“Promising”: Common sugar supplement found to improve cancer treatment in mice

22 Nov 2018 --- Mannose sugar, a widely available nutritional supplement, can both slow tumor growth and enhance the effects of chemotherapy in mice with multiple types of cancer, a study published in Nature has found. The study sheds light on how mannose could be used to help treat cancer by interfering with glucose and reducing how much sugar cancer cells can use. Although the findings are promising, the researchers note patients should not be self-prescribing mannose and further studies are required.

Mannose is a sugar that occurs as a component of many natural polysaccharides.

Tumors use more glucose than normal, healthy tissues. However, it is tough to control the amount of glucose in the body through diet alone. In the study, which was funded by Cancer Research UK and Worldwide Cancer Research, the researchers found that mannose can interfere with glucose to reduce how much sugar cancer cells can use.

“Tumors need a lot of glucose to grow, so limiting the amount they can use should slow cancer progression. The problem is that normal tissues need glucose as well, so we can't completely remove it from the body,” says Professor Kevin Ryan, lead author from the Cancer Research UK Beatson Institute.

“In our study, we found a dosage of mannose that could block enough glucose to slow tumor growth in mice, but not so much that normal tissues were affected. This is early research, but it is hoped that finding this perfect balance means that, in the future, mannose could be given to cancer patients to enhance chemotherapy without damaging their overall health,” he adds. 

The researchers examined how mice with pancreatic, lung or skin cancers responded when mannose was added to their drinking water and given as an oral treatment. They found that adding the supplement significantly slowed the growth of tumors and did not cause any apparent side effects.

To test how mannose could also affect cancer treatment, mice were treated with cisplatin and doxorubicin – two of the most widely used chemotherapy drugs. They found that mannose enhanced the effects of chemotherapy, slowing tumor growth, reducing the size of tumors and even increasing the lifespan of some mice.

Regarding other types of cancer, including leukemia, osteosarcoma, ovarian and bowel cancer, the researchers grew cancer cells in the lab and treated them with mannose to see whether their growth was affected. The results showed that some cells responded well to the treatment, while others did not. It was also found that the presence of an enzyme that breaks down mannose in cells was a good indicator of how effective treatment was.

“Our next step is investigating why treatment only works in some cells so that we can work out which patients might benefit the most from this approach. We hope to start clinical trials with mannose in people as soon as possible to determine its true potential as a new cancer therapy,” says Ryan.

“The next step would be to secure approval and funding before trials could take place,” Dr. Catherine Pickworth of Cancer Research UK tells NutritionInsight.

Mannose is sometimes used for short periods to treat urinary tract infections, but its long-term effects have not been investigated. Therefore, the researchers note the importance of further research being conducted before mannose can be used in cancer patients.

“Although these results are very promising for the future of some cancer treatments, this is very early research and has not yet been tested in humans. Patients should not self-prescribe mannose as there is a real risk of negative side effects that haven't been tested for yet. It's important to consult with a doctor before drastically changing your diet or taking new supplements,” says Martin Ledwick, Cancer Research UK's Head Nurse.

Other natural ingredients have been found to hold promising potential for the treatment of cancers. One striking research found that matcha green tea can kill breast cancer cells by preventing them from “refueling.” The study, published in Aging, indicate that matcha green tea could hold potential for the natural treatment of cancer. The same team also found that an earl grey tea ingredient, bergamot, can kill cancer cells and works as an anti-cholesterol agent.