“Our refining process is basically the same as the one used for vegetable oil, for example,” Barnard explains as he points to a group of large silos in which phosphoric acid and sodium hydroxide are used to make various substances in the oil water-soluble so that they can be washed out. “One thing we do here is to ‘saponify’ free fatty acids and remove them, as they would otherwise reduce the shelf life of the refined oil,” says Barnard. He then moves on to three centrifuges connected in series, which are used to separate out contaminating particles. The gauge glasses downstream of the centrifuges reveal a much brighter and clearer oil.

The oil is then cooled down to about seven degrees Celsius for the next step, a cold filtration process known as “winterization,” which removes more saturated fatty acids. This has a dual effect: On the one hand, it prevents the final product from becoming cloudy at or below room temperature, while on the other hand it raises the proportion of valuable polyunsaturated fatty acids in the product. “The stearins washed out of the filter cloths are used by the animal feeds industry,” says Barnard, who is glad that no part of the fish goes unused these days.

In the next process, patented under the name “Ocean Gold,” the oil is further purified, in part with the help of activated carbon. This procedure filters out impurities such as pigments, trace metals, and oxidation products, as well as dioxin and PCBs, which in the past were used to make insulating oils and softeners. The final step — deodorization — takes place in a high vacuum through which steam is pumped. “The steam carries away most of the odorants in a process that takes hours,” says Barnard, who then peers through a gauge glass into the inside of a container.

The refining process converts 77 tons of every 100 tons of raw oil into an ultrafine golden-yellow oil with only a faint odor, to which flavorings such as cherry — as well as vitamins — can be added. The final product is then either bottled by Seven Seas or sent out to an encapsulation company, where it is filled into soft capsules.

So what’s so fantastic about cod liver oil — and why must it go through this complex refining process? It’s all about health, of course, since cod liver oil is one of the traditional folk medicines whose cause-and-effect relationships have been rediscovered in the modern age.

The first clinical observations of the substance’s value in treating bone diseases and rheumatism were made by Samuel Kay, a doctor from Manchester, who after many years of research reported to the British Medical Society in 1770 that cod liver oil has a positive effect when used to treat arthritis. Additional research conducted in the 20th century revealed that cod liver oil contains Vitamin D, which has been used since 1824 to mitigate the symptoms of rickets, especially in regions that don’t get much sun.

In the 1940s the UK’s National Health Service distributed free cod liver oil to pregnant women, nursing mothers, and children under five. Then, when scientists began closing in on the secrets of omega-3 fatty acids in the late 1970s, they finally found out why Inuit don’t suffer from arthrosis, despite their cholesterol-heavy, one-sided eating habits. It turns out that fish oils contain a large amount of omega-3 fatty acids, which influence eicosanoid metabolism and have anti-inflammatory properties. This so-called “Inuit paradox” is just as surprising as the fact that today’s cod liver oil from Seven Seas no longer tastes like the sea but instead like cherries or oranges.