An exciting new study in yeast contributes to our understanding of the link between cancer cells and sugar (Nature Communications, Oct 13, 2017;8(1):922). Yeast cells, like cancer cells, get most of their energy from fermentation of sugar without needing oxygen. This study shows that fermentation in yeast activates Ras enzymes that increase conversion of normal cells to cancer cells and also increases growth of cancer cells once they are formed.
Differences Between Normal Cells and Cancer Cells
Almost 100 years ago, Otto Warburg showed that cancer cells get most of their energy from sugar without needing oxygen (Biochem. Z, 1924;152:319–344). Normal cells get 15 times as much of their energy from the Krebs Cycle inside mitochondria that converts sugar, fats and protein with oxygen and a much lesser amount of energy from anaerobic glycolysis outside mitochondria that converts sugar to energy without oxygen. Even though cancer and yeast cells can grow much more rapidly than normal cells, they get most of their energy from the much weaker method of burning sugar without oxygen.
Excess Sugar, Overweight and Cancer
This new study suggests that taking in excess sugar increases tissue levels of a chemical pathway that promotes the growth of cancer cells. Scientists have not shown that eating sugar causes cancer, but we do know that eating excess sugar increases risk for obesity and diabetes. Both obesity and diabetes are associated with increased risk for many different cancers.
• Being overweight is associated with the following cancers: colon, rectum, esophagus, kidney, breast (women), endometrium, stomach, liver, gall bladder, pancreas, ovary, thyroid, meningioma, multiple myeloma and B-cell lymphoma as well as the fatal types of prostate cancer and breast cancer in men (N Engl J Med, Aug 25, 2016;375:794-798; Lancet, Aug 30, 2014;384(9945):755-65). The International Agency for Research on Cancer (IARC) reported that being overweight is associated with almost five million cancer deaths each year.
• Full fat cells turn on your immunity to cause cancer-provoking inflammation, insulin resistance and oxidative stress, and obese people have higher blood levels of all of these markers (Br J Nutr, Dec 2011;106 Suppl 3:S5-78).
• Having excess fat in your belly turns on your immunity (Archives of Physiology and Biochemistry, 2009;115(2):86–96) to increase inflammation to increase risk for several cancers (Circulation, 2008;117(13):1658–1667). Belly fat is associated with increased risk for cancers of the colon, rectum, postmenopausal breast, liver, endometrium, esophagus, kidney, stomach, gall bladder, pancreas, ovary, thyroid and multiple myeloma (Cancer Prev Res, September 1, 2017;10(9):494-506). People who are not overweight but have big bellies are still at significantly increased risk for diabetes and cancers. Having excess belly fat increases a protein called fibroblast growth factor-2 (FGF2), that converts normal cells into cancerous ones (Oncogene, August 7, 2017).
• Adding about 4.3 inches (11 cm.) to your waist increases the risk for obesity-related cancers by 13 per cent (breast, bowel, womb, esophagus, pancreas, kidney, liver, upper stomach, gallbladder, ovary, and thyroid). Adding 3.5 inches (8 cm) to the hips is linked to an increased risk of 15 per cent for bowel cancer (British Journal of Cancer, May 2017;116(11):1486).
• A high-sugar diet is associated with spread of existing colon cancer (J Nat Can Inst, Nov 21, 2012;104(22):1702–1711). High blood sugar markedly increases insulin levels which has been shown to increase cancer risk (Med Sci Monit, 2015; 21: 3825–3833).
Ways to Reduce Your Risk for Cancer
There is strong evidence that excess sugar increases risk for heart attacks and strokes, and now we have evidence for a mechanism that can turn normal cells into cancerous ones. Risk for many types of cancers is reduced by:
• restricting calories, which lowers insulin and insulin-like growth factor-I (Frontiers in Physiology, 2012;3(318):1–10), and inflammation (Cancer Research, 2012;72(9):2314–2326).
• restricting sugar in all drinks and added to foods (Nutr Cancer, 2010; 62: 413-424; Am J Clin Nutr, 2010; 91: 1294-1302).
• engaging in a regular exercise program (Nature Reviews Cancer, 2008;8(3):205–211).
• eating lots of fruits, vegetables and other anti-inflammatory foods (BMJ, 2006;333(7578):1109–1111; BMJ, Nov 10, 2011;343).