Green Pasture's Blue Ice™ Fermented Skate Liver Oil is your best choice for cartilage fish oil. Skate liver oil is complete in its offering of many nutrients in a similar balance as cod liver oil. Unlike shark liver oil, skate liver oil is abundant in vitamins A, D, E, K, the full range of omega fatty acides, plus all the unique nutrients found in shark liver oil such as chondroitin, squalene, and alkoxglycerols.
Nutrient assays, including vitamins A and D, for our fermented oils vary widely depending on methodology, lab and batch. Current science struggles to answer the questions we have on our sacred fermented foods.
There are many naturally occurring metabolites and co-factors that make the issue of measuring natural nutrients difficult in the fermented oils. We do know that historical cultures liberally consumed these sacred foods to great benefit without today's standardization of knowledge.