The innate immune system responds in a rapid and non‐specific manner against immunologic threats; inflammation is part of this response. This is followed by a slower but targeted and specific response termed the adaptive or acquired immune response. There is emerging evidence that dietary components, including yeast‐derived β‐glucans, can aid host defense against pathogens by modulating inflammatory and antimicrobial activity of neutrophils and macrophages. Innate immune training refers to a newly recognized phenomenon wherein compounds may “train” innate immune cells, such that monocyte and macrophage precursor biology is altered to mount a more effective immunological response. Although various human studies have been carried out, much uncertainty still exists and further studies are required to fully elucidate the relationship between β‐glucan supplementation and human immune function. This review offers an up‐to‐date report on yeast‐derived β‐glucans as immunomodulators, including a brief overview of the current paradigm regarding the interaction of β‐glucans with the immune system. The recent pre‐clinical work that has partly decrypted mode of action and the newest evidence from human trials are also reviewed. According to pre‐clinical studies, β‐1,3/1,6‐glucan derived from baker's yeast may offer increased immuno‐surveillance, although the human evidence is weaker than that gained from pre‐clinical studies.

Arthrospira platensis (spirulina), a filamentous fresh-water planktonic cyanobacterium, possesses diverse biological activities and a unique nutritional profile, due to its high content of valuable nutrients. This study aimed to further improve the bioactive profile of spirulina, by fermenting it with the lactic acid bacterium Lactobacillus plantarum. In vitro comparison of the total phenolic content (TPC), C-phycocyanin, free methionine, DPPH radical scavenging capacity, ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC) and protein fragmentation via SDS-PAGE in untreated versus 12 to 72 h fermented spirulina is reported here. After 36 h fermentation, TPC was enhanced by 112%, FRAP by 85% and ORAC by 36%. After 24 h, the DPPH radical scavenging capacity increased 60%, while the free methionine content increased by 94%, after 72 h. Past 36 h of fermentation, the total antioxidant capacity (TAC) diminished, possibly due to deterioration of the heat-sensitive antioxidants. However, protein fragmentation and free methionine content increased, linearly, with the fermentation time. Cyanobacterial peptides and other bioactive compounds trapped within the spirulina cell wall are released during fermentation and have a significant potential as a functional ingredient in nutraceuticals and pharmaceuticals, in addition to their nutritive value.

Plant-based proteins are generally characterised by lower Indispensable Amino Acid (IAA) content, digestibility, and anabolic properties, compared to animal-based proteins. However, they are environmentally friendlier, and wider consumption is advocated. Older adults have higher dietary protein needs to prevent sarcopenia, a disease marked by an accelerated loss of muscle mass and function. Given the lower environmental footprint of plant-based proteins and the importance of optimising dietary protein quality among older adults, this paper aims to assess the net peripheral Amino Acid (AA) appearance after ingestion of three different plant protein and fibre (PPF) products, compared to whey protein with added fibre (WPF), in healthy older adults. In a randomised, single-blind, crossover design, nine healthy men and women aged ≥65 years consumed four test meals balanced in AA according to the FAO reference protein for humans, matched for leucine, to optimally stimulate muscle protein synthesis in older adults. A fasted blood sample was drawn at each visit before consuming the test meal, followed by postprandial arterialise blood sampling every 30 min for 3 h. The test meal was composed of a soup containing either WPF or PPF 1–3. The PPF blends comprised pea proteins with varying additional rice, pumpkin, soy, oat, and/or almond protein. PPF product ingestion resulted in a lower maximal increase of postprandial leucine concentration and the sum of branched-chain AA (BCAA) and IAA concentrations, compared to WPF, with no effect on their incremental area under the curve. Plasma methionine and cysteine, and to a lesser extent threonine, appearance were limited after consuming the PPF products, but not WPF. Despite equal leucine doses, the WPF induced greater postprandial insulin concentrations than the PPF products. In conclusion, the postprandial appearance of AA is highly dependent on the protein source in older adults, despite providing equivalent IAA levels and dietary fibre. Coupled with lower insulin concentrations, this could imply less anabolic potential. Further investigation is required to understand the applicability of plant-based proteins in healthy older adults.