***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 : Cardiovascular risk largely depends on diet , antioxidant status , and gene polymorphisms . Low-fat meat ( CM ) and walnut-enriched meat ( WM ) products may exert potential beneficial health effects with respect to conventional meat products . Objective : To compare the effects of consuming WM vs CM on reduced and oxidized glutathione , lipoperoxides , α- and γ-tocopherol levels , and paraoxonase ( PON-1 ) , catalase ( CAT ) , and superoxide dismutase ( SOD ) activities in 22 volunteers ( mean age 54.8 years and body mass index 29.6 kg/m2 ) at high cardiovascular risk carrying different PON-1 192/55 polymorphisms . Design : The study was a 5-week nonblinded , r and omized , crossover , controlled trial . Results : In general term , WM vs CM improved the volunteers ' antioxidant status , with several result modifications occurring after the WM period .  CM consumption increased oxidized glutathione and decreased PON-1 activity ( at least p < 0.05 ) . When WM vs CM effects were compared , SOD , CAT , and PON-1 enzyme activities increased ( at least p < 0.05 ) in PON-1 192QQ carriers . γ-tocopherol levels and SOD and PON-1 activities increased in PON-1 192QR+RR carriers besides the significant decrease of lipoperoxide levels . In PON-1 55LM+MM carriers , the intervention increased significantly all the investigated enzyme activities and glutathione levels , whereas PON-1 55LL carriers increased their PON-1 activities . Conclusions : WM consumption should be preferred to CM . The intake of WM vs CM increased PON-1 but the effect upon other antioxidant enzymes and substrates varied depending on the individual 's PON-1 polymorphism . PON-1 192QR+RR carriers appear the targets for WM consumption as they increased enzyme activities and γ-tocopherol levels and decreased lipoperoxides BACKGROUND This study was conducted to determine the effect of fish oil ( FO ) supplements on high density lipoprotein cholesterol ( HDL-C ) , apolipoprotein-AI ( Apo-AI ) , malondialdehyde ( MDA ) , arylesterase ( Aryl ) , and paraoxonase-1 ( PON1 ) activity in female patients with rheumatoid arthritis ( RA ) . METHODS A total of 90 RA patients were r and omly allocated into two groups that were treated with one FO pearl ( 1 gr ) daily or placebo for three months in addition to conventional treatment .  HDL-C , Apo-AI , and MDA levels as well as PON1 and Aryl activities were measured before and after treatment . Independent t-test was used to match basal parameters of case and control groups . Paired t-test was used to assess significance of the differences . Correlation was evaluated by Pearsons test and the statistical significance was set at P < 0.05 . RESULTS No significant differences were noted between FO and placebo patients with regards to age , disease duration , post-menopausal status , conventional therapy , body mass index ( BMI ) , and numbers of swollen and tender joints at the beginning of the study . There were 83 patients who completed the three-month follow up . Serum levels of HDL-C ( P = 0.018 ) , Apo-AI ( P = 0.165 ) , Aryl ( P = 0.026 ) , and PON1 ( P = 0.049 ) activity increased , whereas MDA levels decreased significantly with FO supplementation ( P = 0.077 ) . Significant correlations between increased PON1 activity and both HDL-C ( P = 0.007 , r = 0.419 ) and Apo-AI ( P < 0.001 , r = 0.742 ) concentrations as well as between HDL-C and Apo AI levels ( P = 0.01 , r = 0.403 ) were found . CONCLUSION According to the results of this study , FO could increase serum HDL-C and PON1 levels and Aryl activity in female patients with RA Paraoxonase is an enzyme associated with HDL in human serum that hydrolyzes oxidized phospholipids and inhibits LDL oxidation , which is an important step in atherogenesis . In animals , addition of oxidized lipids to the circulation reduces paraoxonase activity , and diets rich in oxidized fat accelerate the development of atherosclerosis . The current r and omized , crossover study was design ed to compare the effect of a meal rich in oxidized lipids in the form of fat that had been used for deep-frying in a fast food restaurant and a control meal rich in the corresponding unused fat on postpr and ial serum paraoxonase ( arylesterase ) activity and peroxide content of LDL and its susceptibility to copper ion catalyzed oxidation in 12 healthy men . Four hours into the postpr and ial period , serum paraoxonase activity had decreased significantly after the used fat meal ( -17 % , P=0.005 ) and had increased significantly after the meal rich in unused fat ( 14 % , P=0 . 005 ) . These changes were significantly ( P=0.003 ) different . A time-course study indicated that serum paraoxonase activity remained lower than baseline for up to 8 hours after the used fat meal . Serum apoA1 concentration tended to decrease after the unused fat meal and tended to increase after the used fat meal . These changes were different at a marginal level of significance ( P=0.07 ) . Also , a significantly ( P=0.03 ) greater decrease in apoA1 content of postpr and ial HDL was recorded after the unused fat meal . The peroxide content of LDL tended to decrease after the used fat meal and tended to increase after the control meal . These changes were significantly ( P=0.04 ) different . Susceptibility of isolated LDL to copper ion oxidation and plasma levels of malondialdehyde were unchanged during the study . These data suggest that in the postpr and ial period after a meal rich in used cooking fat , the enzymatic protection of LDL against accumulation of peroxides and atherogenic oxidative modification may be reduced , possibly due to factors associated with apoA1 , without acutely affecting the intrinsic resistance of LDL to in vitro oxidation Olive oil , rich in oleic acid , could play a particular beneficial role in the anti-atherogenic effects attributed to the Mediterranean diet . Paraoxonase ( PON1 ) has emerged as the component of high-density lipoproteins ( HDL ) most likely to explain its ability to attenuate the oxidation of low-density lipoproteins . We hypothesised that oleic acid intake might be associated with changes in PON1-HDL associated particles , and investigated the impact , if any , on this association of the PON1 - 192 polymorphism , a common polymorphism that strongly modulates PON1 activity . Six hundred and fifty-four men r and omly selected from the census were studied .  Oleic acid intake  was calculated from a 72-h recall question naire with specific software . Oleic acid intake groups ( low vs. high ) were created by stratifying the population according the median value as a cut-point . After adjusting for confounding variables , high oleic acid intake was associated with increased HDL cholesterol levels and PON1 activity only in subjects with the QR and the RR genotypes , respectively . Analyses of the variance showed a statistically significant interaction between PON1 - 192 genotypes and  oleic acid intake for log PON1 activity ( P=0.005 ) and a marginally significant interaction for HDL cholesterol ( P=0.066 ) . These results suggest that the beneficial effect of increasing oleic acid intake on HDL and PON1 activity at population level is especially observed in subjects carrying the R allele of the PON1 - 192 polymorphism Paraoxonase-1 ( PON1 ) , a HDL-associated enzyme , may protect against the development of atherosclerosis . Serum PON1 activity and PON1-mediated capacity of HDL to prevent lipoprotein oxidation are modulated by two common polymorphisms at positions 192 ( Gln-->Arg ) and 55 ( Leu-->Met ) of the PON1 gene . We studied the effect of dietary modifications on PON1 activity and the role of PON1 gene polymorphisms in the response . A controlled , crossover dietary intervention of two 5-wk periods was conducted in 37 healthy , nonsmoking women . The two study diets were either low or high in vegetables , and thus in natural antioxidants , with some differences in fatty acid contents . The mean plasma total ( -8 % , P < 0.001 ) , LDL ( -7 % , P < 0.01 ) and HDL ( -7 % , P < 0.001 % ) cholesterol , and apolipoprotein A-I ( -8 % , P < 0.001 ) concentrations were lower after the high vegetable diet period than after the low vegetable diet period . Also , the serum PON1 activity was lower ( P < 0.05 ) after the high vegetable compared with the low vegetable diet period . The reduction of PON1 activity correlated with the reduction in HDL cholesterol ( r = 0.35 , P < 0.05 ) . High baseline PON1 activity was related to the presence of the PON1(192Arg ) allele ( P < 0.001 ) and PON1(55Leu/Leu ) genotype ( P < 0.001 ) . The reduction of PON1 activity due to the high vegetable diet was greatest among the women with the PON1(192Arg ) allele ( P < 0.05 ) and PON1(55Leu/Leu ) genotype ( P < 0.05 ) . In conclusion , a diet high in vegetables , berries and fruit reduces PON1 activity , and the response is modulated by the genetic variance of PON1 BACKGROUND Prospect i ve data relating fruit and vegetable intake to cardiovascular disease ( CVD ) risk are sparse , particularly for women . OBJECTIVE In a large , prospect i ve cohort of women , we examined the hypothesis that higher fruit and vegetable intake reduces CVD risk . DESIGN In 1993 we assessed fruit and vegetable intake among 39876 female health professionals with no previous history of CVD or cancer by use of a detailed food-frequency question naire . We subsequently followed these women for an average of 5 y for incidence of nonfatal myocardial infa rct ion ( MI ) , stroke , percutaneous transluminal coronary angioplasty , coronary artery bypass graft , or death due to CVD . RESULTS During 195647 person-years of follow-up , we documented 418 incident cases of CVD including 126 MIs . After adjustment for age , r and omized treatment status , and smoking , we observed a significant inverse association between fruit and vegetable intake and CVD risk . For increasing quintiles of total fruit and vegetable intake ( median servings/d : 2 . 6 , 4.1 , 5.5 , 7.1 , and 10.2 ) , the corresponding relative risks ( RRs ) were 1.0 ( reference ) , 0.78 , 0.72 , 0.68 , and 0.68 ( 95 % CI comparing the 2 extreme quintiles : 0.51 , 0.92 ; P : for trend = 0.01 ) . An inverse , though not statistically significant , trend remained after additional adjustment for other known CVD risk factors , with RRs of 1.0 , 0.75 , 0.83 , 0.80 , and 0.85 ( 95 % CI for extreme quintiles : 0.61 , 1.17 ) . After excluding participants with a self-reported history of diabetes , hypertension , or high cholesterol at baseline , the multivariate-adjusted RR was 0.45 when extreme quintiles were compared ( 95 % CI : 0.22 , 0.91 ; P : for trend = 0.09 ) . Higher fruit and vegetable intake was also associated with a lower risk of MI , with an adjusted RR of 0.62 for extreme quintiles ( 95 % CI : 0.37 , 1.04 ; P : for trend = 0.07 ) . CONCLUSION These data suggest that higher intake of fruit and vegetables  may be protective against CVD and support current dietary guidelines to increase fruit and vegetable intake Human paraoxonase ( PON1 ) exists in 2 major polymorphic forms and has been shown to protect LDL and HDL against oxidation . The aim of this study was to assess the differences between subjects at increased risk of cardiovascular disease ( CVD ) , taking into account the effects of PON1-Q192R and PON1-L55 M polymorphisms on 1 ) basal serum arylesterase activity , lipid peroxidation ( LPO ) , and LDL-cholesterol ( LDL-C ) , HDL-C , total cholesterol ( TC ) , and oxidized-LDL ( ox-LDL ) concentrations ; 2 ) the relations between arylesterase activity and lipid variables ; and 3 ) the effect of walnut-enriched meat ( WM ) consumption on arylesterase activity and lipid variables .  Twenty-three Caucasians at increased risk of CVD were r and omly assigned to diet order groups in a crossover , nonblinded , placebo-controlled trial , consisting of two 5-wk experimental periods [ WM and control meat ( C 
    Output:
    
Extra virgin olive oil , the main source of fat , has been particularly effective in increasing PON1 activity , an action that could be due to low saturated fatty acid intake , oleic acid enrichment of phospholipids present in high-density lipoproteins that favor the activity , and increasing hepatic PON1 mRNA and protein expressions induced by minor components present in this oil .
Other Mediterranean diet constituents , such as nuts , fruits and vegetables , have been effective in modulating the activity of the enzyme , pomegranate and its compounds being the best characterized items .
Ongoing research on compounds isolated from all these natural products , mainly phenolic compounds and carotenoids , indicates that some of them are particularly effective , and this may enhance the use of nutraceuticals and functional foods capable of potentiating PON1 activity