Cod liver oil has been used for centuries as a super remedy for many ailments and a powerhouse for fighting disease. Research studies from 1918 to 2001 found cod liver oil to have a high nutritional value and many health benefits, especially when it came to bone health. Both vitamin A and D are essential nutrients to metabolize calcium for healthy bones. One ounce of cod liver oil contains 2,700 IU’s (International Units) of vitamin D, the same vitamin generated from sun. Cod liver oil contains more vitamin D per unit weight than any other food. One ounce of cod liver oil also provides 27,000 IU’s of vitamin A, almost three times more than beef liver, the next richest source.
Cod liver oil contains two of the best omega-3 fatty acids; EAP and DHA which are very important for development of the brain and nervous system.
Rickets is an adolescent condition, in humans and dogs, caused by serious vitamin D deficiency. This deficiency in vitamin D results in weak, soft bones, along with slowed growth and skeletal development. In adults, vitamin D deficiency is manifest in osteomalacia, characterized by bone demineralization due to deficiency or impaired metabolism of vitamin D.
Mrs. May Mellanby and her husband, Dr. E. Mellanby authored over 400 studies in the 1920’s on controlling rickets by diet. In her initial studies Mrs. Mellanby used dogs as the source of data.
In her research into rickets in dogs, Mrs. Mellanby discovered the mineral-blocking effect of phytic acid in grains and legumes. Dr. Mellanby demonstrated that diets containing high levels of cereals and lacking vitamin D, are the most effective producers of rickets. Mrs. Mellanby believed that as cereals increase in the diet, vitamin D must also be increased to offset their anticalcifying effects. She went on to prove that no matter how much cereal is fed, if vitamin D is adequate, bone and tooth formation is normal.
The minimum AAFCO recommendations for vitamin D in dog food are 500 IU / Kilogram (227 IU / lb or 14.2 IU / oz). This means one egg has almost double the minimum daily vitamin D recommendations. The maximum AAFCO recommendations are 5,000 IU of vitamin D per day. Many veterinarians claim that AAFCO nutritional recommendations are too low. I have seen a lot of older dogs with bone related problems like hip dysplasia and arthritis. Could these degenerative diseases be related to low calcium metabolism and vitamin D deficiency? Are the high cereal content kibbles of today a contributor? Ask your veterinarian or canine nutritionist their opinion.
Sources of vitamin D
Cod liver oil 2,700 IU per ounce
Shiitake mushrooms 249 IU per four dried mushrooms
Orange juice (fortified) 125 IU per ounce; soy and rice milk are often fortified
Fresh herring 461 IU per ounce; pickled herring has 578 IU per serving.
Salmon 177 IU per ounce; mackerel, sardines, and shrimp are also good.
Eggs 26 IU per egg; almost all of the vitamin D is in the yolk.
Milk (fortified) 12.5 IU per ounce; cheese and yogurt are less likely to be fortified.
Tofu 40 IU per ounce; not all varieties are fortified, so read labels.
Yeast and other fungi (like ergot)
Cod liver oil is available from many pharmaceutical outlets. The natural form of vitamin D found in marine oils is D3 or cholecalciferol. The vitamin D derived from plants is D2 or ergocalciferol, sometimes considered an inferior form of vitamin D since an additional step is required to synthesize this form into the body.
For some additional reading, here are some great articles on cod liver oil and cod liver oil manufacturing.
