Postprandial lipemia and fecal fat excretion in rats is affected by the calcium content and type of milk fat present in Cheddar-type cheeses

Invited Review: The impact of the dairy food matrix on digestion and absorption

The nutritional value of any food product has historically been measured by the calorific value of individual components, harking back to the days of the development of the bomb calorimeter. A fuller understanding of nutrition later took into account the need for specific components, such as proteins, carbohydrates, vitamins and minerals, that ere known to be required for good human health and growth. In milk and milk products, these include casein and whey proteins, lactose, milk fat triacylglycerides, minor lipid components (both charged and neutral), calcium, and micronutrients. Whey proteins are known to be richer in essential amino acids, compared with casein, and also to contain branched chain amino acids for muscle growth. Calcium is found in the form of the calcium phosphate mineral and is dispersed, but largely insoluble in milk. All of this information does not take into account interactions between milk components, and therefore can be considered as a reductionist nutritional approach. This review takes a structural and physical chemical approach to understand how digestibility and nutritional delivery is impacted by microstructures and nutrient component interactions, with a focus on mechanistic explanations.

Dairy products and constituents: a review of their effects on obesity and related metabolic diseases

Obesity has become a global public health problem that seriously affects the quality of life. As an important part of human diet, dairy products contain a large number of nutrients that are essential for maintaining human health, such as proteins, peptides, lipids, vitamins, and minerals. A growing number of epidemiological investigations provide strong evidence on dairy interventions for weight loss in overweight/obese populations. Therefore, this paper outlines the relationship between the consumption of different dairy products and obesity and related metabolic diseases. In addition, we dive into the mechanisms related to the regulation of glucose and lipid metabolism by functional components in dairy products and the interaction with gut microbes. Lastly, the role of dairy products on obesity of children and adolescents is revisited. We conclude that whole dairy products exert more beneficial effect than single milk constituent on alleviating obesity and that dairy matrix has important implications for metabolic health.

Progression of Postprandial Blood Plasma Phospholipids Following Acute Intake of Different Dairy Matrices: A Randomized Crossover Trial

Studies have indicated that the dairy matrix can affect postprandial responses of dairy products, but little is known about the effect on postprandial plasma phospholipid levels. This study investigated postprandial plasma phospholipid levels following consumption of four different dairy products that are similar in micro and macro nutrients, but different in texture and structure: cheddar cheese (Cheese), homogenized cheddar cheese (Hom. Cheese), micellar casein isolate with cream (MCI Drink) or a gel made from the MCI Drink (MCI Gel). The study was an acute randomized, crossover trial in human volunteers with four test days. Blood samples were collected during an 8 h postprandial period and the content of 53 plasma phospholipids was analysed using liquid chromatography-mass spectrometry (LC-MS). No meal-time interactions were revealed; however, for nine of the 53 phospholipids, a meal effect was found. Thus, the results indicated a lower plasma level of specific lyso-phosphatidylethanolamines (LPEs) and lyso-phosphatidylcholines (LPCs) following consumption of the MCI Gel compared to the MCI Drink and Hom. Cheese, which might be attributed to an effect of viscosity. However, further studies are needed in order to reveal more details on the effect of the dairy matrix on postprandial phospholipids.

New insights into the digestion and bioavailability of a high-melting-temperature solid triacylglycerol fraction in bovine milk fat

Clarifying the health risks associated with the consumption of high-melting-temperature solid triacylglycerol (TAG) from milk fat has profound significance for the nutritional evaluation and development of new dairy products. Our previous work effectively separated butterfat into solid/liquid fractions (30S and 30L) at 30 °C and successfully reconstituted milk fat globules (MFGs) with these fractions. The current study examined the postprandial digestive and daily metabolic properties of a high-melting-temperature solid TAG fraction by performing animal experiments (rats) with 30S-reconstituted MFG emulsion gavage for 240 min and 30S-containing diet administration for 4 weeks. Compared to the consumption of whole butterfat, 30S consumption altered apolipoprotein levels and did not lead to dyslipidaemia in the rats. Conversely, 30S administration induced significant body weight loss by enhancing satiety signals (glucagon-like peptide 1, GLP-1; cholecystokinin, CCK; and peptide YY, PYY), increasing faecal losses, and upregulating the level of hepatic lipolysis-associated enzymes (hormone-sensitive lipase, HSL; adipose triglyceride lipase, ATGL; and protein kinase A, PKA). The 30S diet efficiently improved adipocyte hypertrophy and reduced fat accumulation by downregulating the level of acetyl-CoA carboxylase (ACC) in adipose tissue. This study is of relevance to nutrition science and the dairy industry.

Symposium review: The dairy matrix-Bioaccessibility and bioavailability of nutrients and physiological effects

Several studies have linked food structure and texture to different kinetics of nutrients delivery. Changes in some nutrients' release rate, such as proteins and lipids, could induce different physiological effects (e.g., satiety effect, reduction of postprandial lipemia). Recently, experts are proposing to consider the food as a whole instead of looking at specific nutrients, as the combination of food components and the way they are structured could change their physiological effects. This review highlights recent knowledge linking the different levels of structure of dairy products to their digestion, absorption, and physiological effects. Two examples, yogurt and cheese, will be presented to showcase the contributions of dairy food structure to nutrient release rates. One study aimed to validate whether changes in the casein:whey protein ratio or addition of fiber could influence the digestion kinetics of protein and, subsequently, satiety. A static in vitro digestion model has been used on experimental yogurts differing by their casein:whey protein ratio or dietary fiber content. A human trial with healthy men (n = 20) consuming 5 isocaloric and isoproteinemic yogurt snacks before monitoring lunch intake revealed that the yogurt formulation with increased whey protein content significantly reduced subsequent energy intake compared with its control. This result was linked to slower in vitro disintegration rate and soluble protein release for yogurts with increased whey protein, whereas no difference was observed for yogurts with fiber. A second study allowed discrimination between the effects of cheese attributes on lipid release and absorption. Nine commercial cheeses were digested in vitro, and 2 were selected for the in vivo study, in which plasma concentrations of triglycerides (TAG) were followed before and after meal consumption. The in vivo study revealed that cream cheese, but not cheddar, induced a greater increase in TAG concentrations at 2 h than did butter; this difference was linked to their in vitro disintegration. These studies demonstrate that the dairy food matrix per se modulates foods' nutritional properties. Other studies recently published on this topic will also be included, to put in perspective the important role of the dairy food matrix on release of nutrients and their physiological effects, and how this can be compared with other foods.

Anti-Obesity Effects of Dietary Calcium: The Evidence and Possible Mechanisms

Obesity is a serious health challenge worldwide and is associated with various comorbidities, including dyslipidemia, type 2 diabetes, and cardiovascular disease. Developing effective strategies to prevent obesity is therefore of paramount importance. One potential strategy to reduce obesity is to consume calcium, which has been implicated to be involved in reducing body weight/fat. In this review, we compile the evidence for the anti-obesity roles of calcium in cells, animals, and humans. In addition, we summarize the possible anti-obesity mechanisms of calcium, including regulation of (a) adipogenesis, (b) fat metabolism, (c) adipocyte (precursor) proliferation and apoptosis, (d) thermogenesis, (e) fat absorption and excretion, and (f) gut microbiota. Although the exact anti-obesity roles of calcium in different subjects and how calcium induces the proposed anti-obesity mechanisms need to be further investigated, the current evidence demonstrates the anti-obesity effects of calcium and suggests the potential application of dietary calcium for prevention of obesity.