study is therefore designed as an exploratory, randomized proof-of-concept trial to determine whether the combination of leucine and seaweed flour improves serum TTR and whether this response is accompanied by consistent secondary changes in muscle strength, mobility, body composition, and the metabolic-inflammatory profile.