Schwenke, Dawn C.a,b
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Dietary patterns similar to those traditionally followed in the Mediterranean (’Mediterranean diets’) continue to be popular as interventions for reducing risk factors/biomarkers of chronic disease [1,2]. However, it is not clear that such dietary patterns are optimal for promoting health or preventing development or progression of disease over a lifetime. There are very few direct prospective comparisons of the long-term health consequences of Mediterranean diets and other proposed healthful dietary patterns, such as ‘prudent’ diets or the ‘Dietary Approaches to Stop Hypertension’ (DASH) diet . Consequently, there is little evidence that Mediterranean dietary patterns reduce morbidity and mortality compared with other healthful dietary patterns. In fact, as described below, recent literature suggests that the Mediterranean diet as it is commonly understood is far from optimal for reducing death and chronic disease.
Recent work has extended observations on Mediterranean diets to different health endpoints, such as gestational diabetes [4▪] and to total mortality in younger persons with low mortality risk [5▪▪]. Importantly, the future health impact of adherence to a Mediterranean diet pattern has been compared within the same study with several other measures of dietary pattern [4▪]. Also of significance, several reports that evaluated health implications of adherence to a Mediterranean dietary pattern also evaluated corresponding risks associated with individual components of the Mediterranean dietary pattern [5▪▪,6▪▪,7▪]. Those observations, together with insight from other investigations of food components included in the Mediterranean diet [8▪▪,9▪▪,10] and other pertinent observations [11▪,12▪▪,13▪▪] have the potential to help guide optimization of diet prescriptions to promote health and reduce chronic disease morbidity and mortality.
Three recent articles reported on the health implications of both the Mediterranean diet and individual components of the Mediterranean diet [5▪▪,6▪▪,7▪]. Among these, two reported on individuals residing in the Mediterranean region [5▪▪,6▪▪], one on participants in the Greek European Prospective Investigation into Cancer and Nutrition (Greek EPIC) cohort [6▪▪] and the other on Spanish participants in the Seguimiento Universidad de Navarra (SUN) project [5▪▪]. In both of these populations, the typical scoring system described by Trichopoulou et al. was used to assess concordance of individual dietary patterns with the Mediterranean diet. In this scoring system, one point is awarded for levels of consumption above the sex-specific median for the study population (zero points if below) for foods/nutrients frequently consumed as part of a traditional Mediterranean diet (vegetables, legumes, fruits and nuts, cereals, fish and seafood, high ratio of dietary monounsaturated to saturated fat). Similarly, one point is awarded for levels of intake below the sex-specific median for the study population (zero points if above) for foods that are less commonly consumed as part of a traditional Mediterranean diet (dairy, meat and meat products) .
The Greek EPIC study [6▪▪] reported greater adherence to the Mediterranean diet and was associated with reduced risk of death due to coronary heart disease (CHD). After appropriate multivariate adjustment, for every two-point greater concordance of the dietary pattern with the Mediterranean diet, risk of CHD mortality was 19% [95% confidence interval (CI), 1–34%] lower for men, 25% (95% CI, 2–43%) lower for women, and 22% (95% CI, 8–34%) lower for men and women combined. After similar multivariable adjustment, in the younger SUN population [5▪▪] total mortality was 24% (95% CI, 6–39%) lower for every two-point greater concordance of the dietary pattern with the Mediterranean diet. After further adjustment for dietary confounders not included in the definition of the Mediterranean diet (eggs, potatoes, prescription of special diets), the estimated survival advantage associated with greater adherence to a Mediterranean diet strengthened to 28% (95% CI, 9–42%) [5▪▪].
Both the Greek EPIC [6▪▪] and the SUN study [5▪▪], and a third study [7▪] reported on the survival advantage associated with adherence to individual components of a Mediterranean diet. Among the nutrient components of the Mediterranean diet score, both the Greek EPIC study reporting on CHD mortality [6▪▪] and the SUN study reporting on total mortality [5▪▪] found only the fruits and nuts component to be associated with a survival advantage. In each of these studies, the magnitude of the survival advantage associated with adherence to the fruits and nuts component was somewhat larger than for the overall Mediterranean diet score [5▪▪,6▪▪]. Similarly, a third study reporting from the Vasterbotten Intervention Program (VIP) in Northern Sweden [7▪] that used a modified version of the Mediterranean diet score including fruits and juices instead of fruits and nuts found that among the food/nutrient components, only adherence to the fruit component was associated with reduced mortality (women only) and again the estimated survival advantage was stronger for the fruit component than the total modified Mediterranean diet score. Both the SUN [5▪▪] and the VIP [7▪] evaluated the survival advantage associated with moderate alcohol consumption, with protection found in the VIP study but not in the SUN study. Neither the Greek EPIC [6▪▪] nor the SUN study [5▪▪] found the ratio of monounsaturated to saturated fat to confer any survival advantage.
In addition to evaluating the CHD survival advantage associated with each of the nine components of the Mediterranean diet discussed above, the Greek EPIC study [6▪▪] also evaluated other foods not included in the typical  Mediterranean diet score including potatoes, eggs, sugar and sweets, nonalcoholic beverages, olive oil, and saturated fat, monounsaturated fat, and polyunsaturated fat individually [6▪▪]. In the Greek EPIC [6▪▪], both after minimal adjustment and after adjustment for relevant non-nutritional variables, each one standard deviation increase in olive oil consumption (about 21 g/day per 2000 kcal in men and 24 g/day per 2000 kcal in women) was associated with an increase in risk of CHD death. For women, this increase was significant [42% (95% CI, 2–96%)] [6▪▪]. Similarly, for female participants in Greek EPIC, absolute intake of monounsaturated fat was adversely associated with CHD mortality [6▪▪]. In contrast, an article concerning the Spanish cohort of EPIC (Spanish EPIC)  reported that after similar multivariable adjustment, each 10 g/day per 2000 kcal increase in olive oil consumption was associated with a 6% (95% CI, 3–9%) reduction in all-cause mortality; this estimate was increased to 7% (95% CI, 3–10%) after adjustment for dietary variables. Both in minimally adjusted models and after adjustment for relevant non-nutritional variables and dietary variables, the estimated reduction in cardiovascular mortality associated with the same increase in olive oil consumption was 13% (95% CI for the full model, 6–20%) .
Reasons for the differences in results between the Greek EPIC [6▪▪] and the Spanish EPIC  are not clear. However, in the Greek EPIC providing no evidence for benefit of olive oil, median ratio of dietary monounsaturated to saturated fat was high, 1.80 in women and 1.77 in men, and mean olive oil intake (providing almost all dietary monounsaturated fat) in g/day per 2000 kcal was about 45 in men and 48 in women [6▪▪]. In comparison, in the Spanish EPIC that found olive oil to have benefit, mean olive oil intake in g/day per 2000 kcal was 18.2 in men and 20.1 in women , although total fat intake was similar to the Greek EPIC (both about 85–90 g/day per 2000 kcal). These observations suggest that any incremental survival benefit of olive oil occurs only at low levels of intake and are consistent with the Spanish EPIC result that survival benefits of olive oil were most pronounced when consumers of olive oil at the highest quartile of consumption (>29.4 g/2000 kcal per day, no upper level specified) were compared with Spanish EPIC participants who did not consume olive oil . Thus, recent literature does not provide consistent support for the common notion that olive oil is an important protective component of the Mediterranean diet.
Another report concerning dietary fat saturation and risk of sudden death further questions the health benefits of monounsaturated fat. In the Nurses’ Health Study cohort, the investigators found that dietary intake of monounsaturated fatty acids were not related to sudden cardiac death during 30 years [12▪▪]. In contrast, women in the highest quintile of polyunsaturated fat intake had a 43% (95% CI, 22–59%) lower risk of sudden cardiac death than women in the lowest quintile. Women in the highest compared with the lowest quintile of saturated fat intake had a 44% (95% CI, 4–98%) higher risk [12▪▪]. Importantly, after adjustment for CHD and CHD risk factors, the protection associated with polyunsaturated fat remained significant whereas the association was no longer significant for saturated fat.
Several other reports both reinforce the importance of specific Mediterranean diet components on chronic disease and also provide additional guidance that may help fine tune the Mediterranean diet. For example, a report of a combined analysis of Nurses’ Health Study and Health Professionals Follow-up Study participants showed that after appropriate multivariable adjustment, higher intake of red meat was associated with increased incidence of total stroke whereas higher intake of poultry was associated with reduced incidence [8▪▪]. The authors’ results also indicated that risk of total stroke would be reduced by 27% (95% CI, 12–39%), 17% (95% CI, 4–27%), 17% (95% CI, 0–30%), 11% (95% CI, 5–17%), and 10% (95% CI, 4–16%), respectively, if one serving per day of red meat was replaced by one serving of poultry, nuts, fish, low-fat dairy or whole-fat dairy, respectively [8▪▪].
Another study concerning participants in the Multi-Ethnic Study of Atherosclerosis (MESA) provides additional support for the notion that dairy products are more healthful than meat [11▪]. In MESA participants, the investigators demonstrated that a higher intake of saturated fat from dairy products was associated with reduced risk of incident cardiovascular disease (CVD) events (myocardial infarction, resuscitated cardiac arrest, definite and probable angina, CHD death, stroke, stroke death, or other cardiovascular or atherosclerotic death) whereas a higher intake of saturated fat from meat (primarily beef, pork, and lamb) was associated with increased cardiovascular risk [11▪]. The authors also noted that replacement of 2% of energy of meat saturated fat with 2% of energy from dairy saturated fat was associated with a 25% (95% CI, 9–37%) lower cardiovascular risk.
Another study from the European Prospective Investigation into Cancer and Nutrition Study (EPIC) provides additional information concerning the health implications of different types of dairy products [9▪▪]. In this multinational European cohort, after appropriate multivariable adjustment, neither total dairy intake nor fluid milk intake were associated with diabetes incidence. In comparison, cheese and total fermented dairy (sum of cheese, yogurt, and thick fermented milk) were inversely associated with diabetes risk. After additional adjustment for calcium, magnesium, and vitamin D, important nutrients in dairy products, these relationships strengthened, resulting in an estimated 17% (95% CI, 2–30%) and 15% (95% CI, 1–27%) lower risk of incident diabetes for the highest compared with the lowest quintiles of intake of cheese and total fermented dairy products, respectively [9▪▪].
As originally put forth [14,15], the cereal/grain component of the Mediterranean diet score did not discriminate between whole and refined grains. However, accumulating evidence supports the notion that the ability of a Mediterranean-like diet score to predict future risk of chronic disease or mortality would be enhanced by limiting the cereal/grain component to whole grains which are higher in fiber than the corresponding refined grains [16▪]. Recently, another study concerning the EPIC cohort [13▪▪] demonstrated that dietary fiber was inversely related to total mortality and similarly inversely related to death from circulatory diseases, respiratory diseases, digestive diseases, noncardiovascular inflammatory diseases, and smoking-related cancers. Associations were generally stronger for fiber from cereals and vegetables.
The health of patients and populations would be best served by interventions and recommendations that evolve to reflect emerging evidence. The recent literature suggests that it is time to progress beyond the Mediterranean dietary pattern as it is commonly understood. In doing so, it would be wise to retain the components for which there is consistent support (fruit, nuts, and vegetables, moderate alcohol) and make revisions to reflect more recent understanding. Such revisions would include emphasizing whole grains and particularly those that are high in fiber, considering fermented dairy products as a positive factor, limiting the adverse meat component to red and processed meat, and replacing the emphasis on high monounsaturated to saturated fat ratio with emphasis on high polyunsaturated to saturated fat ratio. Importantly, altering dietary patterns to include more fruits and vegetables and replacing red meats with nuts, chicken, fermented dairy, and fish has the potential to not only improve health but also benefit the environment [17▪].
A growing literature indicates that early and sustained exposure to dietary factors [18▪,19] and obesity [20▪] have continuing future health impact. There are several important implications of such findings. First, long-term health will be optimized by early adoption and sustained practice of a healthful dietary pattern and lifestyle. Second, because of the prolonged impact of cumulative life exposure to dietary and lifestyle risk factors, it may not be reasonable to expect substantive differences in incidence of chronic disease or mortality from an intervention that is short in comparison with a person's lifetime and induces only modest changes in known risk factors for disease or death.
Conflicts of interest
There are no conflicts of interest.
This work was supported in part with resources and of facilities at the Phoenix VA Healthcare System. The contents do not represent the views of the Department of Veterans Affairs or the United States Government.
REFERENCES AND RECOMMENDED READING
Papers of particular interest, published within the annual period of review, have been highlighted as:
▪ of special interest
▪▪ of outstanding interest
1. Papandreou C, Schiza SE, Bouloukaki I, et al. Effect of Mediterranean diet versus prudent diet combined with physical activity on OSAS: a randomised trial. Eur Respir J 2012; 39:1398–1404.
2. Diaz-Lopez A, Bullo M, Martinez-Gonzalez MA, et al. Effects of Mediterranean diets on kidney function: a report from the PREDIMED trial. Am J Kidney Dis 2012; 60:380–389.
3. Sacks FM, Obarzanek E, Windhauser MM, et al. Rationale and design of the Dietary Approaches to Stop Hypertension trial (DASH). Ann Epidemiol 1995; 5:108–118.
4▪. Tobias DK, Zhang C, Chavarro J, et al. Prepregnancy adherence to dietary patterns and lower risk of gestational diabetes mellitus. Am J Clin Nutr 2012; 96:289–295.
5▪▪. Martinez-Gonzalez MA, Guillen-Grima F, De Irala J, et al. The Mediterranean diet is associated with a reduction in premature mortality among middle-aged adults. J Nutr 2012; 142:1672–1678.
6▪▪. Dilis V, Katsoulis M, Lagiou P, et al. Mediterranean diet and CHD: the Greek European Prospective Investigation into Cancer and Nutrition cohort. Br J Nutr 2012; 108:699–709.
7▪. Tognon G, Nilsson LM, Lissner L, et al. The Mediterranean diet score and mortality are inversely associated in adults living in the subartic region. J Nutr 2012; 142:1547–1553.
8▪▪. Bernstein AM, Pan A, Rexrode KM, et al. Dietary protein sources and the risk of stoke in men and women. Stroke 2012; 43:637–644.
9▪▪. Sluijs I, Forouhi NG, Beulens JWJ, et al. The amount and type of dairy product intake and incident type 2 diabetes: Results from the EPIC-InterAct Study. Am J Clin Nutr 2012; 96:382–390.
10. Buckland G, Mayen AL, Agudo A, et al. Olive oil and mortality within the Spanish population (EPIC-Spain). Am J Clin Nutr 2012; 96:142–149.
11▪. de Oliveira Otto MC, Mozaffarian D, Kromhout D, et al. Dietary intake of saturated fat by food source and incident cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis. Am J Clin Nutr 2012; 96:397–404.
12▪▪. Chiuve SE, Rimm EB, Sandhu RK, et al. Dietary fat quality and risk of sudden cardiac death in women. Am J Clin Nutr 2012; 96:498–507.
13▪▪. Chuang S-C, Norat T, Murphy N, et al. Fiber intake and total and cause-specific mortality in the Eurpean Prospective Investigation into Cancer and Nutrition cohort. Am J Clin Nutr 2012; 96:164–174.
14. Trichopoulou A, Costacou T, Bamia C, Trichopoulos D. Adherence to a Mediterranean diet and survival in a Greek population. New Eng J Med 2003; 348:2599–2608.
15. Trichopoulos D, Kouris-Blazos A, Wahlqvist ML, et al. Diet and survival in elderly people. Br Med J 1995; 311:1457–1460.
16▪. Ye EQ, Chacko SA, Chou EL, et al. Greater whole-grain intake is associated with lower risk of type 2 diabetes, cardiovascular disease, and weight gain. J Nutr 2012; 142:1304–1313.
17▪. Macdiarmid JI, Kyle J, Horgan GW, et al. Sustainable diets for the future: can we contribute to reducing greenhouse gas emissions by eating a healthy diet? Am J Clin Nutr 2012; 96:632–639.
18▪. van de Laar RJJ, Stehouwer CDA, Van Bussel BCT, et al. Lower lifetime dietary fiber intake is associated with carotid artery stiffness: the Amsterdam Growth and Health Longitudinal Study. Am J Clin Nutr 2012; 96:14–23.
19. Kaikkonen JE, Jula A, Mikkila V, et al. Childhood serum cholesterol ester fatty acids are associated with blood presssure 27 y later in the Cardiovascular Risk in Young Finns Study. Am J Clin Nutr 2012; 95:1422–1431.
20▪. Abdullah A, Wolfe R, Mannan H, et al. Epidemiologic merit of obese-years, the combination of degree and duration of obesity. Am J Epidemiol 2012; 176:99–107.
This article will be of interest for the comparative information for risk of gestational diabetes within the Nurses’ Health Study II cohort accoring to dietary quality as assessed by three measures: a score reflecting adherence to a Mediterranean diet as adapted for the US population, a score reflecting adherence to a dietary pattern designed and demonstrated to reduce blood pressure (the Dietary Alternatives to Hypertension, ‘DASH’ diet), and an alternate healthy eating index reflecting adherence to USDA recommendations and dietary guidelines for Americans prevaling during the 1991–2001 follow-up period and also incorporating information for foods and nutrients associated with reduced chronic disease risk.
This article is of interest because it evaluates the relationship between adherence to a Mediterranean diet and premature death in a middle-aged, highly educated homogeneous Spanish population at low risk of mortality. Of further interest, this article provides comparative mortality risk estimates for individual components of the Mediterranean diet.
This article from the Greek cohort of the European Prospective Investigation into Cancer and Nutrition provides comparative risk estimates for CHD incidence and CHD mortality according to low, moderate, and high adherence to a Mediterranean diet for men and women separately and combined. Of particular interest are risk estimates for CHD incidence and CHD mortality separately for men and women according to one SD increments in individual components of the typical Mediterranean diet score and also other foods/nutrients not included in the typical scoring of a Mediterranean diet including potatoes, eggs, sugar and sweets, nonalcoholic beverages, saturated fat, monounsaturated fat, polyunsaturated fat, and olive oil.
This article from the Vasterbotten Intervention Program (VIP), a population-based cohort in north Sweden is of interest because it provides comparative risk estimates for total and site-specific cancer mortality and total CVD mortality, and that due to myocardial infarction and stroke separately for men and women. Also of interest are mortality risk estimates for the combined effect of the modified Mediterranean diet score and lifestyle factors separately in men and women. Of further interest are the comparative data for risk estimates for individual components of the modified Mediterranean diet score.
This article is of interest because of the large sample size and long follow-up time provided by the combined included populations (Nurses’ Health Study, 26 years, and Health Professionals Follow-Up Study, 22 years) and the data presented. Data include comparative risk estimates for men and women separately for total stroke incidence for multiple protein sources including total red meat, processed red meat, unprocessed red meat, poultry, fish, whole-fat dairy, low-fat dairy, eggs, nuts, and legumes. Other data of interest include comparative risk estimates (for men and women combined) for ischemic and hemorrhagic stroke for each of the protein sources, and for the effects of substituting one protein source for another.
This article from the EPIC will be of interest due to the large cohort (340 234 individuals) representing eight European countries in which incident type 2 diabetes was ascertained during 3.99 million person-years of follow-up. Also of interest are the comparative data for diabetes incidence according to total dairy products (butter excluded) and the following categories of dairy products: milk, yogurt and thick fermented milk, cheese, and combined fermented milk. Estimates are shown for each country individually and the total cohort.
This study is of interest because of the good representation of each of white, African–American, Hispanic, and Chinese individuals and the data presented. Data include risk estimates for CHD incidence for each 5 g per day and for each 5% of energy for total saturated fat as well as separate estimates for saturated fat from each of the following food sources: dairy, meat, butter, plants, and mixed sources. Also of interest are CHD risk estimates for replacement of 2% of energy from saturated fat from one source with 2% of energy from saturated fat from another food source.
This article concerning participants in the Nurses’ Health Study is of interest because of the large sample size (91 981), long follow-up (30 years) and nature of data presented. Comparative data are presented for risk of sudden cardiac death associdated with variation in dietary total fat, saturated fat, polyunsaturated fat, monounsaturated fat, and trans fat. Of particular interest are separate data for total n-6 polyunsaturated fat, linoleic acid, arachidonic acid, total n-3 polyunsaturated fat, α-linolenic acid, and marine fatty acids (eicosapentaenoic and docosahexaenoic acid). For each type of fat/fatty acid, multivariable risk estimates are presented both with and without adjustment for development of cardiovascular risk factors and clinical cardiovascular events.
This study is of interest due to the large (452 717) and diverse population including men and women from 23 centers in 10 European countries who were followed for mean 12.7 years. Of interest are the comparative data for risk of death according to quintile of dietary fiber and per 10 g increase, not only for men and women separately, but also for multiple relevant subgroups defined smoking status and levels of alcohol consumption, BMI, and physical activity.
This article is a meta-analysis that combined data for prospective cohort studies that reported associations between whole-grain intake and risk of type 2 diabetes, total dietary and cereal fiber intake and risk of type 2 diabetes, whole-grain intake and various cardiovascular disease outcomes, total dietary and cereal fiber intake and risk of various cardiovascular outcomes. Also included are the more limited information for randomized controlled trials that intervened with whole-grains to alter metabolic risk factors.
This article will be of interest to readers for the comparative information for greenhouse gas emissions for foods supplied to and produced within the United Kingdom. Included are information for categories of whole fruits, vegetables, legumes, nuts, seeds, grain products, dairy, eggs, poultry, meats, and some types of snacks and prepared food. Also of interest are the description of and results for the application of linear programming to minimize greenhouse gas emissions while ensuring a nutritionally adequate diet.
This article is of interest because of the long (24-year) follow-up in young participants that included median of five repeated assessments of dietary intake between the ages of 13 and 36 years. Also of interest are the comparative data for total dietary fiber, cereal fiber, fruit fiber, and vegetable fiber.
This article is of interest for the comparative information for incident type 2 diabetes according level of obesity, duration of obesity, and obesity-years, a measure analygous to pack-years of smoking, all evaluated in the original cohort of the Framingham Heart Study, for which follow-up was approximately 48 years. Also of interest are the comparative data for men and women and for smokers and nonsmokers.
FURTHER RECOMMENDED READING
▪. Chiuve SE, Fung TT, Rimm EB, et al. Alternate dietary indices both strongly predict risk of chronic disease. J Nutr 2012; 142:1009–1018.
This article will be of interest for the comparative information for risk of chronic disease within the Nurses Health Study and Health Professionals Follow-Up Study cohorts according the dietary quality as indicated by two measures: The Healthy Eating Index-2005 (HEI-2005), reflecting adherence to the 2005 Dietary Guideliness for Americans, and an Alternate Healthy Eating Index (AHEI-2010), an index based on foods and nutrients that predicted chronic disease risk. Separate analyses are presented for cardiovascular disease, coronary heart disease, stroke, diabetes and for the total of these chronic diseases. Of particular interest are results analyses that evaluated the prediction of chronic disease by the AHEI-2010 independent of the HEI-2005.
▪. Odegaard AO, Koh WP, Yuan J-M, et al. Western-style fast food intake and cardiometabolic risk in an eastern country. Circulation 2012; 126:182–188. PubMed | CrossRef
This article from the Singapore Chinese Health Study is of interest for the comparative data for incidence of type 2 diabetes and coronary heart disease mortality according to increasing frequency of consumption of western-style fast foods (hamburgers/cheeseburgers, French fries, pizza, other sandwiches, deep-fried chicken, and hot dogs).
▪. Varraso R, Garcia-Aymerich J, Monier F, et al. Assessment of dietary patterns in nutritional epidemiology: principal component analysis compared with confirmatory factor analysis. Am J Clin Nutr 2012; 96:1079–1092. PubMed | CrossRef
This article is of interest for the data for dietary patterns determined by principal component analysis as compared with confirmatory factor analysis as well as information for relevance and stability (as assessed by bootstrap) within small samples ranging from n = 274 to n = 1236.
▪. Spring B, Schneider K, Mcfadden G, et al. Multiple behavior changes in diet and activity. A randomized controlled trial using mobile technology. Arch Intern Med 2012; 172:789–796. View Full Text | PubMed | CrossRef
This article is of interest for the comparative data for short-term behavior change that can be achieved with the combination of mobile technology, targeted coaching, and financial incentives. Also of interest are the differing effects of encouraging physical activity versus discouraging sedentary leisure time.
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