Vitamin A

Carrots and Vitamin A

Photo Credit: mali maeder 

For years, researchers have been studying the effects of Vitamin A on the immune system.

Vitamin A and Colon Cancer Treatment

The retinoids in vitamin A have been shown to be a promising treatment against colon cancer relapse.  By normalizing mutated stem cells that survive chemotherapy, the relapse is virtually stopped before it can start.  

Retinoids used to treat other cancers

After these findings, more current research is finding acyclic retinoid prevents the relapse of hepatocellular carcinoma (HCC), a deadly form of liver cancer.

And in cases of melanoma, researchers at University of Colorado Anschutz Medical Campus, found the use of retinoic acid helped turn off the suppressor cells (MDSCs) that inhibits the immune system activity against the cancer.

In breast cancer, researchers at Thomas Jefferson University found cells that were fully cancerous did not respond to treatment with retinoic acid, but when used against pre-cancerous cells, not only did the cells look more normal in terms of shape, but they also changed their genetic signature back to normal.  

Unless your doctor is prescribing therapeutic doses of vitamin A, it's best to get your vitamin A from your diet.

Vitamin A as a Cancer Preventative

Vitamin a has a number of benefits to the immune system, and several studies appear to show that it can have a normalizing affect on stem cells, and pre-cancerous cells, so consuming foods rich in vitamin A should be a part of anyone's cancer fighting diet.

Be Careful taking Vitamin A Supplements 

While I am a huge fan of taking good quality supplements to make sure you're getting the right nutrients, and to balance out what might be missing from your diet, there are some fat soluble vitamins that need to be taken with caution. 

Vitamins like vitamin C are not stored in the body, so you can take large doses and your body will eliminate what it doesn't use.  Your body will store vitamin A, and there are some side effects associated with accumulated vitamin A, like intracranial pressure, dizziness, nausea, liver damage, headaches, rash, pain in your joints and bones, osteoporosis, coma, and even death.

Therefore, unless your doctor is prescribing therapeutic doses of vitamin A, it's best to get your vitamin A from your diet, or a smaller dose associated with a daily multi-vitamin.

Vitamin A is found in some animal sources, but yellow and orange pigmented, as well as dark green leafy vegetables are excellent sources of Vitamin A.  While most adults should consume at least 2,000-2,500 IU of vitamin A per day, you can see that's easily achieved through diet. 

At the upper end, I would not worry about vitamin toxicity unless you are consuming vast amounts over long periods of time - you'll know if you start to feel symptoms, and you can always back off.  The top level of vitamin A is considered 10,000 IU for adults, but that is over time.  If you consume sweet potatoes every day over the Thanksgiving weekend, for example, you are probably fine - your body will store what it doesn't need for later, and you'll likely be craving something completely different when the leftovers are gone.  As always, ask your doctor if you have concerns.

Foods that contain Vitamin A

Beef liver: 2.3oz = 21,000 IU

Cod Liver Oil: 1tsp = 4,500 IU

Baked Sweet Potato: 1/2 cup = 19,000 IU

Raw Carrots: 1/2 cup = 10,500 IU

Canned Pumpkin: 1/2 cup = 19,000 IU

Cantaloupe: 1/2 melon = 9,000 IU

Mango: 1 piece of fruit = 3,500 IU

Cooked Kale: 1/2 cup = 8,500 IU

Cooked Collard Greens: 1/2 cup = 7,000 IU

Cooked Spinach: 1/2 cup = 9,000 IU



Treating Colon Cancer with Vitamin A:
Ecole Polytechnique Fédérale de Lausanne. (2015, December 14). Treating colon cancer with vitamin A. ScienceDaily. Retrieved February 17, 2019 from

Can Vitamin A Turn Back the Clock on Breast Cancer?
Thomas Jefferson University. (2014, March 31). Can vitamin A turn back the clock on breast cancer?. ScienceDaily. Retrieved February 18, 2019 from