Rapeseed oil is one of the cheapest oils on the market and is extracted mechanically and chemically. Rapeseed has a very high oil content of about 40%.

Oilseed rape plants, Brassica napus, Brassica rapa, Brassica juncea belong to the Brassicaceae family.

The extraction process requires large specialized plants and goes through these stages:

• Cleaning of the oilseed by dedusting and deferring by mechanical pressing to ensure a better yield.
• Cold pressing with mechanical extraction of the raw oil.
• Clarification of crude oil by separation from sludge (DIN V 51605 directive).
• Clarified oil filtration by 1 micron microfiltration.
• Storage of filtered oil in approved storage tanks.

Rapeseed oil contains erucic acid, an acid that can cause toxicity at high doses.

From the health point of view, numerous studies have been carried out on animals, generally rats and pigs, to test for toxicity: here anomalies in the liver have been noted (1) and here a decrease in the time of blood clotting (2).

Another study analysed the relationship between high consumption of rapeseed oil and the presence of erucic acid in the blood of Chinese children (3).

In the spring of 1981 there was a serious epidemic in Spain due to the consumption of rapeseed oil denatured with aniline for industrial use, but diverted for human consumption. Contamination of rapeseed oil, produced by French companies, may have occurred in tankers during transport, as these tankers had previously transported industrial products, but this remains a hypothesis. This study analyses production processes and possible relations with the epidemic (4).

The rapeseed cultivars have been improved through special plant breeding and now one can find, instead of the traditional rapeseed oil, a variety with low erucic acid, called canola oil. Today, canola oil is the third most important vegetable oil by volume after palm oil (which, as of 2016, is falling rapidly in volume) and soya oil. (5).

Rapeseed oil also has a good amount of alpha linoleic acid (6), a polyunsaturated acid beneficial for human health, however the amounts of erucic acid and alpha linoleic acid depend on the type of processing of rapeseed oil.

Erucic acid is an acid that can cause toxicity in high doses on heart muscle function. However, since 1991, the European Community has established more restrictive cultivation lines for rapeseed, so the amount of this acid in rapeseed oil has drastically decreased.  In 2016, EFSA proposed a lower maximum erucic acid content in edible oils of 2% (instead of 5%) and also suggested a tolerable daily intake of 7 mg erucic acid per kg body weight (7). It appears that these limits are generally respected in the European Union (8) both in oil and in fish products such as salmon and mackerel (9). However, warning should be given about the cumulative intake of this chemical compound.

For more information:

Rapeseed oil studies

References_______________________________________________________________________

(1) Toxicological evaluation of rapeseed products in a subacute feeding study in rats.  Plass R, Bleyl DW, Lewerenz HJ, Kroll J.  Nahrung. 1992;36(3):248-52.

(2) Blood coagulation and osmolar tolerance of erythrocytes in stroke-prone spontaneously hypertensive rats given rapeseed oil or soybean oil as the only dietary fat.  Naito Y, Konishi C, Ohara N.  Toxicol Lett. 2000 Aug 16;116(3):209-15.

(3) Fatty acid composition of blood lipids in Chinese children consuming high erucic acid rapeseed oil.  Laryea MD, Jiang YF, Xu GL, Lombeck I.  Ann Nutr Metab. 1992;36(5-6):273-8.

(4) Manufacturing processes at two French rapeseed oil companies: possible relationships to toxic oil syndrome in Spain.  Posada de la Paz M, Philen RM, Abaitua Borda I, Bernert JT Jr, Gancedo JC, DuClos PJ, Kilbourne EM.  Food Chem Toxicol. 1991 Dec;29(12):797-803.

The Spanish toxic-oil syndrome.  Vallat JM, Guitart R, Leboutet MJ, Loubet A, Rigaud M.  Muscle Nerve. 1984 Oct;7(8):681-2. No abstract available.

(5) Evidence of health benefits of canola oil. Lin, L.; Allemekinders, H.; Dansby, A.; Campbell, L.; Durance-Tod, S.; Berger, A.; Jones, P.J.  Nutr. Rev. 2013, 71, 370–385.

(6) Oil composition of high-fat diet affects metabolic inflammation differently in connection with endotoxin receptors in mice.  -  Laugerette F, Furet JP, Debard C, Daira P, Loizon E, Géloën A, Soulage CO, Simonet C, Lefils-Lacourtablaise J, Bernoud-Hubac N, Bodennec J, Peretti N, Vidal H, Michalski MC.  -  Am J Physiol Endocrinol Metab. 2012 Feb 1;302(3):E374-86. doi: 10.1152/ajpendo.00314.2011. Epub 2011 Nov 15.

(7) Vetter, W., Darwisch, V., & Lehnert, K. (2020). Erucic acid in Brassicaceae and salmon–An evaluation of the new proposed limits of erucic acid in food. NFS journal, 19, 9-15.

Abstract. Erucic acid is a long-chain fatty acid classified as a natural toxin due to detrimental effects on heart muscle functions. Major sources of dietary intake of erucic acid are oil of rapeseeds and other Brassicaceae (formerly Cruciferae) such as mustard. In 2016, the European Food Safety Authority (EFSA) proposed a lower maximum content of erucic acid in edible oils of 2% (instead of 5%) and also suggested a tolerable daily intake of 7 mg erucic acid per kg body weight. In this article, we measured exemplarily samples of rapeseed, mustard, further Brassicaceae and used the data to discuss possible consequences for consumers, producers and the food sector. This data was supplemented with possible analytical problems caused the EFSA proposal and analysis of salmon fillet (erucic acid content: wild catch ~ farmed salmon < organic salmon) which, together with other fish, was verified as a relevant but unregulated source of erucic acid intake. Salmon also contained an isomer of erucic acid whose content was even higher than erucic acid.

(8) Russo, M., Yan, F., Stier, A., Klasen, L., & Honermeier, B. (2021). Erucic acid concentration of rapeseed (Brassica napus L.) oils on the German food retail market. Food science & nutrition, 9(7), 3664-3672.

Abstract. Rapeseed oil is one of the most important vegetable oils in Germany. It has a favorable fatty acid composition but also contains a certain amount of erucic acid (EA). As the result of toxicological considerations regarding this fatty acid, the European Food Safety Authority (EFSA) established a tolerable daily intake (TDI) for EA of 7 mg/kg body weight in 2016. On this basis, the maximum EA levels for vegetable oils allowed in the European Union have been reduced shortly from 50 to 20 g/kg, and for infant formula and follow-on formula from 10 to 4 g/kg. However, rapeseed oil is also recommended for the preparation of homemade food for infants and children. Little is known about the actual EA concentrations of rapeseed oils on the German retail market. Current data are especially important for the necessary reassessment of its recommendation in infant and child nutrition based on the established TDI. Three hundred representative rapeseed oil samples were purchased in retail stores across Germany. EA concentrations, determined by GC-FID, were in a range of 0.17–9.68 g/kg, with 241 samples being even below 4 g/kg. All oils were below the maximum level valid at the time of this investigation, and even below the newly established lower maximum level of 20 g/kg. The major part also met the requirements for infant and follow-on formula. The representative results provide valuable current data for the necessary reassessment of the dietary recommendations for infant and child nutrition based on the established TDI.

(9) Sissener, N. H., Ørnsrud, R., Sanden, M., Frøyland, L., Remø, S., & Lundebye, A. K. (2018). Erucic acid (22: 1n-9) in fish feed, farmed, and wild fish and seafood products. Nutrients, 10(10), 1443.

Abstract. The European Food Safety Authority (EFSA) published a risk assessment of erucic acid (22:1n-9) in 2016, establishing a Tolerable Daily Intake (TDI) for humans of 7 mg kg−1 body weight per day. This report largely excluded the contribution of erucic acid from fish and seafood, due to this fatty acid often not being reported separately in seafood. The Institute of Marine Research (IMR) in Norway analyzes erucic acid and has accumulated extensive data from analyses of fish feeds, farmed and wild fish, and seafood products. Our data show that rapeseed oil (low erucic acid varieties) and fish oil are the main sources of erucic acid in feed for farmed fish. Erucic acid content increases with total fat content, both in farmed and wild fish, and it is particularly high in fish liver, fish oil, and oily fish, such as mackerel. We show that the current TDI could be exceeded with a 200 g meal of mackerel, as at the maximum concentration analyzed, such a meal would contribute 143% to the TDI of a 60 kg person. These data cover a current knowledge gap in the scientific literature regarding the content of erucic acid in fish and seafood.