Conclusions In the context of low SFAs , high-MUFA diets in isocaloric substitution for high-CHO diets did not affect blood pressure in individuals with and without hypertension .
Context Current dietary guidelines for cardiovascular disease risk management recommend restricting intake of saturated fatty acids ( SFAs ) .
However , the optimal macronutrient profile , in the context of a low-SFA diet , remains controversial .
The blood-pressure effect of replacing SFAs in diets with monounsaturated fatty acids ( MUFAs ) compared with carbohydrate has not been quantified to date .
Effects of a Mediterranean-Style Diet on Cardiovascular Risk Factors
Context Some experts attribute a low incidence of heart disease in Mediterranean countries to dietary habits . Contribution In this multicenter , 3-group trial , investigators r and omly assigned 772 adults at high risk for cardiovascular disease to a low-fat diet or to a Mediterranean diet supplemented with either virgin olive oil ( 1 L per week ) or nuts ( 30 g per day ) . After 3 months , the Mediterranean diet groups had lower mean plasma glucose level , systolic blood pressure , and total cholesterolhigh-density lipoprotein cholesterol ratio than the low-fat diet group . Caution s The Mediterranean diet groups received more nutritional education than the low-fat diet group . Implication s Mediterranean diets supplemented with olive oil or nuts may improve cardiovascular risk factors . The Editors Cardiovascular disease is the main cause of death in industrialized countries , but incidence rates have marked geographic differences . The low incidence of coronary heart disease ( CHD ) in Mediterranean countries has been partly ascribed to dietary habits ( 1 - 3 ) . Recent findings from large European cohort studies ( 4 - 6 ) suggest that a high degree of adherence to the Mediterranean diet is associated with a reduction in mortality . In small clinical studies , the Mediterranean diet or some of its components have reduced blood pressure ( 7 ) and have improved lipid profiles ( 8 , 9 ) and endothelial function ( 10 ) . Moreover , a recent cross-sectional study ( 11 ) and a 2-year feeding trial ( 12 ) have shown that adherence to the Mediterranean diet is associated with reduced markers of vascular inflammation . These beneficial effects on surrogate markers of cardiovascular risk add biological plausibility to the epidemiologic evidence that supports a protective effect of the Mediterranean diet . Olive oil , a rich source of monounsaturated fatty acids , is a main component of the Mediterranean diet . Virgin olive oil retains all the lipophilic components of the fruit , -tocopherol , and phenolic compounds with strong antioxidant and anti-inflammatory properties ( 13 , 14 ) . Tree nuts , which are also typical in the Mediterranean diet , have a favorable fatty acid profile and are a rich source of nutrients and other bioactive compounds that may beneficially influence the risk for CHD , such as fiber , phytosterols , folic acid , and antioxidants ( 15 ) . Frequent nut intake has been associated with decreased CHD rates in prospect i ve studies ( 15 ) . Walnuts differ from all other nuts through their high content of polyunsaturated fatty acids , particularly -linolenic acid , a plant n-3 fatty acid ( 16 ) , which may confer additional antiatherogenic properties ( 17 ) . Therefore , we design ed a large-scale feeding trial in high-risk participants to assess the effects of 2 Mediterranean diets , one supplemented with virgin olive oil and the other supplemented with mixed nuts , compared with a low-fat diet on cardiovascular outcomes . We report the results of a 3-month intervention on intermediate markers of cardiovascular risk in the first 772 participants who were recruited into the trial . Supplement . Original Version ( PDF ) Methods Study Design The Prevencin con Dieta Mediterrnea ( PREDIMED ) Study is a large , parallel-group , multicenter , r and omized , controlled , 4-year clinical trial that aims to assess the effects of the Mediterranean diet on the primary prevention of cardiovascular disease ( www.predimed.org ) . An estimated 9000 high-risk participants ( > 5000 participants are already recruited ) will be assigned to 3 interventions : Mediterranean diet with virgin olive oil , Mediterranean diet with mixed nuts , or low-fat diet . The main outcome is an aggregate of cardiovascular events ( cardiovascular death , nonfatal myocardial infa rct ion , or nonfatal stroke ) . The anticipated completion date of the trial is December 2010 . We design ed our present study to assess the 3-month effects of the dietary interventions on surrogate markers of cardiovascular risk in participants entering the study during the first 6 months of recruitment . The institutional review boards of the 10 participating centers approved the study protocol . Participants and Recruitment From October 2003 to March 2004 , we selected 930 potential participants in primary care centers affiliated with 10 teaching hospitals across Spain . Eligible participants were community-dwelling men , 55 to 80 years of age , and women , 60 to 80 years of age , who fulfilled at least 1 of 2 criteria : type 2 diabetes or 3 or more CHD risk factors ( current smoking , hypertension [ blood pressure > 140/90 mm Hg or treatment with antihypertensive drugs ] , low-density lipoprotein [ LDL ] cholesterol level 4.14 mmol/L [ 160 mg/dL ] [ or treatment with hypolipidemic drugs ] , high-density lipoprotein [ HDL ] cholesterol level 1.04 mmol/L [ 40 mg/dL ] , body mass index [ BMI ] 25 kg/m2 , or a family history of premature CHD ) . Exclusion criteria were history of cardiovascular disease , any severe chronic illness , drug or alcohol addiction , history of allergy or intolerance to olive oil or nuts , or low predicted likelihood of changing dietary habits according to the stages-of-change model ( 18 ) . The primary care physicians based participants ' eligibility on review of clinical records and a screening visit . They obtained a list of c and i date s from computer-based records of patients who attended each participating center and review ed their clinical records to exclude those who did not meet eligibility criteria . They then invited suitable c and i date s by telephone to attend a screening visit . The visit included an interview with administration of a 26-item question naire to inquire about medical conditions and risk factors related to eligibility . Of the eligible c and i date s who met entry requirements , 95 % agreed to participate and provided informed consent . R and omization and Intervention After the screening visit , each center r and omly assigned eligible participants to 1 of 3 diet groups by using a computer-generated r and om-number sequence . The coordinating center constructed the r and omization table , and participants were r and omly assigned into blocks of 50 participants balanced by center , sex , and age group ( < 70 years and 70 years ) . We concealed allocation into the intervention groups by using closed envelopes with correlative numbers by prespecified subgroups of sex and age . The baseline examination included the administration of a 14-item question naire , an extension of a previously vali date d question naire ( 19 ) , that assessed the degree of adherence to the traditional Mediterranean diet . We assigned values of 0 or 1 to each item ( Appendix Table 1 ) . We also administered a 137-item vali date d food frequency question naire ( 20 ) ; the vali date d Spanish version ( 21 ) of the Minnesota Leisure Time Physical Activity Question naire ; and a 47-item question naire about education , lifestyle , history of illnesses , and medication use . We performed anthropometric and blood pressure measurements and obtained sample s of fasting blood and spot urine . We repeated all examinations at 3 months . The same dietitian delivered the interventions to the 3 r and omized groups in each center . On the basis of the assessment of individual Mediterranean diet scores , the dietitian gave personalized dietary advice during a 30-minute session to each participant , with recommendations on the desired frequency of intake of specific foods . We advised participants who were allocated to the low-fat diet to reduce intake of all types of fat , and we gave them a leaflet with written recommendations according to the American Heart Association guidelines ( 22 ) . For total fat intake , these recommendations were opposite to those given to participants in the 2 Mediterranean diet groups , who received instructions intended to increase the 14-item Mediterranean diet score , including increased consumption of vegetable fats and oils . We did not suggest any energy restriction . While the participants who were allocated to the low-fat diet did not receive further intervention , those assigned the 2 Mediterranean diet groups had access to more intense intervention in 2 ways . First , they were given a free provision of typical Mediterranean fatty foods ( olive oil or nuts ) . Depending on group assignment , participants were given either free virgin olive oil ( 15 L [ 1 L/wk ] for 3 months ) or free sachets of walnuts , hazelnuts , and almonds ( 1350 g of walnuts [ 15 g/d ] , 675 g of hazelnuts [ 7.5 g/d ] , and 675 g of almonds [ 7.5 g/d ] for 3 months ) . To improve adherence and account for family needs , participants in the corresponding Mediterranean diet groups were given excess olive oil or additional 1000-g packets of nuts . We analyzed the nutrient composition of the olive oil and nuts used in the study by st and ard methods in a reference laboratory ( Appendix Table 2 ) ) . Second , 1 week after inclusion , the dietitian delivered a 1-hour group session with up to 20 participants , with separate sessions for each Mediterranean diet group . Each group session consisted of informative talks and provision of written material s with elaborate descriptions of typical Mediterranean foods and seasonal shopping lists , meal plans , and cooking recipes . Throughout the study , all participants had free and continuous access to their center dietitian for advice and consultation . Measurements Trained personnel measured weight and height by using calibrated scales and a wall-mounted stadiometer , respectively ; waist circumference midway between the lowest rib and the iliac crest by using an anthropometric tape ; and blood pressure in triplicate with a vali date d semiautomatic oscillometer ( Omron HEM-705CP , Hoofddorp , the Netherl and s ) . We calculated energy and nutrient intake from Spanish food composition tables ( 23 ) . At the 3-month visit and when consulted by participants , dietitians assessed any adverse effects from the interventions by administering a checklist of symptoms and gave advice on how to remedy them . The checklist included mouth symptoms ; bloating , fullness , or indigestion ; altered bowel
Conclusions In the context of low SFAs , high-MUFA diets in isocaloric substitution for high-CHO diets did not affect blood pressure in individuals with and without hypertension .
Context Current dietary guidelines for cardiovascular disease risk management recommend restricting intake of saturated fatty acids ( SFAs ) .
However , the optimal macronutrient profile , in the context of a low-SFA diet , remains controversial .
The blood-pressure effect of replacing SFAs in diets with monounsaturated fatty acids ( MUFAs ) compared with carbohydrate has not been quantified to date .