The measurement of F ₂ -isoprostanes by methods utilizing mass spectrometry is widely regarded as the best currently available biomarker of lipid peroxidation. F ₂ -isoprostanes and their metabolites can be measured accurately in plasma, urine, and other body fluids using mass spectrometric techniques, and detailed protocols have been published in several papers. However, many clinical studies and intervention studies with diets or supplements, have employed single “spot” measurements of F ₂ -isoprostanes on either plasma/serum or urine to estimate “oxidative stress.” This review examines the validity of the common assumption that plasma and urinary F ₂ -isoprostane measurements are equivalent. It identifies scenarios where they may not be and where “spot” measurements can be misleading, with examples from the literature. We also discuss the controversial issue of whether and how F ₂ -isoprostane levels in plasma should be standardized against lipids, and, if so, which lipids to use. Antioxid. Redox Signal. 13, 145–156.

Lutein is one of the few xanthophyll carotenoids that is found in high concentration in the macula of human retina. As de novo synthesis of lutein within the human body is impossible, lutein can only be obtained from diet. It is a natural substance abundant in egg yolk and dark green leafy vegetables. Many basic and clinical studies have reported lutein’s anti-oxidative and anti-inflammatory properties in the eye, suggesting its beneficial effects on protection and alleviation of ocular diseases such as age-related macular degeneration, diabetic retinopathy, retinopathy of prematurity, myopia, and cataract. Most importantly, lutein is categorized as Generally Regarded as Safe (GRAS), posing minimal side-effects upon long term consumption. In this review, we will discuss the chemical structure and properties of lutein as well as its application and safety as a nutritional supplement. Finally, the effects of lutein consumption on the aforementioned eye diseases will be reviewed.