Inositol is a phosphorylated carbohydrate, or sugar molecule bound to a phosphate group. It is found in grains, legumes, and red meat. Our bodies transform it into inositol hexaphosphate (IP6), transform IP6 into other inositol phosphate products, and can also transform these products back into inositol. Plant and mammal cells use inositol as a hormone and as a nutrient: Inositol products help cells communicate with one another and perform internal functions.
There are at least seven inositol metabolites, or different versions of this nutrient. Studies indicate that IP6 itself, in combination with inositol proper, may be an effective anti-cancer agent. Another form, myo-inositol, may also have mild anti-cancer properties.
The strongest evidence for inositol’s effectiveness in cancer treatment comes from two studies, one conducted with mice in 2003, and the other in human breast cancer patients, published in 2010. It has long been known that diets based on whole grains and legumes — foods with high natural concentrations of inositol — could potentially reverse colon cancer. However, it was initially believed that cells could only uptake inositol directly from the digestive tract, and that inositol was therefore only effective in treating digestive tract cancers.
The 2003 study in mice, performed by Ivana Vucenik and AbulKalam M. Shamsuddin and published in The Journal of Nutrition, indicates that dietary and supplemental inositol can be taken up by cells in regions of the body far from the digestive tract. The researchers claim inositol has different effects on different types of cancer. They found that in some types it inhibits new tumor growth and shrinks existing tumors, while in others it causes “differentiation and maturation of malignant cells, often resulting in reversion to the normal phenotypes,” in other words, it transforms the cancerous cells back into normal cells. This study found stronger tumor inhibition when inositol is supplied through drinking water than when it is supplied in food.
The 2010 study in breast cancer patients, performed by Ivan Bacic, et al., and published in the Journal of Experimental & Clinical Cancer Research, used IP6 plus inositol treatment along with conventional chemotherapy. The researchers claim inositol treatment prevents cytopenia — a side effect of chemotherapy where white blood cells and platelets are killed off or their production is inhibited. Inositol-treated patients reported a quality of life 30 percent greater than patients in the control group, who did not receive inositol. However, these researchers found no evidence that inositol altered the tumors themselves. This study indicates that inositol is a supportive therapy, not a substitute for conventional anti-cancer treatment.
Inositol may have additional medical benefits. It is an antioxidant, meaning it binds to oxygen ions — waste products of cell metabolism — and prevents them from damaging cells. Inositol may also strengthen and protect the immune system, help lower blood cholesterol levels, prevent kidney stones, protect against cardiovascular disease, and reduce the incidence and severity of depression.
Increasing inositol consumption by changing your diet is completely safe. Safe therapeutic and supplemental dosages, on the other hand, have not yet been established, so taking inositol supplements may pose some risk. Excessive amounts of inositol may bind dietary calcium, iron, magnesium, and zinc and make them unavailable for absorption and use by your body. The Memorial Sloan Kettering Cancer Center claims that inositol can interfere with platelet function and blood clotting, though this claim contradicts findings in the 2010 inositol-cancer study.