Cancer; Nutrition

Sugar, inflammation, and soy: How does nutrition influence breast cancer risk?

Eating a healthy diet composed mainly of plant-based foods can be an effective way to help prevent breast cancer.

Many factors increase the chance of developing breast cancer. Some we can’t change, such as getting older or inheriting genetic mutations in the BRCA1 or BRCA2 genes. But we can control or at least modify a few risk factors – including our diet.

Study after study shows that healthy eating lowers not only your risk of developing breast cancer but also other health problems, such as heart disease. This is due in part to the connection between nutrition and obesity, which is in turn linked to inflammation.

Obesity and being overweight are associated with a higher risk of developing 13 types of cancer, including breast cancer. In fact, 18% of cancers in the U.S. can be linked to excess body weight, physical inactivity, excessive alcohol consumption, or poor nutrition.

No diet is guaranteed to prevent cancer. However, making healthy lifestyle choices can improve your general health and potentially reduce your risk of getting breast cancer.

Food, inflammation, and cancer risk

We’re constantly learning new things about how different foods affect our health. For example, inflammation is a stress response – and chronic inflammation is believed to cause DNA damage associated with cancer-causing genetic changes in normal tissues.

Certain foods stress the body more than others. Sugar and other carbohydrates can contribute to inflammation by causing blood glucose levels and, in response, insulin levels to rise. High levels of insulin – which moves the sugar into the cells – have been shown to stimulate cancer cell division. That activity is thought to support the growth and spread of cancer cells and may be part of the link between poor nutrition and cancer risk or relapse.

Increased fat deposition commonly observed in high-carbohydrate diets also can increase the amount of estrogen in the body, which can trigger cell division, especially in breast and uterine cells, which express the estrogen receptor. While carrying too much body fat is associated with insulin-resistance (high insulin levels) and inflammation, excess fat also produces estrogen.

How you prepare your food is important as well. Regularly consuming processed meats, such as hot dogs, sausages, and deli meats, has been shown to be associated with an increased cancer risk. And cooking foods at high temperatures, such as grilling or frying, can produce harmful compounds linked to increasing inflammation markers.

Prioritize plants in your diet

Moving to a plant-based diet doesn’t mean you have to become a vegetarian. It just means that fresh vegetables, fruits, and legumes (beans, peas, etc.) make up most of what you eat. The nutrients in plant-based, non-commercially processed foods appear to inhibit inflammation and, because of relatively low carbohydrate and high fiber content, don’t cause repeated sharp rises in blood insulin levels.

Think of plant-based foods as the main course and protein and high-fiber carbohydrates as the condiments. That’s the methodology behind the Mediterranean diet, which focuses on a menu of predominantly plants, as well as lean meats, fish, and plant-based fats like olive oil.

Soy, sugar, and fats

Some patients worry that eating too much tofu, miso, or other soy-based foods will cause their estrogen levels to rise. However, you’d practically have to eat nothing but these foods to theoretically increase your risk of breast cancer. The overall body of research shows that soy foods, eaten in moderation, do not increase the risk of cancer recurrence or early death.

You also may have heard that “sugar feeds cancer.” All cells use sugar (glucose) for energy, not just cancer cells. But cancer cells will use whatever they can to get energy. So, even if you cut sugar from your diet entirely, the cancer cells will find another energy source. High sugar and other carbs do increase insulin levels, and insulin receptors on tumor cells can cause cells to divide.

Finally, fats get a bad rap. Your body needs some fat for energy, to absorb vitamins, and to protect your heart and brain. But not all fats are created equal – healthier monounsaturated and polysaturated fats include fish oils rich in omega-3 fatty acids. These can also be found in foods such as avocadoes, eggs, nuts, olive oil, and sunflower seeds.

Related reading: Cancer prevention: The diet, exercise, and weight connection

Tips for eating a healthy diet

Changing how you eat can be difficult at first. But taking a holistic approach of eating unprocessed, nutritious foods is one of the best things you can do for your overall health.

Fatty fish such as wild salmon and mackerel can be part of a healthy diet.

Build your diet around:

  • Vegetables: Eat a colorful variety of vegetables (carrots, squash, broccoli, and sweet potatoes, for example) and some fiber-rich legumes (black beans, lentils, chickpeas, navy beans).
  • Fruits: Choose fruits rich in antioxidants and relatively low in sugar, such as fresh blueberries, blackberries, raspberries, and strawberries.
  • Whole grains: Foods in this group generally contain less sugar and more fiber than their white flour counterparts. Be sure to look at the carbohydrate and fiber content of your whole grains so you can maximize fiber and minimize carbohydrates content per serving.
  • Lean protein: Choose lean cuts of meat (grass-fed if possible), chicken, turkey, or fatty fish such as wild salmon, sardines, or mackerel.

Try to avoid:

  • Red and processed meats: This includes beef, pork, lamb, bacon, hot dogs, sausages, and lunch meat.
  • Highly processed foods and refined grain products: A lot of fast food falls into these categories and tends to be higher in fat and carbohydrates (including added sugar) and low in fiber.
  • Sugar-sweetened beverages: Choose water over soft drinks, sports drinks, juice, and fruit drinks with added sugars.
  • Alcohol: If you choose to drink alcohol, the Centers for Disease Control and Prevention (CDC) suggests limiting consumption to one drink a day for women and two a day for men.

We shouldn’t be expected to completely give up a food we love, but moderation is key.

How a nutrition expert can help

We are fortunate to have a wonderful nutrition team at UT Southwestern. These experts are fully integrated into our breast cancer care team, and they work with patients to make practical dietary changes.

Patients with breast cancer often ask what they should eat for the best chance of beating the disease. Unfortunately, there’s no easy answer. Weight gain can be a side effect of breast cancer treatment, as can appetite changes and nausea. We don’t want patients who are stressed from treatment to also feel the need to make big dietary changes during this difficult time. So, we often advise them to focus on eating what tastes good without overeating.

We also discuss how lifestyle changes can help reduce the risk of recurrence.

Ultimately, eating a healthy diet can have a positive impact on many aspects of your life. Talk with your medical team about how to incorporate a nutrition plan that helps you feel satisfied, nourished, and more energetic while reducing your risk of breast cancer and other diseases.

To talk with a cancer or nutrition expert, call 214-645-8300 or request an appointment online.

Breast Cancer Survivor Story

Brianna Hinojosa-Smith shares her story of being diagnosed with breast cancer at age 40 – when she was in the best shape of her life. With the love and support of her family and her care team at UT Southwestern's Simmons Cancer Center, Brenda says she is feeling stronger than ever now.