Protein bioavailability of Wolffia globosa duckweed, a novel aquatic plant - A randomized controlled trial

Abstract

Background & aims: While the world is extensively looking for alternatives to animal protein sources, it is not clear which plant sources can provide the requisite full complement of essential amino acids (EAAs). Wolffia globosa is an aquatic, edible duckweed, the smallest plant on earth, and it offers all nine EAAs, dietary fibers, polyphenols, iron, zinc and B₁₂ vitamin. This work was designed to evaluate Mankai (a newly developed high-protein strain of W. globosa) as an optional bioavailable source of EAAs for humans (primary outcome), and of further nutrients such as vitamin B₁₂, in comparison to well-established animal and plant protein sources; cheese and peas, respectively.

Methods: 36 men, subjected for 3 days to a stable diet and subsequent overnight (12 h) fast, were randomized to consume one of three iso-protein (30 g) based test-meals (soft cheese, green peas, Mankai). Blood samples were collected at 0, 30, 90 and 180 min.

Results: The 3 h blood concentrations of the EAAs: histidine, phenylalanine, threonine, lysine, and tryptophan, triggered by intake of Mankai, was essentially significant as compared to baseline (p < 0.05) and similar to that of soft cheese and pea changes (p > 0.05 between groups). Although branched-chain-amino-acids (leucine/isoleucine, valine) increased significantly by Mankai within 3 h (p < 0.05 vs. baseline), the change was relatively higher for cheese as compared to Mankai or peas (p < 0.05 between groups). The increase in vitamin B₁₂ by Mankai was higher as compared to changes induced by either cheese (p=0.007) or peas (p=0.047, between groups).

Conclusions: Mankai may provide a high-quality substitute source for animal protein, and a potential bioavailable source of vitamin B₁₂.

Trial registration: ClinicalTrials.gov NCT03020225.

Keywords: Bioavailability; Essential amino acids; Plant protein source; Test meal; Wolffia globosa.