Matt will probably have some thoughts on this, too. Personally, I think CLO is probably great for healing cavities, development during childhood, used prior to conception, during pregnancy and nursing, and other times when extra vit. A is needed. Is it something to take every day for your whole life? I doubt it. Can it be immunosuppressive in large quantities? Yes. However, keep in mind this was refined fish oil, and not fermented cod liver oil. Two different products. Also, it was only shown for prostate cancer. I believe there was an earlier study that showed fish oil is preventive of breast cancer.