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Whole-fat dairy food intake is inversely associated with obesity prevalence: findings from the Observation of Cardiovascular Risk Factors in Luxembourg study Georgina E. Crichton a, b,⁎, Ala'a Alkerwi b a b
Nutritional Physiology Research Centre, University of South Australia, Adelaide, Australia Centre de Recherche Public Santé, Centre d'Etudes en Santé, Strassen, Grand-Duchy of Luxembourg
ARTI CLE I NFO
A BS TRACT
Article history:
Because research focusing on dairy food consumption and the risk for obesity is
Received 5 March 2014
inconsistent and only a few studies have even examined specific dairy products, in regard
Revised 9 July 2014
to type of food and fat content, in relation to obesity risk, this cross-sectional study
Accepted 23 July 2014
investigated whether dairy food consumption is associated with the prevalence of global and abdominal obesity. Data were analyzed from 1352 participants in the Observation of
Keywords:
Cardiovascular Risk Factors in Luxembourg survey. We hypothesized that higher total dairy
Dairy food
food consumption would be independently associated with reduced prevalence of obesity. A
Dairy fat
validated food frequency questionnaire was used to measure intakes of dairy foods. Odds
Global obesity
for global obesity (body mass index ≥30 kg/m2) and abdominal obesity (waist circumference
Abdominal obesity
>102 cm for men and >88 cm for women) were determined based on total dairy food intake
Prevalence
as well as intakes of individual low- and whole-fat dairy products (milk, yogurt, and cheese).
Human
Total dairy food intake was inversely associated with the likelihood of global obesity (odds ratio [OR], 0.51; 95% confidence interval [CI], 0.30-0.89; P < .05) and abdominal obesity (OR, 0.51; 95% CI, 0.32-0.83; P < .01). Participants in the highest tertile of whole-fat dairy intakes (milk, cheese, yogurt) had significantly lower odds for being obese (global obesity: OR, 0.45; 95% CI, 0.29-0.72; P < .01; abdominal obesity: OR, 0.35; 95% CI, 0.23-0.54; P < .001), compared with those in the lowest intake tertile, after full adjustment for demographic, lifestyle, dietary, and cardiovascular risk factor variables. Increasing consumption of dairy foods may have the potential to lower the prevalence of global and abdominal obesity. © 2014 Elsevier Inc. All rights reserved.
Abbreviations: BMI, body mass index; BP, blood pressure; CI, confidence interval; CVD, cardiovascular disease; HDL, high-density lipoprotein; LDL, low-density lipoprotein; OR, odds ratio; ORISCAV-LUX, Observation of Cardiovascular Risk Factors in Luxembourg; WC, waist circumference. ⁎ Corresponding author at: CRP-Santé, Centre d'Etudes en Santé, 1A rue Thomas Edison, L-1445 Strassen, Grand-Duchy of Luxembourg. Tel.: +352 26 970 394; fax: +352 26 970 719. E-mail addresses:
[email protected],
[email protected] (G.E. Crichton). http://dx.doi.org/10.1016/j.nutres.2014.07.014 0271-5317/© 2014 Elsevier Inc. All rights reserved.
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1.
Introduction
The promotion of healthy dietary habits and weight control is an utmost public health priority, given the high prevalence of obesity and associated metabolic disorders in Europe and throughout the world [1,2]. Currently, most dietary guidelines recommend the consumption of 3 daily servings of dairy foods as an important part of a healthy, well-balanced diet [3–5]. Dairy products are rich sources of protein, calcium, nutrients such as vitamin A and D, and other bioactive compounds. In an effort to prevent cardiovascular disease (CVD), many national dietary guidelines recommend the consumption of low-fat or fat-free dairy products which can help minimize the intake of saturated fat and maintain healthy lipid and cholesterol levels [3,4]. However, recent systematic reviews suggest that neither saturated fat [6] nor whole-fat dairy foods [7–9] increase CVD or cardiometabolic risk. A number of recent reviews, using both observational studies [8,10] and randomized controlled trials [11–13], have been published with inconclusive findings. Based on 9 prospective studies, Louie et al [10] concluded that dairy products most likely have a protective effect on weight status, but they acknowledged inconsistent study findings. The authors also found data suggesting that regular fat dairy products may be more beneficial to weight status than low-fat products. In an extensive review of 16 studies, Kratz et al [8] summarized that high-fat dairy consumption, within a typical diet, is inversely associated with obesity risk. Of note, none of the 16 studies reported a positive association between consumption of high-fat dairy foods and measures of adiposity, either cross-sectionally or over time [8]. Meta-analyses of clinical trials are also inconsistent. In a review of 20 clinical trials that included an increased dairy consumption phase for at least 1 month without energy restriction, Benatar et al [13] concluded that increasing both low- and whole-fat dairy food was associated with modest weight gain but had no significant effect on waist circumference (WC). In contrast, a meta-analysis of 14 clinical trials by Abargouei et al [11] showed that increasing dairy intake without energy restriction does not affect weight, body fat, lean mass, or WC. However, in combination with energy restriction, increased dairy consumption led to greater reductions in weight, WC, and body fat mass, and greater gains in lean body mass compared with common weight loss diets. Chen et al [12] expanded upon the review of Abargouei et al, adding additional trials to their meta-analysis (for a total of 29 trials), and they concluded that increased dairy food consumption may have modest but short-lived benefits on body weight and body fat but only in energy-restricted or short-term trials. The reasons for these inconsistencies are not entirely clear. Apart from methodological heterogeneity and diversity of study populations, another obvious explanation would be the type of dairy product being consumed. For example, the fat and nutritional content of food may influence body weight or metabolic mechanisms. Gaps in the literature suggest that more research is still needed, especially in regard to the relationship between obesity and specific types of dairy foods [14].
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In the present study, we aimed to examine the association between the consumption of different types of dairy food and the prevalence of obesity among adults in the Observation of Cardiovascular Risk Factors in Luxembourg (ORISCAV-LUX) survey. We focused on the 3 most commonly consumed dairy products (milk, cheese, and yogurt) and the fat content of these products (low fat vs whole fat), in order to assess associations between these dairy products and global and abdominal obesity, as measured by body mass index (BMI) and WC, respectively. We hypothesized that higher total dairy food consumption would be independently associated with a reduced prevalence of obesity. However, because of the disparate findings in the literature, we did not propose a hypothesis as to whether the associations may differ according to type of dairy product or fat content. To examine our hypothesis and determine whether intakes of milk, cheese, and yogurt are related to obesity status, we used data that were collected from 1352 adult participants from the ORISCAV-LUX study.
2.
Methods and materials
2.1.
Study population
This cross-sectional study used data from participants in ORISCAV-LUX, a nationwide, population-based survey that was designed to gather information on the prevalence of cardiovascular risk factors among the general adult population of Luxembourg. Detailed information about the study design and data collection methods can be found elsewhere [15]. Briefly, a total random sample of 1432 participants, stratified according to age (18-69 years), sex, and district were recruited between November 2007 and January 2009 [15,16]. This represented 32.2% of the 4452 potentially eligible subjects who were contacted for the study [16]. For the current study, data were available for 1352 subjects, after eliminating those with missing data on diet or adiposity. The study was approved by the National Research Ethics Committee and the National Commission for Private Data Protection. All participants were informed and provided written consent.
2.2.
Dietary intakes
Dietary intake was assessed using a semi-quantified food frequency questionnaire, which assessed the frequency of consumption of 134 items over the previous 3 months [17]. Participants were asked how frequently they consumed 1 standardized portion of each food (eg, 1 medium cup [125 mL] of milk). Six frequency response categories ranged from “never or rarely” to “2 or more times per day.” Energy and nutrient intake data were compiled using a French Composition Table [18], which included total carbohydrate (in g/d), total protein (in g/d), total fat (in g/d), total fiber (in g/d), alcohol (in g/d), calcium (in mg/d), and total energy intake (in kcal/d). Dairy products included in the questionnaire were milk (skim or whole), yogurt (low fat or regular), and cheese (low fat or regular). Milk-based desserts such as puddings, ice-cream, and frozen yogurt were not included. To facilitate comparisons
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between the different dairy products, intakes that were expressed in terms of milliliters or grams per day were recalculated into servings per day, which was based on standard serving sizes (250 mL of milk, 125 g of yogurt, and 50 g of cheese) [3,19]. The numbers of servings per day of low-fat milk, cheese, and yogurt were summed to give total intake of low-fat dairy foods, and the total intake of whole-fat dairy foods was also calculated. Total dairy food intake included the sum of all dairy foods (total low-fat plus total whole-fat milk, cheese, and yogurt). In order to create 3 equal groups for meaningful comparison, total dairy food intake was then categorized into tertiles.
2.3.
Anthropometric measures and obesity assessment
Height, body weight, and WC were measured in light clothing and without shoes, according to ORISCAV-LUX standardized protocols [15]. Body weight was measured using a digital column scale (Seca 701, Hamburg, Germany) and recorded to the nearest 0.1 kg. Standing body height was recorded to the nearest 0.2 cm with a portable wall stadiometer (Seca). BMI was calculated as weight in kilograms divided by height in meters squared. WC was measured at the level midway between the 12th rib and the uppermost lateral border of the iliac crest at the end of normal expiration and rounded to the nearest 0.2 cm. Study participants were classified as normal weight (BMI
