Eat to Beat Breast Cancer: Six Foods to Choose (and Six to Lose)
One of the mightiest weapons in the fight against breast cancer may be the fork. Food can play a key role in reducing (or increasing) the odds of getting breast cancer or having a recurrence. While science suggests a healthful plant-based diet can reduce breast cancer risk, certain foods seem to be particularly good at defending against breast cancer, while others are risky. Here are six foods to choose—and six to lose.
Six Foods to Choose
1. Soy Milk
Replacing dairy milk with soy milk can slash the risk of breast cancer. A 2020 observational study found that replacing the typical intake of dairy milk with the typical intake of soy milk was linked to a 32% lower risk of breast cancer. And an analysis of 35 studies (a “meta-analysis”) found that, in Asian countries where soy intake is higher, consuming more soy isoflavones (protective substances found in soy) was linked to a 41% lower risk of breast cancer.
Breast cancer “thrivers” also benefit from consuming soy. A recent study of multiple other studies (another meta-analysis) found that women diagnosed with cancer who consumed more isoflavones—mostly found in soy foods—were less likely to have their cancer come back. They were also less likely to die of any cause.
How might soy be protective? Soy foods may displace meat in the diet, which can be helpful. The isoflavones in soy foods also appear to be beneficial. These isoflavones bear a passing resemblance to estrogen, and they can bind to estrogen receptors in the body. However, there are two distinct types of estrogen receptors: alpha and beta. When activated, the alpha, or “accelerator,” receptor promotes cell growth (not good for reducing cancer risk). Activated beta receptors, on the other hand, act like “brakes,” decreasing cell growth. With around 1600% more affinity, isoflavones in soy preferentially bind to beta receptors, thereby slamming on those brakes, discouraging cell growth.
2. Arugula
Cabbage-family, or cruciferous vegetables, like arugula, cabbage, broccoli, and kale, contain cancer-fighting substances called isothiocyanates. However, among these vegetables, arugula is the champion. A 2020 study found that of 21 cruciferous vegetables, arugula contained the highest amounts of isothiocyanates. Arugula specifically contains the precursor of an isothiocyanate called erucin, a close cousin to the better-known sulforaphane. These researchers also determined that lightly cooking, briefly steaming, stir-frying, or microwaving these vegetables, increased their isothiocyanate content four-fold on average. However, heavy cooking, such as boiling or stewing, decreased the levels of these protective substances.
There are a number of ways that isothiocyanates like erucin may help reduce cancer risk. For example, in dietary concentrations, erucin may interfere with the ability of cancer cells to build their internal “skeletons,” making it harder for them to multiply.
3. Mushrooms
Eating more mushrooms is linked to a 35% lower risk of breast cancer, according to a recent analysis of 10 studies. Ergothioneine, a unique amino acid and powerful antioxidant found in mushrooms, may help protect cells by decreasing oxidative damage to their DNA. Mushrooms also contain a kind of soluble fiber called beta-glucan. This fiber appears to have numerous tumor-fighting effects; however, one of the most promising is the potential ability of beta-glucans to stimulate the immune system to combat cancer cells more effectively.
4. Green tea
Regular consumers of green tea had a 17% lower risk of breast cancer than those who weren’t in the habit of drinking green tea, according to a 2019 meta-analysis. The protective effect may be due to the high concentration of polyphenols in green tea, particularly epigallocatechin-3-gallate, or EGCG. This substance may help prevent DNA damage that can lead to cancer and appears to promote cancer cell death. Interestingly, black tea has less EGCG and does not appear to be protective. Note that green (and black) tea can interfere with iron absorption, so it’s best to enjoy this beverage between meals.
5. Flax seed
Flax seeds are the richest dietary source of lignans, phytochemicals that may help protect against breast cancer. In fact, high lignan intake in postmenopausal women is linked to a 14% lower risk of breast cancer. Flax seeds also contain the essential omega-3 fat alpha-linolenic acid, as well as fiber—increased intake of which has consistently been linked to lower breast cancer risk. To maximize nutrition from flax seeds, they should be purchased ground, or ground at home. Storing ground flax seed in the refrigerator or freezer helps protect their omega-3 fats and keeps them tasting fresh.
6. Garlic and onion
Garlic and onion add savory flavor to any food—and may help ward off breast cancer. In a case-control study of 660 women living in Puerto Rico, those who ate the most garlic and onion were about half as likely to be diagnosed with breast cancer as those who ate the least. Garlic and onions contain sulfur compounds, like ajoene, which has been shown to interfere with pathways involved in the invasion (metastasis) of breast cancer cells.
Six Foods to Lose
1. Lunch meat
Can a ham sandwich increase the risk of breast cancer? Research suggests it can. Scientists with the UK Biobank study followed 262,195 women over 7 years and found that those who ate the most processed meat—including bacon, sausage, and lunch meat—were 21% more likely to develop breast cancer than those who avoided those foods. The amount of processed meat associated with increased risk? Anything above 9 grams per day—about one-third of a slice of lunch-meat ham. A meta-analysis by the same researchers drew a similar conclusion, although the effect size was smaller—a 6% increase in risk for those who consumed the most processed meat relative to those who consumed the least.
2. Alcohol
When it comes to alcohol, the less a woman drinks, the lower her risk of breast cancer. Just one drink per day—whether hard seltzer, beer, or even red wine—raises the risk of breast cancer.
According to the World Cancer Research Fund, for premenopausal women, each glass of wine consumed per day increases the chances of developing breast cancer by about 7%. Two glasses a day increase a woman’s risk by 14%, and so on. The same is true for other alcoholic beverages. A 12-ounce bottle of beer, a five-ounce glass of wine, or a 1.5 ounce shot of liquor all have about the same alcohol content. For older women, the effect is amplified. For each drink a postmenopausal woman consumes daily, her risk of breast cancer increases by about 13%.
Alcohol has a number of detrimental effects on breast health. For example, alcohol can affect the body’s ability to absorb folate, which may play a role in breast cancer. Alcohol can also raise estrogen levels, contribute to DNA damage, and lead to weight gain from added calories. Unfortunately, on average, women in the U.S. increased their alcohol consumption during the pandemic, a trend that appears to be lasting. According to a survey conducted by researchers at RTI International, between February and November 2020, alcohol intake was up 39% on average. And for some groups of women, the increase was far more dramatic: For example, among women with children under age 5, alcohol intake increased by a whopping 323%—worrisome for breast health.
3. Cheese
The Life After Cancer Epidemiology study found that among women previously diagnosed with breast cancer, those consuming one or more servings of high-fat dairy products (e.g., cheese, ice cream, whole milk) daily had 49% higher breast cancer mortality, compared with those consuming less than one-half serving daily. What might account for this connection? One explanation is that cheese, especially full-fat cheese, is high in saturated fat. A meta-analysis of four studies found that breast-cancer-specific death was 51% higher for women in the highest versus lowest category of saturated fat intake. Why? For one, high intake of saturated fat has been linked to increased estrogen levels, which can fuel estrogen-receptor-positive cancer. Saturated fat intake is also linked to increased cholesterol levels. And at least one oxidized metabolite of cholesterol, 27-hydroxycholesterol, can have estrogenic and tumor-promoting properties.
One of the top sources of saturated fat in the U.S. diet? Cheese.
4. Beef
Red meat has long been linked to colorectal cancer, but emerging data suggests that consuming meat is associated with increased breast cancer risk, too. The Nurses’ Health Study II followed more than 88,000 women for about 20 years. Researchers found a dose-response relationship between red meat consumption and breast cancer: for every serving of red meat a woman consumed daily, she had a 13% higher risk of developing breast cancer. While data from meta-analyses are less clear, they tend to show an adverse effect from consuming red meat on breast cancer risk. Of particular concern, however, is the 25% higher risk of aggressive cancers in postmenopausal women who consumed the most red meat in the NIH-AARP Diet and Health study.
Eating meat during the teen years, when breast tissue is developing and likely more sensitive to carcinogens, might further increase risk. One study found that women who reported consuming the most red meat during adolescence had a 43% higher risk of breast cancer before menopause, compared with those who consumed the least.
How might red meat increase breast cancer risk? Cancer-causing substances like polycyclic aromatic hydrocarbons form on the surface of red meat when it’s cooked at high temperatures. Heme iron, found in red meat, can trigger oxidative stress and may promote the formation of cancer-causing N-nitroso compounds in the body. Meat also tends to be high in saturated fat, especially relative to plant protein sources.
5. Muffins
Certainly it’s possible to make a healthy muffin. But commercial muffins are typically a breast cancer disaster. Using nutrition information from three U.S. national coffeeshop chains from September 2021, we determined that an average blueberry muffin has more sugar than a 12-ounce soda, more fat than a scoop of ice cream (one-quarter of it saturated fat), and a measly 1.7 grams of fiber—a fraction of the 25-gram daily fiber recommendation for women.
High saturated fat and low fiber intakes are both associated with increased breast cancer risk. And a recent study found that, in women diagnosed with breast cancer, a greater intake of added sugars after diagnosis was linked to a 20% higher risk of death from all causes, while high intake of refined grains was “suggestively” linked to a higher risk of death from all causes.
While a sprinkling of blueberries may make muffins seem like a healthy choice, don’t be fooled—these breakfast bombs are cake without the icing.
6. Soda
Women with a breast cancer diagnosis may want to skip the soda. A new study of 8,863 women with stage I-III breast cancer found that those who had more than three sugary drinks per week had a 35% higher risk of dying of breast cancer than those who avoided sugary drinks. Those who consumed just 2-3 sugary drinks per week still had a 31% higher chance of dying from breast cancer. Artificially-sweetened drinks were not associated with a higher risk of breast cancer death, although replacing sugary drinks with artificially sweetened drinks did not lower risk.
It’s crucial to harness the power of the fork in the fight against breast cancer. While no single food is guaranteed to cause cancer—and no “superfood” will prevent it—the sum total of foods consumed day in and day out, year after year, undoubtedly affects risk.
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To learn more about reducing breast cancer risk with good nutrition, as well as other lifestyle steps, join Dr. Kristi Funk virtually or in-person at her annual Cancer-Kicking! Summit at Terranea, an oceanfront resort, and also visit the campaign she launched with the Physicians Committee for Responsible Medicine at www.LetsBeatBreastCancer.org. Use coupon code FRAN15 for a discount and a portion of the proceeds will be donated to Cancer Schmancer.
