Lifestyle changes, such as medications, should be tailored to the individual. Lifestyle changes are based on four main pillars: nutrition, sleep, physical activity and stress management. The National Sleep Foundation recommends that an adult get from 7 to 9 h of sleep each night, whereas school-age children should get between 9 and 11 h. The quality of sleep can be improved by making use of the natural circadian rhythm. Furthermore, blue light emitted from the screens of electronic devices should be avoided before bedtime. Physical activity significantly reduces the risk of heart disease, enhances brain function and helps improve mood. Stress management focuses on reducing stress through socializing, spending time outdoors or taking hot, relaxing baths [1].

Nutrition, one of the most important pillars, should focus consistently on consuming healthy foods that provide adequate but not excessive calories. This helps to avoid becoming overweight or underweight and provides the body with the necessary minerals and vitamins [2]. Accordingly, highly processed foods should be avoided, sugar intake reduced, fruit and vegetable consumption increased and fiber-rich products, and those supporting a proper gut microbiome, should be central to the diet [1]. The education of consumers regarding these subjects would benefit from promoting traditional, regional food products grown on organic farms and learning from traditional medicine [2].

Seed oils have been used since antiquity not only as food but also as the first pharmaceuticals and cosmetics [3]. Seed oils are an important part of the diet because they contain fatty acids, including unsaturated fatty acids, such as omega-3 (α-linolenic acid) and omega-6 (linoleic acid) fatty acids, which are not synthesized by the human body and must thus be supplied by the daily diet. Fatty acids are necessary for the transmission of nerve impulses, the synthesis of hemoglobin and for cell division [4]. Seed oils are also rich in significant phytochemicals, such as phenolic compounds, sterols, carotenoids, minerals and vitamins, making these oils useful in the treatment of various diseases. Black seed oil (Nigella sativa L.) is used to treat type 2 diabetes [5,6], and evening primrose oil (Oenothera biennis L.) is used to treat mastalgia [7] and polycystic ovary syndrome [8]. Pumpkin seed oil (Cucurbitapepo L.) is used to treat overactive bladder [9] and chronic nonbacterial prostatitis [10]. Milk thistle oil (Silybum marianum) aids in the treatment of hepatic steatosis [11], and hemp oil (Cannabis sativa L.) helps treat atopic dermatitis [12]. However, seed oils used for these purposes must be produced from high-quality seeds and pressed using techniques that provide oil products that promote health and meet consumers’ expectations in terms of both quality and taste.

In an effort to provide consumers with the highest quality products, analytical methods have been developed to assess the purity of a product, confirm its authenticity or detect adulteration [13]. The adulteration of seed oils is not a challenge for producers, as adulterated and authentic products generally have the same consistency and similar colors, and oils are typically stored in dark bottles to protect them from sunlight. Several analytical methods have been developed to detect the adulteration of seed oils using specialized equipment and expert knowledge. For example, high-resolution mass spectrometry was used by Kotecka-Majchrzak et al. [14] to detect new species-specific peptide markers for 10 cold-pressed seed oils. Wei et al. [15] identified triacylglycerols (TAGs), which might provide a quick method for screening for oil adulteration using ion mobility spectroscopy [16] and total synchronous fluorescence spectroscopy (TSyF) [17]. Untargeted metabolomics coupled with high-resolution mass spectrometry allowed fingerprinting analysis and the identification of specific markers for detecting the adulteration of sesame oil [18]. Metabolomics has been applied in food research to assess food safety, food composition and food adulteration. The application of metabolomic analysis techniques was summarized by Wu et al. [19]. Furthermore, the use of LC-MS along with metabolic studies has contributed to the development of an analytical method to detect adulteration of cameline oil with soybean, peanut and canola oils. Additionally, metabolic studies were carried out to detect adulteration of olive oil with hazelnut oil. It is recommended that in order to confirm the authenticity of the oils or to detect their adulteration using metabolomic together with mass spectrometry larger number of markers is required since their occurrence or intensity may depend on the geographic conditions in which crops are grown [20,21].

In this work, we applied an untargeted approach combining chemometrics and high-performance liquid chromatography coupled with a quadrupole time-of-flight mass spectrometer (LC–QTOF) to detect and identify new oil-specific metabolic markers for five plant oils: black seed oil (Nigella sativa L.), pumpkin seed oil (Cucurbita pepo L.), evening primrose oil (Oenothera biennis L.), hemp oil (Cannabis sativa L.) and milk thistle oil (Silybum marianum). To study the effects of matrix variability on the stability, sensitivity and selectivity of the newly identified metabolic markers, binary oil mixtures of the oils analyzed in this study were prepared with three different oil matrices: sunflower oil (SO), rapeseed oil (RO) and sesame oil (SeO). The effect was evaluated by studying the linearity of the MS signals for oil-specific markers and the limits of detection for each marker were estimated.