The Presence of Lunasin, a Soy-Derived Bioactive Peptide in Plasma: A Randomized Clinical Trial

Abstract

Abstract Objectives Lunasin is a bioactive peptide originally derived from soy protein which is being marketed as a nutraceutical product for its potential beneficial effects. Functionality of lunasin depends on its presence in circulation after digestion and metabolism. We studied safety, tolerability, and presence of lunasin in blood for the first time in humans in a well-controlled randomized clinical trial. Methods In a triple-blinded, placebo-controlled crossover study, 31 subjects (female: 19, male: 12, age = 61 ± 9.9 years) were randomized into an 8-week intervention period with capsules containing either 335 mg/d lunasin-enriched soy extract (LES) or corn fiber (placebo). This was followed by a 3-week wash-out period after which participants switched treatment groups for the next 8 weeks. In this crossover randomized study, plasma samples of subjects were collected after ingestion of a daily dose of lunasin-enriched capsules for 8 weeks, which provided 50 mg/d of lunasin. Enzyme-Linked Immunosorbent Assay was used to detect plasma lunasin level after an overnight fast. In order to assess the dietary intake of lunasin, two 24-hour dietary recalls (one in each intervention period) were obtained from each participant. Dietary intake data were collected and analyzed using Nutrition Data System for Research software version 2015, developed by the Nutrition Coordinating Center (NCC), University of Minnesota, Minneapolis, MN. Results During the intervention, no major safety concerns related to lunasin consumption were noticed. Ingestion of 335 mg/d LES for 8 weeks resulted in higher lunasin level in plasma compared to placebo. Fasting plasma lunasin levels ranged 0–10 ng/mL. The mean lunasin concentration in plasma increased by 44% after 8 weeks of daily supplementation with LES. Conclusions Lunasin was detectable in plasma after overnight fast in higher levels among LES takers. The difference in lunasin concentration was due to LES capsules and not dietary intake of lunasin-containing foods. Funding Sources The study was funded by Soy Labs Inc.