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Modified Mediterranean diet and survival: EPIC-elderly prospective cohort study.

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  • 1. Department of Hygiene and Epidemiology, University of Athens Medical School, Athens 11527, Greece.
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    • Trichopoulou A 1
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BMJ, 08 Apr 2005, 330(7498):991
https://doi.org/10.1136/bmj.38415.644155.8f PMID: 15820966 PMCID: PMC557144

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A comment on this article appears in "Modified Mediterranean diet and survival: key confounder was missed." BMJ. 2005 Jun 4;330(7503):1329; author reply 1329-30. A comment on this article appears in "Modified Mediterranean diet and survival: evidence for diet linked longevity is substantial." BMJ. 2005 Jun 4;330(7503):1329; author reply 1329-30.

Abstract 

Objective

To examine whether adherence to the modified Mediterranean diet, in which unsaturates were substituted for monounsaturates, is associated with longer life expectancy among elderly Europeans.

Design

Multicentre, prospective cohort study.

Setting

Nine European countries (Denmark, France, Germany, Greece, Italy, the Netherlands, Spain, Sweden, United Kingdom).

Participants

74,607 men and women, aged 60 or more, without coronary heart disease, stroke, or cancer at enrolment and with complete information about dietary intake and potentially confounding variables.

Main outcome measures

Extent of adherence to a modified Mediterranean diet using a scoring system on a 10 point scale, and death from any cause by time of occurrence, modelled through Cox regression.

Results

An increase in the modified Mediterranean diet score was associated with lower overall mortality, a two unit increment corresponding to a statistically significant reduction of 8% (95% confidence interval 3% to 12%). No statistically significant evidence of heterogeneity was found among countries in the association of the score with overall mortality even though the association was stronger in Greece and Spain. When dietary exposures were calibrated across countries, the reduction in mortality was 7% (1% to 12%).

Conclusion

The Mediterranean diet, modified so as to apply across Europe, was associated with increased survival among older people.

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Logo of bmjThis ArticleThe BMJ
BMJ. 2005 Apr 30; 330(7498): 991.
PMCID: PMC557144
PMID: 15820966

Modified Mediterranean diet and survival: EPIC-elderly prospective cohort study

Antonia Trichopoulou, associate professor,1 Philippos Orfanos, senior biostatistician,1 Teresa Norat, epidemiologist,2 Bas Bueno-de-Mesquita, project director diet and chronic diseases,3 Marga C Ocké, project director food consumption surveys,3 Petra HM Peeters, associate professor,4 Yvonne T van der Schouw, associate professor,4 Heiner Boeing, chair,5 Kurt Hoffmann, senior scientist,5 Paolo Boffetta, chief,6 Gabriele Nagel, physician,6 Giovanna Masala, medical epidemiologist,7 Vittorio Krogh, medical epidemiologist,8 Salvatore Panico, senior researcher,9 Rosario Tumino, director,10 Paolo Vineis, chair,11 Christina Bamia, chief biostatistician,1 Androniki Naska, lecturer,1 Vassiliki Benetou, medical epidemiologist,1 Pietro Ferrari, statistician,2 Nadia Slimani, nutritionist,2 Guillem Pera, biostatistician,12 Carmen Martinez-Garcia, researcher,13 Carmen Navarro, head,14 Miguel Rodriguez-Barranco, statistician,14 Miren Dorronsoro, vice director,15 Elizabeth A Spencer, nutritionist,16 Timothy J Key, professor,16 Sheila Bingham, deputy director,17 Kay-Tee Khaw, professor,18 Emmanuelle Kesse, researcher,19 Francoise Clavel-Chapelon, research director,19 Marie-Christine Boutron-Ruault, research director,19 Goran Berglund, professor,20 Elisabet Wirfalt, associate professor,20 Goran Hallmans, head of unit of nutritional research,21 Ingegerd Johansson, head of dental school,22 Anne Tjonneland, head,23 Anja Olsen, research assistant,23 Kim Overvad, research director,24 Heidi H Hundborg, senior biostatistician,24 Elio Riboli, head,2 and Dimitrios Trichopoulos, professor25
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Abstract

Objective To examine whether adherence to the modified Mediterranean diet, in which unsaturates were substituted for monounsaturates, is associated with longer life expectancy among elderly Europeans.

Design Multicentre, prospective cohort study.

Setting Nine European countries (Denmark, France, Germany, Greece, Italy, the Netherlands, Spain, Sweden, United Kingdom).

Participants 74 607 men and women, aged 60 or more, without coronary heart disease, stroke, or cancer at enrolment and with complete information about dietary intake and potentially confounding variables.

Main outcome measures Extent of adherence to a modified Mediterranean diet using a scoring system on a 10 point scale, and death from any cause by time of occurrence, modelled through Cox regression.

Results An increase in the modified Mediterranean diet score was associated with lower overall mortality, a two unit increment corresponding to a statistically significant reduction of 8% (95% confidence interval 3% to 12%). No statistically significant evidence of heterogeneity was found among countries in the association of the score with overall mortality even though the association was stronger in Greece and Spain. When dietary exposures were calibrated across countries, the reduction in mortality was 7% (1% to 12%).

Conclusion The Mediterranean diet, modified so as to apply across Europe, was associated with increased survival among older people.

Introduction

The association of diet with several diseases has attracted much attention.1,2 Recently, interest has concentrated on dietary patterns, because they can accommodate the complex interplay of nutrients within a diet.3,4 Dietary patterns have often been studied in relation to the mortality of elderly people,5-9 because of interest in this important age group and because of methodological considerations—for example, the cumulative effects of diet over an extended period and the high frequency of deaths.

The Mediterranean diet has been used in many studies because several of its components have been related to common chronic diseases,2,10 ecological evidence suggests that such a diet may be beneficial to health,11 and variants of this diet have improved the prognosis of patients with coronary heart disease.12,13 The Mediterranean diet is characterised by a high intake of vegetables, legumes, fruits, and cereals (in the past largely unrefined); a moderate to high intake of fish; a low intake of saturated lipids but high intake of unsaturated lipids, particularly olive oil; a low to moderate intake of dairy products, mostly cheese and yogurt; a low intake of meat; and a modest intake of ethanol, mostly as wine.14 Adherence to a Mediterranean diet was operationalised through a 10 unit dietary score by Trichopoulou et al.4,15 Several studies have used variants of this score and have reported inverse associations with overall mortality.4,6,8,9,15 These studies, however, relied on small samples of mostly elderly participants or on the Greek population only.15

We calculated a score reflecting the Mediterranean diet.15 To allow the score to be applied to non-Mediterranean populations, in which intake of monounsaturates from olive oil is minimal, we substituted monounsaturated lipids with the sum of monounsaturated and polyunsaturated lipids in the numerator of the lipid ratio. We investigated the relation of this modified score with overall mortality in a large sample of elderly Europeans participating in EPIC (the European prospective investigation into cancer and nutrition study).16

Participants and methods

EPIC is a multicentre, prospective cohort study investigating the role of biological, dietary, lifestyle, and environmental factors in cancer and other chronic diseases, under the coordination of the International Agency for Research on Cancer.16 Briefly, between 1992 and 2000, 519 978 apparently healthy volunteers were recruited in 23 centres from 10 European countries (Denmark, France, Germany, Greece, Italy, the Netherlands, Norway, Spain, Sweden, and the United Kingdom). The criteria for sample selection and the methods are reported in detail elsewhere.16

Data for participants aged 60 or over at recruitment were included in the EPIC-elderly study. This study aims to identify dietary patterns among elderly Europeans and to investigate the associations of diet with survival.

Dietary intakes

Usual dietary intakes were assessed through compatible instruments (food frequency questionnaires and, in some centres, records of intake over seven or 14 days) that had been developed and validated within each centre.17-19 In addition, a computerised instrument for recall of dietary intake over 24 hours was developed to collect information from a stratified random sample of the aggregate cohort. The aim was to calibrate the measurements across countries.17

Nutrient intakes were calculated using food composition tables specific to the country.20 In the present study, 14 food groups and nutrients were considered: potatoes, vegetables, legumes, fruits, dairy products, cereals, meat and meat products, fish and seafood, eggs, monounsaturated lipids, polyunsaturated lipids, saturated lipids, sugar and confectionery, and non-alcoholic beverages. For each participant, daily intake (grams) of each of the groups and total energy intake (megajoules) were estimated.

Lifestyle, anthropometric, and medical variables

A precoded questionnaire was used to record data on lifestyle and health,16 which included educational achievement, history of illnesses, history of smoking, and physical activity. For participants still in work, the physical demand of their job was recorded. For leisure, time spent on each of several activities was multiplied by an energy cost coefficient; the products were then summed to produce a score of daily physical activity.21 Sex and centre specific thirds of the estimated physical activity score at leisure were used.

Anthropometric measurements were taken in all EPIC centres using similar, standardised procedures, except for France, Oxford (United Kingdom), and Norway. In these centres self reported values were recorded, but actual measurements were obtained for only a fraction of the participants.

Mediterranean diet scale

A scale indicating the degree of adherence to the traditional Mediterranean diet has been constructed by Trichopoulou et al.4,15 Values of zero or one were assigned to each of nine indicated components, using as cut-off values the sex specific medians among the participants. People whose consumption of presumed beneficial components (vegetables, legumes, fruits, cereals, fish) was below the median consumption were assigned a value of zero, and a value of one otherwise. People whose consumption of presumed detrimental components (meat and dairy products) was below the median consumption were assigned a value of one, and a value of zero otherwise. A value of one was given to men consuming from 10 g to less than 50 g of ethanol per day and to women consuming from 5 g to 25 g. For lipid intake, the ratio of the sum of monounsaturates and polyunsaturates to saturates was calculated. This modified Mediterranean diet score, as both monounsaturates and polyunsaturates are included in the numerator of the lipid ratio, can take a value from zero (minimal adherence) to nine (maximal adherence).

Follow-up

Information on the vital status of participants was obtained from mortality registries and by active follow-up. Earliest and latest years of follow-up were 1999 (some participants in the Netherlands) and December 2003 (most centres). Participants were classified as alive at last follow-up, dead, emigrated, refused to participate further, and unknown.

Overall, 100 442 participants of the EPIC cohort were aged 60 years or more at recruitment and had acceptable records of energy intakes (those in the top and bottom 1% of the ratio of energy intake to estimated energy requirement were excluded).22 Vital status has been ascertained for 100 309 (99.9%) of these participants; however, 15 362 were excluded from the EPIC-elderly study database because coronary heart disease, stroke, cancer, or a combination of these had been diagnosed at enrolment. Of the remaining 84 947 participants, 10 340 had missing information for one or more of the dietary, anthropometric, or lifestyle variables, or had died within the year after enrolment. Thus 74 607 individuals were included in the study.

Statistical analysis

Analyses were carried out with Stata 7.0 and SAS 8.2. Descriptive presentation relied on cross tabulations. Survival data were modelled through Cox's proportional hazards regression,23 with length of follow-up as the primary time variable. Adjustment was made for sex, age, self reported diabetes mellitus at enrolment, educational achievement, smoking status, physical activity, waist to hip ratio, body mass index, and total energy intake. In analyses that investigated the relation of the score with mortality, consumption of eggs, potatoes, and sugar and confectionery (which are not part of the score) were also controlled for continuously. Both fixed effects and random effects models were used. Separate proportional hazard models were used for all participants and for participants in each country. Models were stratified by country or by centre (for the country specific analyses).

Dietary exposures across centres were equilibrated using an additive calibration.18 Briefly, the differences between the sex and centre specific means of the values from the food frequency questionnaire and the means of the 24 hour recall values were calculated and added to the questionnaire values. The calibrated score was computed and its association to mortality was investigated using similar models.

Results

Table 1 shows the distribution of the participants in the EPIC-elderly study by country, sex, and age at enrolment. Participants from all countries involved in EPIC are included in the EPIC-elderly study database, except for Norway, which has a comparatively young cohort. These eligible participants were followed up for a median of 89 months (range 1 to 138 months) and contributed 541 872 person years. During follow-up, 4047 participants died. Most deaths occurred in the Swedish, Danish, and UK cohorts. These cohorts are larger than the other EPIC cohorts and have a higher mean age.

Table 1

Distribution of 74 607 participants in EPIC-elderly cohort, by country, sex, and age at enrolment. Values are numbers (percentages)

Age of men
Age of women
Country60-6465-69 ≥70*Total60-6465-69 ≥70*Total
France† NA NA NA NA 6070 (19.4) 3403 (24.5) 57 (1.2) 9530 (19.1)
Italy 1235 (7.7) 195 (3.6) 4 (0.2) 1434 (5.8) 3018 (9.7) 740 (5.3) 201 (4.1) 3959 (7.9)
Spain 1399 (8.8) 187 (3.4) 0 1586 (6.5) 1949 (6.2) 318 (2.3) 0 2267 (4.5)
UK 1457 (9.1) 1472 (27.1) 1445 (46.1) 4374 (17.8) 2294 (7.3) 2086 (15.0) 2000 (40.7) 6380 (12.7)
Netherlands 149 (0.9) 24 (0.4) 0 173 (0.7) 2824 (9.0) 2492 (17.9) 111 (2.3) 5427 (10.8)
Greece 862 (5.4) 1012 (18.6) 889 (28.3) 2763 (11.3) 1653 (5.3) 1682 (12.1) 1281 (26.0) 4616 (9.2)
Germany 3132 (19.6) 520 (9.6) 0 3652 (14.9) 3373 (10.8) 530 (3.8) 0 3903 (7.8)
Sweden 3070 (19.2) 1317 (24.2) 799 (25.4) 5186 (21.1) 3746 (12.0) 1656 (11.9) 1266 (25.8) 6668 (13.3)
Denmark 4663 (29.2) 714 (13.1) 0 5377 (21.9) 6323 (20.2) 989 (7.1) 0 7312 (14.6)
Total 15 967 (100.0) 5441 (100.0) 3137 (100.0) 24 545 (100.0) 31 250 (100.0) 13 896 (100.0) 4916 (100.0) 50 062 (100.0)

EPIC=European prospective investigation into cancer and nutrition. NA=not applicable.

*In statistical models, ≥70 age group was categorised as 70-74 and ≥75.
†No men were included in French EPIC cohort.

The patterns for deaths and accumulated person years by non-nutritional variables were generally as expected (table 2). Table 3 shows the cross classifications of broad categories of the score by non-nutritional variables. The score is higher among older people (≥ 70 years) and lower among current smokers.

Table 2

Number of deaths and accumulated person years among 74 607 participants in EPIC-elderly cohort by age, sex, sociodemographic, anthropometric, and lifestyle variables

Men
Women
VariableNo of deathsAccumulated person yearsAge adjusted death rates*per 1000 person yearsNo of deathsAccumulated person yearsAge adjusted death rates*per 1000 person years
Age:
60-64 1000 112 685 8.87 1023 238 782 4.28
65-69 467 36 122 12.93 699 105 611 6.62
70-74 331 15 071 21.96 286 24 947 11.46
≥75 141 3567 39.53 100 5087 19.66
Smoking status:
Never 426 53 902 7.92 1060 241 400 4.40
Former 928 80 836 11.25 545 83 580 6.65
Current 585 32 707 17.70 503 49 447 10.19
Educational achievement:
None or primary school 1028 75 850 13.57 983 152 914 6.41
Technical school 429 38 049 11.10 486 74 912 6.54
Secondary school 156 17 009 8.37 385 88 109 4.45
University degree 326 36 537 8.93 254 58 492 4.33
Body mass index (kg/m2):
<25 656 52 034 12.05 906 171 848 5.38
≥25 1283 115 411 11.12 1202 202 579 5.92
Waist to hip ratio†:
<0.90 369 35 453 9.76 1841 342 676 5.41
≥0.90 1570 131 992 11.94 267 31 751 8.23
Energy intake (MJ):
<8.374 597 50 146 11.11 1267 221 517 5.80
≥8.374 1342 117 299 11.41 841 152 910 5.52
Physical activity at work:
Retired or sedentary occupation 1579 124 316 12.27 1821 311 057 5.94
Standing occupation 193 22 150 8.73 190 42 526 4.50
Manual work 134 16 437 8.17 84 17 662 4.57
Heavy manual work 33 4542 7.26 13 3182 3.70
Physical activity at leisure‡:
First third (low) 609 47 361 13.13 715 107 355 6.63
Second third 593 53 892 10.89 688 124 040 5.58
Last third (high) 737 66 192 10.74 705 143 032 5.02
Alcohol intake (g):
Low§ 1007 75 162 12.77 1273 212 362 6.12
Moderate 726 77 580 9.37 650 132 620 4.89
High 206 14 703 13.94 185 29 445 6.24
Total 1939 167 445 11.39 2108 374 427 5.67

EPIC=European prospective investigation into cancer and nutrition.

*With direct adjustment, using study population (combined men and women) as standard, except for age.
†Values for some participants were imputed from a linear regression model, with weight and height as independent variables and waist to hip ratio as dependent variable.
‡Sex and centre specific thirds of scores for physical activity at leisure time.
§Men <10 g; women <5 g.
Men >50 g; women >25 g.

Table 3

Baseline characteristics by categories of modified Mediterranean diet score among 74 607 participants in EPIC-elderly study and 4047 deaths

Men
Women
Diet score 0-3
Diet score 4-5
Diet score 6-9
Diet score 0-3
Diet score 4-5
Diet score 6-9
CharacteristicNo (%)No of deathsNo (%)No of deathsNo (%)No of deathsNo (%)No of deathsNo (%)No of deathsNo (%)No of deaths
Age:
60-64 5763 (36.1) 443 6099 (38.2) 388 4105 (25.7) 169 11 580 (37.1) 460 11 784 (37.7) 361 7886 (25.2) 202
65-69 1624 (29.9) 183 1984 (36.5) 183 1833 (33.7) 101 4760 (34.3) 312 5151 (37.1) 265 3985 (28.7) 122
70-74 701 (27.9) 104 900 (35.8) 136 912 (36.3) 91 1249 (30.5) 116 1550 (37.8) 111 1303 (31.8) 59
≥75 97 (15.5) 32 217 (34.8) 62 310 (49.7) 47 166 (20.4) 29 311 (38.2) 36 337 (41.4) 35
Smoking status:
Never 2516 (32.0) 176 2920 (37.2) 162 2417 (30.8) 88 10 292 (31.4) 386 12 239 (37.3) 404 10 253 (31.3) 270
Former 3657 (31.1) 300 4653 (39.6) 387 3449 (29.3) 241 4097 (38.1) 235 4359 (40.5) 211 2305 (21.4) 99
Current 2012 (40.8) 286 1627 (33.0) 220 1294 (26.2) 79 3366 (51.7) 296 2198 (33.7) 58 953 (14.6) 49
Educational achievement:
None or primary school 3828 (33.0) 416 3857 (33.2) 395 3922 (33.8) 217 8073 (36.3) 463 7785 (35.0) 340 6367 (28.7) 180
Technical or professional school 2008 (38.6) 178 2177 (41.8) 174 1023 (19.6) 77 4835 (48.4) 253 3835 (38.4) 175 1327 (13.3) 58
Secondary school 581 (23.5) 46 944 (38.2) 69 947 (38.3) 41 2839 (26.9) 130 4217 (40.0) 145 3481 (33.0) 110
University degree 1768 (33.6) 122 2222 (42.3) 131 1268 (24.1) 73 2008 (27.5) 71 2959 (40.5) 13 2336 (32.0) 70
Body mass index (kg/m2):
<25 2561 (34.7) 265 2912 (39.5) 262 1905 (25.8) 129 7496 (35.1) 402 8344 (39.0) 318 5545 (25.9) 186
≥25 5624 (32.8) 497 6288 (36.6) 507 5255 (30.6) 279 10 259 (35.8) 515 10 452 (36.5) 455 7966 (27.8) 232
Waist to hip ratio*:
<0.90 1716 (34.5) 154 1883 (37.9) 144 1374 (27.6) 71 16 203 (35.9) 811 17 076 (37.9) 666 11 840 (26.2) 364
≥0.90 6469 (33.1) 608 7317 (37.4) 625 5786 (29.6) 337 1552 (31.4) 106 1720 (34.8) 107 1671 (33.8) 54
Energy intake (MJ):
<8.374 2790 (36.6) 238 2670 (35.0) 231 2161 (28.4) 128 12 196 (40.2) 610 10 914 (36.0) 49 7206 (23.8) 208
≥8.374 5395 (31.9) 524 6530 (38.6) 538 4999 (29.5) 280 5559 (28.2) 307 7882 (39.9) 324 6305 (31.9) 210
Physical activity at work:
Retired or sedentary occupation 6157 (33.4) 617 7051 (38.2) 623 5231 (28.4) 339 14 527 (35.0) 776 15 612 (37.6) 664 11 411 (27.5) 381
Standing occupation 1017 (33.0) 80 1111 (36.0) 72 957 (31.0) 41 1913 (33.1) 79 2290 (39.6) 81 1580 (27.3) 30
Manual work 795 (33.0) 52 797 (33.0) 58 820 (34.0) 24 1072 (45.7) 52 788 (33.6) 25 484 (20.7) 7
Heavy manual work 216 (35.5) 13 241 (39.6) 16 152 (25.0) 4 243 (63.1) 10 106 (27.5) 3 36 (9.4) 0
Physical activity at leisure†:
First third 2470 (36.0) 252 2493 (36.3) 236 1901 (27.7) 121 5482 (37.9) 326 5266 (36.4) 257 3732 (25.8) 132
Second third 2643 (33.4) 242 2973 (37.6) 231 2300 (29.1) 120 5828 (35.0) 286 6289 (37.8) 247 4520 (27.2) 155
Last third 3072 (31.5) 268 3734 (38.2) 302 2959 (30.3) 167 6445 (34.0) 305 7241 (38.2) 269 5259 (27.8) 131
Total 8185 762 9200 769 7160 408 17 755 917 18 796 773 13 511 418

EPIC=European prospective investigation into cancer and nutrition.

*Values for some participants were imputed from a linear regression model, with weight and height as independent variables and waist to hip ratio as dependent variable.
†Sex and centre specific thirds of scores for physical activity at leisure time.

Table 4 shows the associations of food groups and nutritional variables with overall mortality. Mortality ratios are adjusted for non-nutritional variables (see table 2) as well as for country, sex, and diabetes mellitus. They were not mutually adjusted, however, because underlying strong associations among food groups create technical problems—one of the reasons for opting for a nutrition score. Some of the associations are both plausible and statistically significant, notably the inverse associations of overall mortality with intake of vegetables, fruits, and cereals, ratio of unsaturated to saturated lipids, and the positive association of overall mortality with saturated lipids.

Table 4

Median and mean (standard deviation) daily intake of selected food groups and associated mortality ratio (95% confidence intervals) for chosen increment in EPIC-elderly study

Men
Women
Food group intake (g/d)MedianMean (SD)MedianMean (SD)Chosen increment*Mortality ratio (95% CI)†
Potatoes 115.1 127.2 (90.9) 75.4 87.8 (67.2) 78 1.01 (0.98 to 1.05)
Vegetables 156.8 198.5 (149.3) 183.8 218.6 (141.9) 145 0.94 (0.90 to 0.98)
Legumes 3.3 12.2 (23.0) 5.0 10.7 (16.8) 19 1.02 (0.99 to 1.06)
Fruits 176.7 232.5 (199.4) 245.7 280.4 (188.4) 193 0.96 (0.92 to 0.99)
Dairy products 285.7 336.7 (251.9) 301.1 341.4 (228.1) 239 1.03 (0.99 to 1.07)
Cereals 212.0 230.4 (115.4) 168.4 185.1 (92.9) 104 0.94 (0.91 to 0.98)
Meat 111.6 119.4 (62.4) 82.2 86.8 (46.7) 55 1.03 (0.99 to 1.07)
Fish 32.2 40.7 (35.0) 26.9 33.5 (28.2) 31 1.00 (0.97 to 1.04)
Eggs 13.1 17.9 (17.9) 12.6 16.6 (16.9) 17 1.04 (1.01 to 1.07)
Confectionery 33.9 43.2 (37.3) 29.0 35.7 (30.3) 33 0.99 (0.96 to 1.03)
Non-alcoholic beverages 1030.5 1065.6 (722.7) 1132.8 1157.8 (770.7) 750 1.02 (0.98 to 1.07)
Monounsaturated lipids 32.2 34.4 (13.7) 25.6 27.6 (11.1) 12 1.05 (0.99 to 1.11)
Saturated lipids‡ 32.4 34.6 (14.2) 27.0 28.5 (11.3) 13 1.07 (1.02 to 1.12)
Polyunsaturated lipids 13.8 15.2 (6.8) 11.5 12.6 (5.8) 6 0.99 (0.96 to 1.03)
Lipid ratios:
Monounsaturated to saturated lipids 0.9 1.1 (0.4) 0.9 1.0 (0.4) 0.4 0.93 (0.88 to 0.99)
Unsaturated to saturated lipids 1.4 1.5 (0.5) 1.4 1.5 (0.5) 0.5 0.95 (0.91 to 0.99)
Energy intake (MJ) 9.609 9.820 (2.616) 7.786 8.004 (2.162) 2.492 1.01 (0.98 to 1.05)

EPIC=European prospective investigation into cancer and nutrition.

*Arbitrary chosen number around average of within sex standard deviation.
†Stratified by country and adjusted for sex, age (60-64, 65-69, 70-74, and ≥75, categorically), diabetes mellitus at baseline (yes, no), waist to hip ratio (in ordered fifths), body mass index (in ordered fifths), educational achievement (none or primary school, technical school, secondary school, university degree, categorically), smoking status (never, former, and four categories of current smoker (cigarettes per day): 1-10, 11-20, 21-30, and >30, ordered), physical activity at occupation (retired or sedentary occupation, standing occupation, manual work, and heavy manual work, categorically), physical activity score at leisure (in centre and sex specific thirds, categorically), alcohol intake (low, moderate, high, categorically), and total energy intake (in ordered fifths) except for energy intake. Not mutually adjusted.
‡All sources.

Table 5 shows the adjusted associations of non-calibrated and calibrated scores with overall mortality. The associations were investigated by comparing mortality of participants with scores of 6 to 9 and 4 to 5 with those scoring 0 to 3, and by estimating the mortality ratio in relation to two unit increments of the score. Evidence shows that an increase in the score is associated with reduced overall mortality, a two unit increment corresponding to a statistically significant 8% reduction in both fixed effects and random effects models. No statistically significant evidence exists of heterogeneity among countries in the effect of score on overall mortality even though the effect is stronger in Greece and Spain and absent in the Netherlands and Germany (table 6). After excluding the Greek data, the reduction of overall mortality with an increase in the score remained statistically significant (mortality ratio for a two unit score increase 0.93, 95% confidence interval 0.89 to 0.97). The results of the analysis over all countries changed little after calibration. A two unit increment of the score corresponds to a statistically significant 7% reduction in mortality in the fixed effects and random effects models.

Table 5

Mortality ratios (95% confidence intervals) for all countries (stratified by country) by category of modified Mediterranean diet score in 74 607 participants in EPIC-elderly study

Fully adjusted mortality ratio*No of deathsMean score (95% CI)Diet score 4-5†P value for heterogeneityDiet score 6-9†P value for heterogeneity2 unit incrementP value for heterogeneity
Non-calibrated:
Fixed effects
4047 4.33 (4.31 to 4.34)
0.91 (0.85 to 0.98)
0.075 0.83 (0.75 to 0.93)
0.658 0.92 (0.88 to 0.96)
0.328
Random effects 4.33 (4.31 to 4.34) 0.95 (0.85 to 1.07) 0.83 (0.75 to 0.93) 0.92 (0.88 to 0.97)
Calibrated:
Fixed effects
4047 4.45 (4.44 to 4.46)
0.93 (0.87 to 1.01)
0.742 0.91 (0.82 to 1.01)
0.376 0.93 (0.89 to 0.98)
0.091
Random effects 4.45 (4.44 to 4.46) 0.93 (0.87 to 1.01) 0.91 (0.82 to 1.02) 0.93 (0.88 to 0.99)

EPIC=European prospective investigation into cancer and nutrition.

*Adjusted for sex, age (60-64, 65-69, 70-74, and ≥75, categorically), diabetes mellitus at baseline (yes, no), waist to hip ratio (in ordered fifths), body mass index (in ordered fifths), educational achievement (none or primary school, technical school, secondary school, university degree, categorically), smoking status (never, former, and four categories of current smoker (cigarettes per day): 1-10, 11-20, 21-30, and >30, ordered), physical activity at work (retired or sedentary occupation, standing occupation, manual work, and heavy manual work, categorically), physical activity at leisure (in centre and sex specific thirds, categorically), consumption of potatoes (continuously), consumption of eggs (continuously), consumption of sugar and confectionery (continuously), and total energy intake (in ordered fifths).
†Reference category diet score 0-3.

Table 6

Mortality ratios† (95% confidence intervals) by country (stratified by centre within country) by category of modified Mediterranean diet score in EPIC-elderly study

CountryNo in cohort/No of deathsMean score (95% CI)Diet score 4-5*Diet score 6-9*2 unit increment
France 9530/302 5.01 (4.98 to 5.04) 1.15 (0.84 to 1.57) 0.93 (0.67 to 1.31) 0.95 (0.82 to 1.10)
Italy 5393/153 5.34 (5.30 to 5.38) 0.89 (0.53 to 1.48) 1.02 (0.60 to 1.72) 0.99 (0.80 to 1.25)
Spain 3853/136 5.61 (5.57 to 5.66) 1.09 (0.51 to 2.32) 0.92 (0.43 to 1.97) 0.81 (0.63 to 1.05)
United Kingdom 10 754/999 4.73 (4.70 to 4.76) 0.82 (0.71 to 0.96) 0.80 (0.68 to 0.96) 0.92 (0.85 to 1.00)
Netherlands 5600/284 2.92 (2.88 to 2.95) 0.94 (0.71 to 1.23) 1.29 (0.72 to 2.33) 1.00 (0.84 to 1.19)
Greece 7379/237 6.25 (6.22 to 6.27) 1.16 (0.47 to 2.88) 0.71 (0.29 to 1.75) 0.70 (0.56 to 0.88)
Germany 7555/253 3.34 (3.31 to 3.38) 1.34 (1.03 to 1.73) 1.09 (0.64 to 1.85) 1.07 (0.89 to 1.28)
Sweden 11 854/789 3.23 (3.20 to 3.25) 0.92 (0.78 to 1.07) 0.69 (0.49 to 0.97) 0.92 (0.83 to 1.02)
Denmark 12 689/894 3.75 (3.72 to 3.78) 0.84 (0.73 to 0.97) 0.79 (0.62 to 1.01) 0.90 (0.82 to 0.98)

EPIC=European prospective investigation into cancer and nutrition.

*Reference category diet score 0-3.
†Adjusted for sex, age (60-64, 65-69, 70-74, and ≥75, categorically), diabetes mellitus at baseline (yes, no), waist to hip ratio (in ordered fifths), body mass index (in ordered fifths), educational achievement (none or primary school, technical school, secondary school, university degree, categorically), smoking status (never, former, and four categories of current smoker (cigarettes per day): 1-10, 11-20, 21-30, and >30, ordered), physical activity at work (retired or sedentary occupation, standing occupation, manual work, and heavy manual work, categorically), physical activity at leisure (in centre and sex specific thirds, categorically), consumption of potatoes (continuously), consumption of eggs (continuously), consumption of sugar and confectionery (continuously), and total energy intake (in ordered fifths).

Discussion

A dietary score that assessed adherence to a modified Mediterranean diet relying on plant foods and unsaturated lipids was associated with a significantly longer life expectancy in apparently healthy elderly people living in nine European countries. This prospective trial, the EPIC-elderly study, relies on the largest available database for the investigation of the role of diet in the longevity of elderly people. The reduction in mortality in relation to a dietary score was more striking than expected from the associations of the score's components with mortality. It has been pointed out that a dietary score may be more discriminatory than each of its components because it captures the extremes of the nutritional exposures of interest and pre-empts nutritional confounding by incorporating possible confounders in the score.3,15

We slightly modified the definition of the score by including polyunsaturates in the numerator of the lipid ratio.4,6,8,9,15 This was necessary because polyunsaturates are the principal unsaturated added lipids in diets in non-Mediterranean countries and have established beneficial effects on coronary heart disease.12 Moreover, the definition of lipid ratio with monounsaturates alone in the numerator would strongly depend on meat consumption in northern European countries in which a principal source of monounsaturates is meat.

We focused on a variant of the Mediterranean diet with potentially wide applicability, because of the strong evidence that the traditional Mediterranean diet is beneficial to health. The principal characteristic of the modified Mediterranean diet score is that it relies on plant foods and unsaturated lipids. Reduction of total lipids, however, is not a prerequisite for a healthy diet provided the lipids are not saturated or trans and are not mainly derived from meat.15,24 The question whether monounsaturates from olive oil, or specific categories of polyunsaturates, are particularly beneficial cannot be answered from this investigation, because the distributions of the intake of the particular lipids are so different in the participating countries as to introduce a strong ecological element into the study. The important point is that a diet that can be operationalised does have a relation with mortality, and that realistically achievable changes in diet—for example, 3 or 4 point increments—are associated with a reduction of total mortality by 11% or 14%, respectively.

The calibration used in this study deals with much of the concern about the comparability of results across different populations. No significant heterogeneity was found among the country specific results with or without calibration for dietary exposures. The results were generally more evident in Greece and Spain, probably because in these countries the modified Mediterranean diet is genuinely a Mediterranean diet (in Italy most of the deaths occurred in northern Italy, where the diet cannot be considered as Mediterranean). It is possible that the association of the score with mortality may vary among populations because of different distribution patterns for food and conceivably non-linear underlying relations of the components of the score with mortality. The parsimonious interpretation of the findings, however, supported by the non-significant heterogeneity in the analyses, is that the modified Mediterranean diet is beneficial to health across populations.

Advantages of this study include its prospective nature, its large size, its reliance on a European population sample, and the calibration of dietary exposures across countries. The study also exploited the availability of information on several non-dietary variables and was able to control for them as potential confounders. Socioeconomic status was controlled for by adjusting for educational achievement, the only factor that is both objectively ascertainable and internationally applicable. Control for physical activity took into account participants still working. Because the study is observational, it is possible for residual confounding from suboptimally measured factors. The association of the score with non-nutritional variables was, however, generally weak (see table 3), reducing the potential for such confounding. Exceptions were the clear associations of the score with sex, age, country, and tobacco consumption, but these variables were validly measured allowing little room for residual confounding.

In conclusion, adherence to a diet relying on plant foods and unsaturated lipids and that resembles the Mediterranean diet, may be particularly appropriate for elderly people, who represent a rapidly increasing group in Europe.

What is already known on this topic

Small cohort studies have shown that Mediterranean type diets increase longevity

No international study with assured comparability of dietary information through calibration has been undertaken

What this study adds

Qualitative aspects of diet predict overall death rate and hence survival

A dietary pattern that resembles that of the Mediterranean is associated with a lower overall death rate

Polyunsaturated lipids are an acceptable substitute when monounsaturated lipids are not readily available

Notes

Contributors: AT is the principal investigator of the EPIC-elderly project. She is guarantor for the paper. PO is the principal biostatistician in this project. Contributors from the participating centres provided the original data, information on the respective populations, and advice on study design and analysis. Participants from the International Agency for Research on Cancer were responsible for coordination of the overall EPIC project and also contributed advice on study design and analysis.

Funding: This study was supported by the quality of life and management of living resources programme of the European Commission (contract No QLK6-CT-2001-00241), coordinated by the Department of Hygiene and Epidemiology, University of Athens Medical School; the Europe against cancer programme of the European Commission coordinated by the International Agency for Research on Cancer; the Greek Ministry of Health and the Greek Ministry of Education; the fellowship “Vasilios and Nafsika Tricha”; Danish Cancer Society; Ligue contre le Cancer (France); Société 3M (France); Mutuelle Générale de l'Education Nationale (France); Institut National de la Santé et de la Recherche Médicale (France); Gustave Roussy Institute and several general councils in France; German Cancer Aid; German Cancer Research Centre; German Federal Ministry of Education and Research; Associazione Italiana per la Ricerca contro il Cancro; Compagnia di San Paolo (Italy); Regione Sicilia, Provincia Regionale Sicilia, Comune di Ragusa, AIRE-ONLUS and AVIS-Ragusa (Italy); national cancer registry and comprehensive cancer centres east Amsterdam and Limburg (Netherlands); Dutch Ministry of Public Health, Welfare and Sports; health research fund (FIS) of the Spanish Ministry of Health (Spain); the Spanish Regional governments of Andalucia, Asturias, Basque country, Murcia, and Navarra (Spain); ISCIII Network RCESP (Spain); Swedish Cancer Society; Swedish Scientific Council, Malmö; regional government of Skåne (Sweden); Cancer Research UK; Medical Research Council (United Kingdom). The researchers were financed independently from the funding organisations.

Competing interests: None declared.

Ethical approval: This study was approved by the ethical committees at the International Agency for Research on Cancer and at participating centres.

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