Echium oil as a sustainable alternative to fish oil: from seeds to the physiological effects in humans (Part 1)

Abstract

Cardiovascular diseases (CVD) are the leading cause of mortality in the world. Despite the advances achieved in the pharmacological and surgical aspects, little progress has been obtained towards prevention. Among the alternatives to reduce CVD risk, the intake of omega 3 fatty acids (n3FA) supplements, in especial the eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), has shown to be one of the most applied in many countries. The main source of EPA and DHA is fish oil. However, there are not enough natural resources to afford the increasing n3FA demand. Thus, new n3FA sources must be investigated. Except for transgenic plants, there is no EPA and DHA in the edible vegetable oils. Individuals synthesize EPA/DHA from alpha-linolenic acid (ALA) present in some vegetable oils, but the conversion rate usually is lower than 4%. Echium plantagineum L. is a plant from the Boraginaceae family that presents seeds containing about 30% oil, being 38% n3FA including 10% of stearidonic acid (SDA), the first product from ALA conversion to EPA/DHA. Alternatively, the rate of SDA conversion to EPA/DHA is around 6-fold higher than from ALA, making the Echium oil known as a Pro-EPA oil. However, due to its high level of polyunsaturated fatty acids, Echium oil is highly susceptible to oxidative damage, reducing its shelf-life and applicability in other food matrices. In fact, during oil extraction and storage, the formation of unpleasant off-odors caused by fatty acid oxidation occurs, negatively impacting the consumer's acceptance. Thus, this project presents four hypothesis.The first one is that the "fishy" odor formed during the crushing of the Echium seeds is a volatile secondary product of fatty acid oxidation catalyzed by lipoxygenases isoforms. The second hypothesis is that by inhibiting lipoxygenases (if the previous hypothesis is confirmed) and combining antioxidants with different extraction methods, it is possible to obtain an oil with better stability and less "fishy" odor. Then, we hypothesize that a combination of a radical scavenger molecule with a metal chelator will improve oxidative stability of the oil during storage, and finally, once a better oil is obtained, the last hypothesis is that individuals who intake Echium oil, as part of their normal diet, will present a higher concentration of EPA and DHA after 30 days than individuals who intake soybean (the most popular) and linseed (other alternative n3FA vegetable source) oils. To test these hypotheses, the lipoxygenase isoforms activity will be evaluated in the Echium seeds, and three more factors will be combined to avoid the off-odor formation during processing and storage of the oil. The selected factors are the addition of an antioxidant during the seeds crushing, the improvement of the extraction method by using a CO2 supercritical technique and the addition of a polyphenol and a metal chelator before the oil is packaged. Half of the samples will be kept into 200 mL closed amber flasks and will be evaluated after 6 months at room temperature to evaluate the product's shelf-life, while the other half will be kept for 30 days without the caps in order to simulate the oil consumption in a domestic environment. In the last step of this project, about 30 individuals will be advised to consume Echium oil during 30 days, and the concentration of EPA and DHA in their plasma will be compared with the equivalent consumption of soybean and linseed oils, using a cross-over interventional design. Classical chemical markers of oil oxidation and fatty acids analysis will be carried out in each step of the study. Our results will contribute to the Brazilian agency's (ANVISA) decision about the approval or not of the commercialization of Echium oil in Brazil and also to make Echium oil viable for human consumption.