Reducing Breast Cancer Recurrence and Mortality: A Look at What The Research Suggests About the Role of Our Diets

While existing research doesn’t support the notion that specific foods can increase survival, there is considerable evidence that dietary patterns can make a significant difference for women fighting breast cancer! Let’s take a look at some of these dietary patterns.

Dietary fat intake
In the Women’s Intervention Nutrition Study (WINS), R.T. Chlebowski and colleagues demonstrated that when women reduced their fat intake to 20% or less, they reduced their risk of breast cancer recurrence by an average of 24%! (http://jnci.oxfordjournals.org/content/98/24/1767.long).

One currently popular diet hyped as being good for all of us is a diet rich in animal proteins and low in carbohydrates, because the assumption is that all carbohydrates are unhealthy. However, these diets are not good for any of us and, in fact, can actually be the recipe for a bad outcome for breast cancer patients! Why? Because, as those of you familiar with Life Over Cancer already know – all carbohydrates are NOT created equal. Simple and refined carbs can lead to glycemia and insulinemia, both of which can drive cancer growth! On the other hand, complex carbs do not raise blood glucose and insulin. In fact, the research demonstrates that controlling glycemia and insulin levels through the use of complex carbohydrates not only reduces the risk of recurrence, but also reduces mortality! (http://www.ncbi.nlm.nih.gov/pubmed/11773152)

Vegetables and fruits
Vegetables and fruits are fundamental to any healthy diet, and are part of healthy dietary recommendations for the prevention of cancer as well as other diseases. As it relates to breast cancer, Cheryl Rock and colleagues assessed carotenoid levels of patients in a breast cancer diet trial and found that those in the top 2/3 of carotenoid levels over the course of the study were 33% less likely to have a breast cancer recurrence or new breast cancer. (http://www.ncbi.nlm.nih.gov/pubmed/19190138). Carotenoids are found in both vegetables and fruits; yellow and orange fruits and vegetables and dark green leafy vegetables are particularly good sources. Dark green vegetables also contain lutein, including kale, collards, spinach and Swiss chard. Other high carotenoid vegetables and fruits include carrots, sweet potatoes, pumpkins, winter squash, apricots, mangoes, cantaloupe, and tomatoes. As far as fruit juices, while it’s OK to occasionally enjoy some of these fruits as juices, we generally recommend eating them as whole fruits. However, if you choose to drink juices, you might consider diluting them with water by 25% – 50% in order to reduce the sugar load. Eating whole fruit provides extra fiber and helps control calories as well as excess fructose consumption. It’s important to note that high fiber intake is associated with lower overall mortality in breast cancer patients (including both breast cancer deaths and deaths from other causes). http://www.ncbi.nlm.nih.gov/pubmed/?term=fiber+breast+cancer+belle; http://www.ncbi.nlm.nih.gov/pubmed/17044767. Foods high in fiber include raspberries, pears, barley, whole wheat spaghetti, brown rice (as opposed to white rice), beans (all types, e.g. split peas, lentils, kidney beans, black beans), green peas, broccoli, cauliflower, and turnip greens.

Dairy
Several studies have shown that high-fat dairy intake is significantly related to higher breast cancer mortality as well as mortality from other diseases. Low fat dairy did not demonstrate a direct correlation to breast cancer mortality. http://www.ncbi.nlm.nih.gov/pubmed/?term=kroenke+dairy+breast+cancer. So, if you’re going to use dairy products, choose low-fat varieties of milk, yogurt or cheese. Better still – and what we recommend to our patients at the Block Center – consider some of the dairy alternatives available today, including soy milk, almond milk (available in low-fat and unsweetened), and rice or oat milk.

Fish and Fish Oil

High intake of omega-3 fatty acids from fish in the diet has been correlated with reduced breast cancer events (recurrences, new breast cancers) and reduced overall deaths from breast cancer and other causes: pubmed.ncbi.nlm.nih.gov/25936773/.
Fish that are high in omega-3 fats include salmon, sardines, anchovies, tuna, cod, haddock, Atlantic mackerel, halibut and other fish from northern oceans. We recommend reducing or avoiding tropical fish, like tilapia, or farmed catfish, which are not high in omega-3s.

Soy
There has long been controversy as to whether an estrogen-sensitive breast cancer patient might worsen their disease by consuming soy products. In fact, a few leading breast cancer specialists have railed against the consumption of soy, raising worries of its safety. At the same time, breast cancer research at the Block Center demonstrated enhanced outcomes among patients consuming increased levels of soy. And now, emerging science from both the laboratory and from large scale epidemiological studies have confirmed what our early data suggested. Bottom line, soy is not harmful for breast cancer patients, and may, in fact, be quite helpful. (http://www.ncbi.nlm.nih.gov/pubmed/20426596).

A particularly interesting 2013 study pooled the results from 3 large American studies and 1 Chinese study of the diets of breast cancer patients after diagnosis. This combined study found that soy foods turned out to be associated with better survival with an impressive 15% reduction in risk of death for all breast cancer patients regardless of menopausal status or presence of estrogen receptors. They also found that soy foods were associated with lower recurrence rates in postmenopausal women whose tumors lacked estrogen receptors, as well as those who had both estrogen and progesterone receptors. (http://www.ncbi.nlm.nih.gov/pubmed/?term=chi+post-diagnosis+soy).

When you add soy foods to your diet, emphasize the relatively un-processed types of soy, such as tofu, edamame, miso and tempeh. These are healthier and less caloric than highly processed soy meat substitutes. Additionally, when used as a substitute for meat, soy may be helpful in controlling weight, since it’s lower in calories.

Insulin Levels
A 2002 study found that breast cancer patients with high insulin levels, which are correlated with high body mass index, had elevated risks of breast cancer mortality and recurrence. (http://www.ncbi.nlm.nih.gov/pubmed/11773152). Several studies since then have implicated elevated insulin, and elevated blood glucose and related variables to breast cancer. To reduce elevated insulin and blood glucose, we suggest consuming low-glycemic index foods, which have been found to only minimally raise blood glucose levels. Avoiding refined flours, refined sugar and related products (white and brown sugar, molasses, honey, cane juice and others), and eating nuts such as almonds or walnuts can help. In one study, almonds reduced C-peptide, a marker for insulin production, more effectively than whole-wheat muffins: (http://www.ncbi.nlm.nih.gov/pubmed/?term=jenkins+almonds+whole+wheat+c-peptide). Alternatives to refined sugars include sweeteners such as stevia and limited quantities of other natural sweeteners such as agave or brown rice syrup. And, a sweet piece of nutritious fruit can make a delicious dessert!

In addition to these dietary recommendations, it is important to mention that there is research demonstrating that both obesity and weight gain following a breast cancer diagnosis can lower the chances of survival, as pointed out in a 2019 review article: (https://pubmed.ncbi.nlm.nih.gov/31277273/). Obesity and weight gain after diagnosis can both lower survival chances. If your weight is not ideal, a plan for weight loss that incorporates sound nutritional choices and exercise is a powerful way to improve your outcome.

Our general dietary recommendations
At the Block Center, we recommend a diet low in saturated fats and high in fiber, plant-based sources of protein, cold water fish rich in omega-3 fatty acids, complex carbohydrates, fruits and berries rich in antioxidants, and nuts, seeds and cruciferous vegetables, foods containing other substances such as allium compounds, dithiolthiones, flavonoids, glucosinolates, indoles, isothiocyanates, phenols, and d-limonene. This nutritional strategy is intended to do several things, including:

• Help curtail inflammation, which is essential for combating recurrence and progression. In fact, elevated inflammatory markers can increase risk and mortality by 2 to 3-fold, whereas countering this can be the difference in the proliferation and dissemination of breast cancer cells, or never seeing the cancer again!
• Reduce free-radical damage.
• Minimize platelet activation (which can lead to dangerous blood clotting).
• Manage blood sugar surges.
• Reduce serum levels of insulin-like growth factor 1, or IGF-1 (which stimulates cell multiplication and inhibits cell death).

Evidence shows that reducing glycemia, insulinemia, inflammation and oxidation makes a huge difference in every challenge a breast cancer patient faces, including improving the biological integrity needed to counter growth as well as reducing the risk of recurrence.

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