Not all Proteins are Equal. Maretha Vermaak CEP of Milk SA Dietitian SASDT 2015

Transcription

1 Not all Proteins are Equal Maretha Vermaak CEP of Milk SA Dietitian SASDT 2015

2 Introduction Dairy products are a feasible means to help meet the demands of a growing world market as well as the nutritional needs of the global population The demand: Nutrition-related non-communicable diseases are responsible for unacceptable high rates of morbidity mortality in South Africa justifying efforts to improve the dietary intake of th population. FBDG: Have milk, maas and yoghurt everyday can play an important role in meeting this objective. Vorster HH et al Have milk, maas or yoghurt every day : a food-based dietary guideline for South Africa. S Afr J Clin Nutr., 26(3):S57-S65.

3 Introduction Where does milk fit into the diet: Milk is the first food for all mammals and provides the necessary energy and nutrients to ensure proper growth and development Epidemiologic studies confirm the importance of milk in the human diet Evidence is emerging to reinforce the role of milk consumption in preventing several chronic diseases Only lactose intolerance and cow milk protein allergy are considered adverse reactions to milk consumption Perreira PC Milk nutritional composition and its role in human health. Nutrition, doi: /j.nut McGregor RA and Poppit SD Milk protein for improved metabolic health: a review of the evidence. Nutrition and Metabolism, 10:46

4 Assessing protein quality Why is milk protein different: Methods to assess the quality of protein are traditionally related to the ability of a protein to meet the demand for amino acids and nitrogen Methods used to determined protein quality ranged from nitrogen balance biological value profile protein efficiency ratio net protein utilisation and amino acid scores It is now realised that factors such as digestibility and bioavailability are also important aspects of protein quality Boye J et al Protein quality evaluation twenty years after the introduction of the protein digestibility-corrected amino acid score method. Br J Nutr., 108:S183-S212.

5

6 Assessing protein quality Amino acid score methods: The essential amino acid score and protein digestibility corrected amino acid score (PDCAAs) classified milk proteins to be the best protein source The PDCAAs score had some limitations: The biological value of a protein could not exceed 100% This means that proteins with essential amino acids beyond those in the reference protein as with milk do not get due credit It also did not take into account amino acid availability, anti-nutritional factors of plant protein and gastointestinal factors Therefore more recently the digestible indispensable amino acid score (DIAAS) has been developed and has confirmed the high quality of milk protein Boye J et al Protein quality evaluation twenty years after the introduction of the protein digestibility-corrected amino acid score method. Br J Nutr., 108:S183-S212.

7 Milk Proteins Milk typically contains 33g protein per liter Milk proteins can be divided into soluble whey (20%) and insoluble casein (80%) Both are high quality proteins in terms of amino acid requirements digestibility and Bioavailability Additionally Bio active Peptides

8 Bioactive Peptides Bioactive peptides in dairy has distinctive functions resulting in milk and dairy being classified as functional foods. Functional foods can be defined as foods containing significant levels of biologically active components that provide specific health benefits beyond the traditional nutrients they contain Enzymatic hydrolysis of milk proteins yields bioactive peptides that have multiple biological roles that can benefit human health Dairy proteins possess antimicrobial antioxidant anticarcinogenic and immunostimulatory activities The biologically active components of dairy make it a functional food Bhat ZF and Bhat H Milk and dairy products as functional foods: A review. International Journal of Dairy Science, 6(1):1-12. Perreira PC Milk nutritional composition and its role in human health. Nutrition, doi: /j.nut

9 Whey is especially rich in branched chain amino acids leucine isoleucine valine as well as lysine Functional roles: Whey proteins β -Lactoglobulin α - Lactoalbumin Imunoglobulins Lactoferrin P Lactoperoxidase Lysozyme Whey Retinol and fatty acids binding Possible antioxidant Lactose production, calcium transport, imunnomodulator, anticarcinogen Immune protection Antimicrobial, antioxidant, immunomodulator, iron absorption, anticarcinogen Antimicrobial Antimicrobial, synergy actions with Immunoglobulins and Lactoferrin

10 Casein Casein has a higher proportion of histidine methionine and phenylalanine Functional roles: Casein proteins α-casein β-casein Mineral binding and transport (Ca, PO4, Fe, Zn, Cu) k-casein Other bioactive peptides yielded after hydrolysis of casein have cardiovascular nervous immune and digestive system benefits through their antioxidant, cytomodulatory, immunomodulatory, antihypertensive, antithrombotic and analgesic actions

11 Fast vs Slow Proteins Whey and casein proteins are absorbed at different rates in the digestive system Whey proteins, also termed fast proteins, remain in a liquid state in the stomach, thus increasing amino acid availability and absorption Caseins, or slow proteins clot in the low ph of the stomach, resulting in a slower postprandial availability of amino acids These different digestion and absorption rates impact on the postprandial amino acid responses Pal S and Radavelli-Bagatini The effects of whey protein on cardiometabolic risk factors. Obesity Reviews, 14: McGregor RA and Poppit SD Milk protein for improved metabolic health: a review of the evidence. Nutrition and Metabolism, 10:46

12 Milk and Health

13 Health benefits of Milk and Dairy Obesity and weight loss Inflammation diseases Sarcopenia Hypertension Cardio vascular disease Diabetes Metabolic Syndrome

14 Obesity and Weight loss Loss of skeletal muscle during weight loss is undesirable because skeletal muscle: is important for mobility and activities of daily living plays a major role in tissue glucose uptake and thus glycaemic control Including dairy products in weight loss diets has been shown to decrease adiposity, while preserving lean mass In two meta-analyses of randomised controlled trials high-dairy energy-restricted diets led to a significantly greater reduction in body weight waist circumference, and fat mass while preserving/ increasing lean mass significantly more than conventional weight loss diets Abargouei AS et al Effect of dairy consumption on weight and body composition in adults: a systematic review and meta-analysis of randomized controlled clinical trials. Int J Obes., 36: Chen M et al Effects of dairy intake on body weight and fat: a meta-analysis of randomized controlled trials. Am J Clin Nutr., 96:

15 Obesity and Weight loss Whey proteins can affect levels of satiety due to the fast appearance of amino acids in plasma which may help to decrease excessive food intake and prevent weight gain Dairy BCAAs enhance muscle protein synthesis and muscle mass and protect against loss of lean mass during weight loss Milk proteins may also influence gut hormones by stimulating anorexigenic hormones involved in satiety May ghrelin and thermogenesis, thus increasing REE Luhovyy BL et al Whey proteins in the regulation of food intake and satiety. Journal of the American College of Nutrition, 26(6):704S 12S. Lam S et al The influence of whey protein and glycomacropeptide on satiety in adult humans. Physiology and Behavior, 96(1):162 8.

16 Inflammation Chronic low-grade inflammation is present in obesity Serum levels of pro-inflammatory cytokines are elevated These cytokines can increase insulin resistance inhibit glucose uptake and increase skeletal protein catabolism Dairy consumption has beneficial effects on markers of low-grade inflammation (C-reactive protein and adiponectin) in obese subjects In-vitro evidence shows that dairy proteins have immuno-modulatory effects Whey protein may inhibit the proliferation of lymphocytes Lactoferrin and lactoperoxidase can suppress interferon Calder PC et al Dietary factors and low-grade inflammation in relation to overweight and obesity. Brit J Nutr., 106(Suppl 3):S5-S78. McGregor RA and Poppit SD Milk protein for improved metabolic health: a review of the evidence. Nutrition and Metabolism, 10:46

17 Muscle mass and sarcopenia Sarcopenia is defined as Age-related loss of skeletal muscle mass and strength Resistance exercise has the ability to increase muscle protein mass and strength There is a growing body of evidence that has highlighted the potential of milk-based proteins to enhance the benefits of exercise in maintaining and enhancing muscle mass in older adults Cermak NM et al Protein supplementation augments the adaptive response of skeletal muscle to resistance-type exercise training: a metaanalysis. Am J Clin Nutr., 96:

18 Muscle mass and sarcopenia Whey protein support rapid increases in muscle protein synthesis Casein support sustained increases in muscle protein synthesis and decreases in muscle protein breakdown Milk is a very good source of leucine which is especially important in stimulating muscle protein synthesis The anabolic effect of milk may be an effective way for maintenance of muscle mass and strength in the healthy elderly and fast recovery in the frail elderly Norton C and Jakeman P Towards a sustainable dairy sector: The underappreciated role of dairy protein in the preservation of lean tissue in the elderly. International Journal of Dairy Technology, 66(3):

19 Hypertension Hypertension is a major cardiovascular risk factor Several studies have reported a significant association between low fat dairy consumption and hypertension A dose-response meta-analysis of prospective cohort studies in almost subjects showed that total dairy, low fat dairy and milk were all linearly associated with a lower risk of hypertension DASH advises daily consumption of low fat milk and other dairy products Engberink MF et al Inverse association between dairy intake and hypertension: the Rotterdam Study. A J Clin Nutr., 89(6): Soedamah-Muthu SS, Verberne LDM, Ding EL, Engberink MF and Geleijnse JM Dairy consumption and incidence of hypertension: A dose-response meta-analysis of prospective cohort studies. Hypertension, 60: Bazzano LA et al Dietary Approaches to Prevent Hypertension. Current Hypertension Reports

20 Hypertension Bioactive peptides in milk have a direct inhibitory action of angiotensin converting enzyme reducing blood pressure These include peptides from both whey and casein Ricci I and Artachio R Milk protein peptides with angiotensin I-converting enzyme inhibitory (ACEI) activity. Crit Rev Food Sci Nutr., 50(5):

21 cardiovascular Disease Dyslipidemia is one of the main metabolic risk factors associated with CVD risk Milk protein has been shown to improve the lipid profile and reduce cardiovascular risk factors Arterial stiffness is a independent risk factor for CVD and is higher in those with hypercholesterolemia consumption of whey protein seems to reduce arterial stiffness Griffin BA Dairy, dairy, quite contrary: further evidence to support a role for calcium in counteracting the cholesterol-raising effect of SFA in dairy foods. Brit J Nutr., 1-2. Pal S and Radavelli-Bagatini The effects of whey protein on cardiometabolic risk factors. Obesity Reviews, 14:

22 cardiovascular Disease Protective effects of dairy on LDL and HDL cholesterol and blood pressure are related to both calcium and biopeptides in milk Exact mechanisms explaining the effect of dairy on postprandial lipidaemia is not yet well understood Dairy proteins may suppress postprandial lipidaemia due to their insulinotropic effects Griffin BA Dairy, dairy, quite contrary: further evidence to support a role for calcium in counteracting the cholesterol-raising effect of SFA in dairy foods. Brit J Nutr., 1-2. Pal S and Radavelli-Bagatini The effects of whey protein on cardiometabolic risk factors. Obesity Reviews, 14:

23 Diabetes Various studies have shown that a higher versus lower dairy intake significantly reduced the risk of T2D A dose-response analysis showed a decrease of 6% in T2D risk per each additional daily serving of total dairy and a 10% risk reduction per additional serving of low-fat dairy In a meta-analysis of cohort studies, the highest vs. lowest dairy intake (3 5 vs. 1.5 servings per day) was associated with a lower risk of T2D The Dietary Guidelines Advisory Committee concluded that moderate evidence indicates that dairy products are associated with a reduced risk of T2D

24 Diabetes Elevated fasting glucose is a key metabolic risk factor Insulin is sensitive to both the composition and concentration of plasma AAs and thus both whey and casein stimulate increased insulin secretion Whey proteins are digested quickly and result in a rapid secretion of insulin that decreases the postprandial glucose response The high content of BCAA in whey protein may also play a role in the higher insulin response and improved insulin sensitivity due to their effect on pancreatic β-cells Pal S and Radavelli-Bagatini The effects of whey protein on cardiometabolic risk factors. Obesity Reviews, 14: McGregor RA and Poppit SD Milk protein for improved metabolic health: a review of the evidence. Nutrition and Metabolism, 10:46

25 Metabolic Syndrome There is increasing evidence indicating that dairy products may reduce the risk of metabolic syndrome The mechanism appears to be via the effects of different dairy components on specific risk factors blood glucose level insulin metabolism body weight and adipose distribution blood pressure Sousa GTD, Lira FS, Rosa JC, de Oliveira EP, Oyama LM, Santos R V, et al Dietary whey protein lessens several risk factors for metabolic diseases: a review. Lipids in Health and Disease, 11:67. Crichton GE, Bryan J, Buckley J, Murphy KJ Dairy consumption and metabolic syndrome: a systematic review of findings and methodological issues. Obes Rev.,12:e

26 Conclusion Consumption of dairy products is associated with decreased prevalence of metabolic related disorders... Dairy protein may indirectly improve metabolic health by aiding loss of body weight and fat mass through enhanced satiety, whilst promoting skeletal muscle growth and function through anabolic effects of dairy protein-derived BCAAs. BCAAs enhance muscle protein synthesis, lean body mass and skeletal muscle metabolic function. Specific protein components in milk may provide a way to maximise benefits for metabolic health. McGregor RA and Poppit SD Milk protein for improved metabolic health: a review of the evidence. Nutrition and Metabolism, 10:46

27