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United States Department of Agriculture

Agricultural Research Service

Research Project: DIET AND BIOMARKERS OF CARDIOVASCULAR HEALTH Title: Long-term fatty acid stability in human serum cholesteryl ester, triglyceride, and phospholipid fractions

Authors
item Matthan, Nirupa -
item Ip, Blanche -
item Resteghini, Nancy -
item Ausman, Lynne -
item Lichtenstein, Alice -

Submitted to: Journal of Lipid Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 6, 2010
Publication Date: September 5, 2010
Citation: Matthan, N.R., Ip, B., Resteghini, N., Ausman, L., Lichtenstein, A.H. 2010. Long-term fatty acid stability in human serum cholesteryl ester, triglyceride, and phospholipid fractions. Journal of Lipid Research. 51:2826-2832.

Interpretive Summary: The fatty acid profiles of various biological specimens that are collected and stored from epidemiological/clinical studies are increasingly being used to determine the relationship between types of fat consumed in the diet and risk of cardiovascular disease (CVD). While it is recommended that analysis be performed on fresh or recently collected samples, most studies collect and store blood samples for subsequent analysis. Data is limited and inconsistent regarding the stability of fatty acids in these samples. This is important because the reliability of the analysis affects the validity of the conclusions drawn and subsequently the association with CVD risk. To address this, we measured the fatty acid profile of previously unthawed serum samples from 22 subjects who participated in a controlled feeding trial. Initial analysis was performed after trial completion, with the repeat analysis after 8-10 years of storage, using gas chromatography. No significant differences were observed among the majority of fatty acids. When differences were identified, they were limited to low abundance fatty acids. These differences were quantitatively small and likely attributable to technical improvements in methodology rather than sample degradation. Thus, our findings suggest that serum fatty acid profiles generated from samples collected up to 10 years prior to analysis and stored at -80 degrees C yield reliable data that may be useful in establishing dietary fat-disease relationships.

Technical Abstract: Fatty acid profiles of biological specimens from epidemiological/clinical studies can serve as biomarkers to assess potential relationships between diet and chronic disease risk. However, data are limited regarding fatty acid stability of archived specimens following long-term storage, a variable that could impact result validity. Our objective was to determine the effect of prolonged storage at -80 degrees C on the fatty acid profiles of serum cholesteryl ester (CE), triglyceride (TG) and phospholipid (PL) fractions. This was accomplished by determining the fatty acid profile of previously unthawed serum samples from 22 subjects who participated in a controlled feeding trial. Initial analysis was performed after trial completion and the repeat analysis after 8-10 years of storage, using gas chromatography (GC). No significant differences were observed among the majority of fatty acids, regardless of lipid fraction. Reliability coefficients were high for the fatty acid classes. When differences were identified, they were limited to low abundance fatty acids, less than or equal to 1.5 mol%. These differences were quantitatively small and likely attributable to technical improvements in GC methodology rather than sample degradation. Thus, our data demonstrate that storage at -80 degrees C up to 10 years does not significantly influence serum CE, TG or PL fatty acid profiles.

Last Modified: 10/22/2014
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