Great information here, but I would not recommend the particular brand of oil Wilcock advertises, but Rosita brand instead because of the testimonials of people I know personally, and also what it says on their website -- which is all true according to these same people who are insistent upon high quality and purity of their food and supplements who investigate these kind of claims for themselves...

"The process of extraction is unique and based on age-old principles. No other company on this planet is aware of our remarkably natural and ancient extraction technique. No chemicals, heat, steam, or mechanical pressure are ever used in production. Metal is never used to manipulate the livers for fear of metal-induced lipid oxidation. Rosita Ratfish Liver Oil™ is the real oil contained in the liver cells of fresh liver: straw colored and without an unpleasant odor and flavor. The oil maintains exactly the same form and nutritional composition that nature gave it, without being altered in any way. Here's a link to their site -- https://evclo.com/products/ratfish-liver-oil/