Maturitas 77 (2014) 221–228

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Maturitas journal homepage: www.elsevier.com/locate/maturitas

Review

Dairy products on metabolic health: Current research and clinical implications Marine S. Da Silva, Iwona Rudkowska ∗ Endocrinology and Nephrology, CHU de Québec Research Center, Quebec, QC, Canada

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Article history: Received 18 December 2013 Accepted 22 December 2013 Keywords: Dairy products Obesity Dyslipidemia Hyperglycemia Hypertension Inflammation

a b s t r a c t 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. © 2014 Elsevier Ireland Ltd. All rights reserved.

Contents 1. 2. 3. 4. 5. 6. 7.

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Body weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Glucose homeostasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Blood lipids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Blood pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inflammatory and oxidative stress markers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Competing interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Funding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Provenance and peer review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1. Introduction Dairy products consumption is widely recommended in a healthy diet not only for bone growth and maintenance, but also as a protein, calcium and magnesium sources for an adequate diet. The majority of dietary guidelines recommend 2–3 servings of dairy

∗ Corresponding author at: Endocrinology and Nephrology, T-4-55B, CHU de Québec Research Center CHUL – 2705, Boul. Laurier, Québec, QC G1V 4G2, Canada. Tel.: +1 418 525 4444x46380. E-mail address: [email protected] (I. Rudkowska). 0378-5122/$ – see front matter © 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.maturitas.2013.12.007

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products a day. Nevertheless, dairy products remain largely underconsumed in many populations [1–5]. For example, dairy intake is below the levels recommended for most Americans, with individuals 2 years of age and older consuming 1.8 servings daily on average: therefore, 85% of the population is not meeting recommendations for consumption of dairy foods (3 servings of dairy products per day) [4]. Similarly, results from the 2004 Canadian Community Health Survey (CCHS) – Nutrition indicate that more than one-third (46–79% of men and 65–84% of women) of Canadian adults do not meet the minimum recommendations from Canada’s Food Guide for dairy intake (2 servings of dairy products per day) [5]. Therefore, there is great potential to increase dairy products consumption to reach optimal intake.

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M.S. Da Silva, I. Rudkowska / Maturitas 77 (2014) 221–228

Dairy products have been hypothesized to have a favorable role on risk factors associated with the metabolic syndrome (MetS). MetS constitutes a cluster of risk factors for an increased mortality, including obesity, impaired glucose homeostasis, hypertension and atherogenic dyslipidemia [6]. It is increasingly appreciated that individuals with MetS are in a chronic, low-grade inflammatory state. Complications of MetS include type 2 diabetes mellitus (T2DM) and atherosclerosis, which lead to coronary artery disease (CAD) and cerebral strokes, and an increased cancer risk [6]. According to National Health and Examination Survey (NHANES) 2003–2006 [7], approximately 34% of people studied met the MetS revised criteria from the National Cholesterol Education Program Adult Treatment Panel III (NCEP: ATPIII). The prevalence of MetS is high and rising in all western societies, probably as a result of the obesity epidemic [8]. Given the increasing amount of evidence on the beneficial role of dairy products consumption for optimum health, targeting optimal dairy intake may represent an additional key strategy to decrease MetS risk factors. The objective is to review the scientific evidence, including meta-analyses and clinical trials since they provide the strongest evidence, on the association between dairy products consumption and MetS risk factors including body weight, glucose homeostasis, lipid profile, blood pressure or inflammatory and oxidative stress profiles, to support recommendations for adequate or greater intake of dairy product.

2. Body weight Prospective cohort studies have provided evidence of a suggestive but not consistent protective effect of dairy consumption on risk of overweight and obesity [9]. Reports from different parts of the world, including developing countries, have shown an excessive weight gain within populations. Excess body weight increases the risk of several clinical conditions, e.g., cardiovascular diseases (CVDs) including hypertension and cerebrovascular disorders, T2DM, liver disease, and certain type of cancers, all of which being considered as major health problems in westernized societies. The potential mechanisms that dairy product intake may be protective against weight gain include a reduced lipogenesis and an increased lipolysis in adipose tissue. Secondly, a meta-analysis suggested that a high calcium intake may lead to increase fecal fat excretion potentially leading to weight loss [10]. Thirdly, a systematic review of randomized clinical trials confirmed the role of calcium in fat oxidation [11]. Forth, whey protein may also play a role in muscle sparing and lipid metabolism [12]. Finally, research has also suggested that lactose and dairy proteins may enhance satiety [13,14]. Overall, there are several mechanisms by which dairy products may influence weight management. A recent meta-analysis of clinical trials concluded that increasing dairy intake (calcium intake of 550–1000 mg per day from dairy products (approximately 1.8–3.3 servings dairy products) compared to control subjects who consumed 290–800 mg calcium daily (approximately 1–2.7 servings of dairy products)) without energy restriction does not significantly affect weight, body fat mass, lean mass and waist circumference [15]. Clinical studies reviewed in this paper (Table 1) concluded that a dairy-supplemented diet was not associated with greater weight loss than control diet, neither in an isocaloric diet [16–19] nor in an energy-restricted diet [20–23]. Yet, the majority of clinical studies with an energy-restriction diet indicated that dairy-rich diets augment weight loss, fat loss and reduce adiposity [24–29]. Similarly, the meta-analysis showed that the high consumption of dairy with an energy-restriction diet (500 kcal less than the requirement) led to 1.29 kg greater weight loss, 1.11 kg greater reduction in body fat mass, 0.72 kg gain in body lean mass and 2.43 cm additional reduction in waist circumference compared

with controls [15]. Wennersberg et al. [30] reported an absence of changes in body weight or body fat during 6 months of 3–5 portions/day of dairy products consumption but proposed that the positive effects on waist circumference in subjects with a low baseline calcium intake may demonstrate a possible threshold in relation to effects on body composition. Other studies indicated no beneficial effects of dairy intervention on body fat in long-term (≥1 year) [31]. In sum, these studies suggest that the inclusion of 3–5 portions/day of dairy products may have modest benefits in facilitating weight loss in energy-restricted diets. 3. Glucose homeostasis Observational studies have found that eating patterns incorporating higher amounts of dairy products would decrease the risk of developing type 2 DM (T2DM) on average by 14% [32]. A meta-analysis of cohort studies found an inverse linear association of consumption of total dairy products, low-fat dairy products, cheese and yogurt (200–400 g/day of dairy products) and risk of T2DM [33,34]. Although most observational studies have demonstrated an association between insufficient dairy consumption and an imbalance of glucose metabolism, many also have reported conflicting results [35,36]. The mechanisms underlying the effects of dairy on T2DM development may consist of the calcium and vitamin D content in dairy foods [9] and the possible positive effect dairy consumption on weight management [10]. Finally, van Meijl and Mensink [37] demonstrated that the intake of milk with a fatcontaining meal enhances postprandial insulin responses but may blunt glucose increases. Numerous clinical trials with healthy subjects or subjects with a deteriorated metabolism (Table 1) demonstrated no effects of dairy consumption on glucose metabolism [14,16,17,19,20,22,26,29,38]. However, it was previously demonstrated, in 34 obese African Americans, that a high dairy diet (1200 mg calcium/day including 3 servings of dairy) resulted in a decrease in plasma insulin together with a decrease in total body fat and an increase in lean mass, whereas there were no significant changes in the low dairy diet group (low calcium (500 mg/day) and low dairy (

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 increas...
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