Cod Liver Oil was in the past a primary source of vitamin A, essential for bone growth, health of skin and mucous membranes, and night vision. Today, many other preparations containing vitamin A are available. Before the 1920s, most cod liver oil came from Norwegian Cod. In 1924 William Harrison, Ontario sales manager of a Canadian drug company, became interested in a report that liver oil from cod caught off the Grand Banks of Newfoundland was a much richer source of vitamin A than the Norwegian oil. In January 1925 Harrison and associates, W.A.S. Ayerst, Hugh McPherson and W.J. McKenna, incorporated as Ayerst, McKenna and Harrison Ltd. Letters of patent not only granted the company rights to "produce, manufacture, purchase, sell, import, export chemicals, drugs and medicines of all kinds," but also some rights it never used, eg, "to sell snuff, spices, leaf tobacco, cheroots, shellacs, and crockery."

By April 1925 the company had 16 employees and immediately started researching the preparation of liver oil from Newfoundland cod. Its first department of biology consisted of a chicken-wire fence stretched from floor to ceiling. White rats were bought at $5 a head and were fed a normal diet fortified with cod liver oil. The experiment was a success. The white rats visibly thrived on the experimental supplementary diet. For the first time the potency of cod liver oil could be determined, regulated and assured. As soon as the new product became commercially available, Canadian physicians enthusiastically prescribed it; soon it was also sold in the US and worldwide. In 1929 Ayerst introduced the first cod liver oil concentrate in capsule form, under the brand name Alphamettes, a product that became available in pharmacies in Canada and the US for many years until the development of multivitamin formulations.