RESUMEN
BACKGROUND: There is convincing evidence that replacing dietary saturated fats with polyunsaturated fats (PUFA) decreases risk of cardiovascular diseases. Therefore, PUFA rich foods such as vegetable oils, fatty fish, and marine omega-3 supplements are recommended. However, PUFA are easily oxidizable and there is concern about possible negative health effects from intake of oxidized lipids. Little is known about the degree of lipid oxidation in such products. OBJECTIVE: To assess the content of lipid oxidation products in a large selection of vegetable oils and marine omega-3 supplements available in Norway. Both fresh and heated vegetable oils were studied. DESIGN: A large selection of commercially available vegetable oils and marine omega-3 supplements was purchased from grocery stores, pharmacies, and health food stores in Norway. The content of lipid oxidation products were measured as peroxide value and alkenal concentration. Twelve different vegetable oils were heated for a temperature (225°C) and time (25 minutes) resembling conditions typically used during cooking. RESULTS: The peroxide values were in the range 1.04-10.38 meq/kg for omega-3 supplements and in the range 0.60-5.33 meq/kg for fresh vegetable oils. The concentration range of alkenals was 158.23-932.19 nmol/mL for omega-3 supplements and 33.24-119.04 nmol/mL for vegetable oils. After heating, a 2.9-11.2 fold increase in alkenal concentration was observed for vegetable oils. CONCLUSIONS: The contents of hydroperoxides and alkenals in omega-3 supplements are higher than in vegetable oils. After heating vegetable oils, a large increase in alkenal concentration was observed.
RESUMEN
OBJECTIVE: To evaluate whether our current practice of giving iron 18 mg daily to 6-week-old infants with very low birth weight (VLBW) was associated with increased oxidative stress markers or decreased antioxidant status. STUDY DESIGN: The study was a prospective observational study of 21 healthy VLBW infants (born at gestational age <32 weeks, birth weight <1500 g). Blood and urine were sampled twice before starting iron supplementation at 6 weeks postnatal age and after 1 week of iron supplementation at age 7 weeks. Urine 8-isoprostane was analyzed by gas chromatography-mass spectrometry and plasma total hydroperoxides were measured. Antioxidant status was assessed by ascorbic acid (vitamin C), alpha-tocopherol (vitamin E), ferric-reducing ability of plasma, and plasma glutathione. RESULTS: After 1 week of iron supplementation, no significant changes in urine 8-isoprostane or plasma total hydroperoxides were seen, and plasma antioxidants were largely unchanged. CONCLUSIONS: Markers of oxidative stress in urine and plasma antioxidant status in healthy VLBW infants fed human milk remained unchanged after high-dose oral iron supplementation.