***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 Lowering the price of fruit and vegetables is a promising strategy in stimulating the purchase of those foods . However , the true effects of this strategy are not well studied and it is unclear how the money saved is spent . The aim of this study is to examine the effects of a 25 % discount on fruits and vegetables on food purchases in a supermarket environment . Methods A r and omized controlled trial with two research conditions was conducted : a control condition with regular prices  ( n = 52 ) and an experimental condition with a 25 % discount on fruits and vegetables  ( n = 63 ) . The experiment was carried out using a three-dimensional web-based supermarket , which is a software application in the image of a real supermarket . Data were collected in 2010 in the Netherl and s. Participants received a fixed budget and were asked to buy weekly household groceries at the web-based supermarket . Differences in fruit and vegetable purchases , differences in expenditures in other food categories and differences in total calories were analyzed using independent sample s t-tests and multiple linear regression models accounting for potential effect modifiers and confounders . Results The purchased amount of fruit plus vegetables was significantly higher in the experimental condition compared to the control condition ( Δ984 g per household per week , p = .03 ) after appropriate adjustments . This corresponds to a 25 % difference compared to the control group . Both groups had similar expenditures in unhealthier food categories , including desserts , soda , crisps , c and y and chocolate . Furthermore , both groups purchased an equal number of food items and an equal amount of calories , indicating that participants in the discount condition did not spend the money they saved from the discounts on other foods than fruits and vegetables . Conclusion A 25 % discount on fruits and vegetables was effective in stimulating purchases of those products and did neither lead to higher expenditures in unhealthier food categories nor to higher total calories purchased . Future studies in real supermarkets need to confirm these findings The role of dietary fat in the regulation of energy intake was assessed by manipulating a conventional diet and measuring spontaneous food consumption .  Twenty-four women each consumed a sequence of three 2-wk dietary treatments in which 15 - 20 % , 30 - 35 % , or 45 - 50 % of the energy was derived from fat . These diets consisted of foods that were similar in appearance and palatability but differed in the amount of high-fat ingredients used . Relative to their energy consumption on the medium-fat diet , the subjects spontaneously consumed an 11.3 % deficit on the low-fat diet and a 15.4 % surfeit on the high-fat diet ( p less than 0.0001 ) , result ing in significant changes in body weight ( p less than 0.001 ) . A small amount of caloric compensation did occur ( p less than 0.02 ) , which was greatest in the leanest subjects ( p less than 0.03 ) . These results suggest that habitual , unrestricted consumption of low-fat diets may be an effective approach to weight control The purpose of this study was to evaluate the impact of adopting a Mediterranean diet on dietary cost and energy density in free-living conditions . The 12-wk nutritional intervention consisted of 2 group courses and 7 individual sessions with a dietician in a sample of 73 healthy women . To evaluate the dietary response to the nutritional intervention , a registered dietician administered a FFQ at 0 , 6 , 12 , and 24 wk . Total daily dietary cost was calculated using a price list including all items from the FFQ . Our findings indicated that daily energy cost evaluated at wk 12 vs. wk 0 [ 1046 + /- 217 vs. 967 + /- 192 kJ/Canadian dollars ( CAN$ ) , respectively , P = 0.18 ] and total daily dietary cost ( 8.61 + /- 2.13 vs. 8.75 + /- 2.50 CAN$/d per participant , respectively , P = 0.58 ) did not change . Total daily energy density at wk 12 decreased compared with wk 0 ( 2.56 + /- 0.76 vs. 2.20 + /- 0.67 kJ/g ; P < 0.0001 ) . Adherence to the Mediterranean diet led to increased cost related to vegetables , fruits , legumes , nuts and seeds , canola/olive oil , whole grains , poultry , and fish ( P < or = 0.01 ) and to reduced dietary cost for red meat , refined grains , desserts and sweets , and fast food ( P < or = 0.008 ) . In conclusion , these data suggest that adherence to a nutritional intervention program promoting the Mediterranean food pattern is not associated with increased daily dietary cost or energy cost but led to a reduction in energy density . Consequently , increased cost should not be considered a barrier to the promotion and adoption of a Mediterranean diet PURPOSE Degrees of nutrient intake and food groups have been linked to differential chronic disease risk . However , intakes of specific nutrients may also be associated with differential diet costs and unobserved differences in socioeconomic status ( SES ) . The present study examined degrees of nutrient intake , for every key nutrient in the diet , in relation to diet cost and SES . METHODS Socio-demographic data for a stratified r and om sample of adult respondents in the Seattle Obesity Study were obtained through telephone survey . Dietary intakes  were assessed using  food frequency question naire ( FFQ )  ( n = 1,266 ) . Following st and ard procedures , nutrient intakes were energy-adjusted using the residual method and converted into quintiles . Diet cost for each respondent was estimated using Seattle supermarket retail prices for 384 FFQ component foods . RESULTS Higher intakes of dietary fiber , vitamins A , C , D , E , and B12 , beta carotene , folate , iron , calcium , potassium , and magnesium were associated with higher diet costs . The cost gradient was most pronounced for vitamin C , beta carotene , potassium , and magnesium . Higher intakes of saturated fats , trans fats and added sugars were associated with lower diet costs . Lower cost lower quality diets were more likely to be consumed by lower SES . CONCLUSION Nutrients commonly associated with a lower risk of chronic disease were associated with higher diet costs . By contrast , nutrients associated with higher disease risk were associated with lower diet costs . The cost variable may help somewhat explain why lower income groups fail to comply with dietary guidelines and have highest rates of diet related chronic disease BACKGROUND The inverse relation between energy density ( kcal/g ) and energy cost ( price/kcal ) has been interpreted to suggest that produce ( fruit , vegetables ) is more expensive than snacks ( cookies , chips ) . OBJECTIVE The objective of this study was to show the method ologic weakness of comparing energy density with energy cost . DESIGN The relation between energy density and energy cost was replicated in a r and om-number data set . Additionally , observational data were collected for produce and snacks from an online supermarket . Variables included total energy  ( kcal ) , total weight ( g ) , total number of servings , serving size ( g/serving ) , and  energy density  ( kcal/g ) . Price measures included energy cost ( $ /kcal ) , total price ( $ ) , unit price ( $ /g ) , and serving price ( $ /serving ) . Two-tailed t tests were used to compare price measures by food category . Relations between energy density and price measures within food categories were examined with the use of Spearman rank correlation analysis . RESULTS The relation between energy density and energy cost was shown to be driven by the algebraic properties of these variables . Food category was strongly correlated with both energy density and food price measures . Energy cost was higher for produce than for snacks . However , total price and unit price were lower for produce . Serving price and serving size were greater for produce than for snacks . Within food categories , energy density was uncorrelated with most measures of food price , except for a weak positive correlation with serving price within the produce category . CONCLUSION The findings suggest the relation between energy density and food price is confounded by food category and depends on which measure of price is used OBJECTIVE To examine the effectiveness of two methods of increasing fruit and fruit juice intake in pregnancy :  midwives ' advice and vouchers exchangeable for juice . DESIGN Pregnant women were r and omly allocated to three groups : a control group , who received usual care ; an advice group , given advice and leaflets promoting fruit and fruit juice consumption ; and a voucher group , given vouchers exchangeable for fruit juice from a milk delivery firm . Dietary question naires were administered at ~16 , 20 and 32 weeks of pregnancy . Serum beta-carotene was measured at 16 and 32 weeks . SETTING An antenatal clinic in a deprived area . SUBJECTS Pregnant women aged 17 years and over . RESULTS The study comprised 190 women .  Frequency of fruit consumption declined during pregnancy in all groups , but that of fruit juice increased substantially in the voucher group . Serum beta-carotene concentration increased in the voucher group , from 106.2 to 141.8 micromol l(-1 ) in women with measurements on both occasions ( P = 0.003 ) , decreased from 120.0 to 99.8 micromol l(-1 ) in the control group ( P = 0.005 ) , and was unchanged in the advice group . CONCLUSIONS Pregnant women drink more fruit juice if they receive vouchers exchangeable for juice supplied by the milk delivery service . Midwives ' advice to eat more fruit has no great effect . Providing vouchers for fruit juice is a simple method of increasing its intake in a deprived population and may be useful for other sections of the community Here , we describe the measurement characteristics of a 13-item dietary screener used in the Prostate Cancer Prevention Trial . We used data from 10,913 men who completed the 13-item dietary screener , a food frequency question naire ( FFQ ) , and question naires on demographic and health-related characteristics and from 146 men who also completed multiple 24-h dietary recalls in a sub study . The analyses in this report focused on percentage energy from fat and saturated fat and used the mean estimates from the dietary recalls as the criterion measures . Absolute nutrient estimates from the screener were about one-third of the estimates from the recalls and the FFQ . Validity was defined as the Pearson correlation of the criterion measures of fat with the corresponding measures from the FFQ and the screener . The FFQ was a statistically significantly more precise measure of percentage energy from fat ( r = 0.71 ) and saturated fat ( r = 0.72 ) than was the screener ( r = 0.50 and 0.53 , respectively ) . There were also statistically significant differences in how well these instruments could detect variation in dietary fat across various participant characteristics , suggesting that the screener may not perform as well as the FFQ across demographic strata such as education ( P < 0.001 ) . The results from this study suggest that the use of short dietary screeners as the sole assessment instrument may result in a serious loss of information regarding important exposures ( e.g. , fat intake ) and lost opportunities to enhance our knowledge regarding dietary factors and cancer risk The Dietary Approaches to Stop Hypertension ( DASH ) diet is perhaps the best example of how a nutrient dense dietary pattern can prevent chronic disease . In r and omized trials , DASH dietary patterns lowered blood pressure  in hypertensive individuals.1 Subsequent trials and observational studies have consistently found that DASH-type diets reduced cardiovascular and metabolic BACKGROUND Reducing fruit and vegetable ( F&V ) prices is a frequently considered policy to improve dietary habits in the context of health promotion . However , evidence on the effectiveness of this intervention is limited . OBJECTIVE The objective was to examine the effects of a 50 % price discount on F&Vs or nutrition education or a combination of both on supermarket purchases . DESIGN A 6-mo r and omized controlled trial within Dutch supermarkets was conducted . Regular supermarket shoppers were r and omly assigned to 1 of 4 conditions : 50 % price discounts on F&Vs , nutrition education , 50 % price discounts plus nutrition education , or no intervention .  A total of 199 participants provided baseline data ; 151 ( 76 % ) were included in the final analysis .  F&V purchases were measured by using supermarket register receipts at baseline , at 1 mo after the start of the intervention , at 3 mo , at 6 mo ( end of the intervention period ) , and 3 mo after the intervention ended ( 9 mo ) . RESULTS Adjusted multilevel models showed significantly higher F&V purchases ( per household/2 wk ) as a result of the price discount ( + 3.9 kg ; 95 % CI : 1.5 , 6.3 kg ) and the discount plus education intervention ( + 5.6 kg ; 95 % CI : 3.2 , 7.9 kg ) at 6 mo compared with control . Moreover , the percentage of participants who consumed recommended amounts of F&Vs ( ≥400 g/d ) increased from 42.5 % at baseline to 61.3 % at 6 mo in both discount groups ( P = 0.03 ) . Education alone had no significant effect . CONCLUSIONS Discounting F&Vs is a promising intervention strategy because it result ed in substantially higher F&V purchases , and no adverse effects were observed . Therefore , pricing strategies form an important focus for future interventions or policy . However , the long-term effects and the ultimate health outcomes require further investigation . This trial was registered at the IS RCT N Trial Register as number IS RCT N56596945 
    Output:
    
Data Synthesis : Foods of lower nutritional value and lower- quality diets generally cost less per calorie and tended to be selected by groups of lower socioeconomic status .
A number of nutrient-dense foods were available at low cost but were not always palatable or culturally acceptable to the low-income consumer .
Acceptable healthier diets were uniformly associated with higher costs .
Food budgets in poverty were insufficient to ensure optimum diets .
Conclusions : Socioeconomic disparities in diet quality may be explained by the higher cost of healthy diets .