the 2013 aha / acc guideline on lifestyle management to reduce cardiovascular risk recommends a healthy dietary pattern with 5% to 6% of calories from sfa for lowering ldlc , a primary target for cvd risk reduction . both mufa and pufa
the food sources of mufa in the mediterranean diet provide many micronutrients and bioactives that also may confer cardioprotective benefits . the predimed ( prevencin con dieta mediterrnea ) trial reported that a mediterranean diet supplemented with mufarich foods that included either extravirgin olive oil or mixed nuts ( walnuts , almonds , hazelnuts ) reduced the incidence of major cvd events by 30% after approximately 5 years in men and women ( 50 to 80 years of age ) at high risk for cvd .
avocados are another nutrientdense source of mufa , rich in vitamins , minerals , fiber , phytosterols and polyphenols that have not been studied extensively .
the hass variety , which is mainly consumed in the united states , is relatively high in mufa and other fatsoluble vitamins .
one hass avocado ( 136 g , without skin and the seed ) contains 13 g of oleic acid , which is similar to the amount of oleic acid in 1.5 oz ( 42 g ) almonds or 2 tablespoons ( 23 g ) of olive oil . based on their fatty acid and nutrient profile ,
evidence about the beneficial effects of avocados on the lipid / lipoprotein profile is based on relatively few diet studies .
studies with avocados ( 0.5 to 2 avocados per day ) have reported similar or greater tg , ldlc , and tclowering effects while maintaining hdlc compared with lowfat , cholesterollowering diets .
there are several limitations , however , of previous studies that include the presence of diabetes , cvd , and other illnesses in some participants , weightloss during the feeding period , lack of control of the background diet , and variations in the diet interventions , including the length of the feeding period and diet design , as well as a small sample size .
furthermore , in these studies , avocados were a source of mufa that was substituted for other macronutrients to evaluate only the effect of fat content on lipids and lipoproteins .
the present study evaluated the effects of avocados on traditional and novel lipid risk factors by replacing sfa with carbohydrate ( cho ) or mufa from avocados or high oleic acid oils .
this diet design also enabled us to evaluate the effects of a lower fat and 2 moderate fat diets , the latter of which differed in nutrients and bioactive components provided by avocados .
therefore , we were able to further evaluate the nutrients and bioactive compounds in avocados beyond mufa on established and emerging cardiometabolic risk factors .
a randomized , 3period crossover study design was implemented . a 2week  runin  average american diet ( aad : 34% fat , 51% cho , 16% protein [ pro ] ) was fed to participants before they were randomly assigned to a treatment sequence of 3 diet periods ( 5 weeks each ) with a 2 week compliance break between diet periods .
the study design is presented in figure 1 . the nutrient profile and major food groups for the lf , mf , and av diets are shown in table 1 .
the lf diet was designed by replacing 6 to 7% of energy from sfa with cho ( from grains that were incorporated in the diet in place of sfa ) in the aad .
likewise , the av and mf diets were designed by replacing 6 to 7% of energy from sfa with mufa using either one hass avocado ( 136 g fruit pulp , 13 g mufa ) per day ( for the av diet ) or high oleic acid oils ( eg , sunflower oil and canola oil , for the mf diet ) as the main sources of mufa . to match the macronutrients and fatty acids in the mf and av diets , and to adjust for the different calorie levels , high oleic acid oils , lowfat cheese , and nuts were used in both diets . about 90% of foods in the 2 diets were identical .
thus , the major difference between the nutrient profiles of the av and mf diets were due to the bioactives from one avocado beyond its fatty acid profile . nutrient profile and food groups of study diets aad indicates average american diet ; av , avocado diet ; lf , lowerfat diet ; mf , moderatefat diet ; mufa , monounsaturated fatty acids ; pufa , polyunsaturated fatty acids ; sfa , saturated fatty acids . based on 2100 kcals / day .
aad indicates average american diet ; av , avocado diet ; lf , lowerfat diet ; mf , moderatefat diet .
menus ( 6day rotating ) were developed using food processor sql software ( esha research , salem , or ) for 7 calorie levels ( 1800 to 3600 kcals ) to meet participants energy requirements .
the harrisbenedict equation with a physical activity factor was used to estimate each participant 's basal metabolic rate ( bmr ) and daily energy requirements . during the 2week runin
the 3 experimental diets met current foodbased dietary recommendations except for dairy products in lower calorie levels ( 1600 to 2100 kcals ) , which provided around 2 servings per day .
participants were weighed daily ( monday through friday ) to assess diet compliance and ensure that body weight was maintained .
participants were asked to maintain their habitual level of physical activity throughout the study . at the end of each diet period ,
serum and edta plasma were collected and stored at 80c until the end of the study .
one day lf , mf and av diet menus * av indicates avocado diet ; lf , lowerfat diet ; mf , moderatefat diet . one of the 6 rotating menus used in the study ; all menus have 7 calorie levels ( 1800 to 3600 kcal ) . the institutional review board at the pennsylvania state university
healthy , overweight men and women ( 21 to 70 years old , bmi 25 to 35 kg / m ) with ldlc in the 25th to 90th percentile ( nhanes ; 105 to 194 mg / dl for males ; 98 to 190 mg / dl for females ) and normal blood pressure ( 140/90 mm hg ) or well controlled with blood pressurelowering medication were recruited .
all participants were nonsmokers , free of cvd , diabetes , liver , or renal disease , and not taking lipidlowering medications or supplements .
nine participants were excluded during the 2week runin diet due to a schedule conflict , personal health issue , or inability to comply .
five participants dropped out during the study but completed as least one diet treatment ( figure 2 ) .
study participants were predominantly caucasian and nonhispanic ( n=41 ) with 3 asians and 1 african american .
baseline characteristics of study participants ( n=45 , 27 males and 18 females ) are shown in table 3 .
participants atherosclerotic cardiovascular disease ( ascvd ) risk and metabolic syndrome ( mets ) criteria at baseline are shown in table 4 .
baseline characteristics of study participants ( n=45 ) * bmi indicates body mass index ; dbp , diastolic blood pressure ; hdlc , highdensity lipoprotein cholesterol ; hscrp , high sensitivity creactive protein ; ldlc , lowdensity lipoprotein cholesterol ; sbp , systolic blood pressure ; tc , total cholesterol .
baseline values were obtained before randomization , at the end of 2 weeks runin aad .
participants ascvd risk and mets criteria at baseline ascvd risk estimate is calculated using the web based risk estimator tools .
avcsd indicates atherosclerotic cardiovascular disease ; mets , metabolic syndrome . the ascvd 10year risk is only calculated for the 40 to 79 year range .
endpoint visits took place in the clinical research center ( crc ) at pennsylvania state university .
serum lipid , lipoprotein subclasses cholesterol , and apolipoproteins were assayed using vertical auto profile ( vap ii ) ( atherotech diagnostics lab , birmingham , al ) , which directly measures cholesterol in all lipoprotein classes .
plasma lipoprotein particle number and size were assessed by a proton magnetic resonance spectroscopy assay ( nmr lipoprofile iii ; liposcience , raleigh , nc ) , which measures the particle concentrations of lipoprotein subclasses and average particle size of lipoproteins .
serum high sensitivity creactive protein ( hscrp ) was determined by a nephelometric method utilizing latex particles coated with monoclonal antibodies ; the analytical sensitivity was 0.2 mg / dl ( quest diagnostics ; assay cv <
plasma fasting insulin was measured by immunoassay ; fasting glucose was measured by spectrophotometry ( quest diagnostics ; assay cv was < 8% for both ) .
blood pressure was measured 3 times by a standard mercury stadiometer ( w. a. baum co , copiague , ny ) after sitting for 5 minutes ( before the blood draw ) and the average of the second and third measurements was used for the final value .
statistical analyses were performed with sas ( version 9.2 ; sas institute inc ) and minitab software ( version 16 ; minitab inc ) .
the mixed models procedure ( proc mixed ) was used comparing the effects of 3 diets on the change value ( from baseline ) of all outcome variables .
potential carryover effects were assessed by including diet sequence , period and dietperiod interaction as a fixed effect in the model ; age , bmi , sex , dietsex interaction were included as covariates . the shapirowilk test was used to assess normality of residuals in the mixed model .
fisher 's ztransformation was used to compare the correlations between lipid biomarkers in different diets .
ascvd 10year and lifetime risk was calculated using the online ascvd risk estimator tool ( http://tools.cardiosource.org/ascvd-risk-estimator/ ) for every participant at baseline and at the end of each diet period .
the change in risk score for each diet was estimated as the median with 95% ci by the wilcoxon signed rank test .
the ascvd risk estimate is based on each participant 's age , gender , race , smoking status , diabetes status , hypertension treatment , blood pressure , total cholesterol , and hdlc . due to the large variation in previous avocado studies , we determined sample size based on a pistachio study that used a similar diet design ( similar difference in macronutrients between the lowfat diet and the moderatefat , pistachio diet ) . using the sas procedure procpower with pairedmeans statement ,
a final sample size of 37 was needed to provide 95% power to detect a 10% decrease in ldlc by the avocado diet versus the lowerfat diet with a 2tailed =0.05 . considering a 10% to 20% dropout rate
a randomized , 3period crossover study design was implemented . a 2week  runin  average american diet ( aad : 34% fat , 51% cho , 16% protein [ pro ] ) was fed to participants before they were randomly assigned to a treatment sequence of 3 diet periods ( 5 weeks each ) with a 2 week compliance break between diet periods .
the study design is presented in figure 1 . the nutrient profile and major food groups for the lf , mf , and av diets are shown in table 1 .
the lf diet was designed by replacing 6 to 7% of energy from sfa with cho ( from grains that were incorporated in the diet in place of sfa ) in the aad .
likewise , the av and mf diets were designed by replacing 6 to 7% of energy from sfa with mufa using either one hass avocado ( 136 g fruit pulp , 13 g mufa ) per day ( for the av diet ) or high oleic acid oils ( eg , sunflower oil and canola oil , for the mf diet ) as the main sources of mufa . to match the macronutrients and fatty acids in the mf and av diets , and to adjust for the different calorie levels , high oleic acid oils , lowfat cheese , and nuts were used in both diets . about 90% of foods in the 2 diets were identical .
thus , the major difference between the nutrient profiles of the av and mf diets were due to the bioactives from one avocado beyond its fatty acid profile . nutrient profile and food groups of study diets aad indicates average american diet ; av , avocado diet ; lf , lowerfat diet ; mf , moderatefat diet ; mufa , monounsaturated fatty acids ; pufa , polyunsaturated fatty acids ; sfa , saturated fatty acids . based on 2100 kcals / day .
aad indicates average american diet ; av , avocado diet ; lf , lowerfat diet ; mf , moderatefat diet .
menus ( 6day rotating ) were developed using food processor sql software ( esha research , salem , or ) for 7 calorie levels ( 1800 to 3600 kcals ) to meet participants energy requirements .
the harrisbenedict equation with a physical activity factor was used to estimate each participant 's basal metabolic rate ( bmr ) and daily energy requirements . during the 2week runin
the 3 experimental diets met current foodbased dietary recommendations except for dairy products in lower calorie levels ( 1600 to 2100 kcals ) , which provided around 2 servings per day .
participants were weighed daily ( monday through friday ) to assess diet compliance and ensure that body weight was maintained .
participants were asked to maintain their habitual level of physical activity throughout the study . at the end of each diet period ,
serum and edta plasma were collected and stored at 80c until the end of the study .
one day lf , mf and av diet menus * av indicates avocado diet ; lf , lowerfat diet ; mf , moderatefat diet . one of the 6 rotating menus used in the study ; all menus have 7 calorie levels ( 1800 to 3600 kcal ) . the institutional review board at the pennsylvania state university
healthy , overweight men and women ( 21 to 70 years old , bmi 25 to 35 kg / m ) with ldlc in the 25th to 90th percentile ( nhanes ; 105 to 194 mg / dl for males ; 98 to 190 mg / dl for females ) and normal blood pressure ( 140/90 mm hg ) or well controlled with blood pressurelowering medication were recruited .
all participants were nonsmokers , free of cvd , diabetes , liver , or renal disease , and not taking lipidlowering medications or supplements .
nine participants were excluded during the 2week runin diet due to a schedule conflict , personal health issue , or inability to comply .
five participants dropped out during the study but completed as least one diet treatment ( figure 2 ) .
study participants were predominantly caucasian and nonhispanic ( n=41 ) with 3 asians and 1 african american .
baseline characteristics of study participants ( n=45 , 27 males and 18 females ) are shown in table 3 .
participants atherosclerotic cardiovascular disease ( ascvd ) risk and metabolic syndrome ( mets ) criteria at baseline are shown in table 4 .
baseline characteristics of study participants ( n=45 ) * bmi indicates body mass index ; dbp , diastolic blood pressure ; hdlc , highdensity lipoprotein cholesterol ; hscrp , high sensitivity creactive protein ; ldlc , lowdensity lipoprotein cholesterol ; sbp , systolic blood pressure ; tc , total cholesterol .
baseline values were obtained before randomization , at the end of 2 weeks runin aad .
participants ascvd risk and mets criteria at baseline ascvd risk estimate is calculated using the web based risk estimator tools .
avcsd indicates atherosclerotic cardiovascular disease ; mets , metabolic syndrome . the ascvd 10year risk is only calculated for the 40 to 79 year range .
endpoint visits took place in the clinical research center ( crc ) at pennsylvania state university .
serum lipid , lipoprotein subclasses cholesterol , and apolipoproteins were assayed using vertical auto profile ( vap ii ) ( atherotech diagnostics lab , birmingham , al ) , which directly measures cholesterol in all lipoprotein classes . plasma lipoprotein particle number and size were assessed by a proton magnetic resonance spectroscopy assay ( nmr lipoprofile iii ; liposcience , raleigh , nc ) , which measures the particle concentrations of lipoprotein subclasses and average particle size of lipoproteins .
serum high sensitivity creactive protein ( hscrp ) was determined by a nephelometric method utilizing latex particles coated with monoclonal antibodies ; the analytical sensitivity was 0.2 mg / dl ( quest diagnostics ; assay cv < 8% ) .
plasma fasting insulin was measured by immunoassay ; fasting glucose was measured by spectrophotometry ( quest diagnostics ; assay cv was < 8% for both ) .
blood pressure was measured 3 times by a standard mercury stadiometer ( w. a. baum co , copiague , ny ) after sitting for 5 minutes ( before the blood draw ) and the average of the second and third measurements was used for the final value .
statistical analyses were performed with sas ( version 9.2 ; sas institute inc ) and minitab software ( version 16 ; minitab inc ) .
the mixed models procedure ( proc mixed ) was used comparing the effects of 3 diets on the change value ( from baseline ) of all outcome variables .
potential carryover effects were assessed by including diet sequence , period and dietperiod interaction as a fixed effect in the model ; age , bmi , sex , dietsex interaction were included as covariates .
fisher 's ztransformation was used to compare the correlations between lipid biomarkers in different diets .
ascvd 10year and lifetime risk was calculated using the online ascvd risk estimator tool ( http://tools.cardiosource.org/ascvd-risk-estimator/ ) for every participant at baseline and at the end of each diet period .
the change in risk score for each diet was estimated as the median with 95% ci by the wilcoxon signed rank test .
the ascvd risk estimate is based on each participant 's age , gender , race , smoking status , diabetes status , hypertension treatment , blood pressure , total cholesterol , and hdlc . due to the large variation in previous avocado studies , we determined sample size based on a pistachio study that used a similar diet design ( similar difference in macronutrients between the lowfat diet and the moderatefat , pistachio diet ) . using the sas procedure procpower with pairedmeans statement , a final sample size of 37
was needed to provide 95% power to detect a 10% decrease in ldlc by the avocado diet versus the lowerfat diet with a 2tailed =0.05 . considering a 10% to 20% dropout rate
diet compliance was very good . based on selfreported monitoring , adherence for all participants was 90% as assessed by the number of days participants consumed all study foods and no nonstudy foods .
all 3 diets significantly decreased ldlc and total cholesterol ( tc ) versus baseline ( table 5 , figure 3 ) . compared with the runin aad diet , the lf and mf diets reduced ldlc ( lf : 5.3% , p=0.004 ; mf : 5.8% ; p=0.0004 ) and tc ( lf : 4% ; mf : 4.7% ; p<0.01 for both ) similarly . however , the reduction in ldlc and tc by the av diet ( 10% and 8% ; p<0.0001 for both ) was significantly greater ( p<0.05 ) than the lf and mf diets .
hdlc decreased less ( p<0.05 ) on the mf diet and av diet versus the lf diet . also , the lf diet significantly increased tg and vldlc by 17.6% and 10.9% , respectively ( p<0.001 for both ) , while the mf and av diets did not .
the mf and av diets decreased nonhdlc ( 5.1% and 9.3% , p<0.01 for both ) , but the lf diet did not .
furthermore , the av diet elicited a greater ( p=0.01 ) reduction in nonhdlc ( 9.3% , p<0.0001 ) versus the mf diet ( 5.1% , p=0.01 ) .
tc / hdlc and ldlc / hdlc significantly decreased after the av diet ( 4.9% and 6.6% ) and were significantly lower ( p=0.04 and p<0.0001 ) than after the mf and lf diets .
the lf diet also increased tg / hdlc by 27.3% ( p<0.0001 ) from baseline , whereas the mf and av diets had no effect on tg / hdlc and were significantly lower ( p<0.01 ) than the lf diet .
the av and mf diets decreased apob100 from baseline , whereas the lf diet did not .
the ratio of apob / apoa1 was decreased by the av diet but was not affected by the mf and lf diets ( table 5 , figure 3 ) .
effect of diets on lipids , lipoproteins , apolipoproteins , glucose , insulin , crp , and blood pressure all values are meanssems .
aad indicates average american diet ; av , avocado diet ; dbp , diastolic blood pressure ; hscrp , high sensitive creactive protein ; hdlc , highdensity lipoprotein cholesterol ; homa , homeostatic model assessment ; idlc , intermediatedensity lipoprotein cholesterol ; ldlc , lowdensity lipoprotein cholesterol ; lf , lowerfat diet ; lp(a ) , lipoprotein(a ) ; mf , moderatefat diet ; sbp , systolic blood pressure ; tc , total cholesterol ; vldlc , verylowdensity lipoprotein cholesterol .
values in diet treatments with different superscript letters ( a , b , and c ) are significantly different ( tukey posthoc test by sas , p<0.05 ) .
values with different letters ( a , b , and c ) are significantly different ( tukey posthoc test by sas , p<0.05 ) .
av indicates avocado diet ; apoa1 , apolipoprotein a1 ; apob , apolipoprotein b ; hdlc , highdensity lipoprotein cholesterol ; idlc , intermediatedensity lipoprotein cholesterol ; ldlc , lowdensity lipoprotein cholesterol ; lf , lowerfat diet ; mf , moderatefat diet ; tc , total cholesterol ; tg , triglycerides ; vldl , verylowdensity lipoprotein .
although ldlc was reduced on all three diets , the number of ldl particles ( ldlp ) did not decrease significantly after the lf and mf diets ( figure 4 , table 6 ) .
there was a trend for a reduction in ldlp by the mf diet ( 38 nmol / l , p=0.07 ) , however , this was significantly less ( p=0.05 ) than the reduction by the av diet ( 80.1 nmol / l , p=0.001 ) .
the difference was due to the increase in small ldlp by the lf and mf diets ( table 6 ) .
similar reductions from baseline ( p<0.001 for all ) in large ldlp were observed on the lf , mf , and av diets .
mean ldl particle size decreased on all 3 diets : lf ( 0.24 nm , p<0.0001 ) , mf ( 0.21 nm , p<0.0001 ) , and av ( 0.12 nm , p=0.008 ) .
ldl particle size was significantly larger ( p=0.03 ) after the av diet compared with the lf diet ( table 6 ) .
the change in ldl particle size was highly correlated with the change in large ldlp ( r=0.68 , p<0.0001 ) , and the change in total ldlp was highly correlated with the change in small ldlp ( r=0.62 , p<0.0001 ) ( figure 5 ) .
effect of diets on lipoprotein particle size and subclasses ( particle number from nmr lipoprofile ) all values are meanssems .
aad indicates average american diet ; av , avocado diet ; hdlp , highdensity lipoprotein particle number ; idlp , intermediatedensity lipoprotein particle number ; ldlp , lowdensity lipoprotein particle number ; lf , lowerfat diet ; mf , moderatefat diet ; vldlp , verylowdensity lipoprotein particle number .
significant change compared to baseline aad , p<0.05 ; values in diet treatments with different superscript letters ( a , b , and c ) are significantly different ( tukey posthoc test by sas , p<0.05 ) .
( a ) change in ldl subclasses cholesterol ; ( b ) change in total , large and small ldl particle numbers .
values with different letters ( a , b , and c ) are significantly different ( tukey posthoc test by sas , p<0.05 ) .
av indicates avocado diet ; ldlc , lowdensity lipoprotein cholesterol ; ldlp , lowdensity lipoprotein number ; lf , lowerfat diet ; mf , moderatefat diet .
( a ) correlation between the change in small ldlp and the change in total ldlp ; ( b ) correlation between the change in large ldlp and the change in total ldlp ; ( c ) correlation between the change in small ldlp and the change in ldl particle size ; ( d ) correlation between the change in large ldlp and the change in ldl particle size .
av indicates avocado diet ; ldlp , lowdensity lipoprotein particle number ; lf , lowerfat diet ; mf , moderatefat diet .
the ldl subclass results from nmr and vap profile generally concurred : we observed similar reductions in the large , buoyant ldl cholesterol ( ldl1 + 2 ) on the lf , mf , and av diets compared with baseline ( p<0.0001 for all ) ( table 7 , figure 4 ) .
however , only the av diet reduced small , dense ldl cholesterol ( ldl3 : 4.0 mg / dl , p=0.01 ; ldl3 + 4 : 4.1 mg / dl , p=0.04 ) .
the mf diet did not affect ldl3 and ldl4 whereas the lf diet increased ldl4 from baseline ( table 7 ) .
vap ldl peak max time ( lower value represents higher density of ldl particles ) also decreased from baseline by the lf and mf diet , but not with the av diet .
the levels of ldl1 + 2 and large ldlp , ldl3 + 4 and small ldlp were highly correlated at baseline ( r=0.71 and 0.70 , p<0.0001 for both ) ; their change values on the diets also were correlated ( r=0.42 and 0.36 , p<0.0001 for both ) ( figure 6 ) .
effect of diets on lipoprotein subclasses ( cholesterol concentration from vap test ) all values are meanssems .
aad indicates average american diet ; av , avocado diet ; hdl , highdensity lipoprotein ; idlc , intermediatedensity lipoprotein cholesterol ; ldl , lowdensity lipoprotein ; lf , lowerfat diet ; mf , moderatefat diet ; remnant lp , lipoprotein remnants ; vap , vertical auto profile ; vldlc , verylowdensity lipoprotein cholesterol .
significant change compared to baseline aad , p<0.05 ; values in diet treatments with different superscript letters ( a / b ) are significantly different ( tukey posthoc test by sas , p<0.05 ) .
( a ) correlation between the change in small ldlp and the change in ldl3 + 4 ; ( b ) correlation between the change in large ldlp and the change in ldl1 + 2 .
av indicates avocado diet ; ldl , lowdensity lipoprotein ; ldlp , lowdensity lipoprotein particle number ; lf , lowerfat diet ; mf , moderatefat diet .
the lf diet increased cholesterol in vldl1 + 2 and vldl3 , whereas the mf and av diets had no affect ( table 7 , figure 7 ) .
lipoprotein remnants ( vldl3+idl ) were decreased by the av diet ( 2.4 mg / dl , p=0.008 ) and increased by the lf diet ( 1.5 mg / dl , p=0.02 ) .
the change in vldl subclass particle number ( table 6 ) was mostly consistent with vap results except for the decrease in small vldlp by the lf diet ( in contrast to the increase in vldl3 ) , which may be due to small vldl particles that were cholesterol enriched after the lf diet ( table 7 , figure 7 ) .
similar to the change in vldl1 + 2 , large and medium vldlp were increased by the lf diet , however , they were not affected by the mf and av diets . the av diet but
not mf diet decreased small vldlp from baseline ( 5.8 nmol / l , p=0.001 ) .
vldl particle size was increased by the lf diet and was significantly larger than by the mf diet ( p=0.01 ) but not different from the av diet ( table 6 ) .
( a ) change in vldl and idl subclasses cholesterol concentration ; lipoprotein remnant particles consist of vldl3 and idl .
values with different letters are significantly different ( tukey posthoc test by sas , p<0.05 ) .
av indicates avocado diet ; idl , intermediatedensitylipoprotein ; idlp , intermediatedensitylipoprotein particle number ; lf , lowerfat diet ; mf , moderatefat diet ; vldlc , verylowdensity lipoprotein cholesterol ; vldlp , verylowdensity lipoprotein particle number .
however , hdl3 was significantly decreased after the lf diet but not after the mf and av diets ( table 7 ) .
unlike hdlc , the total hdlp was not affected by all diets ( table 6 ) .
after the lf diet , there was a trend for small hdlp to be lower than the mf ( p=0.06 ) and av diets ( p=0.08 ) , which is consistent with the hdl3 change ( tables 6 and 7 ) .
hdl particle size was slightly decreased by the lf ( 0.07 nm ) , mf ( 0.1 nm ) , and av ( 0.01 nm ) diets versus baseline ( p<0.01 for all ) ( table 6 ) .
fasting hscrp , insulin , glucose , homa ( homeostatic model assessment ) score , systolic and diastolic blood pressure were not affected by any diet ( table 5 ) .
this study is the first randomized controlled feeding trial to our knowledge to evaluate the additional ldlc lowering effect of avocados beyond their mufa content .
this also is the first feeding study to use 2 advanced lipidtesting methods to evaluate the effects of lf versus mf diets on lipoprotein subclass changes .
our results demonstrate greater benefits on lipid / lipoprotein profiles when sfa is replaced by mufa than cho , which is consistent with current dietary recommendations .
an important finding we observed is that the av diet lowered ldlc , tc , ldlp , nonhdlc , tc / hdlc , and ldl / hdlc significantly more than the mf diet .
this has important implications for future research that needs to be conducted to determine the functional effects of fruits and vegetables on lipid / lipoprotein risk factors that are independent of the substitution of macronutrients . in our study ,
both vap and nmr analyses demonstrated that the lf , av , and mf diets decreased large , buoyant ldl ( ldl1 + 2 , large ldlp ) similarly ; however , only the av diet significantly decreased cholesterol in small , dense ldl ( sdldl ) and lipoprotein remnants from baseline , and lowered small ldlp concentration compared to the mf and lf diets .
the mf diet did not have the same benefit as the av diet , which clearly indicates that other nutrients / bioactives beyond fatty acids contribute to the health benefits of avocados .
we hasten to add that the mf diet did have beneficial effects but , importantly , the nutrientdense food source of mufa ( ie , an avocado ) had superior effects . of note , is that the mufa literature is variable with respect to cardiovascular effects which may reflect the food source(s ) of mufa used .
identifying other nutrientdense foods that contain mufa that confer additional cardiovascular benefits , or other nutrientdense foods ( ie , fruits and vegetables ) that can be consumed with high mufa oils will be important for evolving future dietary guidance .
the effects of the av diet on sdldl may be due to the combined effects of mufa and other bioactives , especially phytosterols and fiber .
avocados are the richest fruit source of sitosterol ; one hass avocado ( 136 g ) provides 114 mg of plant sterols , and 100 g provides 2.11 g soluble fiber and 2.7 g insoluble fiber . avocados also contain a unique sevencarbon ( c7 ) ketosugar  mannoheptulose and its polyol form perseitol ( about 4 g per fruit ) , which may suppress insulin secretion and promote calorie restriction .
sialvera et al reported that plant sterol supplementation ( 4 g per day for 2 months ) decreased sdldl cholesterol in mets patients on a western diet ; lamarche et al also reported that including plant sterols ( 1 g per 1000 kcals ) , viscous fiber ( 9 g per 1000 kcals ) , soybean protein and almonds in a lowsfa diet for 4 weeks decreased sdldl cholesterol ( 21% , p<0.01 ) in patients with mildly elevated ldlc .
daily consumption of highfiber oat cereal providing 14 g dietary fiber / day for 12 weeks decreased sdldl cholesterol ( 17.3% , p<0.05 ) in overweight men .
although the combination of fiber and plant sterols in avocados may contribute to the effect , there may be other bioactives and nutrients that also contribute because of the relatively lower dose of fiber and plant sterols delivered by one avocado compared to other supplementation studies .
dietary mufa has been associated with lower sdldl when substituted for sfa , although the results reported are inconsistent .
gill et al reported that ldl3 was 25% lower after a highmufa diet ( 13.7% energy ) versus a lowmufa diet ( 7.8% energy ) in hypercholesterolemic participants .
kratz et al reported that a high mufa diet ( 38.7% energy from fat , 23.2% energy from mufa ) provided by refined olive oil significantly reduced ldl peak particle diameter ( 0.36 nm , p=0.012 ) versus a high sfa diet ( 16% energy from sfa ) . in another study
there was no effect of replacing sfa with mufa on ldl particle size . in the predimed study ,
only one study showed that the addition of walnuts to freeliving subjects habitual diets elicited a 13% reduction in the number of sdldl particles .
lamarche et al showed that a dietary portfolio that incorporated plant sterols , soy protein , viscous fiber , and almonds decreased sdldl by 21% ( p<0.01 ) .
holligan et al reported a significant decrease in sdldl cholesterol after consumption of a moderate fat diet including 2 servings / day of pistachios in healthy adults with high ldlc .
one explanation for the inconsistent results is that there might be some synergistic effects of the dietary fiber , plant sterols , mufa , and other bioactive compounds or nutrients in specific foods and different background diets .
further studies are needed to characterize the bioactives in avocados and investigate the mechanisms by which avocados affect sdldl production .
the prediction of cvd risk by the 2013 prevention guidelines ascvd risk estimator showed significant improvement for overall 10 year and lifetime risk by the mf and av diets but not the lf diet ( table 8) .
the predicted reduction in chd risk by the av diet could be greater due to changes in nonhdlc , apob , ldlp , sdldl , lipoprotein remnants , and lipid / lipoprotein ratios .
recent clinical studies have found that the ldlattributable atherosclerotic risk is better predicted by ldlp and sdldl than by using standard lipid / lipoprotein measurements in patients at high risk for mets and/or diabetes .
furthermore , sdldl and total ldlp have potential importance for comprehensively monitoring the efficacy of lifestyle interventions on cvd risk . in the present study ,
sdldl concentration was correlated with an atherogenic lipid / lipoprotein profile , which tracks with atherogenic dyslipidemia ( figure 8) .
importantly , in our study , larger ldl particles and ldlc decreased similarly by the lf , mf , and av diets , which indicate all 3 diets would decrease risk of cardiovascular disease .
however , because of the effects of the lf diet on tg and hdlc , there was no benefit on 10year and lifetime risk of ascvd .
although the longterm benefit of lf diet versus aad was not tested in our study , this is another illustration of the importance of replacing saturated fat with unsaturated fat , ie , mufa as reported herein . predicted changes in ascvd risk by the three diets aad indicates average american diet ; av , avocado diet ; avcsd , atherosclerotic cardiovascular disease ; lf , lowerfat diet ; mf , moderatefat diet .
the change in risk from baseline is the estimated median with 95% ci by the wilcoxon signed rank test .
( a ) correlations between ldl3 + 4 and tg , ldl1 + 2 and tg ; ( b ) correlations between ldl3 + 4 and vldlc , ldl1 + 2 and vldlc ; ( c ) correlations between ldl3 + 4 and hdlc , ldl1 + 2 and hdlc .
aad indicates average american diet ; av , avocado diet ; hdlc , highdensity lipoprotein cholesterol ; ldlc , lowdensity lipoprotein cholesterol ; lf , lowerfat diet ; mf , moderatefat diet ; tg , triglycerides ; vldlc , verylowdensity lipoprotein cholesterol .
the change in ldl particle size and subclasses due to the mf and av diets we observed differs from some mediterranean diet studies . in predimed study , the mediterranean diet supplemented with nuts significantly increased ldl size ( 0.2 nmol / l ) and large ldlp ( 53.8 nmol / l ) , and decreased very small ldlp ( 111
nmol / l ) in a subgroup of subjects ( n=156 ) at high cvd risk .
richard et al reported that consumption of a mediterranean diet for 5 weeks decreased small ldl particles ( 11.7% ) , and increased ldl peak particle size ( 0.18 nm ) compared with an isoenergetic north american control diet ( 5 weeks ) . in our study , both the mf and av diets significantly decreased large ldlp and ldl particle size .
these differences may reflect the higher fat content and other foods / nutrients in the mediterranean diet . also , unlike the mediterranean diet studies , our participants were at lower risk for mets and chd ( table 4 ) , thereby demonstrating benefits of the diets we studied for the primary prevention of cvd .
several studies have demonstrated that nonhdlc is a better predictor of cvd risk compared with ldlc because it takes into account the atherogenic vldl and lp remnant particles . in our study ,
the av and mf diets significantly decreased nonhdlc and apob compared to baseline while the lf diet did not .
vldl and idl , especially the small , dense lp remnant particles , are independently associated with the prediction , progression , and residual risk of cvd .
also , the reduction of tg / hdlc by the mf and av diet ( compared to the lf diet ) indicated a beneficial effect of mufa on insulin sensitivity .
it must be appreciated that most participants in our study did not have mets ( even though they were at risk because they were overweight or obese ) , and the prediction value of advanced lipid measures versus standard lipid / lipoprotein needs to be further evaluated in different populations in longerterm intervention studies .
hdlc was decreased by all diets in our study , but total hdlp did not change . the mesa study ( multiethnic study of atherosclerosis )
reported that hdlp but not hdlc was independently associated with chd after adjusting for ldlp and other confounding factors . in our study , the lf diet decreased hdl3 , which is important for cholesterol efflux and may be upregulated by mufa .
moreover , small , dense hdl3 particles may protect ldl against oxidationand attenuate apoptosis in endothelial cells as shown in recent studies .
studies are needed to determine if hdl functionality is improved by a moderate fat diet with avocados .
it was a wellcontrolled clinical trial and we achieved a high level of diet compliance , weight maintenance , and had a low dropout rate .
the latter is attributable to the runin diet period , which familiarized participants with the study .
moreover , our study was designed to differentiate the effects of bioactive compounds in avocados beyond fatty acids .
one limitation of our study design is that one avocado per day contributed a different percentage of energy over different calorie levels ( 7% to 13% over the 6 calorie levels ) .
another limitation is that our study participants did not lose weight , which is the first line of treatment for overweight / obesity .
clearly , weight loss would elicit beneficial effects on lipids / lipoproteins and cvd risk status .
nonetheless , for individuals who do not lose weight , we have shown that a moderate fat diet high in mufa , especially from one avocado per day has beneficial effects on lipids / lipoproteins and cvd risk status .
finally , our participants did not represent the ethnic diversity of the u.s . population .
our study has shown that one hass avocado per day has beneficial effects beyond their fatty acid profile on decreasing ldlc and other emerging cvd risk factors . herein , we present new information that a moderate fat diet low in sfa and high in mufa from an avocado daily achieved greater reductions in ldlc , sdldlc , ldlp , nonhdlc , ldl / hdlc , and tc / hdlc than a high mufa diet with a similar macronutrient and fatty acid profile .
thus , inclusion of a food source rich in mufa and bioactives confers additional cvd benefits compared to a mufamatched , low sfa diet .
wang , fleming , hill , and krisetherton : designed the research and wrote the manuscript ; wang , bordi , fleming , and krisetherton : conducted the clinical trial ; wang : collected samples , analyzed data and performed statistical analysis ; krisetherton and wang : had primary responsibility for the final content of the manuscript ; and all authors : read and approved the final manuscript .
wang , bordi , fleming , hill , and krisetherton reported no conflict of interest in this study .
the authors sincerely thank devon bordi , marcella smith , tracey banks , dr mosuk chow , and ningtao wang , who provided excellent assistance in the clinical trial implementation and statistical analyses .
 backgroundavocados are a nutrientdense source of monounsaturated fatty acids ( mufa ) that can be used to replace saturated fatty acids ( sfa ) in a diet to lower low density lipoprotein cholesterol ( ldlc ) . 
 wellcontrolled studies are lacking on the effect of avocado consumption on cardiovascular disease ( cvd ) risk factors.methods and resultsa randomized , crossover , controlled feeding trial was conducted with 45 overweight or obese participants with baseline ldlc in the 25th to 90th percentile . 
 three cholesterollowering diets ( 6% to 7% sfa ) were fed ( 5 weeks each ) : a lowerfat diet ( lf : 24% fat ) ; 2 moderatefat diets ( 34% fat ) provided similar foods and were matched for macronutrients and fatty acids : the avocado diet ( av ) included one fresh hass avocado ( 136 g ) per day , and the moderatefat diet ( mf ) mainly used high oleic acid oils to match the fatty acid content of one avocado . compared with baseline , the reduction in ldlc and nonhighdensity lipoprotein ( hdl ) cholesterol on the av diet ( 13.5 mg / dl , 14.6 mg / dl ) was greater ( p<0.05 ) than the mf ( 8.3 mg / dl , 8.7 mg / dl ) and lf ( 7.4 mg / dl , 4.8 mg / dl ) diets . furthermore , only the av diet significantly decreased ldl particle number ( ldlp , 80.1 nmol / l , p=0.0001 ) , small dense ldl cholesterol ( ldl3 + 4 , 4.1 mg / dl , p=0.04 ) , and the ratio of ldl / hdl ( 6.6% , p<0.0001 ) from baseline.conclusionsinclusion of one avocado per day as part of a moderatefat , cholesterollowering diet has additional ldlc , ldlp , and nonhdlc lowering effects , especially for small , dense ldl . 
 our results demonstrate that avocados have beneficial effects on cardiometabolic risk factors that extend beyond their hearthealthy fatty acid profile.clinical trial registrationurl : http://www.clinicaltrials.gov . 
 unique identifier : nct01235832 . 
Clinical Trial Registration
Introduction
Methods
Study Protocol
Participants
Laboratory Measurements
Statistical Analyses
Results
Discussion
Conclusion
Author Contributions
Acknowledgments