Dietary Long‐Chain Fatty Acids and Carbohydrate Biomarkers Evaluation in a Controlled Feeding Study in Participants from the Women's Health Initiative Cohort
Authors: Song Xiaoling , Huang Ying , Neuhouser Marian , Tinker Lesley , Vitolins Mara , Siddique Juned , Prentice Ross , Lampe Johanna 
Published: November 2023

We used an individualized controlled feeding study to assess the utility of serum phospholipid fatty acids (PLFA) as biomarkers of dietary intake of fatty acids, total fat, and carbohydrate. 153 postmenopausal women from the Women's Health Initiative were provided a 2‐wk controlled diet that mimicked each participant's habitual food intake as estimated from 4‐d food records and adjusted for estimated energy requirement using established methods (1; 2). 41 PLFA were measured using gas chromatography in end‐of‐feeding‐period fasting serum samples and expressed in both relative (weight percentage of total) and absolute (μg/ml) concentrations. R2 from linear regression of (ln‐transformed) consumed fatty acids (individual, groups, and broad categories) on (ln‐transformed) corresponding measures of serum PLFA ranged from 0.2% for consumed cis mono‐unsaturated fatty acid (MUFA) 16:1 to 47.1% for poly‐unsaturated fatty acid (PUFA) 22:6 (DHA) when using relative concentration of PLFA as a potential biomarker, and ranged from <0.1% for PUFA 22:5 and % energy from PUFA to 38.3% for PUFA 20:5 (EPA) when using absolute concentration of PLFA. These linear regression models were further enriched by other important participant‐related variables (age, race/ethnicity, BMI, season of study participation, education level, and estimated energy intake from doubly labeled water). EPA and DHA were the only fatty acids that achieved R2 >36% — benchmark set by established urinary recovery biomarkers of energy and protein — with or without additional covariates; incorporation of the additional covariates increased R2 to 46.5% and 50.3% respectively for EPA and DHA using their relative serum PLFA concentrations, and to 41.2% and 39.8% respectively using their absolute serum PLFA concentrations. When all 41 PLFA and the other participant‐related variables were initially included in the selection model, cross‐validated R2 achieved >36% for consumed total carbohydrate (41.6% using relative PLFA concentration and 37.1% using absolute PLFA concentration), total saturated fatty acids (SFA, 39.8% and 39.9%), % energy from SFA (45.2% and 47.2%), and total trans fatty acids (37.5% and 36.4%) with potential PLFA biomarkers in either concentration metric. These serum PLFA biomarkers performed similarly to established energy and protein urinary recovery biomarkers in describing intake variations for several nutrients, and thus appear suitable for application in this population of postmenopausal women. This approach represents an important methodological contribution toward the utilization of nutritional biomarkers to assess macronutrient intake.Support or Funding InformationThis work was supported by National Cancer Institute (NCI) grant R01 CA119171. WHI is supported by National Heart, Lung, and Blood Institute, National Institutes of Health, U.S. Department of Health and Human Services through contracts, HHSN268201100046C (Fred Hutch), HHSN268201100001C (SUNY Buffalo), HHSN268201100002C (The Ohio State University), HHSN268201100003C (Stanford), HHSN268201100004C (Wake Forest), and HHSN271201100004C (WHI Memory Study).
R2 from linear regression models with consumed nutrient as dependent variable. Serum PLFA biomarkers were measured in both relative and absolute concentrations.

wt% serum PLFA
μg/ml serum PLFA

Consumed Nutrient
R2 (%) Model 1
R2 (%) Model 2
Cross‐validated R2 (%) Model 3
R2 (%) Model 1
R2 (%) Model 2
Cross‐validated R2 (%) Model 3

PUFA 20:5 (EPA), g/d
44.1
46.5
na
38.3
41.2
na

PUFA 22:6 (DHA), g/d
47.1
50.3
na
35.0
39.8
na

Total carbohydrate, g/d
na
na
41.6
na
na
37.1

Total SFA, g/d
na
na
39.8
na
na
39.9

% energy from SFA
na
na
45.2
na
na
47.2

Total trans fatty acids, g/d
na
na
37.5
na
na
36.4

PLFA, phospholipid fatty acid; PUFA, poly‐unsaturated fatty acid; SFA, saturated fatty acid; na, not applicable
Model 1 independent variable: corresponding measure of serum PLFA
Model 2 independent variables: corresponding measure of serum PLFA, participant age, race/ethnicity, BMI, season of study participation, education level, and estimated energy intake from doubly labeled water
Model 3 independent variables: all 41 serum PLFA, participant age, race/ethnicity, BMI, season of study participation, education level, and estimated energy intake from doubly labeled water