Reducing sugar, extra body fat and cancer prevention

By Arvind M. Dhople, Ph.D., Professor Emeritus, Florida Tech

                The latest findings about the dangers of eating sugar and carrying extra body fat may spell bad news when it comes to dietary freedom, but being aware of them gives people the power to lower their cancer risk.  Recent studies confirmed that two diet-related culprits can contribute to the development of cancer: eating sugar, which increases the body’s production of insulin, and having excess body fat, which leads to inflammation.  Perhaps surprisingly, these processes happen not only in those who are obese or over weight but also in people who are considered a normal size based on their body mass index (BMI).

                The bottom line is that avoiding both sugar and overeating are important ways for everyone to help prevent cancer.  Sugar was always a villain, but sugar is a new villain now because it’s contributing to inflammation in cancer, not just diabetes and obesity – as if that was not enough.

                Eating a lot of sugar, especially quickly digested types such as high-fructose corn syrup, can launch a dangerous cascade of events.  Ingesting sugar raises glucose levels in the blood, triggering the pancreas to produce insulin.  The enzyme PI3K responds by producing a lipid known as PIP3 that helps insulin move glucose into the muscles and livers.  However, if generated at too high a level and not removed through normal body processes, PIP3 is capable of causing cancer.  That dynamic can kick in when people eat too much sugar over a long period of time, leading to a condition called insulin resistance, in which the muscles and liver no longer respond to insulin.

                Fifty percent of Americans are insulin-resistant, but most don’t yet have type 2 diabetes because their pancreas makes enough insulin to keep glucose in control – but they have high insulin around the clock.  Insulin-resistance can progress into type 2 diabetes, but even if it doesn’t, if a tiny tumor is growing in the body and it develops a genetic mutation in the PI3K pathway, it will respond to high serum insulin, activate PI3K and drive glucose into the tumor, not muscle.

                Insulin resistance can be treated.  The drug metformin lowers the amount of glucose in a person’s body.  But diet can make an even bigger difference.  On the high-fat, low-carbohydrate ketogenic diet, both glucose and insulin levels drop. 

                The ketogenic diet isn’t reserved for people who are insulin-resistance; almost anyone interested in preventing cancer can follow it.  The diet not only control insulin levels but also boosts weight loss, depriving any malignant cells of the glucose they crave.  Short of adopting a ketogenic diet, strictly eliminating sugar offers an east way to prevent insulin resistance, and there is no health risk in eating a sugar-free diet.

                Excess body fat also raises the risk of cancer, whether the person is obese or of normal size.  Normal-size women who are postmenopausal and have higher amounts of truncal fat, insulin and leptin (a hormone that controls appetite) – termed “metabolically obese” – are at increased risk of breast cancer.    

                Excess body fat is also associated with a worse outcome for some types of cancer.  Yet, people don’t see an effort to control excess body fat in cancer patients today.  Diseases associated with excess fat include cancers of the esophagus, stomach, colon, liver, gallbladder, pancreas, breast, ovary, kidney, brain (meningioma), thyroid and blood (multiple myeloma).  In breast cancer, obesity is a risk factor for the type driven by the hormone estrogen in postmenopausal women and signals a poorer prognosis.

                Excess body fat is associated with a variety of systemic changes, including elevated blood levels of hormones such as insulin and estrogen, which can contribute to the development of some breast cancers.  It is also linked to body chemicals that kick off the inflammatory process and local changes in breast tissue, such as inflammation.

                Potential ways to counteract inflammation include losing weight and using medicines that block estrogen production, such as aromatase inhibitors, which treat hormone-driven breast cancer, or newer obesity drugs.

                Researchers recommend a healthy, calorie-restricted diet that includes reduced fructose intake.  Exercise alone will not bring significant weight loss, but can help preserve muscle mass during diet-driven weight loss and also lower insulin resistance.  Although q reliable, noninvasive way to test for inflamed breast tissue is still needed.