Limited Supply of Protein and Lysine Is Prevalent among the Poorest Households in Malawi and Exacerbated by Low Protein Quality

Protein glycation compromises the bioavailability of milk protein-derived lysine in vivo in healthy adult males: a double-blind, randomized cross-over trial

BACKGROUND

Industrial processing and storage of milk products can strongly increase protein glycation level. Previously, we have reported that ingestion of highly glycated milk protein attenuates the postprandial rise in plasma lysine concentrations compared to the ingestion of an equivalent amount of milk protein with a low glycation level. Whether the attenuated increase in plasma lysine availability is attributed to compromised protein digestion and subsequent lysine absorption remains to be established.

OBJECTIVES

The present study combined stable-isotope methodology with the ingestion of specifically produced, intrinsically labeled protein to assess protein digestion and amino acid absorption following ingestion of milk protein with a high versus low glycation level in vivo in humans.

METHODS

Fifteen recreationally active, healthy young males participated in this double-blinded, randomized cross-over study. Subjects ingested 40 g intrinsically L-[1-13C]-lysine-labeled milk protein with either a low (3%) or high (50%) glycation level. Continuous intravenous infusion of L-[4,4,5,5-2H4]-lysine was combined with frequent blood sample collection during a 6-h postprandial period to evaluate dietary protein-derived lysine release into the circulation.

RESULTS

Postprandial plasma lysine concentrations were lower following the ingestion of milk protein with a high versus low glycation level (time × treatment effect: P = 0.002; ƞ2 = 0.214), resulting in a 23 mmol/L x 360 min (95% confidence interval [CI]: 13, 32) lower incremental area under the curve (0 ± 12 vs 23 ± 11 mmol/L x 360 min, respectively, P < 0.001). The postprandial release of milk protein-derived lysine into the circulation was attenuated following ingestion of the protein with the high versus low glycation level (time × treatment effect: P < 0.001; ƞ2 = 0.640) and was 31% (95% CI: 26, 36) lower over the full 6-h postprandial period (18 ± 4 vs 49 ± 10% of the ingested lysine, respectively, P < 0.001).

CONCLUSIONS

A high level of milk protein glycation strongly reduces postprandial plasma lysine availability in vivo in humans. Industrial processing and storage of (milk) protein products can strongly modulate protein bioavailability and, as such, lower the nutritional value of a protein source. This trial was registered at www.

CLINICALTRIALS

gov as NCT05479916.

Whole maize flour could enhance food and nutrition security in Malawi

Maize is the staple cereal in Malawi, with a daily per capita consumption of 383 g (dry matter basis), primarily consumed in the form of nsima, a thick porridge. We combined a milling experiment with focus group discussions (FGDs) to provide insights into mass and nutrient losses during maize grain dehulling and maize flour consumption patterns in rural Malawi. Milling batches (30 kg) of four maize grain varieties were dehulled at three abrasive disk dehullers under controlled conditions. The impact of maize variety and dehuller design on mass and nutrient losses during dehulling was statistically significant (p < 0.05), with a mean mass loss of 28.1 ± 5.7%, and nutrient losses of 9.8 ± 1.9% for protein, 61.7 ± 2.0% for zinc, and 47.7 ± 3.6% for iron. Six FGDs conducted in rural areas of Lilongwe District revealed a preference for refined flour due to convenience and cultural norms, despite the nutritional benefits of whole grain flour, which was recognized for its ability to provide satiety, particularly during periods of maize scarcity. Participants also highlighted switching between flour types based on seasonal maize availability, social stigma associated with whole grain flour, and awareness of nutrient losses during dehulling. Given Malawi's precarious food insecurity situation, transitioning from dehulled maize flour nsima to whole maize flour or less refined nsima, is imperative. Our study findings can have food and nutritional savings for other southern Africa countries where the dehulling is a common practice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s44187-025-00311-y.

Determinants of adoption of quality protein maize varieties in Misrak Badewacho District, Southern Ethiopia: policy implications

This study aimed to identify the determinants of adoption of quality protein maize (QPM) varieties. QPM varieties are promoted as a solution to the problem of undernutrition, and their adoption is especially important in areas where maize is a nutritional staple food source. This study employed a cross-sectional design. A multistage sampling procedure was used to collect primary data from 143 sampled maize producers, which were analyzed using SPSS version 22. A binary logit model was used to identify major determinants. The results indicated that access to QPM seed, land size, on-farm income, involvement in off/non-farm activities, frequency of contact with development agents (Das), educational level of the household head, and participation of farmers on field days were statistically significant determinants of QPM variety adoption. Credit use was also a significant determinant of the adoption of QPM varieties but showed a negative influence. Therefore, this study recommends that all relevant stakeholders working at different levels in QPM production and extension pay attention to the factors that could affect farmers' decisions to adopt QPM in the study area. Furthermore, all concerned bodies should work together to enhance the adoption of QPM varieties.

Doctoral training to support sustainable soil geochemistry research in Africa

Africa's potential for scientific research is not yet being realized, for various reasons including a lack of researchers in many fields and insufficient funding. Strengthened research capacity through doctoral training programmes in higher education institutes (HEIs) in Africa, to include collaboration with national, regional and international research institutions, can facilitate self-reliant and sustainable research to support socio-economic development. In 2012, the Royal Society and the UK's Department for International Development (now the Foreign, Commonwealth and Development Office) launched the Africa Capacity Building Initiative (ACBI) Doctoral Training Network which aimed to strengthen research capacity and training across sub-Saharan Africa. The ACBI supported 30 core PhD scholarships, all registered/supervised within African HEIs with advisory support from the UK-based institutes. Our 'Soil geochemistry to inform agriculture and health policies' consortium project, which was part of the ACBI doctoral training programme network, was implemented in Malawi, Zambia and Zimbabwe between 2014 and 2020. The aims of our consortium were to explore linkages between soil geochemistry, agriculture and public health for increased crop productivity, nutrition and safety of food systems and support wider training and research activities in soil science. Highlights from our consortium included: (i) the generation of new scientific evidence on linkages between soils, crops and human nutrition; (ii) securing new projects to translate science into policy and practice; and (iii) maintaining sustainable collaborative learning across the consortium. Our consortium delivered high-quality science outputs and secured new research and doctoral training funding from a variety of sources to ensure the continuation of research and training activities. For example, follow-on Global Challenges Research Funded Translation Award provided a strong evidence base on the prevalence of deficiencies in children under 5 years of age and women of reproductive age in Zimbabwe. This new evidence will contribute towards the design and implementation of a nationally representative micronutrient survey as an integral part of the Zimbabwe Demographic and Health Surveys conducted by the Ministry of Health and Child Care. The award also generated new evidence and a road map for creating quality innovative doctorates through a doctoral training landscape activity led by the Zimbabwe Council for Higher Education. Although our project and the wider ACBI has contributed to increasing the self-reliance and sustainability of research within the region, many challenges remain and ongoing investment is required.

Meeting the global protein supply requirements of a growing and ageing population

Human dietary patterns are a major cause of environmental transformation, with agriculture occupying ~ 50% of global land space, while food production itself is responsible for ~ 30% of all greenhouse gas emissions and 70% of freshwater use. Furthermore, the global population is also growing, such that by 2050, it is estimated to exceed ~ 9 billion. While most of this expansion in population is expected to occur in developing countries, in high-income countries there are also predicted changes in demographics, with major increases in the number of older people. There is a growing consensus that older people have a greater requirement for protein. With a larger and older population, global needs for protein are set to increase. This paper summarises the conclusions from a Rank Prize funded colloquium evaluating novel strategies to meet this increasing global protein need.

Local Sources of Protein in Low- and Middle-Income Countries: How to Improve the Protein Quality?

Protein inadequacy is a major contributor to nutritional deficiencies and adverse health outcomes of populations in low- and middle-income countries (LMICs). People in LMICs often consume a diet predominantly based on staple crops, such as cereals or starches, and derive most of their daily protein intakes from these sources. However, plant-based sources of protein often contain low levels of indispensable amino acids (IAAs). Inadequate intake of IAA in comparison with daily requirements is a limiting factor that results in protein deficiency, consequently in the long-term stunting and wasting. In addition, plant-based sources contain factors such as antinutrients that can diminish protein digestion and absorption. This review describes factors that affect protein quality, reviews dietary patterns of populations in LMICs and discusses traditional and novel small- and large-scale techniques that can improve the quality of plant protein sources for enhanced protein bioavailability and digestibility as an approach to tackle malnutrition in LMICs. The more accessible small-scale food-processing techniques that can be implemented at home in LMICs include soaking, cooking, and germination, whereas many large-scale techniques must be implemented on an industrial level such as autoclaving and extrusion. Limitations and considerations to implement those techniques locally in LMICs are discussed. For instance, at-home processing techniques can cause loss of nutrients and contamination, whereas limitations with larger scale techniques include high energy requirements, costs, and safety considerations. This review suggests that combining these small- and large-scale approaches could improve the quality of local sources of proteins, and thereby address adverse health outcomes, particularly in vulnerable population groups such as children, adolescents, elderly, and pregnant and lactating women.

Genomic prediction reveals unexplored variation in grain protein and lysine content across a vast winter wheat genebank collection

Globally, wheat (Triticum aestivum L.) is a major source of proteins in human nutrition despite its unbalanced amino acid composition. The low lysine content in the protein fraction of wheat can lead to protein-energy-malnutrition prominently in developing countries. A promising strategy to overcome this problem is to breed varieties which combine high protein content with high lysine content. Nevertheless, this requires the incorporation of yet undefined donor genotypes into pre-breeding programs. Genebank collections are suspected to harbor the needed genetic diversity. In the 1970s, a large-scale screening of protein traits was conducted for the wheat genebank collection in Gatersleben; however, this data has been poorly mined so far. In the present study, a large historical dataset on protein content and lysine content of 4,971 accessions was curated, strictly corrected for outliers as well as for unreplicated data and consolidated as the corresponding adjusted entry means. Four genomic prediction approaches were compared based on the ability to accurately predict the traits of interest. High-quality phenotypic data of 558 accessions was leveraged by engaging the best performing prediction model, namely EG-BLUP. Finally, this publication incorporates predicted phenotypes of 7,651 accessions of the winter wheat collection. Five accessions were proposed as donor genotypes due to the combination of outstanding high protein content as well as lysine content. Further investigation of the passport data suggested an association of the adjusted lysine content with the elevation of the collecting site. This publicly available information can facilitate future pre-breeding activities.

In vitro determination of the protein quality of maize varieties cultivated in Malawi using the INFOGEST digestion method

There is an urgent need to alleviate protein deficiencies in low-income countries where cereal-based diets dominate. The objective of this study was to use the INFOGEST static digestion method and a recently established analytical workflow to determine the in vitro amino acid digestibility and protein quality of seven maize varieties grown in Malawi. Protein quality was measured using the in vitro digestible indispensable amino acid score (DIAAS). Amino acid digestibility was higher for the dehulled, low fibre, provitamin A maize flour (66%), compared to whole grain maize flours (51-61%), suggesting that the presence of fibre reduced digestibility (p < 0.05). Lysine was the limiting amino acid in all varieties, with the following DIAAS values for each variety; Provitamin A maize - 24, SC 719 - 32, Mtsikinya - 37, SC 167 - 39, Quality protein maize (QPM) - 40, Bantum - 40, SC 403 - 44. In addition to the variety of maize, protein quality was dependent on the level of processing and the agronomic practice applied with higher protein quality for the SC 403 variety in which zinc enriched fertilizer was applied. Comparing protein quality data with published in vivo data showed that DIAAS data were in closer agreement than amino acid digestibility data, which was slightly lower than published values, with mean in vitro amino acid digestibilities of 56-70% compared to a mean in vivo value of 77%. Overall, the in vitro method was able to correctly predict both the direction and magnitude of response. The INFOGEST digestion method coupled with the new analytical workflow will therefore be useful in the screening of high protein cereal crops and subsequent development of cereal-based foods with high protein quality.