Guidance about Foods for Cancer Patients

By Dr. Kirsten West, ND, LAc, FABNO

In the years I have been in practice, it is clear that diet and nutrition are key factors in cancer treatment, prevention, and long-term survival. Two important studies that have been released recently are reinforcing the link between diet and nutrition and long-term breast cancer survival specifically.

Not surprisingly, they together point to a diet high in vegetable and fruit intake and mindful of the amount and quality of carbohydrates. It is important to remember that no one diet fits every survivor’s nutritional needs, but these studies offer some good basic guidance.

Both studies were long-term studies that were funded in part by the American Institute for Cancer Research (AICR) and were led by nutritional epidemiologist Maryam Farvid, PHD. Approximately 250,000 women participated through large Nurses’ Health studies. Participants joined the studies in either 1976 or 1989. All women were cancer-free at the time they participated in the study and 55 or younger when they joined the study, which means that some of the women had been participating for up to 30 years at the time of publication. By 2011, nearly 9,000 study participants had been diagnosed with breast cancer, and about 2,500 had died. [1]

Fruits & Vegetables

Women in both studies regularly answered questions about their dietary habits, family history, activity, and other cancer risk factors. One of the studies was published in the journal Cancer Research and focused on the link between overall vegetable and fruit intake.

The article showed that women who ate the greatest amount of fruits and vegetables after their breast cancer diagnosis had an overall lower risk of dying from any cause compared to those who ate the least amounts. [1]

Predictably, overall vegetable intake had the greatest effect on survival rates, with cruciferous vegetables (such as broccoli, cauliflower, and Brussels sprouts) and green leafy vegetables being among the best. Women who ate a full serving of cruciferous vegetables daily had a 13% lower risk of dying from any cause during the study than those who didn’t eat any.

The study showed that whole fruits alone didn’t have much impact on mortality, with the exception of blueberries. The study showed that whole blueberries may be linked to a lower risk of dying from cancer or any other cause. In the AICR article, Maryam Farvid said that it could be due to the antioxidants and other nutrients in the berries, but relatively few study participants were eating high amounts of blueberries. More research is needed in this area, but it is an interesting result. [1] This is not the first time blueberries have achieved accolades in cancer research.

Furthermore, the study drew a specific link between drinking apple juice and an increased risk of dying from breast cancer. The study participants who were considered to consume the highest amounts of apple juice drank an average of one cup each week. Apple juice was separated into its own category for evaluation, and all other juices were combined into a second juice category.

Apple juice clearly increased the risk of dying from breast cancer compared to other types. [1] I do believe that it is the high sugar content found in juice that leads to metabolic imbalance and therefore, hastened disease. Even vegetable juice, is high in sugar.

The study separated women into subgroups to evaluate habits and dietary patterns based on different intake levels. Those characteristics included total fruit intake, total vegetable intake, age at diagnosis, BMI, physical activity, daily alcohol consumption, daily fiber consumption, daily animal fat consumption, total fat intake as a percentage of overall calories, total calorie intake, and whether or not participants were current smokers or had ever used oral contraceptives or postmenopausal hormones. Participants completed questionnaires every four years after being diagnosed. [2]

Carbs

The second study was published in Cancer Epidemiology Biomarkers & Prevention. It focused on the types and amount of carbohydrates study participants consumed. We know that carbs, and the resulting insulin release, may promote cancer growth. [3]

This study measured the impact of glycemic index, glycemic load, insulin index, and insulin load on breast cancer survival. As with the previous study, participants completed a dietary questionnaire every four years.

As I stated in September’s Health Hunters, quality foods matter, and highly processed foods, including sugar – and sugar substitutes – contribute to obesity and health problems linked to inconsistent blood sugar and insulin levels. The study found that women who ate foods with a higher glycemic load and glycemic index were at a higher risk of dying from cancer or any cause during the study. [3] The glycemic load measures food’s impact on blood glucose and takes into account all carbs in food. The glycemic index assigns a numeric score from 0 to 100 to a food based on how dramatically it increases blood sugar.

For glycemic load, a low ranking is 10 or below. Medium is 11-19, and high is 20 or more. For example, raw broccoli has a glycemic index ranking of 15 and a glycemic load rank of 0.5. Compare that to a slice of processed white bread, which has a glycemic index ranking of 90 and a glycemic load of 43.9. [4] Glycemic load can be sneaky. For example, carrots have a higher glycemic index than ice cream. Subsequently, carrot juice carries an even higher glycemic load.

The insulin ranking index showed similar findings, with higher insulin-raising diets associated with women dying from any cause compared to those who ate lower insulin-raising diets. Fiber also may have contributed to longer survival during the study period. [1]

The studies identified some limitations, which do warrant additional research. The study participants were primarily White, so findings may not apply as directly to other racial and/or ethnic groups. The studies also did not directly take into account how a cancer recurrence or another disease may have affected what women ate. [1] However, it is helpful guidance for the more than 3 million breast cancer survivors living in the United States today.

One Size Does Not Fit All

It is important to remember that each individual’s breast cancer and dietary needs are unique. Every person is different. Every cancer is different, and the interaction between each creates a unique dynamic. The most effective way to identify what food intake is best for each person is through labs, epigenetics (tying closely to ancestry), and tumor characteristics.
When we do not have the best information from testing, I generally recommend a low-carb, Mediterranean diet. It alone heralds the best research to date. Simply put – it is a dietary intake rich in whole foods, high amounts of olive oil and olives, nuts and seeds, herbs and spices, clean proteins, some fruits, and many vegetables. Furthermore, the above studies clearly show diet does matter and steering clear of sugars and processed carbs is key.

There are many other therapeutic forms of eating, including but not limited to the ketogenic diet, a vegetarian diet, a paleo diet, and a carnivore diet. I think the ketogenic diet can be quite therapeutic as an alternative option.

However, it must be done wisely, with the help of a well-versed ketogenic practitioner, and must make sense given epigenetics and a person’s unique terrain. If for specific reasons, a ketogenic diet does not make sense, there are other ways to reach ketosis. One well-proven routine is intermittent fasting, a practice I believe we should all incorporate into our lives. It can be helpful despite individual differences, and there are many ways to incorporate intermittent fasting.

Dietary intake plays a big role in breast cancer survivorship and prevention. We can identify the best nutritional intake for a given individual and any individual cancer through testing and assessment.

For example, triple-negative breast cancer is often referred to as “diabetes of the breast.” Hormone-positive cancer is likely driven by metabolic issues and stress – both play a big role in glucose management. We often see patterns that point to these issues once testing and assessments are complete. However, there is no single cause, but we know that the interaction of terrain with the environment may either lead to “dis-ease” or wellness.

We must also remember that food is meant to be communal and shared with those we love. It ties emotions and nurture, which begin in childhood. Fostering that connection is important. What we eat should not be separate from who we share it with.

The bottom line is that dietary intake must be individualized, as there is no one-size-fits-all diet. Test, assess, and address! And when in doubt, pretend you live with those you love most – your tribe – enjoying a meal on the shores of Greece.

Resources
Nelson, M. R. (2021, March 18). Two new studies suggest diet can help breast cancer survivors live longer. American Institute for Cancer Research. https://www.aicr.org/news/two-new-studies-suggest-diet-can-help-breast-cancer-survivors-live-longer/
Aacrjournals.org. (n.d.). https://aacrjournals.org/cancerres/article/80/22/5134/645894/Postdiagnostic-Fruit-and-Vegetable-Consumption-and
Farvid MS;Tamimi RM;Poole EM;Chen WY;Rosner BA;Willett WC;Holmes MD;Eliassen AH; (n.d.). Postdiagnostic dietary glycemic index, glycemic load, dietary insulin index, and insulin load and breast cancer survival. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. https://pubmed.ncbi.nlm.nih.gov/33219162/
Learn about the glycemic index (GI). Glycemic Index Guide. (2023, June 16). https://glycemic-index.net/