Effects of Whey Protein or Its Hydrolysate Supplements Combined with an Energy-Restricted Diet on Weight Loss: A Randomized Controlled Trial in Older Women

Impacts of supplementation with milk proteins on inflammation: a systematic review and meta-analysis

BACKGROUND

Impacts of milk proteins (MPs) on inflammation are uncertain. The current systematic review and dose-response meta-analysis of randomized controlled trials (RCTs) evaluated the effects of whey protein (WP), casein protein (CP), or MP supplementation on serum levels of cytokines and adipokines in adults.

METHODS

A comprehensive search of various online databases was conducted to find appropriate clinical trials published until September 2024. A random-effect statistical model was implemented.

RESULTS

The meta-analysis included 53 RCTs. It was indicated that MP supplements had no substantial effects on serum values of C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), adiponectin, and leptin. However, there were statistically significant decreases in serum levels of interleukin-6 (IL-6) following supplementation with MP (weighted mean difference (WMD): - 0.25 pg/mL, 95% CI - 0.48, - 0.03; P = 0.026) in the intervention group compared with the control group.

CONCLUSION

This study revealed that MP supplementation may not have any considerable impacts on the levels of cytokines and adipokines.

Influence of dietary protein and fiber intake interactions on the human gut microbiota composition and function: a systematic review and network meta-analysis of randomized controlled trials

Quantity and source of dietary protein intakes impact the gut microbiota differently. However, these effects have not been systematically studied. This review aimed to investigate these effects whilst controlling for fiber intake. Seven databases were searched, with 50 and 15 randomized controlled trials selected for the systematic review and network meta-analysis respectively. Most gut microbiota-related outcomes showed no significant differences between different protein and fiber intake combinations. Compared to Normal Protein, High Fiber intakes, High Protein, Low Fiber (HPLF) intakes showed greater fecal valerate (SMD = 0.79, 95% CrI: 0.35, 1.24) and plasma trimethylamine N-oxide (TMAO) (SMD = 2.90, 95% CrI: 0.16, 5.65) levels. HPLF intakes also showed greater fecal propionate (SMD = 0.49, 95% CrI: 0.02, 1.07) and valerate (SMD = 0.79, 95% CrI: 0.31, 1.28) levels compared to High Protein, High Fiber intakes. Greater plasma TMAO levels were observed with greater animal protein intakes. Overall, protein quantity and source do not generally alter the gut microbiota composition, although protein quantity can influence microbiota function via modulations in proteolytic fermentation. Both protein and fiber intake should be considered when assessing the impact of dietary protein on the gut microbiota. This trial was registered at PROSPERO (CRD42023391270).

Enhanced protein intake on maintaining muscle mass, strength, and physical function in adults with overweight/obesity: A systematic review and meta-analysis

BACKGROUND & AIMS

Weight loss in individuals with obesity and overweight leads to metabolic and health benefits but also poses the risk of muscle mass reduction. This systematic review and meta-analysis of randomized controlled trials aims to determine the initial protein amount necessary for achieving weight loss while maintaining muscle mass, strength, and physical function in adults with overweight and obesity.

METHODS

Relevant literature databases, including Medical Literature Analysis and Retrieval System Online (Medline), Excerpta Medica (Embase), the Cumulative Index to Nursing and Allied Health Literature (CINHAL), and Web of Science, were electronically searched up to 15 March 2023. We examined the effect of additional protein intake on muscle mass, strength, and physical function in adults with overweight or obesity targeting weight loss. The risk of bias was assessed using the Cochrane RoB 2.0 tool. Results were synthesized using standardized mean differences (SMD) and 95% confidence intervals (CI) via a random-effects model.

RESULTS

Forty-seven studies (n = 3218) were included. In the muscle mass analysis, twenty-eight trials with 1989 participants were encompassed. Results indicated that increased protein intake significantly prevents muscle mass decline in adults with overweight or obesity aiming for weight loss (SMD 0.75; 95% CI 0.41 to 1.10; p < 0.001). Enhanced protein intake did not significantly prevent decreases in muscle strength and physical function. An intake exceeding 1.3 g/kg/day is anticipated to increase muscle mass, while an intake below 1.0 g/kg/day is associated with a higher risk of muscle mass decline. The risk of bias in studies regarding muscle mass ranged from low to high.

CONCLUSIONS

Adults with overweight or obesity and aim for weight loss can more effectively retain muscle mass through higher protein intake, as opposed to no protein intake enhancement.

Cow's Milk Bioactive Molecules in the Regulation of Glucose Homeostasis in Human and Animal Studies

Obesity disrupts glucose metabolism, leading to insulin resistance (IR) and cardiometabolic diseases. Consumption of cow's milk and other dairy products may influence glucose metabolism. Within the complex matrix of cow's milk, various carbohydrates, lipids, and peptides act as bioactive molecules to alter human metabolism. Here, we summarize data from human studies and rodent experiments illustrating how these bioactive molecules regulate insulin and glucose homeostasis, supplemented with in vitro studies of the mechanisms behind their effects. Bioactive carbohydrates, including lactose, galactose, and oligosaccharides, generally reduce hyperglycemia, possibly by preventing gut microbiota dysbiosis. Milk-derived lipids of the milk fat globular membrane improve activation of insulin signaling pathways in animal trials but seem to have little impact on glycemia in human studies. However, other lipids produced by ruminants, including polar lipids, odd-chain, trans-, and branched-chain fatty acids, produce neutral or contradictory effects on glucose metabolism. Bioactive peptides derived from whey and casein may exert their effects both directly through their insulinotropic effects or renin-angiotensin-aldosterone system inhibition and indirectly by the regulation of incretin hormones. Overall, the results bolster many observational studies in humans and suggest that cow's milk intake reduces the risk of, and can perhaps be used in treating, metabolic disorders. However, the mechanisms of action for most bioactive compounds in milk are still largely undiscovered.

Nourishing the gut: the impact of diet on host-gut microbiota interaction

PURPOSE OF REVIEW

Understanding the spectrum of drivers that influence the gut microbiome (GM) remains a crucial field of investigation. Among these factors, diet has received particular attention, as it could explain up to 20% of the variability in GM composition between individuals. This review focuses on the complex relationships between different dietary patterns and GM in humans, based on recent findings.

RECENT FINDINGS

Current evidence underscores the multifaceted impact of diet on GM richness, diversity, and overall composition. Key contributing factors encompass dietary habits, nutritional interventions, food quality and variety, macronutrient distribution, timing of feeding, and selective exclusion of certain foods.

SUMMARY

The intricate interplay between diet and GM is of fundamental importance in shaping the interaction between the host and the environment. Further understanding the causal impact of diet on GM has promising potential for the advancement of strategies to promote health and mitigate cardio-metabolic disease risks through dietary interventions.

GRAPHICAL ABSTRACT

http://links.lww.com/COCN/A21.

Effects of Animal and Vegetable Proteins on Gut Microbiota in Subjects with Overweight or Obesity

The gut microbiota plays a pivotal role in the balance between host health and obesity. The composition of the gut microbiota can be influenced by external factors, among which diet plays a key role. As the source of dietary protein is important to achieve weight loss and gut microbiota modulation, in the literature there is increasing evidence to suggest consuming more plant proteins than animal proteins. In this review, a literature search of clinical trials published until February 2023 was conducted to examine the effect of different macronutrients and dietary patterns on the gut microbiota in subjects with overweight and obesity. Several studies have shown that a higher intake of animal protein, as well as the Western diet, can lead to a decrease in beneficial gut bacteria and an increase in harmful ones typical of obesity. On the other hand, diets rich in plant proteins, such as the Mediterranean diet, lead to a significant increase in anti-inflammatory butyrate-producing bacteria, bacterial diversity and a reduction in pro-inflammatory bacteria. Therefore, since diets rich in fiber, plant protein, and an adequate amount of unsaturated fat may help to beneficially modulate the gut microbiota involved in weight loss, further studies are needed.

Evidence of Immunomodulatory Food-Protein Derived Peptides in Human Nutritional Interventions: Review on the Outcomes and Potential Limitations

The immune system is somehow related to all the metabolic pathways, in a bidirectional way, and the nutritional interventions affecting these pathways might have a relevant impact on the inflammatory status of the individuals. Food-derived peptides have been demonstrated to exert several bioactivities by in vitro or animal studies. Their potential to be used as functional food is promising, considering the simplicity of their production and the high value of the products obtained. However, the number of human studies performed until now to demonstrate effects in vivo is still scarce. Several factors must be taken into consideration to carry out a high-quality human study to demonstrate immunomodulatory-promoting properties of a test item. This review aims to summarize the recent human studies published in which the purpose was to demonstrate bioactivity of protein hydrolysates, highlighting the main results and the limitations that can restrict the relevance of the studies. Results collected are promising, although in some studies, physiological changes could not be observed. When responses were observed, they sometimes did not refer to relevant parameters and the immunomodulatory properties could not be clearly established with the current evidence. Well-designed clinical trials are needed in order to evaluate the role of protein hydrolysates in immunonutrition.

Physical Activity and Diet in Older Women: A Narrative Review

Physical activity and diet are essential for maintaining good health and preventing the development of non-communicable diseases, especially in the older adults. One aspect that is often over-looked is the different response between men and women to exercise and nutrients. The body's response to exercise and to different nutrients as well as the choice of foods is different in the two sexes and is strongly influenced by the different hormonal ages in women. The present narrative review analyzes the effects of gender on nutrition and physical activity in older women. Understanding which components of diet and physical activity affect the health status of older women would help target non-pharmacological but lifestyle-related therapeutic interventions. It is interesting to note that this analysis shows a lack of studies dedicated to older women and a lack of studies dedicated to the interactions between diet and physical activity in women. Gender medicine is a current need that still finds little evidence.