Cod liver oil is an important source of vitamin D and the long-chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which aid in the prevention of type 1 diabetes.
At Ulleval University Hospital in Norway, researchers investigated whether cod liver oil or other vitamin D supplements could reduce the risk of type 1 diabetes in children. They looked at supplementation in both the mother during pregnancy and in the child during the first year of life. In a nationwide study with 545 cases of childhood-onset type 1 diabetes and 1,668 control subjects, families completed a questionnaire on intake of cod liver oil and other vitamin D supplements, as well as other nutrients. From this data, researchers concluded that the use of cod liver oil in the first year of life was associated with a significantly lower risk of type 1 diabetes.
In another study from Norway, researchers evaluated the use of cod liver oil and vitamin D supplements during pregnancy by a mailed questionnaire. They received responses from 85 diabetic subjects and 1,071 control subjects, and found when mothers took cod liver oil during pregnancy, their offspring did have a lower risk of type 1 diabetes.
The body can only make the omega-3 fatty acids DHA and EPA from eating foods such as flaxseed and canola oils, walnuts, soybeans, whole grains and leafy greens, or from eating oily fish such as salmon, trout, sardines, mackerel and fresh tuna.
Sources: Am J Clin Nutr. 2003 Dec;78(6):1128-34; Diabetologia. 2000 Sep;43(9):1093-8