Dairy product consumption and the metabolic syndrome
The metabolic syndrome is an important risk factor for type 2 diabetes mellitus and CVD. Epidemiological studies have now suggested protective effects of dairy product consumption on the development of this syndrome. Here we review the physiological effects and possible mechanisms involved of three main dairy constituents (Ca, protein, fat) on important components of the metabolic syndrome. Ca supplements improve the serum lipoprotein profile, particularly by decreasing serum total and LDL-cholesterol concentrations. They also lower systolic and diastolic blood pressure. Insufficient evidence exists for a significant role of Ca supplements or dairy in body-weight management. Effects of Ca may be related to intestinal binding to fatty acids or bile acids, or to changes in intracellular Ca metabolism by suppressing calciotropic hormones. Dietary proteins may increase satiety in both the short and longer term, which may result in a reduced energy intake. They have also been reported to improve the serum lipoprotein profile as compared with carbohydrates. Dairy proteins are precursors of angiotensin-I-converting enzyme-inhibitory peptides, which may lower blood pressure. Such effects, however, have inconsistently been reported in human studies. Finally, conjugated linoleic acid, which effectively lowers body weight in animals, has no such effect in humans in the quantities provided by dairy products. To reduce the intake of SFA, the consumption of low-fat instead of high-fat dairy products is recommended. In conclusion, more research is warranted to better understand the physiological effects and the mechanisms involved of dairy products in the prevention and treatment of the metabolic syndrome.[1]
Milk and dairy product composition.
The first section of this chapter provides detailed information on the composition of animal milks used for human consumption, including milk from both major dairy species (cow, buffalo, goat and sheep) and minor species (yak, mithun, musk ox, mare, donkey, dromedary and Bactrian camels, llama, alpaca, reindeer and moose). Macro- and micronutrient contents of milks are given for the various species, mineral and vitamin contents in the milks are compared with the recommended nutrient intakes for children between one and three years old and those suitable for children who are allergic to cow milk are noted. Nutritional claims that would be permitted according to the CODEX Guide to Food Labelling are considered for the various milks. Interspecies differences in protein, fat and lactose contents are highlighted. The contribution of milk to dietary energy, protein and fat in various regions of the world is considered. The effects of feeding and lactation state on milk composition are considered. The second part of the chapter presents less-detailed information on the composition of treated liquid milks and dairy products, including fermented milk products, cheese, butter and ghee, cream and whey products. The current definitions according to the FAO Classifications of Commodities/CODEX are given, together with the impact of processing on nutrient profiles. Finally, milk products from milk from underutilized species are presented.[2]
Increased Dairy Product or Calcium Intake: Is Body Weight or Composition Affected in Humans?
To assess the possible impact of increased intakes of dairy products or calcium on body weight or composition, a MEDLINE search was conducted to identify randomized trials of supplementation with calcium or dairy products. Nine studies of dairy product supplementation were located: In seven, no significant differences in the change in body weight or composition were detected between treatment and control groups. However, two studies conducted in older adults observed significantly greater weight gain in the dairy product groups. The interpretation of these findings is complicated by the inability to accurately determine the extent of dietary compensation for the increment in energy intake provided by the added dairy products. This is not an issue in the interpretation of studies of calcium supplementation, of which 17 were identified. Only one study found greater weight loss in the supplemented group; in the remaining studies, changes in body weight and/or body fat were strikingly similar between groups. In conclusion, the data available from randomized trials of dairy product or calcium supplementation provide little support for an effect in reducing body weight or fat mass. However, the studies reviewed were not specifically designed or powered to address this issue; such studies are required.[3]
ADSA Foundation Scholar Award Fluid Dairy Product Quality and Safety: Looking to the Future
The fiercely competitive nature of the US beverage industry will drive the fluid milk sector of the dairy industry to improve product quality and shelf life to enable dairy beverages to compete with innovative new introductions as well as with currently popular shelf-stable products. The recent substantial growth in the volume of flavored milk sales specifically suggests that attention is needed to improve these products. Further, increasing public awareness and regulatory attention directed toward food safety issues highlight the need for the dairy industry to proactively address and eliminate emerging food safety issues that may negatively impact the image of dairy products. Shelf life and sensory profiles of high temperature short time pasteurized fluid milk products are presented, illustrating the need for greater attention to controlling contaminating microorganisms in processed fluid milk products. Bacterial spoilage patterns of flavored versus unflavored milks are compared, and suggestions are presented for extending flavored product shelf lives. Strategies currently applied to extend shelf life are reviewed. Food safety issues facing the dairy industry are presented within the context of an overview of foodborne illnesses in the United States. The pressing need to determine thermal resistance characteristics of Mycobacterium paratuberculosis is described.[4]
Yogurt and dairy product consumption to prevent cardiometabolic diseases: epidemiologic and experimental studies
Dairy products contribute important nutrients to our diet, including energy, calcium, protein, and other micro- and macronutrients. However, dairy products can be high in saturated fats, and dietary guidelines generally recommend reducing the intake of saturated fatty acids (SFAs) to reduce coronary artery disease (CAD). Recent studies question the role of SFAs in cardiovascular disease (CVD) and have found that substitution of SFAs in the diet with omega-6 (n−6) polyunsaturated fatty acids abundant in vegetable oils can, in fact, lead to an increased risk of death from CAD and CVD, unless they are balanced with n−3 polyunsaturated fat. Replacing SFAs with carbohydrates with a high glycemic index is also associated with a higher risk of CAD. Paradoxically, observational studies indicate that the consumption of milk or dairy products is inversely related to incidence of CVD. The consumption of dairy products has been suggested to ameliorate characteristics of the metabolic syndrome, which encompasses a cluster of risk factors including dyslipidemia, insulin resistance, increased blood pressure, and abdominal obesity, which together markedly increase the risk of diabetes and CVD. Dairy products, such as cheese, do not exert the negative effects on blood lipids as predicted solely by the content of saturated fat. Calcium and other bioactive components may modify the effects on LDL cholesterol and triglycerides. Apart from supplying valuable dairy nutrients, yogurt may also exert beneficial probiotic effects. The consumption of yogurt, and other dairy products, in observational studies is associated with a reduced risk of weight gain and obesity as well as of CVD, and these findings are, in part, supported by randomized trials.[5]
Reference
[1] van Meijl, L.E., Vrolix, R. and Mensink, R.P., 2008. Dairy product consumption and the metabolic syndrome. Nutrition research reviews, 21(2), pp.148-157.
[2] Wijesinha-Bettoni, R. and Burlingame, B., 2013. Milk and dairy product composition. Milk and dairy products in human nutrition, pp.41-102.
[3] Barr, S.I., 2003. Increased dairy product or calcium intake: is body weight or composition affected in humans?. The Journal of nutrition, 133(1), pp.245S-248S.
[4] Boor, K.J., 2001. ADSA foundation scholar award fluid dairy product quality and safety: looking to the future. Journal of Dairy Science, 84(1), pp.1-11.
[5] Astrup, A., 2014. Yogurt and dairy product consumption to prevent cardiometabolic diseases: epidemiologic and experimental studies. The American journal of clinical nutrition, 99(5), pp.1235S-1242S.
