Disclaimer: Consult with a doctor before deciding on a treatment plan for cancer.
Vitamin A is an important substance that helps the body properly rebuild tissues and fight infection. So it makes sense that vitamin A would play an important role in fighting cancer. Vitamin A is typically used a helper-therapy in a variety of cancer diets although some research has shown that certain types of cancer such as Acute Promyelocytic Leukemia goes into remission in response to vitamin A therapy as stand-alone treatment 80% of the time. On the other hand, lung cancer patients who smoke are advised against taking vitamin A supplements.
Vitamin A is actually a group of related substances that are collectively known as “retinoids”. A deficiency of this vitamin can cause night-blindness, xerophthalmia, and a decreased resistance to infection. Epidemiological studies have shown that the risk of certain types of cancer is higher among people with a low dietary intake of vitamin A .
Vitamin A and retinol influence normal growth, vision, reproduction, skin and mucous membrane health, cellular differentiation, development proliferation, and normal cell death (apoptosis), which is one of the reasons why this vitamin is so important in the treatment of cancer. Vitamin A and the retinoids (a class of compounds that are chemically related to vitamin A) play an essential biological role in a variety of physiological processes and researchers in diverse disciplines such as dermatology, embryology, and cancer have developed interest in the value of vitamin A and the retinoids in promoting the proliferation of healthy cells and tissues .
Studies have shown that all-trans retinoic acids (which are vitamin A-related compounds) are able to differentiate between malignant cancer cells in patients with Acute Promyelocytic Leukemia to induce remission of the disease. Research has shown an 80% remission rate from Acute Promyelocytic Leukemia using all-trans retinoic acids as a stand-alone treatment .
Scientists have shown that the retinoids could be used therapeutically to prevent and play a role in treating cancer. Animal studies have shown that vitamin A and beta-carotene can boost cancer patients’ immune response, slow tumor growth, and decrease the size of established tumors .
Vitamin A is found in orange fruits and vegetables such as the following:
- Butternut squash
- Apricots 
Rather than promoting the value of naturally-occurring vitamin A and retinoids in foods, pharmaceutical companies developed a synthetic version of vitamin A known as Fenretinide (N-4-hydroxyphenyl-retinamide or 4-HPR). It was developed as a low-dose chemo-preventative agent for breast cancer, prostate cancer, and bladder cancer. This drug can cause vitamin A deficiency by competing with real vitamin A in the body .
Safety and Effectiveness
Studies have shown that beta-carotene can increase the production of human immunity factors such as monocytes, lymphocytes, and macrophages which enhances the immune system’s cancer-fighting abilities .
How Vitamin A Is Administered
Both vitamin A and beta-carotene (a vitamin A precursor) are fat soluble so patients should take vitamin A supplements with foods that contains fat .
The Binzel Diet recommends that patients take 125,000 I.U of vitamin A per day .
Possible Negative Effects
Serious side effects from taking vitamin A are rare. The following are some of the less serious side effects patients may experience when taking high doses of vitamin A:
- Perioral dermatitis .
Extremely high doses of vitamin A could cause liver damage .
Patients with kidney disorders as well as pregnant women should talk to their doctor before taking vitamin A supplements .
While side effects from natural vitamin A supplementation is rare, the side effects caused by Fenretinide include the following:
- Inability to see in dim light
- Dry skin
- Abdominal cramping
- Hepatic dysfunction 
Because Fenretinide is a synthetic version of vitamin A, it competes with naturally-occurring vitamin A in the body to cause a vitamin A deficiency in patients who use this drug .
Other Important Information
Beta-carotene is a less-toxic form of vitamin A that patients can take to avoid side effects of taking high doses of vitamin A .
Some research has shown that there is an increased risk of lung cancer and lung cancer recurrence among patients who smoke and take high doses of vitamin A.
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