A Nutritionist’s Perspective on Cancer

As part of my recent series on cancer and nutrition, I invited Karen Mohn, CalvertHealth’s Registered Dietician who works with persons undergoing various forms of chemotherapy and with oncology patients in general, to provide her views on the intersection of cancer and nutrition.

What are the possible contributions of diet, whether positive or negative, to one’s risk of cancer?
The interaction of diet or nutrition and cancer risk is complex. There are no specific foods that can completely prevent cancer. But there are eating habits that over time have been shown to reduce the risk of developing cancer. A diet that promotes a healthy weight, protects the immune system, reduces inflammation, and promotes healthy digestive tract function exerts definite anti-cancer effects. On the other hand, a diet characterized by frequent or heavy intake of processed foods, red meat, and refined carbohydrates seems to promote the development of some cancers. Unfortunately, research on the influence of diet on cancer risk has largely been laboratory based. Clinical trials and other such investigations involving diet in human subjects are difficult to conduct and findings are often unreliable due to confounding variables. But we may conclude from available data that a diet of whole foods with a variety of nutrients will prove beneficial to efforts to avoid development of some kinds of cancer, whereas consumption of processed and convenience foods seems likely to contribute to cancer development. There is an established link between frequent, habitual ingestion of smoked meats and stomach cancer, for example.

Once cancer has become a reality in someone’s life, what do you believe is the role of nutrition and diet in helping secure a successful or positive outcome the treatment of that person’s condition?
During cancer therapy, nutrition plays a vital role in the treatment plan. Good nutritional intake can help build up strength, enhance one’s overall sense of well-being, increase energy, maintain body weight and nutrition stores, and lower the risk of infection. Most importantly, healthy nutritional intake can help a person under treatment to heal and recover faster.

What myths or commonly held misconceptions have you encountered with respect to nutrition and cancer?
The most common misconception is that sugar causes cancer cells to grow. There is the false idea that cancer cells thrive on carbohydrates and can be starved if one cuts out sugar and like substances. However, both simple and complex carbohydrates are vital body fuel sources, so eliminating carbohydrates will adversely affect one’s energy levels while exerting no meaningful impact on cancer cell growth. Of course, it is desirable to control one’s consumption of sugar because this can contribute to weight gain and other chronic diseases. There is no reputable research proving all sugar is definitely unhealthy, so persons with cancer need not avoid it.

Are there any “superfoods” concerning cancer?
“Superfood” is a marketing term used by some advocates who claim that certain foods possess superior health benefits due to their concentration of nutrients. Good research has shown that eating certain foods can beneficially influence a person’s risk of cancer. Cruciferous vegetables such as broccoli, cauliflower, and brussels sprouts are linked to lower risk of colorectal cancer due to their content of sulforaphane and other nutrients. This property has earned these vegetables designation as superfoods. Legumes, which include beans, lentils, and peas, are all low in fat, high in protein, and rich in insoluble fiber, which aids in digestion and overall healthy gut function and microbiome status. Because of these positive nutritional properties of legumes, they also have been considered a category of “superfood.” Indeed, the popular ideas of a plant-based diet for prevention and treatment of cancer grew out of the superior properties of legumes with respect to cancer. The spices turmeric and cinnamon have been linked to a decreased risk of cancer due to their anti-inflammatory properties. Salmon, mackerel, and other fatty fish are rich in omega-3 fatty acids, as are certain plant foods such as flax seed. These substances can block the development of certain types of cancer. Berries earned their “superfood” designation because they are rich in antioxidants and phytochemicals, which are cancer-fighting compounds. There are several other food contenders for the “superfood” title, but no solid research has shown that regular intake of them prevents or helps treat cancer. Consistently ingesting a diet rich in a variety of vegetables, fruits, whole grains, lean meats, and healthy fats is still the best way to lower one’s risk of cancer or assist in the treatment of cancer. All the so-called “superfoods” should be part of a wise and informed diet.

What is the most important idea you want people to grasp about nutrition and cancer?
Consuming a healthy diet can help prevent cancer and contribute beneficially to the treatment of cancer. Eating whole foods containing a variety of nutrients, balancing intake of lean protein, complex carbohydrates (including fruits, vegetables, and whole grains), and healthy fats at all stages of life can help to prevent cancer and mitigate the stresses of cancer treatment.