## 4 Conclusions  
In conclusion, the heating of PUFAs and, to a much lesser extent, MUFAs present in EU-available seed and other CFO products according to high temperature standard frying practices, which predominantly represents the prime purpose for which they are used by consumers, substantially promotes their peroxidation, a process giving rise to the generation of very high levels of cytotoxic and genotoxic aldehydes. The \({}^{1}\)H NMR analysis of these samples, which was also performed for one of the first times on a low-field (60 MHz) benchtop spectrometer, confirmed the thermally promoted, time-dependent production of a range of aldehyde LOPs in all oils investigated, the highest levels being observed in PUFA-rich sunflower or corn oils. Lower quantities of these LOPs were formed in monounsaturated fatty acid (MUFA)-rich canola and extra-virgin olive oils, and their generation was preceded by one or more significant lag phases. As expected, only low levels of selected aldehydes were formed in SFA-laden coconut oil during these laboratory-simulated shallow frying episodes. Advantages offered by the \({}^{1}\)H NMR method employed for multicomponent LOP analysis were comparatively reviewed against those of two routinely employed spectrophotometric methods available (the CDs and TBARS spectrophotometric methods). Indeed, such analytical NMR technologies clearly offer major advantages over these alternative methods, most especially in the context of their ability to identify and determine a wide range of these toxins simultaneously, together with their UFA lipidic precursors and minor species (sample preparation is rapid and facile). It is therefore concluded that at least some of the current spectrophotometric/colourimetric laboratory methodologies available for determining and monitoring toxic LOPs in unused or used CFOs are unspecific and poorly quantitative in view of the adverse artefactual generation of such oxidation products during sample preparation phases (e.g., the heating stage of the TBARS assay), or the undesirable incorporation of positively responding interferants in simpler spectrophotometric assays such as those involving oil CD determinations. This study also revealed the potential applications of LF (60 MHz), near-portable NMR spectrometers for evaluating the quality and acylglycerol FA status of neat, used and unused CFOs, and the determination of aldehyde LOPs in such frying media. Indeed, such an approach may be suitable for 'on-site' use by edible oil manufacturers, both large and small, together with fast-food restaurants. One further, albeit novel, application is the direct, multicomponent analysis of such CFOs frequently used by street vendors in African nations and elsewhere, and in principle such analyses could be delivered and provided at the point-of-contact by suitably equipped, road-based mobile laboratory transport units. The gastrointestinal tract is continually exposed to such toxic aldehydes, and subsequent to digestion they are absorbed into the lymphatic system or directly into the systemic circulation [23]. A further important consideration is that the wealth of previous investigations focused on the possible beneficial health effects of dietary PUFAs should be dissected and revisited, particularly those featuring feeding trials with humans or animals or, alternatively, associated epidemiological and cohort meta-analysis ones. On reflection, it certainly appears that many of these previously conducted studies may indeed have been flawed, since researchers involved have either ignored or neglected the confounding adverse health effects associated with LOPs (which undoubtedly were present in the oils or diets involved), together with the molecular nature and concentrations of such agents therein.