At this time, vitamin A obtained from shark liver oil could be a profitable operation.
The curative properties of cod liver oil and shark liver oil were known long before vitamins were identified and their therapeutic properties were ascertained.
In 1921, only 6,015 gallons of medicinal cod liver oil were produced, and all this oil was being produced, in Massachusetts and Maine, and, shark liver oil was being manufactured only in North Carolina, in connection with the shark leather industry (Tressler, 1923).
While there's much persuasive evidence-based medical research on vitamin C and immune function," Hemingway says, "I believe in the power of shark liver oil to positively affect immunity and blood cell counts.
Although she's careful to eat fruits, vegetables, and proteins that confer maximum immune benefits," Hemingway says, "Regular doses of vitamins A, C, and E, cod liver oil, and shark liver oil help protect me from catching colds and viruses.
Now, after extensive research, an Australian company, Bodycare, has started selling in the UK a spray, called Ketsugo, made from a synthetic version of shark liver oil
Avoid supplements made from halibut, shark liver oils
or cod liver oil, because they may contain excessive and unhealthy levels of vitamin A.