Butylated hydroxytoluene can protect polyunsaturated fatty acids in dried blood spots from degradation for up to 8 weeks at room temperature.

BACKGROUND: Dried blood spots (DBS) from fingertip prick blood can enable high throughput fatty acid profiling but may be prone to lipid peroxidation during storage. The use of butylated hydroxytoluene (BHT) on chromatography paper can prevent polyunsaturated fatty acid (PUFA) loss but examinations on the length of storage times possible are not comprehensive. METHOD: In the first study, venous whole blood was saturated on paper strips pre-soaked with 0, 2.5 or 5.0 mg/mL BHT and exposed to air for up to 28 days. In a second study, the effect of sealing DBS on 5.0 mg/mL BHT-soaked chromatography strips in capped test tubes or vacuum sealed polypropylene bags with and without nitrogen purging was examined over eight weeks. The fatty acid composition of the DBS were determined by gas chromatography and the effect of sample storage on omega-3 biomarkers were examined. RESULTS: PUFA and omega-3 biomarkers in DBS stored without BHT were dramatically reduced by day 3. In general, BHT delayed decreases in eicosapentaenoic + docosahexaenoic acid from baseline (3.2 ± 0.2 wt%) to 28 days (2.6 ± 0.03 wt%) of storage. In the % n-3 highly unsaturated fatty acids (HUFA) in total HUFA biomarker, BHT was more effective at preventing changes, particularly with 5.0 mg/mL BHT where no differences were detected up to 28 days. Sealed storage with BHT tended to increase the stability of the PUFA in DBS and nitrogen purging did not appear to provide additional benefits. The % n-3 HUFA in total HUFA biomarker also appeared to be more stable in the sealed storage study. CONCLUSIONS: The storage of DBS in sealed containers with BHT may prevent PUFA degradation for up to 8 weeks. The % n-3 HUFA in total HUFA biomarker appears to provide a more consistent assessment of omega-3 status throughout storage as compared with other omega-3 blood biomarkers.

Omega-3 polyunsaturated fatty acid profiling using fingertip-prick whole blood does not require overnight fasting before blood collection.

Fatty acid profiling through the rapid analysis of capillary blood collected by fingertip prick could enable economical screening for omega-3 polyunsaturated fatty acid (PUFA) status, although the typical requirement of fasting prior to sample collection may limit application. We hypothesize that moderate changes in omega-3 biomarkers determined from fingertip-prick blood will occur and correspond to omega-3 PUFA content of the meals. Eight participants consumed a single breakfast with high fat, high fat with omega-3 functional foods, and low fat and low fat with fish oil capsules in a cross-over design. The fatty acid composition of fingertip-prick blood total lipid and venous blood erythrocyte total lipid, plasma total lipid, plasma triacylglycerol, and plasma phospholipids were analyzed at baseline and 1, 2, 3 and 4 hours after each single breakfast consumption. Omega-3 blood biomarkers; % of omega-3 highly unsaturated fatty acid (HUFA) in total HUFA, weight % of eicosapentaenoic acid+docosahexaenoic acid, weight % of eicosapentaenoic acid+omega-3 docosapentaenoic acid+docosahexaenoic acid, and the ratio of total omega-6 PUFA to total omega-3 PUFA in fingertip-prick blood, did not change from baseline during the postprandial period (P > .05). However, meal type yielded lower (P < .05) % omega-3 HUFA in total HUFA in the low fat meal (22.8 ± 3.9) as compared with the low fat with omega-3 (24.2 ± 3.9) and, the high fat (23.8 ± 4) meals. The ratio of total omega-6 PUFA to total omega-3 PUFA was generally higher in meals without omega-3 compared with omega-3. In conclusion, determinations of omega-3 status by fingertip-prick blood sampling may not require prior overnight fasting.