- Supplement was also increased low-grade prostate cancer risk by 44%
- One theory is that pills may dampen down the immune system
- Omega-3 fish oils are one of the most popular supplements in the UK
Fish-oil supplements credited with a range of health benefits could trigger prostate cancer.
Experts found that omega-3 fatty acids may raise the risk of the most lethal form of the disease by more than 70 per cent.
Researchers warned against omega-3 pills, and recommended eating just one or two meals of oily fish per week.
Fish-oil supplements are said to protect against heart attacks and strokes, stave off arthritis, boost brain power and prevent behaviour disorders in children.