***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND The effects of a carbohydrate-restricted diet on weight loss and risk factors for atherosclerosis have been incompletely assessed . METHODS We r and omly assigned 132 severely obese subjects ( including 77 blacks and 23 women ) with a mean body-mass index of 43 and a high prevalence of diabetes ( 39 percent ) or the metabolic syndrome ( 43 percent ) to a carbohydrate-restricted ( low-carbohydrate ) diet or  a calorie- and fat-restricted ( low-fat ) diet . RESULTS Seventy-nine subjects completed the six-month study . An analysis including all subjects , with the last observation carried forward for those who dropped out , showed that subjects on the low-carbohydrate diet lost more weight than those on the low-fat diet ( mean [ + /-SD ] , -5.8+/-8.6 kg vs. -1.9+/-4.2 kg ; P=0.002 ) and had greater decreases in triglyceride levels ( mean , -20+/-43 percent vs. -4+/-31 percent ; P=0.001 ) , irrespective of the use or nonuse of hypoglycemic or lipid-lowering medications . Insulin sensitivity , measured only in subjects without diabetes , also improved more among subjects on the low-carbohydrate diet ( 6+/-9 percent vs. -3+/-8 percent , P=0.01 ) . The amount of weight lost ( P<0.001 ) and assignment to the low-carbohydrate diet ( P=0.01 ) were independent predictors of improvement in triglyceride levels and insulin sensitivity . CONCLUSIONS Severely obese subjects with a high prevalence of diabetes or the metabolic syndrome lost more weight during six months on a carbohydrate-restricted diet than on a calorie- and fat-restricted diet , with a relative improvement in insulin sensitivity and triglyceride levels , even after adjustment for the amount of weight lost . This finding should be interpreted with caution , given the small magnitude of overall and between-group differences in weight loss in these markedly obese subjects and the short duration of the study . Future studies evaluating long-term cardiovascular outcomes are needed before a carbohydrate-restricted diet can be endorsed BACKGROUND Adherence to a Mediterranean diet may improve longevity , but relevant data are limited . METHODS We conducted a population -based , prospect i ve investigation involving 22,043 adults in Greece who completed an extensive , vali date d , food-frequency question naire at base line .  Adherence to the traditional Mediterranean diet was assessed by a 10-point Mediterranean-diet scale that incorporated the salient characteristics of this diet ( range of scores , 0 to 9 , with higher scores indicating greater adherence ) . We used proportional-hazards regression to assess the relation between adherence to the Mediterranean diet and total mortality , as well as mortality due to coronary heart disease and mortality due to cancer , with adjustment for age , sex , body-mass index , physical-activity level , and other potential confounders . RESULTS During a median of 44 months of follow-up , there were 275 deaths . A higher degree of adherence to the Mediterranean diet was associated with a reduction in total mortality ( adjusted hazard ratio for death associated with a two-point increment in the Mediterranean-diet score , 0.75 [ 95 percent confidence interval , 0.64 to 0.87 ] ) . An inverse association with greater adherence to this diet was evident for both death due to coronary heart disease ( adjusted hazard ratio , 0.67 [ 95 percent confidence interval , 0.47 to 0.94 ] ) and death due to cancer ( adjusted hazard ratio , 0.76 [ 95 percent confidence interval , 0.59 to 0.98 ] ) . Associations between individual food groups contributing to the Mediterranean-diet score and total mortality were generally not significant . CONCLUSIONS Greater adherence to the traditional Mediterranean diet is associated with a significant reduction in total mortality BACKGROUND There is conflicting evidence on the benefits of foods rich in vitamin E ( alpha-tocopherol ) , n-3 polyunsaturated fatty acids ( PUFA ) , and their pharmacological substitutes . We investigated the effects of these substances as supplements in patients who had myocardial infa rct ion . METHODS From October , 1993 , to September , 1995 , 11,324 patients surviving recent ( < or = 3 months ) myocardial infa rct ion were r and omly assigned supplements of n-3 PUFA ( 1 g daily , n=2836 ) , vitamin E ( 300 mg daily , n=2830 ) , both ( n=2830 ) , or none ( control , n=2828 ) for 3.5 years . The primary combined efficacy endpoint was death , non-fatal myocardial infa rct ion , and stroke . Intention-to-treat analyses were done according to a factorial design ( two-way ) and by treatment group ( four-way ) . FINDINGS Treatment with n-3 PUFA , but not vitamin E , significantly lowered the risk of the primary endpoint ( relative-risk decrease 10 % [ 95 % CI 1 - 18 ] by two-way analysis , 15 % [ 2 - 26 ] by four-way analysis ) . Benefit was attributable to a decrease in the risk of death ( 14 % [ 3 - 24 ] two-way , 20 % [ 6 - 33 ] four-way ) and cardiovascular death ( 17 % [ 3 - 29 ] two-way , 30 % [ 13 - 44 ] four-way ) . The effect of the combined treatment was similar to that for n-3 PUFA for the primary endpoint ( 14 % [ 1 - 26 ] ) and for fatal events ( 20 % [ 5 - 33 ] ) . INTERPRETATION Dietary supplementation with n-3 PUFA led to a clinical ly important and statistically significant benefit . Vitamin E had no benefit . Its effects on fatal cardiovascular events require further exploration The effects of variations in dietary carbohydrate and fat on various aspects of carbohydrate and lipoprotein metabolism were evaluated in 10 healthy , postmenopausal women . The two diets were isoenergetic , assigned in r and om fashion , and consisted ( as a % of total energy ) of 15 % protein , 60 % carbohydrate , and 25 % fat ( 60%-carbohydrate diet ) or 15 % protein , 40 % carbohydrate , and 45 % fat ( 40%-carbohydrate diet ) .  Fasting plasma triacylglycerol , very-low-density-lipoprotein ( VLDL ) triacylglycerol , and VLDL-cholesterol concentrations were higher ( P < 0.05 - 0.001 ) after the 60%-carbohydrate diet , whereas high-density-lipoprotein ( HDL ) cholesterol was lower ( P < 0.05 ) . Plasma insulin and triacylglycerol concentrations were also higher ( P < 0.001 ) from 0800 to 0000 with the 60%-carbohydrate diet than with the 40%-carbohydrate diet . In addition , when vitamin A was given with the noon meal , the ensuing concentrations of retinyl palmitate were also higher after ingestion of the 60%-carbohydrate diet .  Resistance to insulin-mediated glucose disposal , quantified at baseline by determining the steady state plasma glucose ( SSPG ) concentration at the end of a 180-min infusion of somatostatin , insulin , and glucose , correlated with the incremental increases in postpr and ial concentrations of plasma glucose ( r = 0.68 , P = 0.06 ) , insulin ( r = 0.82 , P < 0.02 ) , triacylglycerol ( r = 0.77 , P < 0.05 ) , and retinyl palmitate ( r = 0.68 , P = 0.06 ) and with the Sf > 400 triacylglycerol ( r = 0.77 , P < 0.05 ) , Sf 20 - 400 triacylglycerol ( r = 0.72 , P < 0.05 ) , and Sf > 400 retinyl palmitate ( r = 0.75 , P < 0.01 ) lipoprotein fractions . Because all of these changes would increase risk of ischemic heart disease in postmenopausal women , it seems reasonable to question the wisdom of recommending that postmenopausal women consume low-fat , high-carbohydrate diets BACKGROUND Metabolic studies suggest that saturated fatty acids differ in their effects on blood lipids . OBJECTIVE The objective was to examine the associations between intakes of individual saturated fatty acids and their food sources in relation to the risk of coronary heart disease ( CHD ) .  DESIGN This was a prospect i ve cohort study of 80082 women in the Nurses ' Health Study aged 34 - 59 y. Subjects had no known cardiovascular disease , cancer , hypercholesterolemia , or diabetes , and completed vali date d food-frequency question naires in 1980 . RESULTS During 14 y of follow-up , we documented 939 incident cases of major CHD events . In multivariate analyses in which age , smoking , and other covariates were controlled for , intakes of short- to medium-chain saturated fatty acids ( 4:0 - 10:0 ) were not significantly associated with the risk of CHD . In contrast , intakes of longer-chain saturated fatty acids ( 12:0 - 18:0 ) were each separately associated with a small increase in risk . The multivariate RR for a 1 % energy increase from stearic acid was 1.19 ( 95 % CI : 1.02 , 1.37 ) . The ratio of polyunsaturated to saturated fat was strongly and inversely associated with CHD risk ( multivariate RR for a comparison of the highest with the lowest deciles : 0.58 ; 95 % CI : 0.41 , 0.83 ; P for trend < 0.0001 ) . Conversely , higher ratios of red meat to poultry and fish consumption and of high-fat to low-fat dairy consumption were associated with significantly greater risk . CONCLUSION A distinction between stearic acid and other saturated fats does not appear to be important in dietary advice to reduce CHD risk , in part because of the high correlation between stearic acid and other saturated fatty acids in typical diets BACKGROUND Data on the relation between alpha-linolenic acid intake and coronary artery disease ( CAD ) are limited . Other dietary components appear to modify the reported relation between alpha-linolenic acid intake and CAD . OBJECTIVE We examined whether dietary alpha-linolenic acid intake was inversely associated with risk of CAD . DESIGN We prospect ively studied 667 men aged 64 - 84 y from the Zutphen Elderly Study who were free of CAD at baseline .  Dietary intake was assessed by using a cross-check dietary history method . RESULTS During the 10-y follow-up , we documented 98 cases of CAD . After adjustment for age , st and ard coronary risk factors , and intake of trans fatty acids and other nutrients , alpha-linolenic acid intake was not significantly associated with CAD risk . The relative risk of CAD for the highest compared with the lowest tertile of alpha-linolenic acid intake was 1.68 ( 95 % CI : 0.86 , 3.29 ) . alpha-Linolenic acid intake from sources containing trans fatty acids was also nonsignificantly , yet positively , associated with CAD risk .  alpha-Linolenic acid intake from foods that did not contain trans fatty acids was not associated with CAD risk , the relative risk of CAD for the highest compared with the lowest tertile was 1.15 ( 95 % CI : 0.63 , 2.11 ) . CONCLUSION We did not observe a beneficial effect of dietary alpha-linolenic acid intake on the risk of 10-y CAD incidence . Investigating this hypothesis was complicated by the association between intakes of alpha-linolenic acid and trans fatty acids . Given the results of current prospect i ve studies , a protective cardiac effect of alpha-linolenic acid is question able BACKGROUND Previous studies on diet and coronary heart disease ( CHD ) focused primarily on individual nutrients or foods . OBJECTIVE We examined whether overall dietary patterns derived from a food-frequency question naire ( FFQ ) predict  risk of CHD in men . DESIGN This was a prospect i ve cohort study of 44875 men aged 40 - 75 y without diagnosed cardiovascular disease or cancer at baseline in 1986 . RESULTS During 8 y of follow-up , we documented 1089 cases of CHD ( nonfatal myocardial infa rct ion and fatal CHD ) . Using factor analysis , we identified 2 major dietary patterns using dietary data collected through a 131-item FFQ . The first factor , which we labeled the " prudent pattern , " was characterized by higher intake of vegetables , fruit , leg 
    Output:
    
RESULTS Strong evidence supports valid associations ( 4 criteria satisfied ) of protective factors , including intake of vegetables , nuts , and " Mediterranean " and high- quality dietary patterns with CHD , and associations of harmful factors , including intake of trans-fatty acids and foods with a high glycemic index or load .
Among studies of higher method ologic quality , there was also strong evidence for monounsaturated fatty acids and " prudent " and " western " dietary patterns .
Insufficient evidence ( < or = 2 criteria ) of association is present for intake of supplementary vitamin E and ascorbic acid ( vitamin C ) ; saturated and polyunsaturated fatty acids ; total fat ; alpha-linolenic acid ; meat ; eggs ; and milk .
Among the dietary exposures with strong evidence of causation from cohort studies , only a Mediterranean dietary pattern is related to CHD in r and omized trials .
The evidence supports a valid association of a limited number of dietary factors and dietary patterns with CHD .