There is some evidence of the beneficial role of food patterns and lifestyles on metabolic syndrome (1,2). The Mediterranean food pattern (MFP) has acquired an emerging role in cardiovascular epidemiology (3). It is characterized by a high consumption of fruits, vegetables, legumes, grains, moderate alcohol intake, a moderate-to-low consumption of dairy products and meats/meat products, and a high monounsaturated–to–saturated fat ratio. Although some cross-sectional studies have suggested that the MFP (or some of its components) may reduce the incidence of the metabolic syndrome (1,4), there are no prospective studies assessing this association.

Our aim was to prospectively assess the relationship between adherence to the MFP and the subsequent development of metabolic syndrome in the Seguimiento Universidad de Navarra (SUN) dynamic cohort, composed of Spanish university graduates followed up for 6 years (5).

The SUN Study uses methodology similar to that of large American cohorts (6), but recruitment is permanently open (it is designed as a dynamic cohort). Baseline assessment of participants consists of a self-administered questionnaire sent by postal mail, gathering information on lifestyle factors and including a 136-item validated food frequency questionnaire (7). Biennially mailed follow-up questionnaires are used to collect a wide variety of information about diet, lifestyle, and medical conditions (5).

Among the 18,000 graduates currently participating in the SUN cohort, 5,360 members were recruited more than 6 years ago and therefore were eligible for this assessment. Some (n = 1,627) are currently undergoing the process of completing their 6-year follow-up questionnaire (Q6). Only 236 other participants can be definitively classified as lost to follow-up because they have not returned their Q6 after five consecutive mailings. The rest of the participants (n = 3,497) returned their Q6 and were successfully retained.

Participants were excluded if at baseline they had implausible values for total energy intake, had BMI >30 kg/m2 or reported risk factors (diabetes, hypertension, hypercholesterolemia, or hypertriglyceridemia), or met the criteria for metabolic syndrome. After exclusions, 2,563 participants initially free of metabolic syndrome or risk factors were available for analyses.

A previously applied score (8,9) was used to asses the degree of adherence to the MFP. Beneficial components were monounsaturated–to–saturated fat ratio, legumes, cereals, vegetables, fruits, fish, and alcohol. Subjects whose consumption was at or above the sex-specific median were assigned 1 point. For alcohol, the consumption of 5–25 g/day (women) and 10–50 g/day (men) qualified subjects to receive 1 point. Meats (or meat products) and dairy products were assessed negatively. Individuals whose consumption was below the sex-specific median were assigned 1 point. Therefore, the total score of adherence to the MFP had a potential range from 0 to 9 points. Metabolic syndrome was defined according to the International Diabetes Federation criteria (10).

In the Q6, self-reported information about these criteria was collected (waist circumference [cm], blood pressure [mmHg], triglycerides [mg/dl], HDL cholesterol [mg/dl], and plasma glucose [mg/dl]). Waist circumference was measured in a horizontal plane, midway between the inferior margin of the ribs and the superior border of the iliac crest (11). All participants were sent a tape measure with the Q6, and an explanation of how to measure their waist. If BMI was >30 kg/m2, central obesity was assumed and waist circumference not taken into account.

Nonconditional logistic regression was used to assess the association between baseline adherence to the MFP and the cumulative incidence of metabolic syndrome during follow-up after adjusting for age, sex, smoking, physical activity, and total energy intake.

Median follow-up time was 74 months. Adherence to the MFP was higher among women, older subjects, ex-smokers, and more physically active participants. Participants with higher baseline adherence to the MFP exhibited lower levels of all risk factors after 6 years’ follow-up except plasma glucose. HDL levels were higher among participants who better adhered to the MFP. However, we found significant differences only regarding waist circumference and marginally significant differences for HDL. Subjects with the highest adherence to the MFP had lower cumulative incidence of the metabolic syndrome than those with the lowest adherence. This difference also persisted when we adjusted for age, sex, physical activity, smoking, and total energy intake (Table 1).

This is the first prospective cohort study that has evidenced an inverse relationship between adherence to an MFP and the cumulative incidence of the metabolic syndrome. Our results are consistent with previous findings (12). Some studies have also reported inverse associations between adherence to MFP and obesity (1315), diabetes, insulin resistance (16,17), or hypertension (18,19). However, most of these studies were cross-sectional, and only two longitudinal prospective studies are available for the assessment of the relationship of MFP with obesity—not with the metabolic syndrome (13,14). Therefore, there is scarcity of data and no complete consistency (1).

Residual confounding because of a healthier lifestyle associated with higher adherence to the MFP might be a limitation of our study. However, after adjusting for lifestyle, changes were minimal, and the multivariate-adjusted results were too striking to be explained by residual confounding.

Other potential limitations of our study are related to the self-reported information. However, there is evidence indicating that self-reported information on hypertension is valid for epidemiologic studies (20), especially among highly educated populations (21). Moreover, we have previously validated the self-reported diagnosis of hypertension (22), weight (23), and physical activity (24) in subsamples of our cohort. Furthermore, >45% of our participants were health professionals. As a consequence, their self-reported information is likely to be of better quality than that of other studies based on self-report (25).

The prospective design or our study implies that information about risk factors for the metabolic syndrome, food habits, and lifestyles was collected before the diagnosis of the disease, thus avoiding a reverse causation bias. Another strength is that the food frequency questionnaire was previously validated in Spain (7). In summary, our findings add new information about the role of MFP for the prevention of the metabolic syndrome.

Table 1—

Baseline adherence to the MFP* and risk (cumulative incidence) of the metabolic syndrome after 6 years’ follow-up

MFP score
0–23–56–9P for trend
n 535 1,523 505  
Cumulative incidence of metabolic syndrome (%) 2.6 2.5 0.8 0.003 
Crude OR (95% CI) 1 (ref.) 0.95 (0.55–1.77) 0.30 (0.10–0.91) 0.134 
Age- and sex-adjusted OR (95% CI) 1 (ref.) 0.76 (0.40–1.45) 0.18 (0.06–0.56) 0.006 
Multivariate-adjusted OR (95% CI) 1 (ref.) 0.80 (0.42–1.54) 0.20 (0.06–0.63) 0.013 
6-year follow-up levels of each risk factor§     
Waist circumference (cm) 82.5 ± 12 82.2 ± 12 82.0 ± 12 0.038 
Systolic blood pressure (mmHg) 112.5 ± 14 112.5 ± 13 113.3 ± 13 0.648 
Diastolic blood pressure (mmHg) 68.9 ± 11 68.8 ± 10 69.8 ± 10 0.664 
Plasma glucose (mg/dl) 86.1 ± 11 85.8 ± 11 87.3 ± 17 0.524 
HDL cholesterol (mg/dl) 63.8 ± 15 66.1 ± 19 64.1 ± 19 0.087 
Triglycerides (mg/dl) 80.0 ± 38 81.2 ± 47 78.0 ± 40 0.116 
MFP score
0–23–56–9P for trend
n 535 1,523 505  
Cumulative incidence of metabolic syndrome (%) 2.6 2.5 0.8 0.003 
Crude OR (95% CI) 1 (ref.) 0.95 (0.55–1.77) 0.30 (0.10–0.91) 0.134 
Age- and sex-adjusted OR (95% CI) 1 (ref.) 0.76 (0.40–1.45) 0.18 (0.06–0.56) 0.006 
Multivariate-adjusted OR (95% CI) 1 (ref.) 0.80 (0.42–1.54) 0.20 (0.06–0.63) 0.013 
6-year follow-up levels of each risk factor§     
Waist circumference (cm) 82.5 ± 12 82.2 ± 12 82.0 ± 12 0.038 
Systolic blood pressure (mmHg) 112.5 ± 14 112.5 ± 13 113.3 ± 13 0.648 
Diastolic blood pressure (mmHg) 68.9 ± 11 68.8 ± 10 69.8 ± 10 0.664 
Plasma glucose (mg/dl) 86.1 ± 11 85.8 ± 11 87.3 ± 17 0.524 
HDL cholesterol (mg/dl) 63.8 ± 15 66.1 ± 19 64.1 ± 19 0.087 
Triglycerides (mg/dl) 80.0 ± 38 81.2 ± 47 78.0 ± 40 0.116 

Data are means ± SD unless otherwise indicated.

*

Trichopoulou’s MFP score;

International Diabetes Federation criteria;

logistic regression adjusted for age, sex, physical activity (MET h/week), smoking (never, former, current), and total energy intake (kcal/day);

§

Mean values adjusted for age and sex;

Adjusted for age and sex (ANCOVA).

The SUN Study is funded by the Spanish Ministry of Health (Instituto de Salud Carlos III, Fondo de Investigaciones Sanitarias projects PI030678, PI040233, PI042241, PI050514, PI050976, and PI070240; RD 06/0045) and by the Navarra Regional Government Department of Health (PI41/2005).

1.
Alvarez Leon E, Henriquez P, Serra-Majem L: Mediterranean diet and metabolic syndrome: a cross-sectional study in the Canary Islands.
Public Health Nutr
9
:
1089
–1098,
2006
2.
Giugliano D, Ceriello A, Esposito K: The effects of diet on inflammation: emphasis on the metabolic syndrome.
J Am Coll Cardiol
48
:
677
–685,
2006
3.
Martinez-Gonzalez MA, Sanchez-Villegas A: The emerging role of Mediterranean diets in cardiovascular epidemiology: monounsaturated fats, olive oil, red wine, or the whole pattern?
Eur J Epidemiol
19
:
7
–8,
2004
4.
Panagiotakos DB, Chrysohoou C, Pitsavos C, Stefanadis C: Association between the prevalence of obesity and adherence to the Mediterranean diet: the ATTICA study.
Nutrition
22
:
449
–456,
2006
5.
Segui-Gomez M, De la Fuente C, Vazquez Z, de Irala J, Martinez-Gonzalez MA : Cohort profile: the ‘Seguimiento Universidad de Navarra’ (SUN) study.
Int J Epidemiol
35
:
1417
–1422,
2006
6.
Martinez-Gonzalez MA, Sanchez-Villegas A, de Irala J, Marti A, Martinez JA: Mediterranean diet and stroke: objectives and design of the SUN project.
Nutr Neurosci
5
:
65
–73,
2002
7.
Martin-Moreno JM, Boyle P, Gorgojo L, Maisonneuve P, Fernandez-Rodriguez JC, Salvini S, Willett WC: Development and validation of a food frequency questionnaire in Spain.
Int J Epidemiol
22
:
512
–519,
1993
8.
Trichopoulou A, Kouris-Blazos A, Wahlqvist ML, Gnardellis C, Laqiou P, Polychronopoulos E, Vassilakou T, Lipworth L, Trichopoulos D: Diet and overall survival in elderly people.
BMJ
311
:
1457
–1460,
1995
9.
Trichopoulou A, Costacou T, Bamia C, Trichopoulos D: Adherence to a Mediterranean diet and survival in a Greek population.
N Engl J Med
348
:
2595
–2596,
2003
10.
Alberti KG, Zimmet P, Shaw J: Metabolic syndrome: a new world-wide definition: a consensus statement from the International Diabetes Federation.
Diabet Med
23
:
469
–480,
2006
11.
Klein S, Allison DB, Heymsfield SB, Kelley DE, Leibel RL, Nonas C, Kahn R; Association for Weight Management and Obesity Prevention; NAASO, The Obesity Society; American Society for Nutrition; American Diabetes Association: Waist circumference and cardiometabolic risk: a consensus statement from Shaping America’s Health: Association for Weight Management and Obesity Prevention; NAASO, The Obesity Society; the American Society for Nutrition; and the American Diabetes Association.
Am J Clin Nutr
85
:
1197
–1202,
2007
12.
Panagiotakos DB, Pitsavos C, Chrysohoou C, Skoumas J, Tousoulis D, Toutouza M, Toutouzas P, Stefanadis C : Impact of lifestyle habits on the prevalence of the metabolic syndrome among Greek adults from the ATTICA study.
Am Heart J
147
:
106
–112,
2004
13.
Mendez MA, Popkin BM, Jakszyn P, Berenquer A, Tormo MJ, Sanchez MJ, Quiros JR, Pera G, Navarro C, Martinez C, Larranaga N, Dorronsoro M, Chirlaque MD, Barricarte A, Ardanaz E, Amiano P, Aqudo A, Gonzalez CA : Adherence to a Mediterranean diet is associated with reduced 3-year incidence of obesity.
J Nutr
136
:
2934
–2938,
2006
14.
Sanchez-Villegas A, Bes-Rastrollo M, Martinez-Gonzalez MA, Serra-Majem L: Adherence to a Mediterranean dietary pattern and weight gain in a follow-up study: the SUN cohort.
Int J Obes (Lond)
30
:
350
–358,
2006
15.
Schroder H, Marrugat J, Vila J, Covas MI, Elosua R: Adherence to the traditional Mediterranean diet is inversely associated with body mass index and obesity in a Spanish population.
J Nutr
134
:
3355
–3361,
2004
16.
Panagiotakos DB, Tzima N, Pitsavos C, Chrysohoou C, Zampelas A, Toussoulis D, Stefanadis C : The association between adherence to the Mediterranean diet and fasting indices of glucose homoeostasis: the ATTICA Study.
J Am Coll Nutr
26
:
32
–38,
2007
17.
Panagiotakos DB, Pitsavos C, Chrysohoou C, Stefanadis C: The epidemiology of type 2 diabetes mellitus in Greek adults: the ATTICA study.
Diabet Med
22
:
1581
–1588,
2005
18.
Panagiotakos DB, Pitsavos CH, Chrysohoou C, Skoumas J, Papadimitriou L, Stefanadis C, Toutouzas PK: Status and management of hypertension in Greece: role of the adoption of a Mediterranean diet: the ATTICA study.
J Hypertens
21
:
1483
–1489,
2003
19.
Psaltopoulou T, Naska A, Orfanos P, Trichopoulous D, Mountokalakis T, Trichopoulou A: Olive oil, the Mediterranean diet, and arterial blood pressure: the Greek European Prospective Investigation into Cancer and Nutrition (EPIC) study.
Am J Clin Nutr
80
:
1012
–1018,
2004
20.
Tormo MJ, Navarro C, Chirlaque MD, Barber X, the EPIC Group of Spain: Validation of self diagnosis of high blood pressure in a sample of the Spanish EPIC cohort: overall agreement and predictive values.
J Epidemiol Community Health
54
:
221
–226,
2000
21.
Colditz GA, Martin P, Stampfer MJ, Willett WC, Sampson L, Rosner B, Hennekens CH, Speizer FE: Validation of questionnaire information on risk factors and disease outcomes in a prospective cohort study of women.
Am J Epidemiol
123
:
894
–900,
1986
22.
Alonso A, Beunza JJ, Delgado-Rodriguez M, Martinez-Gonzalez MA: Validation of self reported diagnosis of hypertension in a cohort of university graduates in Spain.
BMC Public Health
5
:
94
,
2005
23.
Bes-Rastrollo M, Perez Valdivieso JR, Sanchez-Villegas A, Alonso A, Martínez-González MA: Validacion del peso e indice de masa corporal auto-declarados de los participantes de una cohorte de graduados universitarios.
Rev Esp Obes
3
:
183
–189,
2005
[in Spanish]
24.
Martinez-Gonzalez MA, Lopez-Fontana C, Varo JJ, Sanchez-Villegas A, Martinez A: Validation of the Spanish version of the physical activity questionnaire used in the Nurses’ Health Study and the Health Professionals’ Follow-up Study.
Public Health Nutr
8
:
920
–927,
2005
25.
Alonso A, Segui-Gomez M, de Irala J, Sanchez-Villegas A, Beunza JJ, Martinez Gonzalez MA: Predictors of follow-up and assessment of selection bias from dropouts using inverse probability weighting in a cohort of university graduates.
Eur J Epidemiol
21
:
351
–358,
2006

Published ahead of print at http://care.diabetesjournals.org on 21 August 2007. DOI: 10.2337/dc07-1231.

A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.

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