Can Your Diet Influence Your Breast Cancer Risk? A Miriam Hospital Expert Says Yes

Posted Monday, October 01, 2012

October is Breast Cancer Awareness Month

Could what you eat potentially impact your risk of breast cancer or breast cancer recurrence? According to Mary M. Flynn, PhD, RD, LDN, research dietitian at The Miriam Hospital, your nutritional habits can influence some risk factors for breast cancer.

“I don’t think we will ever get to the day when we will say ‘Eat this diet and you will never get breast cancer,’ but I think there are enough published studies to make more specific diet recommendations than have been made to date,” Flynn says.

Most women who are diagnosed with breast cancer are told to follow a low-fat diet. However, Flynn says this is interesting because there are no published studies that demonstrate women who eat a low-fat diet, or simply decrease the fat in their diet, will lower their risk of breast cancer or recurrence. 

“To the contrary, I think you can make a better case that eating a low-fat diet could increase your risk of breast cancer,” Flynn says. This is because a lower fat diet typically increases blood levels of glucose and the hormone insulin, which is needed to store blood glucose and other blood nutrients.  Excess levels of both blood glucose and insulin – common in overweight or obese individuals – have been linked to higher rates of cancers, including breast cancer.

Flynn adds that being overweight at time of diagnosis, as well as gaining weight through cancer treatment, can also increase recurrence risk.  She believes achieving and maintaining a healthy body weight is the most important thing an individual can do to lower their risk of breast cancer and breast cancer recurrence.

She advises eating a healthy, plant-based diet full of fruits and vegetables. Plant-based diets are not only linked to better overall health, but all plant foods contain compounds known as phytonutrients that have been shown to decrease risk factors for breast cancer and other chronic diseases. 

Flynn also recommends the following dietary changes:

• Use extra virgin olive oil (the juice of the olive, a plant product). Women raised on diets that include olive oil have a very low breast cancer rates.  In fact, some studies show that the more olive oil a women has used in her life, the lower her risk of breast cancer. Extra virgin olive oil is loaded with risk-reducing phytonutrients and it can also improve insulin function, leading to lower blood levels of both insulin and glucose.  However, Flynn cautions that not all extra virgin olive oil sold in the United States is actually extra virgin.  She suggests consumers visit websites such as www.extravirginity.com to make sure they are purchasing true extra virgin olive oil.

• Eat more vegetables, especially those dark in color and from the cruciferous or cabbage family. While it is great to eat a variety of vegetables, studies have shown some vegetables are better at preventing breast cancer than others. For example, the deeper or darker a vegetable’s color, the healthier it is. The color is due to cancer-fighting carotenoids, or the red, orange, and yellow pigments in fruits and vegetables.  Flynn encourages the use of more frozen vegetables: because they are kept on the plant longer than most “fresh” vegetables, they tend to be darker in color, which boosts their health benefits. She also says carotenoids need fat to be absorbed so it’s important to cook vegetables in olive oil – which also helps them taste better. 
  
  Two carotenoids that appear to have importance cancer-prevention roles are alpha-carotene and lycopene. Vegetables that contain alpha-carotene include broccoli, carrots, kale, spinach and other dark greens, sweet potatoes and winter squash. Lycopene is found mainly in tomatoes, yet Flynn says we absorb lycopene best when eating processed tomatoes, such as canned tomatoes or commercial sauce, rather than fresh tomatoes. She recommends including canned or processed tomato products weekly.
  
  The cabbage or cruciferous family of vegetables (including broccoli, brussel sprouts, cabbage, cauliflower and kale) contain a phytonutrient that studies have shown can shift estrogen metabolism to a form that does not drive breast cancer. It can also prevent some cancers from starting.
  
  Cruciferous vegetables contain sulfur components, which give them their characteristic taste and smell.  Many people do not find this vegetable group very appealing due to the sulfur, but Flynn says cooking – or especially roasting – these vegetables in olive oil greatly improve their taste. She suggests using one tablespoon of extra virgin olive oil per cup of vegetables.  Toss the vegetables in the olive oil, arrange in a single layer in a baking pan or a sheet with a small side (not a cookie sheet, or the oil might spill into the oven) and roast for about 30 minutes at 400 F, turning the vegetables over half way through.

Flynn also suggests avoiding or consuming less of the following foods:

• Vegetable oils, such as soybean, safflower, corn oils, and products made with them, including margarine, salad dressing and mayonnaise. Vegetable oils are primarily polyunsaturated fats, which oxidize or break down in the body. Excessive oxidation can start and drive cancer.

• Red meat, which has been related to a higher risk of breast cancer, especially if grilled. Grilling produces chemical compounds known as heterocyclic amines (HCA) that act like nicotine and can drive cancers.  Red meat also contains amino acids that stimulate insulin production and increase oxidation in the body, both of which can increase cancer risk.

Filed under: Comprehensive Cancer Center, Miriam,