Dear Dr. Gott: I am a fairly young man of 90 years. I was born in Norway in 1919 and similar to most Norwegians ate a lot of fish. A few of us might take cod-liver oil as a supplement, but in view of the general Norwegian diet, it might be less important.

When I arrived in this country at the age of 28, I started taking cod-liver oil regularly with breakfast every single day. When a nephew of mine from Norway visited some time ago, I asked him what he thought of the value of cod-liver oil. Arthritis was his specialty, and he thought it was useful against rheumatoid problems. He said it works painlessly, almost like oiling a joint.

I have basically no signs of pain anyplace in my body, except I fell off a roof and broke my leg when I was 78. That hurt! I still swim one lap over one-quarter mile once a week and keep telling my relatives in Norway I think I'll swim a kilometre some day and get my name in the paper. I could do it. I don't remember the last time I had a cold or was ill for any reason. I never have to get up in the night.

The last time I went to see my physician for a regular checkup, he had another doctor examine me. Afterwards when they reviewed my lab results, my doctor said they were incredible and that he thought maybe he should eat the way I do.

Part of my health is no doubt due to my genes, but I believe it is also due to the fact that I, especially during the last 20 to 25 years, have begun realising that our bodies are made up of everything we eat. In order to stay healthy, we ought to consume a great variety of foods and include cod-liver oil.

Reply: What can I say? As I have written in the past, it was common in my generation for parents to force their children to take cod-liver oil, which was thought to be healthful. Today, it is known to be. It is a good source of omega-3, vitamins A and D, and essential fatty acids EPA and DHA. These fatty acids appear to provide resistance to illnesses such as the common cold and influenza. Omega-3 fatty acids are a form of polyunsaturated fats the body derives from food. Because the body cannot produce fatty acids, they must be obtained through the foods we eat or supplements we take. Studies are limited and inconclusive but suggest this addition may be beneficial for cardiac conditions, eczema, behavioural disorders, inflammatory disorders such as arthritis and more. The jury is still out as to whether it can actually lower cholesterol levels.

Cod liver acts as a natural anticoagulant, so if readers choose to add the supplement, I suggest they run it past their primary-care physician before doing so. The Food and Drug Administration has not approved it, but there is little harm (and perhaps a great deal of good) in adding cod-liver oil to the diet. Heaven knows you appear to be a walking, talking testimonial to this theory.