Notwithstanding mass vaccination against specific SARS-CoV-2 variants, there is still a demand for complementary nutritional intervention strategies to fight COVID-19. The bovine milk protein lactoferrin (LF) has attracted interest of nutraceutical, food and dairy industries for its numerous properties—ranging from anti-viral and anti-microbial to immunological—making it a potential functional ingredient in a wide variety of food applications to maintain health. Importantly, bovine LF was found to exert anti-viral activities against several types of viruses, including certain SARS-CoV-2 variants. LF’s potential effect on COVID-19 patients has seen a rapid increase of in vitro and in vivo studies published, resulting in a model on how LF might play a role during different phases of SARS-CoV-2 infection. Aim of this narrative review is two-fold: (1) to highlight the most relevant findings concerning LF’s anti-viral, anti-microbial, iron-binding, immunomodulatory, microbiota-modulatory and intestinal barrier properties that support health of the two most affected organs in COVID-19 patients (lungs and gut), and (2) to explore the possible underlying mechanisms governing its mode of action. Thanks to its potential effects on health, bovine LF can be considered a good candidate for nutritional interventions counteracting SARS-CoV-2 infection and related COVID-19 pathogenesis.

The aim of this study was to investigate the loss of docosahexaenoic acid (DHA) from three supplements (two powders and one oil) after digestion (rumen and gastrointestinal) and their effects on the number and composition of rumen bacteria, using an in vitro approach. The concentration of supplements has a significant impact on the DHA loss rate and algal oil exhibited the highest rate of loss, but bioaccessibility was not significantly different from the other supplements. 16S rRNA sequencing showed that three DHA supplements altered the bacterial composition of in vitro batch cultures inoculated with rumen microorganisms from cows, and caused changes in the relative abundance of important bacterial phyla, families, and genera. DHA supplements altered the abundance of bacterial species, including Prevotella, Ruminobacter, Succiniclassicum, Succinivibrio, Lachnospiraceae, and Muribaculaceae. Importantly, these changes may be associated with the ruminal response in biohydrogenation. Algal oil has the most significant impact on rumen microbiota by reducing the richness and diversity of rumen microbiota, and significantly altering the composition of multiple important microbiota.

This study aimed to establish fatty acid profiles of regular raw milk and docosahexaenoic acid (DHA)-biofortified raw milk and to compare the volatile substance composition of the two types of raw milk. The fatty acid composition of the two types of raw milk was analyzed by gas chromatography–mass spectrometry (GC). The results revealed the absence of C15:1, C17:1, C18:2, C22:1, and C24:1 in both types of raw milk, while C20:3 and C22:6 were exclusively found in DHA-biofortified raw milk. The fatty acid levels generally followed a pattern of initial increase and subsequent decrease during lactation, with higher concentrations of short- and medium-chain fatty acids being observed in regular raw milk. The C16:0, C18:3, C20:3, and C20:5 contents in the two types of raw milk varied significantly at different lactation stages. The gas chromatography–mass spectrometry (GC-MS) analysis of the volatile substances revealed the presence of aldehydes, ketones, esters, acids, and sulfur-containing compounds. The volatile substance content in the DHA-biofortified raw milk was generally higher than that in the regular raw milk, which was attributed to the elevated levels of unsaturated fatty acids in biofortified DHA raw milk.

The objective of this study was to assess the effects of parity and lactation stage on the content and conversion rate of DHA in milk from dairy cows fed ruminally protected algae powder. A total of 800 cows were blocked by parity and divided into eight groups (n = 100, three groups of primiparous cows and five groups of multiparous cows) in a six-month experimental period. The lactation period was divided into three stages: 16 – 100 d, 101 – 200 d, and 201–305 d. All cows were fed 100 g of DHA-rich algae powder twice a day, with the DHA content > 13%. Milk samples were collected monthly, and daily milk yield and dry matter intake were recorded. Using infrared spectroscopy, we determined the content of protein, fat, lactose, and total solids in milk and calculated the DHA conversion rate. The results showed that parity and lactation stage had no significant effects on milk composition. However, milk yield and dry matter intake were higher in multiparous cows than in primiparous cows. The DHA content and conversion rate in milk were not significantly different between parity groups but were positively correlated with lactation stage and negatively correlated with milk fat content.

Docosahexaenoic acid (DHA) is an essential omega-3 polyunsaturated fatty acid with important health benefits. However, DHA enrichment in ruminant milk is limited by inefficient post-absorptive transport. This study evaluated whether combined supplementation of rumen-protected algae powder (RPA) and rumen-protected choline (RPC) enhances DHA enrichment in goat milk. Nine lactating dairy goats were assigned to three groups (n = 3/group) for 28 days: RPA alone, RPA + low-dose RPC (5 g/d), and RPA + high-dose RPC (10 g/d). Milk DHA content, bioconversion efficiency, serum biochemical parameters, and lipid profiles were analyzed. Compared with RPA alone, low- and high-dose RPC increased milk DHA content to 27.98 and 33.50 mg/100 mL, respectively, representing increases of 23.0% and 47.3%, and enhanced DHA bioconversion efficiency to 20.66% and 24.29% compared with 16.86% in the RPA group. RPC supplementation increased serum VLDL and triglyceride concentrations, and lipidomics revealed increased DHA-containing triglycerides (TG-DHA). These findings suggest that RPC may enhance DHA enrichment in goat milk by promoting VLDL-mediated DHA transport. Further studies with larger animal populations are required to confirm these effects. These findings contribute to a better understanding of nutritional regulation of DHA transfer and provide insights into strategies for developing DHA-enriched dairy products.