Circulating biomarkers of dairy fat and risk of incident stroke in U.S. men and women in 2 large prospective cohorts. Biomarkers of Dairy Fatty Acids and Risk of Cardiovascular Disease in the Multi‐Ethnic Study of Atherosclerosis Differential oxidation of individual dietary fatty acids in humans. trans-Fatty Acid Isomers in Adipose Tissue Have Divergent Associations with Adiposity in Humans Plasma phospholipid trans fatty acids and risk of heart failure. Plasma phospholipid and dietary fatty acids as predictors of type 2 diabetes: interpreting the role of linoleic acid. Relation between the intake of milk fat and the occurrence of conjugated linoleic acid in human adipose tissue. Odd-chain fatty acids as a biomarker for dietary fiber intake: a novel pathway for endogenous production from propionate. Impact of myristic acid versus palmitic acid on serum lipid and lipoprotein levels in healthy women and men. Plasma phospholipid pentadecanoic acid, EPA, and DHA, and the frequency of dairy and fish product intake in young children Uses and misuses of the STROBE statement: bibliographic study Correlation Between Serum Phospholipid Fatty Acids and Dietary Intakes Assessed a Few Years Earlier Evaluation of the Relative Concentration of Serum Fatty Acids C14:0, C15:0 and C17:0 as Markers of Children's Dairy Fat Intake Dairy product consumption and risk of type 2 diabetes in an elderly Spanish Mediterranean population at high cardiovascular risk Circulating Biomarkers of Dairy Fat and Risk of Incident Diabetes Mellitus Among Men and Women in the United States in Two Large Prospective Cohorts ω-3 Polyunsaturated Fatty Acid Biomarkers and Coronary Heart Disease: Pooling Project of 19 Cohort Studies. Serum pentadecanoic acid (15:0), a short-term marker of dairy food intake, is inversely associated with incident type 2 diabetes and its underlying disorders.
BACKGROUND Previous observational studies of self-reported dairy product consumption and stroke risk have reported mixed findings . Few studies have used circulating biomarkers that provide objective measures of dairy fat intake . OBJECTIVES We tested the hypothesis that the circulating biomarkers of dairy fat , pentadecanoic acid ( 15:0 ) , heptadecanoic acid ( 17:0 ) , and trans palmitoleate ( trans 16:1n-7 ) , were associated with lower incidence of stroke , especially ischemic stroke . Secondarily , we evaluated 14:0 , which is obtained from dairy products and beef , and also endogenously synthesized . DESIGN In participants from 2 large US cohorts ( the Health Professionals Follow-Up Study : 51,529 men ; the Nurses ' Health Study : 121,700 women ) with stored blood sample s in 1993 - 1994 ( n = 18,225 ) and 1989 - 1990 ( n = 32,826 ) , respectively , we prospect ively identified 594 incident stroke cases ( median follow-up : 8.3 y ) and matched them 1:1 to risk-set- sample d control subjects by age , sex , race , and smoking . Total plasma and red blood cell ( RBC ) fatty acids were measured by using gas-liquid chromatography . Covariates were assessed by using vali date d question naires . Stroke events and subtypes were adjudicated by using medical records or other supporting documentation . We used conditional logistic regression to estimate associations of fatty acids with incident stroke , and cohort-specific findings were combined by inverse-variance weights . RESULTS After adjustment for demographic characteristics , lifestyle , cardiovascular disease risk factors , diet , and other circulating fatty acids , no significant associations with total stroke were seen for plasma 15:0 ( pooled HR for highest compared with lowest quartiles : 0.85 ; 95 % CI : 0.54 , 1.33 ) , 17:0 ( 0.99 ; 0.67 , 1.49 ) , trans 16:1 n-7 ( 0.89 ; 0.55 , 1.45 ) , or 14:0 ( 1.05 ; 0.62 , 1.78 ) . Results were similar for ischemic and hemorrhagic stroke subtypes , for RBC fatty acids , and in several different sensitivity analyses . CONCLUSION In 2 large prospect i ve cohorts , circulating biomarkers of dairy fat were not significantly associated with stroke Background Evidence regarding the role of dairy fat intake in  cardiovascular disease (  CVD ) has been mixed and inconclusive . Most earlier studies have used self‐reported measures of dietary intake and focused on relatively racially homogeneous population s. Circulating biomarkers of dairy fat in a multiethnic cohort provide objective measures of dairy fat intake and facilitate conclusions relevant to population s with different diets and susceptibility to CVD . Methods and Results In a multiethnic cohort of 2837 US adults aged 45 to 84 years at baseline ( 2000–2002 ) , phospholipid fatty acids including 15:0 , 14:0 , and trans‐16:1n7 were measured using st and ardized methods , and the incidence of CVD prospect ively adjudicated . Self‐reported whole‐fat dairy and butter intakes had strongest associations with 15:0 , rather than 14:0 or trans‐16:1n7 . In multivariate models including demographics and lifestyle and dietary habits , each SD‐unit of 15:0 was associated with 19 % lower CVD risk ( hazard ratio [ 95 % CI ] 0.81 [ 0.68 to 0.98 ] ) and 26 % lower coronary heart disease ( CHD ) risk ( 0.74 [ 0.60 to 0.92 ] ) . Associations were strengthened after mutual adjustment for 14:0 and trans‐16:1n‐7 and were similar after adjustment for potential mediators . Plasma phospholipid 14:0 and trans‐16:1n‐7 were not significantly associated with incident CVD or CHD . All findings were similar in white , black , Hispanic , and Chinese American participants .  Conclusion Plasma phospholipid 15:0 , a biomarker of dairy fat , was inversely associated with incident CVD and CHD , while no association was found with phospholipid 14:0 and trans‐16:1n‐7 . These findings support the need for further investigation of CVD effects of dairy fat , dairy‐specific fatty acids , and dairy products in general BACKGROUND Dietary fatty acids that are more prone to oxidation than to storage may be less likely to lead to obesity . OBJECTIVE The aim of this study was to determine the effect of chain length , degree of unsaturation , and stereoisomeric effects of unsaturation on the oxidation of individual fatty acids in normal-weight men . DESIGN Fatty acid oxidation was examined in men consuming a weight-maintenance diet containing 40 % of energy as fat .  After consuming the diet for 1 wk , subjects were fed fatty acids labeled with (13)C in the methyl or carboxyl position ( 10 mg/kg body wt ) . The fatty acids fed in r and om order were laurate , palmitate , stearate , oleate , elai date ( the trans isomer of oleate ) , linoleate , and linolenate blended in a hot liquid meal . Breath sample s were collected for the next 9 h and the oxidation of each fatty acid was assessed by examining liberated (13)CO(2 ) in breath . RESULTS Cumulative oxidation over the 9-h test ranged from a high of 41 % of the dose for laurate to a low of 13 % of the dose for stearate . Of the 18-carbon fatty acids , linolenate was the most highly oxidized and linoleate appeared to be somewhat conserved . (13)C recovery in breath from the methyl-labeled fatty acids was approximately 30 % less than that from the carboxyl-labeled fatty acids . CONCLUSIONS In summary , lauric acid is highly oxidized , whereas the polyunsaturated and monounsaturated fatty acids are fairly well oxidized . Oxidation of the long-chain , saturated fatty acids decreases with increasing carbon number The aim of this study was to evaluate the association between adipose tissue trans-fatty acid isomers and  adiposity .  This cross-sectional study included 1,785 subjects from Costa Rica . Fatty acid concentrations ( as a percentage of the total fatty acids ) in subcutaneous adipose tissue were assessed by gas – liquid chromatography . Dietary intakes were assessed with a food frequency question naire . Multivariate linear regression models were used to relate adipose tissue trans-fatty acid content to BMI , waist circumference , and skinfold thickness while adjusting for age , sex , and area of residence . To account for variations in lifestyle , we adjusted for smoking , physical activity , income , self-reported history of diabetes and hypertension , and for adipose tissue alpha-linolenic acid and energy intake in a third model . After adjustments , positive associations were found between 18:2t-fatty acids ( primarily from partially hydrogenated oils ) and BMI , waist circumference , and skinfold thickness ( P for each association < 0.01 ) . Rumenic acid was positively associated with skinfold thickness ( P < 0.0001 ) , but not with BMI or waist circumference ( P > 0.05 ) . Inverse associations were found between 16:1n-7t-fatty acids and skinfold thickness and between 18:1t-fatty acids and BMI and waist circumference ( P < 0.0001 ) . This study suggests that individual trans-fatty acid isomers may have divergent effects on adiposity . 18:2t-fatty acids show consistent positive associations with measures of adiposity . These isomer-specific associations are an interesting new finding . Other prospect i ve and intervention studies are necessary to examine these relationships further BACKGROUND Although trans fatty acids ( TFAs ) may increase the risk of dyslipidemia and coronary artery disease ( CAD ) , limited data are available on their association with heart failure ( HF ) . OBJECTIVE Our goal was to assess associations of plasma and dietary TFAs with HF and CAD . DESIGN We used a prospect i ve , nested case-control design to select 788 incident HF cases and 788 matched controls from the Physicians ' Health Study for biomarker analyses and a prospect i ve cohort for the dietary analyses .  Plasma fatty acids were assessed by using gas chromatography , and dietary intake was estimated by using a food-frequency question naire . Self-reported HF was ascertained by using annual follow-up question naires with validation in a sub sample . We used conditional logistic ( or Cox ) regression to estimate multivariable-adjusted ORs ( or HRs ) for HF and CAD . RESULTS Multivariable-adjusted ORs ( 95 % CIs ) for HF across consecutive quintiles of plasma trans 18:2 ( linoleic acid ) fatty acids were 1.0 ( reference ) , 1.10 ( 0.79 , 1.54 ) , 0.88 ( 0.62 , 1.25 ) , 0.71 ( 0.49 , 1.02 ) , and 0.67 ( 0.45 , 0.98 ) ( P-trend = 0.01 ) . Each SD of plasma trans 18:2 was associated with a 22 % lower risk of HF ( 95 % CI : 6 % , 36 % ) . Plasma trans 16:1 and 18:1 were not associated with risk of HF ( P > 0.05 ) . Dietary trans fats were not associated with incident HF or CAD . CONCLUSIONS Our data are consistent with a lower risk of HF with higher concentrations of plasma trans 18:2 but not with trans 16:1 or trans 18:1 fatty acids in male physicians .  Dietary TFAs were not related to incident HF or CAD BACKGROUND Dietary fatty acids may be associated with diabetes but are difficult to measure accurately . OBJECTIVE We aim ed to investigate the associations of fatty acids in plasma and diet with diabetes incidence . DESIGN This was a prospect i ve case-cohort study of 3737 adults aged 36 - 72 y.  Fatty acid intake ( /kJ ) and plasma phospholipid fatty acids ( % ) were measured at baseline , and diabetes incidence was assessed by self-report 4 y later . Logistic regression excluding ( model 1 ) and including ( model 2 ) body mass index and waist-hip ratio was used to calculate odds ratios ( ORs ) for plasma phospholipid and dietary fatty acids . RESULTS In plasma phospholipid , positive associations with diabetes were seen for stearic acid [ OR model 1 , highest versus lowest quintile : 4.14 ( 95 % CI : 2.65 , 6.49 ) , P for trend < 0.0001 ] and total saturated fatty acids [ OR model 1 : 3.76 ( 2.43 , 5.81 ) , P for trend < 0.0001 ] , whereas an inverse association was seen for linoleic acid [ OR model 1 : 0.22 ( 0.14 , 0.36 ) , P for trend < 0.0001 ] . Dietary linoleic [ OR model 1 : 1.77 ( 1.19 , 2.64 ) , P for trend = 0.002 ] , palmitic [ OR model 1 : 1.65 ( 1.12 , 2.43 ) , P for trend = 0.012 ] , and stearic [ OR model 1 : 1.46 ( 1.00 , 2.14 ) , P for trend = 0.030 ] acids were positively associated with diabetes incidence before adjustment for body size . Within each quintile of linoleic acid intake , cases had lower baseline plasma phospholipid linoleic acid proportions than did controls . CONCLUSIONS Dietary saturated fat intake is inversely associated with diabetes risk . More research is required to determine whether linoleic acid is an appropriate dietary substitute BACKGROUND Conjugated linoleic acid ( CLA ) is a group of naturally occurring fatty acids mainly present in fats from ruminants . CLA has been shown to be a potential anticarcinogen . OBJECTIVE In this study , the relation between bovine milk fat intake and the occurrence of CLA in human adipose tissue was investigated . DESIGN One hundred twenty-three men weighed and recorded the foods they consumed for 1 wk . Afterward , recall interviews were conducted by telephone monthly for 7 consecutive months to inquire about food consumption during the previous 24 h. The entire dietary recording procedure was repeated once . The fatty acid composition of adipose tissue and serum was analyzed . RESULTS The average amount of one isomer of CLA--9-cis,11-trans-octadecadienoic acid (9c,11t-18:2)--as a percentage of total fatty acids was found to be 0.50 % in adipose tissue and 0.25 % in serum . The amount of 9c,11t-18:2 in adipose tissue was significantly correlated with milk fat intake ( r = 0.42 ) . The percentage of 9c,11t-18:2 in both adipose tissue and in serum was strongly correlated with myristoleic acid ( 14:1 ) . CONCLUSION The amount of 9c,11t-18:2 in human adipose tissue was significantly related to milk fat intake Background : The risk of type 2 diabetes is inversely correlated with plasma concentrations of odd-chain fatty acids [ OCFAs ; pentadecanoic acid ( 15:0 ) and heptadecanoic acid ( 17:0 ) ] , which are considered as biomarkers for dairy fat intake in humans . However , rodent studies suggest that OCFAs are synthesized endogenously from gut-derived propionate . Propionate increases with dietary fiber consumption and has been shown to improve insulin sensitivity . Objective : We hypothesized that OCFAs are produced in humans from dietary fibers by a novel endogenous pathway . Design : In a r and omized , double-blind crossover study , 16 healthy individuals were supplemented with cellulose ( 30 g/d ) , inulin ( 30 g/d ) , or propionate ( 6 g/d ) for 7 d. In addition , human hepatoma cells were incubated with different propionate concentrations . OCFAs were determined in plasma phospholipids and hepatoma cells by gas chromatography . Results : Cellulose did not affect plasma OCFA levels , whereas inulin and propionate increased pentadecanoic acid by ∼17 % ( P < 0.05 ) and 13 % ( P = 0.05 ) , respectively . The effect on heptadecanoic acid was even more pronounced , because it was elevated in almost all participants by inulin ( 11 % ; P < 0.01 ) and propionate ( 13 % ; P < 0.001 ) . Furthermore , cell culture experiments showed a positive association between propionate and OCFA levels ( R2 = 0.99 , P < 0.0001 ) , whereas palmitate ( 16:0 ) was negatively correlated ( R2 = 0.83 , P = 0.004 ) . Conclusions : Our data show that gut-derived propionate is used for the hepatic synthesis of OCFAs in humans . The association of OCFAs with a decreased risk of type 2 diabetes  may therefore also relate to dietary fiber intake and not only dairy fat . This trial was registered at www.germanctr.de as DRKS00010121 The cholesterol-raising effect of dietary saturated fatty acids is largely accounted for by lauric , myristic , and palmitic acids . Dairy fat is a major source of myristic acid , and palm oil is especially rich in palmitic acid . Myristic acid is suspected of being much more cholesterolemic than palmitic acid , but direct comparisons have been lacking . We therefore fed 36 women and 23 men three diets that differed from each other in palmitic , oleic , and myristic acid content by about 10 % of total energy . We used palm oil , high-oleic acid sunflower oil , and a specially produced high-myristic acid fat to achieve these differences . Each diet was consumed for 3 weeks in r and om order . Mean serum cholesterol was 4.53 mmol/L on the high-oleic acid diet , 4.96 mmol/L on the palmitic acid diet , and 5.19 mmol/L on the myristic acid diet ( P < .0001 for all comparisons ) . Myristic acid raised low-density lipoprotein ( LDL ) cholesterol by 0.11 mmol/L , high-density lipoprotein ( HDL ) cholesterol by 0.12 mmol/L , and apolipoprotein ( apo ) A-I by 7.2 mg/dL relative to palmitic acid ; increases relative to oleic acid were 0.50 mmol/L for LDL cholesterol , 0.15 mmol/L for HDL cholesterol , 6.0 mg/dL for apoB , and 8.9 mg/dL for apoA-I ( P < .01 for all comparisons ) . The HDL cholesterol and apoA-I levels on the palmitic and oleic acid diets were the same . None of the responses differed significantly between woman and men . Myristic acid and palmitic acid both caused high LDL cholesterol and apoB levels and low HDL to LDL ratios . ( ABSTRACT TRUNCATED AT 250 WORDS Background There is a lack of studies comparing dietary assessment methods with the biomarkers of fatty acids in children . Objective The objective was to evaluate the suitability of a food frequency question naire ( FFQ ) to rank young children according to their intake of dairy and fish products by comparing food frequency estimates to the plasma phospholipid fatty acids pentadecanoic acid , eicosapentaenoic acid ( EPA ) , and docosahexaenoic acid ( DHA ) . Design Cross-sectional data for the present study were derived from the prospect i ve cohort ‘ Environmental Triggers of Type 1 Diabetes Study ’ . Infants were recruited from the Norwegian general population during 2001–2007 . One hundred and ten ( age 3–10 years ) children had sufficient volumes of plasma and FFQ filled in within 2 months from blood sampling and were included in this evaluation study . The quantitative determination of plasma phospholipid fatty acids was done by fatty acid methyl ester analysis . The association between the frequency of dairy and fish product intake and the plasma phospholipid fatty acids was assessed by a Spearman correlation analysis and by investigating whether participants were classified into the same quartiles of distribution . Results Significant correlations were found between pentadecanoic acid and the intake frequency of total dairy products ( r=0.29 ) , total fat dairy products ( r=0.39 ) , and cheese products ( r=0.36 ) . EPA and DHA were significantly correlated with the intake frequency of oily fish ( r=0.26 and 0.37 , respectively ) and cod liver/fish oil supplements ( r=0.47 for EPA and r=0.50 DHA ) . To a large extent , the FFQ was able to classify individuals into the same quartile as the relevant fatty acid biomarker . Conclusions The present study suggests that , when using the plasma phospholipid fatty acids pentadecanoic acid , EPA , and DHA as biomarkers , the FFQ used in young children showed a moderate capability to rank the intake frequency of dairy products with a high-fat content and cod liver/fish oil supplements Objectives Appropriate reporting is central to the application of findings from research to clinical practice . The Strengthening the Reporting of Observational Studies in Epidemiology ( STROBE ) recommendations consist of a checklist of 22 items that provide guidance on the reporting of cohort , case – control and cross-sectional studies , in order to facilitate critical appraisal and interpretation of results . STROBE was published in October 2007 in several journals including The Lancet , BMJ , Annals of Internal Medicine and PLoS Medicine . Within the framework of the revision of the STROBE recommendations , the authors examined the context and circumstances in which the STROBE statement was used in the past . Design The authors search ed the Web of Science data base in August 2010 for articles which cited STROBE and examined a r and om sample of 100 articles using a st and ardised , piloted data extraction form . The use of STROBE in observational studies and systematic review s ( including meta-analyses ) was classified as appropriate or inappropriate . The use of STROBE to guide the reporting of observational studies was considered appropriate . Inappropriate uses included the use of STROBE as a tool to assess the method ological quality of studies or as a guideline on how to design and conduct studies . Results The authors identified 640 articles that cited STROBE . In the r and om sample of 100 articles , about half were observational studies ( 32 % ) or systematic review s ( 19 % ) . Comments , editorials and letters accounted for 15 % , method ological articles for 8 % , and recommendations and narrative review s for 26 % of articles . Of the 32 observational studies , 26 ( 81 % ) made appropriate use of STROBE , and three uses ( 10 % ) were considered inappropriate . Among 19 systematic review s , 10 ( 53 % ) used STROBE inappropriately as a tool to assess study quality . Conclusions The STROBE reporting recommendations are frequently used inappropriately in systematic review s and meta-analyses as an instrument to assess the method ological quality of observational studies The fatty acid composition of serum phospholipids has been shown to reflect dietary intakes in the previous weeks or months . However , how serum phospholipids relate to fatty acid intakes over a few years has hardly been examined . We design ed a cross-sectional study within the E3N cohort , the French component of the European Prospect i ve Investigation into Cancer and Nutrition in which female participants completed a 208-item diet history question naire in 1993–1995 and provided blood sample s in 1995–1998 . The study included 1,114 women who were free of cancer at the time of blood collection .  Serum phospholipid fatty acid composition was assessed by capillary gas chromatography . Partial Spearman correlations adjusted for age and body mass index showed weak to moderate , although statistically significant , positive associations between dietary and serum oleic , linoleic , arachidonic , eicosapentaenoic , and docosahexaenoic acids . Moreover , serum oleic acid was directly associated with olive oil , linoleic acid with sunflower oil , pentadecanoic acid with dairy products , long-chain n-3 fatty acids with fatty fish , and trans-monounsaturated fatty acids with manufactured foods . In conclusion , serum phospholipid pentadecanoic acid , oleic , trans-monounsaturated , and polyunsaturated fatty acids are suitable biomarkers for usual dietary intakes , although the association may weaken as the time lag between dietary assessment and blood collection increases Background / Aims : Biomarkers can provide objective measures of dietary exposure , but their relationship with dietary intake in different population s needs to be characterized . This study aim ed to determine the association between C14:0 , C15:0 and C17:0 and  children 's dairy fat intake  , and to ascertain whether these fatty acids can be used as biomarkers for detecting change in dairy fat intake . Methods : Data from a r and omized controlled trial ( 114 healthy children of 4 - 13 years of age ) was used . The intervention was a replacement of regular-fat dairy foods with reduced-fat or low-fat items .  Serum fatty acid composition was measured and dairy intake was assessed via 3 × 24-hour diet recalls at baseline and at 12 weeks ( the end of the intervention ) . Correlation analysis was used to evaluate the relationship between dietary intake and fatty acids at baseline and at week 12 , and for the change in biomarkers and diet between these time points . Results : Total dairy fat intake correlated with C14:0 , C15:0 and C17:0 at baseline ( n = 114 ; r = 0.24 ; r = 0.42 ; r = 0.25 respectively , all p < 0.05 ) , but not at week 12 . The change in the total amount of dairy fat ( g/day ) after 12 weeks was associated with a change in serum C15:0 ( n = 59 ; r = 0.27 ; p = 0.04 ) . Conclusions : C15:0 is a useful biomarker of dairy fat intake in children and can detect short-term changes in the absolute intake of dairy fat Abstract Purpose The possible effects of dairy consumption on diabetes prevention remain controversial . The aim of this study was to investigate the association between the dairy consumption and  type 2 diabetes ( T2D ) risk  in an elderly Mediterranean population at high cardiovascular risk . Methods We prospect ively followed 3,454 non-diabetic individuals from the PREDIMED study .  Dairy consumption was assessed at baseline and yearly using food frequency question naires and categorized into total , low-fat , whole-fat , and subgroups : milk , yogurt , cheeses , fermented dairy , concentrated full fat , and processed dairy .  Hazard ratios ( HRs ) were calculated using Cox proportional hazards regression models . Results During a median follow-up of 4.1 years , we documented 270 incident T2D cases . After multivariate adjustment , total dairy product consumption was inversely associated with T2D risk [ 0.68 ( 95 % CI 0.47–0.98 ) ; P-trend = .040 ] . This association appeared to be mainly attributed to low-fat dairy ; the multivariate HRs ( 95 % CIs ) comparing the highest versus the lowest tertile consumption were 0.65 ( 0.45–0.94 ) for low-fat dairy products and 0.67 ( 0.46–0.95 ) for low-fat milk ( both P-trend < .05 ) . Total yogurt consumption was associated with a lower T2D risk [ HR 0.60 ( 0.42–0.86 ) ; P-trend = .002 ] . An increased consumption of total low-fat dairy and total yogurt during the follow-up was inversely associated with T2D ; HRs were 0.50 ( 0.29–0.85 ) , 0.44 ( 0.26–0.75 ) , and 0.55 ( 0.33–0.93 ) , respectively . Substituting one serving/day of a combination of biscuits and chocolate and whole grain biscuits and homemade pastries for one serving/day of yogurt was associated with a 40 and 45 % lower risk of T2D , respectively . No significant associations were found for the other dairy subgroups ( cheese , concentrated full fat , and processed dairy products ) . Conclusions A healthy dietary pattern incorporating a high consumption of dairy products and particularly yogurt may be protective against T2D in older adults at high cardiovascular risk Background — In prospect i ve studies , the relationship of self-reported consumption of dairy foods with risk of diabetes mellitus is inconsistent . Few studies have assessed dairy fat , using circulating biomarkers , and incident diabetes mellitus . We tested the hypothesis that circulating fatty acid biomarkers of dairy fat , 15:0 , 17:0 , and t-16:1n-7 , are associated with lower incident diabetes mellitus . Methods and Results — Among 3333 adults aged 30 to 75 years and free of prevalent diabetes mellitus at baseline , total plasma and erythrocyte fatty acids were measured in blood collected in 1989 to 1990 ( Nurses ’ Health Study ) and 1993 to 1994 ( Health Professionals Follow-Up Study ) . Incident diabetes mellitus through 2010 was confirmed by a vali date d supplementary question naire based on symptoms , diagnostic tests , and medications . Risk was assessed by using Cox proportional hazards , with cohort findings combined by meta- analysis . During mean±st and ard deviation follow-up of 15.2±5.6 years , 277 new cases of diabetes mellitus were diagnosed . In pooled multivariate analyses adjusting for demographics , metabolic risk factors , lifestyle , diet , and other circulating fatty acids , individuals with higher plasma 15:0 had a 44 % lower risk of diabetes mellitus ( quartiles 4 versus 1 , hazard ratio , 0.56 ; 95 % confidence interval , 0.37–0.86 ; P-trend=0.01 ) ; higher plasma 17:0 , 43 % lower risk ( hazard ratio , 0.57 ; 95 % confidence interval , 0.39–0.83 ; P-trend=0.01 ) ; and higher t-16:1n-7 , 52 % lower risk ( hazard ratio , 0.48 ; 95 % confidence interval , 0.33–0.70 ; P-trend < 0.001 ) . Findings were similar for erythrocyte 15:0 , 17:0 , and t-16:1n-7 , although with broader confidence intervals that only achieved statistical significance for 17:0 . Conclusions — In 2 prospect i ve cohorts , higher plasma dairy fatty acid concentrations were associated with lower incident diabetes mellitus . Results were similar for erythrocyte 17:0 . Our findings highlight the need to better underst and the potential health effects of dairy fat , and the dietary and metabolic determinants of these fatty acids IMPORTANCE The role of ω-3 polyunsaturated fatty acids for primary prevention of coronary heart disease ( CHD ) remains controversial . Most prior longitudinal studies evaluated self-reported consumption rather than biomarkers . OBJECTIVE To evaluate biomarkers of seafood-derived eicosapentaenoic acid ( EPA ; 20:5ω-3 ) , docosapentaenoic acid ( DPA ; 22:5ω-3 ) , and docosahexaenoic acid ( DHA ; 22:6ω-3 ) and plant-derived α-linolenic acid ( ALA ; 18:3ω-3 ) for incident CHD . DATA SOURCES A global consortium of 19 studies identified by November 2014 . STUDY SELECTION Available prospect i ve ( cohort , nested case-control ) or retrospective studies with circulating or tissue ω-3 biomarkers and ascertained CHD . DATA EXTRACTION AND SYNTHESIS Each study conducted st and ardized , individual-level analysis using harmonized models , exposures , outcomes , and covariates . Findings were central ly pooled using r and om-effects meta- analysis . Heterogeneity was examined by age , sex , race , diabetes , statins , aspirin , ω-6 levels , and FADS desaturase genes . MAIN OUTCOMES AND MEASURES Incident total CHD , fatal CHD , and nonfatal myocardial infa rct ion ( MI ) . RESULTS The 19 studies comprised 16 countries , 45 637 unique individuals , and 7973 total CHD , 2781 fatal CHD , and 7157 nonfatal MI events , with ω-3 measures in total plasma , phospholipids , cholesterol esters , and adipose tissue . Median age at baseline was 59 years ( range , 18 - 97 years ) , and 28 660 ( 62.8 % ) were male . In continuous ( per 1-SD increase ) multivariable-adjusted analyses , the ω-3 biomarkers ALA , DPA , and DHA were associated with a lower risk of fatal CHD , with relative risks ( RRs ) of 0.91 ( 95 % CI , 0.84 - 0.98 ) for ALA , 0.90 ( 95 % CI , 0.85 - 0.96 ) for DPA , and 0.90 ( 95 % CI , 0.84 - 0.96 ) for DHA . Although DPA was associated with a lower risk of total CHD ( RR , 0.94 ; 95 % CI , 0.90 - 0.99 ) , ALA ( RR , 1.00 ; 95 % CI , 0.95 - 1.05 ) , EPA ( RR , 0.94 ; 95 % CI , 0.87 - 1.02 ) , and DHA ( RR , 0.95 ; 95 % CI , 0.91 - 1.00 ) were not . Significant associations with nonfatal MI were not evident . Associations appeared generally stronger in phospholipids and total plasma . Restricted cubic splines did not identify evidence of nonlinearity in dose responses . CONCLUSIONS AND RELEVANCE On the basis of available studies of free-living population s globally , biomarker concentrations of seafood and plant-derived ω-3 fatty acids are associated with a modestly lower incidence of fatal CHD BACKGROUND Growing evidence suggests that dairy consumption is associated with lower  type 2 diabetes risk .  However , observational studies have reported inconsistent results , and few have examined dairy 's association with the underlying disorders of insulin resistance and β-cell dysfunction . OBJECTIVE We investigated the association of the dairy fatty acid biomarkers pentadecanoic acid ( 15:0 ) and trans-palmitoleic acid ( trans 16:1n-7 ) with type 2 diabetes traits by evaluating 1 ) prospect i ve associations with incident diabetes after 5 y of follow-up and 2 ) cross-sectional associations with directly measured insulin resistance and β-cell dysfunction . DESIGN The study analyzed 659 adults without diabetes at baseline from the triethnic multicenter Insulin Resistance Atherosclerosis Study ( IRAS ) .  Diabetes status was assessed by using oral-glucose-tolerance tests . Frequently sample d intravenous-glucose-tolerance tests measured insulin sensitivity ( SI ) and β-cell function [ disposition index ( DI ) ] . Serum fatty acids were quantified by using gas chromatography . Logistic and linear regression models were adjusted for demographic , lifestyle , and dietary variables . RESULTS Serum 15:0 was a significant biomarker for total dairy intake in the IRAS cohort . It was associated with a decreased incident diabetes risk ( OR : 0.73 , P = 0.02 ) and was positively associated with log SI ( β : 0.84 , P = 0.03 ) and log DI ( β : 2.21 , P = 0.02 ) in fully adjusted models . trans 16:1n-7 was a marker of total partially hydrogenated dietary fat intake and was not associated with outcomes in fully adjusted models . CONCLUSIONS Serum 15:0 , a marker of short-term intake of this fatty acid , was inversely associated with diabetes risk in this multiethnic cohort . This study may contribute to future recommendations regarding the benefits of dairy products on type 2 diabetes risk
Context Dairy intake in humans is commonly assessed using question naires , but the data collected are often biased .
As a result , there is increasing interest in biomarkers of dairy fat .
To date , there has been no overview of the fatty acids suitable for use as biomarkers of dairy fat intake .
Objective This systematic review and meta- analysis of observational studies was performed to identify circulating fatty acids as biomarkers of total dairy and dairy fat intakes in the general population .