Breast Cancer Nutrition Myths

Eating for better breast health

If you’re at higher risk of developing cancer, are currently undergoing treatment or are a survivor, you no doubt know that you need to pay attention to what you’re eating to keep yourself healthy and keep the cancer at bay.

But what exactly to eat — and when — isn’t always straightforward. Nutritional information is constantly evolving, which can be confusing. As such, many myths about how best to eat for breast cancer health abound.

Why nutritional myths live on

“Behind every nutrition myth, there’s a kernel of truth,” says Cathy Leman, a dietitian, personal trainer, nutrition therapist, speaker, writer and breast cancer survivor based in Chicago.

The reasons they live on are many, including:

— Many health care professionals are taught little about nutrition and may not have confidence in their knowledge or inadvertently share outdated or incorrect information.

— Some may provide only limited information or not have good answers for patients with regard to nutrition, which can be confusing for the patient.

— Nutritional science is continually evolving, and what might have been true a few years ago, may now look different with additional evidence.

— Sensationalized reports about nutrition studies sometimes misrepresent or exaggerate findings.

Here’s a look at 10 common myths related to breast cancer nutrition.

Myth 1: I have to cut out all sugar from my diet because sugar feeds cancer cells.

“The No. 1 question I get from all cancer patients, including breast cancer patients, is whether or not sugar feeds cancer,” says Lisa Skrenchuk, a registered dietitian nutritionist and board certified specialist in oncology nutrition with the Sobrato Cancer Center at Santa Clara Valley Medical Center in California. “Technically the answer is yes, because glucose — the form of sugar that is used in the body — actually feeds every cell in the body. In fact, all food feeds cancer, sugar included.”

How this myth came about is based in scientific understanding of cancer metabolism, says Kailey Proctor, an oncology dietitian with the Center for Cancer Prevention and Treatment at St. Joseph Hospital in Orange County, California.

“Cancer cells have more insulin receptors to take in the sugar compared to healthy cells,” Proctor continues. That glucose energy gets gobbled up by cancer cells quickly “via the insulin receptors because they have a greater ability to do so compared to healthy cells. Thus, a special sweet treat doesn’t cause cancer, but your diet shouldn’t solely be composed of processed or added sugar as it’s easy to gain weight on these foods. Becoming obese or overweight is one factor we do know increases the risk of cancer and/or a recurrence,” Proctor explains.

What’s more, cancer cells have the ability to shift gears and use ketone bodies, which are derived from fat, as an energy source,” Skrenchuk says. “Indeed, in a prolonged fasted state among cancer patients, fat and muscle breakdown occurs, thus allowing tumors to continue to grow while you lose weight and strength.”

If you’re going through treatment, “remember that your healthy cells need energy during this time,” says Hollie Zammit, an oncology dietitian with Orlando Health in Florida. “If you try to cut out all sugar from your diet, cancer cells will find a way to convert other nutrients or tissues in your body, such as fat and muscle, into sugar for energy. This won’t help treatment, but it could leave your healthy cells low on energy.”

Bottom line: “Enjoy sweet treats and desserts in moderation, no more than 25 grams of added sugar a day for adults, and 12 grams for children. If you’re overweight, avoid gaining weight and work towards a healthier weight,” aiming for a total body weight loss of 7% or more, depending on how much excess weight you’re carrying, Skrenchuk says.

Myth 2: Soy products contain estrogen and cause breast cancer.

“Soy contains isoflavones, which have a similar structure to the hormone estrogen, but it’s not the same as female estrogen,” Zammit says.

Current evidence suggests this idea that soy products cause breast cancer isn’t true, and in fact, soy might actually be helpful, Skrenchuk says. “The consensus among health experts is that breast cancer patients can safely eat soy foods, and that it may even provide a beneficial effect.”

Some evidence suggests that isoflavones could “possibly decrease your risk of breast cancer by binding to your estrogen receptors in breast tissue and decrease the likelihood that estrogen-triggered cell growth will occur,” Zammit says. “Current research shows that overall, soy is safe for women to consume if they are at risk, have breast cancer or are in remission.”

Myth 3: Dairy foods cause breast cancer because of added hormones.

“The hormones are not added to the dairy,” Leman explains. Rather they’re “given to the cow to increase production.”

It’s too simplistic. “Dairy is a complex product, and we’ve got to look at all the compounds in dairy,” including protein, casein, lactose and calcium, rather than focus on a single element, Leman says. How the animal has been raised can also make a difference in the quality of the dairy it produces.

Bottom line: There’s not enough information to make a definitive, across the board recommendation for or against including dairy in your diet if you have breast cancer. “If you enjoy dairy, it’s OK to eat it,” Leman says. “If you’re worried about hormones, look for milk that’s not from cows treated with bovine growth hormones,” which will be listed on the container. Or try a plant-based milk.

And if you don’t like dairy or are allergic to it, don’t eat it. You can get the healthy nutrients found in dairy, such as calcium and protein, from other foods.

Myth 4: Alcohol changes the estrogen in your body.

This myth is almost accurate, but not quite.

“There appears to be a concerning link between breast cancer and alcohol,” says Michelle MacDonald, clinical dietitian supervisor at National Jewish Health in Denver.

The Nurses Health Study, a large epidemiological study, found that two drinks a day elevated the chance of developing breast cancer significantly, MacDonald says. The findings noted that while the current average risk in the U.S. is that 12 out of 100 women develop cancer in their lifetimes, the increased risk attributed to alcohol meant that “14 to 15 out of 100 women may develop the disease. It’s a little worrisome,” she says.

But it’s not because alcohol consumption changes the estrogen itself. Rather, it may be increasing the circulating levels of estrogen in the body, Leman says. Higher levels of estrogen in the body are a concern for women, especially those with estrogen-receptor positive breast cancer, which is the most common form.

So yes, you should limit your intake of alcohol if you have breast cancer or are at risk of developing it. Studies show a modest but significant association between alcohol consumption and the increased risk of breast cancer recurrence, and in some studies, this association is stronger in postmenopausal women.

It also appears there’s a dose-response situation here. “The degree of increased risk is directly related to the amount of alcohol consumed, starting with a small increase in breast cancer even with one drink every other day,” MacDonald says. And, it doesn’t matter whether you’re drinking beer, wine or hard liquor — it’s the ethanol in the beverage that appears to be the issue.

So how much can you drink? “What I always hear researchers say at conferences and in the research is that there’s no safe lower limit,” Leman says, meaning that any amount of alcohol consumption could elevate your risk.

In addition, alcohol is a “concentrated form of calories, so that can contribute to weight gain and weight gain, and excess weight is a risk factor” for developing breast cancer or experiencing a recurrence, she adds.

For her own risk tolerance, Leman says she quit drinking when she was diagnosed with breast cancer. “I love, love red wine. But I hate breast cancer more.”

Myth 5: Acidic blood increases risk of recurrence.

It’s true that in lab studies, cancer cells have been found to thrive in a somewhat acidic environment and can’t survive in a highly alkaline environment. Eating patterns like the alkaline diet claim to lower that acidity and make the body less hospitable to cancer.

“Like other myths, there’s a little truth to this,” Leman says. “The immediate environment around cancers cells, which is called the microenvironment, that can become acidic,” she explains.

But whether the foods you eat create those conditions has not been proven. It’s true that eating acidic foods can increase the acidity of your urine, “but acidity or alkalinity in your urine doesn’t indicate a change in your overall body pH.”

Currently, she adds, “there’s no good evidence to prove that diet can manipulate your whole-body pH or that it has an impact on cancer.” And, it’s worth noting that the body regulates itself to operate within a narrow pH range. When the body falls outside that range, it could be life threatening.

Myth 6: Organic produce is healthier and offers more protection against recurrence.

For produce to be labeled as organic, it must meet certain restrictions regarding the use of pesticides and other growing practices.

“Some research says there may be a little bit higher nutrient composition in organic produce, maybe because the soil is different,” Leman says. For now, however, “there’s little scientific evidence that indicates eating organic produce lowers cancer risk.”

Bottom line: “We need more research into the role of organic foods in reducing risk. In the meantime, no one’s ever going to tell you that you’re eating too much broccoli,” whether it’s organically or conventionally produced, Leman says.

Myth 7: Estrogen foods make cancer worse or will make it come back.

Dietary phytoestrogens are naturally occurring bioactive compounds found in plants — vegetables, fruit, legumes and certain grains — that mimic estrogen in the body. But Leman notes that “plant estrogen is not the same as naturally occurring hormones in the body.”

Some studies have indicated that phytoestrogens do not bind to estrogen receptors on cells as tightly as estrogen that’s manufactured in the body, so their impact may be less pronounced. The evidence and study results are ambiguous, Leman says, “but in general, available evidence for the association between dietary phytoestrogens and endocrine biomarkers is inconclusive.”

There’s not enough evidence to say for sure whether foods that contain bio-estrogens are a problem for people with breast cancer.

Phytoestrogens are found in many of the healthiest foods, and as such, Leman says she doesn’t try to avoid them. “I see where people are concerned about phytoestrogens if they’ve had hormonally-driven cancers. Yet they’re replacing them with a lot more processed or fast food,” which is definitely not a healthier choice.

Myth 8: Prolonged fasting can prevent recurrence and make you lose weight.

Intermittent fasting has been garnering a lot of attention lately as a solution to a lot of health issues, including weight loss and modifying risk of diabetes. There’s also been some discussion of whether it might help combat cancer risk, as it may help lower levels of inflammation in the body.

There’s also “a lot of evidence from animal studies that intermittent fasting does have favorable effects on insulin metabolism and inflammation, but human studies have not supported those findings yet,” Leman says.

That said, “one large prospective study of patients with early stage breast cancer shows that a nightly fast of less than 13 hours was associated with a 36% higher risk of breast cancer recurrence,” Leman says. Study participants who fasted longer than 13 hours were less likely to experience a breast cancer recurrence.

Bottom line: “Intermittent fasting can be beneficial for some people because it causes them to put their awareness on their eating habits and to be more deliberate when they’re eating.” She says it can help folks who tend to snack at night curb that habit, which could lead to weight loss.

Myth 9: Special diets cure cancer.

A lot has been suggested about certain special diets, such as the vegan diet (which contains no animal products at all) and the ketogenic diet (which is a very high-fat, super low-carb approach to eating) might reduce risk of cancer or its recurrence. For both diets, the evidence of their impact on breast cancer risk is limited.

With regard to the keto diet, there is some logic here, Leman says. “From a metabolic standpoint, it makes sense, but we don’t have anything definitive. So far, the vast majority of claims regarding keto and cancer are drawn from lab studies and animal studies,” Leman says, some of which are encouraging. But it’s important to remember that cell and animal studies are quite different from studies conducted in humans.

There is also some truth that a plant-based diet is connected with better health overall — specifically for its ability to control diabetes and heart disease. But those benefits may not extend to a stricter vegan or vegetarian diet.

If you adopt either a vegan or a ketogenic diet, there’s the added benefit of becoming more aware of what you’re eating, which could lead to smaller portion sizes and removing some of the junk from your diet. But bottom line: “There’s no one special diet that’s been scientifically proven to reduce the risk for breast cancer,” Leman says.

Myth 10: Dietary fat has been linked to breast cancer.

One of the main drivers of the recommendation to follow low-fat diets in the 1980s and up until recently was the belief that fat in the diet increases the risk of breast and other cancers,” says MacDonald.

Yet, she adds, “there’s no association between the percentage of calories from fat in the diet and risk of breast and other cancers.”

However, there’s a difference between dietary fat and body fat, and being overweight or obese is “strongly related to the risk of postmenopausal breast cancer and many other cancers.” Even if you’re just a little overweight, that’s a significant increased risk of dying of cancer, and the heavier you are, the higher your risk climbs.

What should I eat?

“During treatment, the highest priority is to maintain weight and muscle mass so you can safely endure treatment and maintain strength,” Skrenchuk says. “Weight loss and muscle mass loss is associated with increased risk for infection, hospitalization and severe side effects. However, weight gain is more common than weight loss for individuals undergoing treatment for breast cancer.”

To keep your weight in check, she recommends adopting a Mediterranean or other plant-based diet that’s rich in:

— Fruits.

— Vegetables.

— Whole grains.

Plant proteins.

“The Mediterranean diet is the most evidence-based diet for those seeking to reduce their cancer risk and is an excellent starting point.”

In addition, Zammit says you should try to limit your consumption of added sugars, saturated fat and high-sodium food items.

And stay flexible because treatment for breast cancer may affect what you’re able to eat and can change how certain foods taste to you. “The side-effects you may encounter from treatment will dictate what foods to increase and or decrease in your diet.”

Skrenchuk also urges you to stay hydrated. “Most women will need 3 liters, or about 100 ounces of fluid per day.”

Bottom line: “There is no one food that will cause breast cancer; nor is there one food or food group that will cure breast cancer,” Proctor says.

How to tell nutritional myths from fact

We’re awash in information all day long, and it can sometimes be difficult to parse fact from fiction. When you’re looking for reliable nutritional information, Leman recommends doing the following five things:

1. Look for information that’s sensible rather than sensational. If it sounds too good to be true, it probably is.

2. Look for evidence versus belief. Is the source showing you the evidence that backs up a claim, or is the information couched as personal belief?

3. Look for advice that supports creating overall behavior change versus “do this one thing.” Nutrition is a complex animal, and it’s unlikely that “one simple trick” will make a substantial positive impact.

4. Look for phrases like “reduce risk,” rather than “cure” or “guarantee.” Nutritional science is constantly evolving and we don’t have all the answers. Anyone who claims to have a guaranteed solution is likely selling snake oil.

5. Look for credible, trustworthy, evidence-based sources. Always consider whether your source has the education, background and training to offer the kind of advice they’re peddling.

Breast Cancer: 10 Nutrition Myths

— You have to cut out all sugar from your diet because sugar feeds cancer cells.

— Soy products contain estrogen that cause breast cancer.

— Dairy foods cause breast cancer because of added hormones.

— Alcohol changes the estrogen in your body.

— Acidic blood increases risk of recurrence.

— Organic produce is healthier and offers more protection against recurrence.

— Estrogen foods make cancer worse or will make it come back.

— Prolonged fasting can prevent recurrence and make you lose weight.

— Special diets cure cancer.

— Dietary fat has been linked to breast cancer.

More from U.S. News

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Breast Cancer Nutrition Myths originally appeared on usnews.com

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