Effects of milk and milk constituents on postprandial lipid and glucose metabolism in overweight and obese men

Metabolic Syndrome and Biotherapeutic Activity of Dairy (Cow and Buffalo) Milk Proteins and Peptides: Fast Food-Induced Obesity Perspective-A Narrative Review

Metabolic syndrome (MS) is defined by the outcome of interconnected metabolic factors that directly increase the prevalence of obesity and other metabolic diseases. Currently, obesity is considered one of the most relevant topics of discussion because an epidemic heave of the incidence of obesity in both developing and underdeveloped countries has been reached. According to the World Obesity Atlas 2023 report, 38% of the world population are presently either obese or overweight. One of the causes of obesity is an imbalance of energy intake and energy expenditure, where nutritional imbalance due to consumption of high-calorie fast foods play a pivotal role. The dynamic interactions among different risk factors of obesity are highly complex; however, the underpinnings of hyperglycemia and dyslipidemia for obesity incidence are recognized. Fast foods, primarily composed of soluble carbohydrates, non-nutritive artificial sweeteners, saturated fats, and complexes of macronutrients (protein-carbohydrate, starch-lipid, starch-lipid-protein) provide high metabolic calories. Several experimental studies have pointed out that dairy proteins and peptides may modulate the activities of risk factors of obesity. To justify the results precisely, peptides from dairy milk proteins were synthesized under in vitro conditions and their contributions to biomarkers of obesity were assessed. Comprehensive information about the impact of proteins and peptides from dairy milks on fast food-induced obesity is presented in this narrative review article.

Role of Fluid Milk in Attenuating Postprandial Hyperglycemia and Hypertriglyceridemia

Postprandial plasma glucose and triglyceride concentrations are predictive of relative cardiovascular disease (CVD) risk, and the pathogenesis of both insulin resistance and atherosclerosis has been attributed to acute states of hyperglycemia and hypertriglyceridemia. Postprandial lipemia and hyperglycemia suppress vascular reactivity and induce endothelial dysfunction. Epidemiological studies suggest that chronically-high consumption of milk and milk products is associated with a reduced risk of type 2 diabetes, metabolic syndrome, and CVD. The addition of dairy products to meals high in carbohydrates and fat may lessen these risks through reductions in postprandial glucose and triglyceride responses. Purported mechanisms include dairy proteins and bioactive compounds, which may explain the inverse relationship between dairy consumption and cardiometabolic diseases. The current review evaluates the available literature describing the relationships between metabolic dysfunction, postprandial metabolism, and vascular dysfunction and discusses the potential role of milk and dairy products in attenuating these impairments.

Changes in alanine aminotransferase in adults with severe and complicated obesity during a milk-based meal replacement programme

Introduction

Excess adiposity is associated with fat accumulation within the liver, and non-alcoholic steatohepatitis (NASH) is highly prevalent in bariatric patients. Elevated alanine aminotransferase (ALT) is associated with prevalent NASH. We sought to determine the influence of a milk-based meal replacement weight-loss programme on ALT levels in adults with severe and complicated obesity.

Methods

We conducted a retrospective cohort study of patients who completed a 24-week meal replacement programme, comprised of a weight loss phase followed by weight stabilisation and maintenance phases, each 8 weeks long. ALT was quantified using an enzymatic assay with spectrophotometric detection. We examined changes over time in ALT using the non-parametric Wilcoxon singed-rank test and the Friedman test.

Results

Of 105 patients, 56 were female, mean age was 51.2 ± 11.2 (range 18.0–71.6) years. There was an unanticipated but transient increase in ALT from 28.0 [20.0, 40.5] iu/L at baseline to 40.0 [26.0, 55.0] iu/L after 2 weeks (p < 0.0005), followed by a gradual reduction to 21.0 [17.0, 28.3] iu/L by 24 weeks (p < 0.0005). The overall reductions in ALT were more pronounced in patients who had elevated levels at baseline. Body weight decreased from 144.2 ± 28.0 kg at baseline to 121.6 ± 25.4 kg at 24 weeks (p < 0.0005) and body mass index (BMI) decreased from 50.7 ± 8.1 kg m⁻² at baseline to 43.0 ± 7.6 kg m⁻² by 24 weeks (p < 0.0005).

Conclusion

In adults with severe and complicated obesity undergoing a milk-based meal replacement programme, there was an initial unanticipated rise in ALT in the first 2 weeks, followed by a gradual overall reduction by 24 weeks. These findings suggest that rapid weight loss secondary to significant caloric restriction might induce a transient deterioration in hepatic steatosis prior to an ultimate overall improvement.

The Influence of Different Foods and Food Ingredients on Acute Postprandial Triglyceride Response: A Systematic Literature Review and Meta-Analysis of Randomized Controlled Trials

The use of postprandial triglyceride (ppTG) as a cardiovascular disease risk indicator has gained recent popularity. However, the influence of different foods or food ingredients on the ppTG response has not been comprehensively characterized. A systematic literature review and meta-analysis was conducted to assess the effects of foods or food ingredients on the ppTG response. PubMed, MEDLINE, Cochrane, and CINAHL databases were searched for relevant acute (<24-h) randomized controlled trials published up to September 2018. Based on our selection criteria, 179 relevant trials (366 comparisons) were identified and systematically compiled into distinct food or food ingredient categories. A ppTG-lowering effect was noted for soluble fiber (Hedges' giAUC = -0.72; 95% CI: -1.33, -0.11), sodium bicarbonate mineral water (Hedges' gAUC = -0.42; 95% CI: -0.79, -0.04), diacylglycerol oil (Hedges' giAUC = -0.38; 95% CI: -0.75, -0.00), and whey protein when it was contrasted with other proteins. The fats group showed significant but opposite effects depending on the outcome measure used (Hedges' giAUC = -0.32; 95% CI: -0.61, -0.03; and Hedges' gAUC = 0.16; 95% CI: 0.06, 0.26). Data for other important food groups (nuts, vegetables, and polyphenols) were also assessed but of limited availability. Assessing for oral fat tolerance test (OFTT) recommendation compliance, most trials were ≥4 h long but lacked a sufficiently high fat challenge. iAUC and AUC were more common measures of ppTG. Overall, our analyses indicate that the effects on ppTG by different food groups are diverse, largely influenced by the type of food or food ingredient within the same group. The type of ppTG measurement can also influence the response.

Effects of a Milk-Based Meal Replacement Program on Weight and Metabolic Characteristics in Adults with Severe Obesity

OBJECTIVE

Low energy meal replacement regimens can induce short-term weight loss in patients with severe obesity, but usually require specially formulated dietary supplements. We sought to determine the effects of a milk-based meal replacement program on anthropometric and metabolic characteristics in adults with severe obesity.

METHODS

We conducted a retrospective cohort study of patients attending our hospital-based bariatric medicine service who completed a 24-week program consisting of eight weeks of milk-based meal replacement followed by weight stabilisation and maintenance phases. Patients were seen fortnightly by the bariatric physician, nurse and dietitian. We assessed changes in anthropometric and metabolic outcomes in completers at 0, 8, 16 and 24 weeks.

RESULTS

Of 105 program completers available for follow-up, 53.3% were female. Mean age was 51.1±11.2 years. Body weight decreased from 144.0±27.6 kg at baseline to 121.1±25.0 kg at 24 weeks (P<0.001), a mean total body weight loss of 15.9±6.0%, with a reduction in body mass index from 50.6±8.0 to 42.6±7.6 kg m^-2 (P<0.001). In patients with diabetes, haemoglobin A1c decreased from 66.3±13.0 to 48.3±13.5 mmol/mol (P<0.001) and diabetes medication use decreased significantly. There were significant improvements also in lipid profiles and reductions in antihypertensive medication use.

CONCLUSION

These preliminary findings suggest that completion of a 24-week milk-based meal replacement program has large effects on important outcomes in adults with severe obesity. However, attrition was high. Prospective assessment of the efficacy, safety, durability and cost-effectiveness of this intervention seems warranted.

Utilising a milk-based meal replacement programme in a bariatric patient with poorly controlled type 2 diabetes mellitus

A 45-year-old man with poorly controlled type 2 diabetes (T2DM) (HbA1c 87 mmol/mol) despite 100 units of insulin per day and severe obesity (BMI 40.2 kg/m2) was referred for bariatric intervention. He declined bariatric surgery or GLP1 agonist therapy. Initially, his glycaemic control improved with dietary modification and better adherence to insulin therapy, but he gained weight. We started a low-energy liquid diet, with 2.2 L of semi-skimmed milk (equivalent to 1012 kcal) per day for 8 weeks (along with micronutrient, salt and fibre supplementation) followed by 16 weeks of phased reintroduction of a normal diet. His insulin was stopped within a week of starting this programme, and over 6 months, he lost 20.6 kg and his HbA1c normalised. However, 1 year later, despite further weight loss, his HbA1c deteriorated dramatically, requiring introduction of linagliptin and canagliflozin, with good response. Five years after initial presentation, his BMI remains elevated but improved at 35.5 kg/m2 and his glycaemic control is excellent with a HbA1c of 50 mmol/mol and he is off insulin therapy. Whether semi-skimmed milk is a safe, effective substrate for carefully selected patients with severe obesity complicated by T2DM remains to be determined. Such patients would need frequent monitoring by an experienced multidisciplinary team. Learning points: Meal replacement programmes are an emerging therapeutic strategy to allow severely obese type 2 diabetes patients to achieve clinically impactful weight loss. Using semi-skimmed milk as a meal replacement substrate might be less costly than commercially available programmes, but is likely to require intensive multidisciplinary bariatric clinical follow-up. For severely obese adults with poor diabetes control who decline bariatric surgery or GLP1 agonist therapy, a milk-based meal replacement programme may be an option. Milk-based meal replacement in patients with insulin requiring type 2 diabetes causes rapid and profound reductions in insulin requirements, so rigorous monitoring of glucose levels by patients and their clinicians is necessary. In carefully selected and adequately monitored patients, the response to oral antidiabetic medications may help to differentiate between absolute and relative insulin deficiency.

Casein Hydrolysate with Glycemic Control Properties: Evidence from Cells, Animal Models, and Humans

Evidence exists to support the role of dairy derived proteins whey and casein in glycemic management. The objective of the present study was to use a cell screening method to identify a suitable casein hydrolysate and to examine its ability to impact glycemia related parameters in an animal model and in humans. Following screening for the ability to stimulate insulin secretion in pancreatic beta cells, a casein hydrolysate was selected and further studied in the ob/ob mouse model. An acute postprandial study was performed in 62 overweight and obese adults. Acute and long-term supplementation with the casein hydrolysate in in vivo studies in mice revealed a glucose lowering effect and a lipid reducing effect of the hydrolysate (43% reduction in overall liver fat). The postprandial human study revealed a significant increase in insulin secretion ( p = 0.04) concomitant with a reduction in glucose ( p = 0.03). The area under the curve for the change in glucose decreased from 181.84 ± 14.6 to 153.87 ± 13.02 ( p = 0.009). Overall, the data supports further work on the hydrolysate to develop into a functional food product.

The influence of dietary and supplemental calcium on postprandial effects of a high-fat meal on lipaemia, glycaemia, C-reactive protein and adiponectin in obese women

Non-fasting hypertriacylglycerolaemia is a risk factor for CVD and the amount of fat in a meal seems to be the main factor influencing postprandial lipaemia. Although several studies suggest that Ca can increase faecal fat excretion, it is not known whether Ca can decrease postprandial TAG. This study aimed to evaluate the influence of dietary Ca (DC) and supplemental Ca (SC) on lipaemia, glucose metabolism, C-reactive protein (CRP) and adiponectin during postprandial period in obese women challenged with a high-fat meal. In this cross-over controlled trial, sixteen obese women aged 20-50 years were randomly assigned to receive three test meals (approximately 2900 kJ; 48 % fat): high DC (547 mg DC), high SC (HSCM; 500 mg SC-calcium carbonate) and low Ca (42 mg DC). Blood samples were collected in the fasting period and at minutes 120 and 240 after meals to evaluate total cholesterol and fractions, TAG, glucose, insulin, high-sensitivity CRP and adiponectin. Serum levels of TAG and insulin increased significantly after all test meals. Only after HSCM total cholesterol did not present a significant increase and LDL-cholesterol had a significant decrease. Postprandial glucose, HDL-cholesterol, CRP and adiponectin did not present significant changes after the three test meals. The comparative analysis of the effects of the three test meals on serum lipids, glucose, insulin, CRP and adiponectin revealed no significant meal-by-time interaction. These results suggest that in obese women challenged with a high-fat meal DC and SC do not interfere with postprandial lipaemia, glucose metabolism, CRP and adiponectin.

Postprandial Glycemic and Insulinemic Responses to Common Breakfast Beverages Consumed with a Standard Meal in Adults Who Are Overweight and Obese

Breakfast beverages with different nutrient compositions may affect postprandial glycemic control differently. We assessed the effects of consuming (1) common breakfast beverages (water, sugar-sweetened coffee, reduced-energy orange juice (OJ), and low-fat milk (LFM)); and (2) fat-free, low-fat, and whole milk with breakfast on postprandial plasma glucose and insulin responses in adults who were overweight/obese. Forty-six subjects (33F/13M, body mass index: 32.5 ± 0.7 kg/m², age: 50 ± 1 years, mean ± SEMs) consumed a standard sandwich with one of the six beverages on separate mornings in randomized order. The test beverages (except water) each contained 12 g digestible carbohydrate. Plasma glucose and insulin concentrations were measured from blood obtained pre- and post-meal at 30-min intervals for 4 h and incremental areas under the curve (AUC) were computed. We found (1) among different beverage types, glucose AUC was higher for coffee versus water, OJ, and LFM. Insulin AUC was higher for coffee and LFM versus OJ and water; (2) Glucose AUCs were not different among water and milks while insulin AUC was higher for milks versus water. In conclusion, consumption of water, reduced-energy OJ, or milk (irrespective of fat content) with a meal may be preferable to consuming sugar-sweetened coffee for glucose control in middle-aged adults who are overweight and obese.

Comprehensive Review of the Impact of Dairy Foods and Dairy Fat on Cardiometabolic Risk

Because regular-fat dairy products are a major source of cholesterol-raising saturated fatty acids (SFAs), current US and Canadian dietary guidelines for cardiovascular health recommend the consumption of low-fat dairy products. Yet, numerous randomized controlled trials (RCTs) have reported rather mixed effects of reduced- and regular-fat dairy consumption on blood lipid concentrations and on many other cardiometabolic disease risk factors, such as blood pressure and inflammation markers. Thus, the focus on low-fat dairy in current dietary guidelines is being challenged, creating confusion within health professional circles and the public. This narrative review provides perspective on the research pertaining to the impact of dairy consumption and dairy fat on traditional and emerging cardiometabolic disease risk factors. This comprehensive assessment of evidence from RCTs suggests that there is no apparent risk of potential harmful effects of dairy consumption, irrespective of the content of dairy fat, on a large array of cardiometabolic variables, including lipid-related risk factors, blood pressure, inflammation, insulin resistance, and vascular function. This suggests that the purported detrimental effects of SFAs on cardiometabolic health may in fact be nullified when they are consumed as part of complex food matrices such as those in cheese and other dairy foods. Thus, the focus on low-fat dairy products in current guidelines apparently is not entirely supported by the existing literature and may need to be revisited on the basis of this evidence. Future studies addressing key research gaps in this area will be extremely informative to better appreciate the impact of dairy food matrices, as well as dairy fat specifically, on cardiometabolic health.

Inflammatory and metabolic responses to high-fat meals with and without dairy products in men

Postprandial inflammation is an important factor for human health since chronic low-grade inflammation is associated with chronic diseases. Dairy products have a weak but significant anti-inflammatory effect on postprandial inflammation. The objective of the present study was to compare the effect of a high-fat dairy meal (HFD meal), a high-fat non-dairy meal supplemented with milk (HFM meal) and a high-fat non-dairy control meal (HFC meal) on postprandial inflammatory and metabolic responses in healthy men. A cross-over study was conducted in nineteen male subjects. Blood samples were collected before and 1, 2, 4 and 6 h after consumption of the test meals. Plasma concentrations of insulin, glucose, total cholesterol, LDL-cholesterol, HDL-cholesterol, TAG and C-reactive protein (CRP) were measured at each time point. IL-6, TNF-α and endotoxin concentrations were assessed at baseline and endpoint (6 h). Time-dependent curves of these metabolic parameters were plotted, and the net incremental AUC were found to be significantly higher for TAG and lower for CRP after consumption of the HFM meal compared with the HFD meal; however, the HFM and HFD meals were not different from the HFC meal. Alterations in IL-6, TNF-α and endotoxin concentrations were not significantly different between the test meals. The results suggest that full-fat milk and dairy products (cheese and butter) have no significant impact on the inflammatory response to a high-fat meal.

Dairy products on metabolic health: current research and clinical implications

Dairy products have been thought to have a beneficial role in the metabolic syndrome (MetS). MetS constitutes a cluster of risk factors for an increased mortality, including obesity, impaired glucose homeostasis, hypertension and atherogenic dyslipidemia. Individuals with MetS are also often in a chronic, low-grade inflammatory state. The objective of this review is to examine recent meta-analyses and clinical studies on the association between dairy products consumption and these MetS risk factors. Findings from studies demonstrate that weight loss related to dairy product intake is due to the combination of an energy-restricted diet with consumption of dairy products. Further, a limited number of studies have shown beneficial effects of dairy consumption on plasma lipids, blood pressure, glucose homeostasis or inflammatory and oxidative stress profiles. Overall, this review article suggests that adults should consume at least 2-3 servings of dairy products per day within a well-balanced diet and a healthy lifestyle for metabolic health. Yet, higher dairy product consumption may have additional beneficial effects, but more well-designed intervention studies are needed to ascertain these effects.