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# Vitamin A suppresses vitamin D's effect
- URL: https://www.foodconsumer.org/vitamin_a_suppresses_vitamin_d_0303100646/
- Published: 2010-03-03T18:45:00.000Z
- Updated: 2026-09-22T18:45:58.000Z
- Description: A British Medical Journal paper found that low past vitamin D levels predict later colon cancer, but a table on page eight shows the benefit almost entirely negated in people with the highest retinol intake, about 3,000 IU a day. Mercola says this may explain conflicting results across studies.
- Author: Food Consumer
- Tags: Nutrition, #vivvo-import

Warning: New Proof Confirms if You Take this Supplement, Vitamin D Will Not Work as Well

Posted by: [Dr. Mercola](http://blogs.mercola.com/members/Dr.-Mercola/default.aspx?ref=foodconsumer.org)   
March 02 2010

The *British Medical Journal* has published a remarkable paper confirming that low vitamin D levels obtained in the past are a risk factor for developing colon cancer in the future. But the contained an even more significant finding -- as this site has [reported before](http://articles.mercola.com/sites/articles/archive/2008/12/23/important-cod-liver-oil-update.aspx?ref=foodconsumer.org), vitamin A, even in relatively low amounts, can thwart vitamin D's association with reduced rates of colon cancer. This is the largest study to date showing vitamin A blocks vitamin D's effect.

Hidden on page eight of the paper was one sentence and a small table, showing that the benefits of vitamin D are almost entirely negated in those with the highest vitamin A (retinol) intake. And the retinol intake did not have to be that high -- only about 3,000 IU/day. Young autistic children often take 3,500 IU of retinol a day in their powdered multivitamins, which doesn't count any additional vitamin A given in high single doses.

The finding explains some of the anomalies in other papers on vitamin D and cancer -- similar studies sometimes have widely different results. This may be because the effect of vitamin A was not taken into account. In some countries, cod liver oil, which contains vitamin A, is commonly used as a vitamin D supplement, and in others it is used more rarely, causing differences in the results.

  
**Sources:**

![](https://storage.ghost.io/c/f5/c2/f5c28c07-f2c7-440d-8161-125a09d9bc91/content/images/2026/08/ad07fcc2c1b88ea962a7acfb617d9fce0d5472f0.gif)

[**The Natural Advocate February 28, 2010**](http://thenaturaladvocate.blogspot.com/2010/02/remarkable-paper-in-british-medical.html?ref=foodconsumer.org)