Nutritional, mineral, and bioactive composition of indigenous leafy vegetables from the Congo Basin: A systematic review and meta-analysis.

Indigenous leafy vegetables from the Congo Basin represent a strategic resource for nutritional security and dietary diversification in Central Africa. However, their biochemical composition remains fragmented, limiting their scientific and nutraceutical valorisation. This study presents a systematic review and meta-analysis covering the period 2009-2025, aiming to consolidate and harmonise published data on the nutritional, mineral, vitamin, antinutritional and bioactive composition of eight representative species: Gnetum africanum, Amaranthus hybridus, Corchorus olitorius, Celosia argentea, Adansonia digitata, Crassocephalum rubens, Bidens pilosa and Justicia flava. The literature search was conducted in ScienceDirect, ResearchGate and Google Scholar databases, in accordance with PRISMA 2020 recommendations. Quantitative data extracted were harmonised on a dry weight (DW) basis and converted according to FAO/INFOODS standards. Weighted means were estimated using a random-effects model, and inter-study heterogeneity was assessed using I2 statistics and the Cochran Q test. The results indicate a high nutritional density among the studied species, with mean contents of proteins (14-28 g/100 g DW), calcium (0.9-2.8 g/100 g DW), iron (0.09-0.31 g/100 g DW) and vitamin C (60-260 mg/100 g DW). Principal Component Analysis (PCA) identified two functional groupings: (i) species with a dense nutritional profile (A. hybridus, C. olitorius, C. argentea) and (ii) species with a marked bioactive profile (A. digitata, C. rubens, B. pilosa). The heatmap revealed significant interspecific variability in antinutrients, dominated by oxalates and phytates. The positive correlation observed between the K/Na ratio and Fe content suggests an ionic balance favourable to mineral bioavailability. The tripartite network highlights relationships between species, secondary metabolites and pharmacological activities, illustrating the nutraceutical versatility of these vegetables. Overall, the leafy vegetables of the Congo Basin exhibit high nutritional density and antioxidant potential, with low levels of antinutrients. While these compositional features align with EFSA criteria for functional foods, further clinical and intervention studies are needed to confirm their direct health benefits in human populations. The valorisation within sustainable nutrition policies and the prevention of non-communicable metabolic diseases represents a major opportunity to strengthen local food systems and promote sustainable public health in Central Africa.