In the 19th century, cod liver oil was often used to boost vitamin D levels in children living in sun-deprived climates (and, in turn, protect them from rickets). Today, many people use cod liver oil to soothe the symptoms of arthritis. Indeed, research suggests that the anti-inflammatory effects of cod liver oil may benefit patients dealing with osteoarthritis or rheumatoid arthritis. There's also some evidence that cod liver oil may fight upper respiratory tract infections, such as the common cold).
While cod liver oil was once notorious for its unappealing taste, newer products tend to offer a more pleasant flavor. However, since certain types of cod may be endangered, choosing fish oil supplements made from sustainable sources (such as salmon oil) may be more ecologically responsible. Like cod liver oil, other forms of fish oil help supply your body with heart-healthy, inflammation-fighting omega-3 fatty acids.