Cod liver oil
omega-3 plus vitamins A and D. Fish oil & probiotics.
- Verdict
- No benefit foundIt was tested as a cancer remedy and didn't work.
- How sure
- Rung 2 · LimitedFew, small or conflicting human studies, or only indirect measures such as blood markers.
The rung shows how sure the science is, not how big the effect is. How to read these ratings
Cancers affected
None shown
What the evidence shows
Cod liver oil itself hasn't been tested for cancer. Its parts have: omega-3 pills (1 g a day) didn't lower cancer in the 25,871-person VITAL trial, and vitamin A supplements haven't been shown to prevent cancer. Unlike fish oil, it contains preformed vitamin A; too much causes headaches, blurred vision, nausea and dizziness, and can cause birth defects in pregnancy.
What to do
Don't take it to prevent cancer. If you take it, count its vitamin A toward the daily upper limit (3,000 mcg for adults), and don't take high-dose vitamin A if you're pregnant.
Sources
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Related
Every supplement we rated, or follow one cancer step by step: breast cancer, colorectal cancer, lung cancer and prostate cancer.