By Dr. Mercola
Recent data has emerged asserting that young women who eat more apples, bananas, grapes, oranges and kale may reduce their risk of developing breast cancer later in life.
More specifically, young women consuming more apples, bananas and grapes between the ages of 13 and 18, and oranges and kale in early adulthood, may decrease their risk of developing premenopausal breast cancer by 25 percent.1
Additionally, nearly 250,000 new breast cancer cases are diagnosed every year in the U.S., according to the American Cancer Society.3 Researchers behind the study concluded:
"If this apparent risk reduction is applied to lifetime risk of breast cancer, the absolute number of breast cancers that could potentially be prevented by higher intake of fruits would be substantial."
Increased Vegetable Intake Also Linked to Lower Breast Cancer Risk
Most of the headlines relating to this study are touting eating more fruit as a way to prevent breast cancer, but this could be a potentially dangerous assumption. For starters, this was not a controlled study; it relied on dietary recall, which is notoriously inaccurate.
This alone could have skewed the results, but the other important factor is the study looked at fruit and vegetable consumption. It found higher intake of fruits and vegetables rich in alpha-carotene during early adulthood was specifically associated with lower breast cancer risk.
Alpha-carotene is found in yellow-orange vegetables (sweet potatoes, carrots, winter squash, etc.) and dark-green vegetables (broccoli, green beans, spinach, turnip greens, collard greens, lettuce, etc.).
If you're wondering what to eat to prevent cancer, there is no question that vegetables are more important than fruits. That being said, eating whole fruits, which contain antioxidants and fiber, is far preferable to eating processed foods and junk food.
As noted by clinical nutritionist Lona Sandon from the University of Texas Southwestern Medical Center:
"Fruit has vitamins, minerals and all sorts of plant compounds that appear to be healthy for us, and it's also worth noting that if teens are consuming more fruit, what are they not consuming instead? Are they eating less candy, cookies, cakes and soda? That may play a role as well."4
What you want to be careful of is using this study to justify eating all the fruit you want, especially if you're a sedentary adult who is not eating healthy to begin with. Limiting fruit consumption is a wise choice for most people.
The exception is people who are young and very active, and therefore able to burn most of the sugar off through large amounts of physical activity, especially high-intensity interval training. In this case, moderate fruit consumption is not likely to be problematic.
How the Study Arrived at Its Lowered Breast Cancer Conclusion
Hundreds of other studies have noted that not just fruits but vegetables, herbs, and phytonutrients, as well as many other factors may be at least partial responsibility for breast cancer prevention.
The cohort study5 used data from the Nurses' Health Study II (NHSII), which began in 1989 and included female registered nurses between the ages of 25 and 42. The featured study included more than 90,000 women, with a follow-up rate exceeding 96 percent of "total potential person years" from 1991 to 2013.
Food-frequency questionnaires (FFQ) and food lists were categorized into five subgroups of leafy greens, yellow and orange vegetables, crucifers, citrus and drupe fruits, berries, and vitamin C content.
Scientists believed the FFQ to be reliable in assessing breast cancer risk as in past studies it has shown higher fruit and vegetable intake was associated with lower risks of diabetes and coronary heart disease, which indirectly supports its validity.
However, as mentioned, the study relied on dietary recall, which means some of the reported fruit and vegetable intakes may be flawed. The researchers noted an, " … adolescent diet might be misclassified because assessments were done when women were aged 33 to 35."
How Do Other Foods Offer Breast Cancer Defense?
Part of the breast cancer protection in apples is derived from the peels, which are loaded with exceptionally high amounts of antioxidants. Past research has found anti-proliferative effects in apple peel extract led to decreased growth of both breast and prostate cancer cells.6
Plums and peaches entered the deliberation as cancer-fighting fruits, according to a Texas A&M study. In fact, the antioxidant level of two polyphenols in particular helped kill breast cancer cells without fazing healthy cells.
That is very encouraging, especially since the conventional treatment approach for this diagnosis kills healthy cells as well.7
Pomegranates,8 berries, green tea and many other whole foods have also been found to be cancer inhibiting. Garlic impedes cancer's cell-cycling process due to the organosulfur compounds.9 Other foods credited with breast cancer prevention include:
A 1- to 1/2 cup serving of beans contains a beneficial amount of cancer-fighting fiber.
Broccoli contains the compound sulforaphane, which can reduce the number of breast cancer stem cells.
Omega-3 fats in fish such as wild-caught Alaskan salmon reduce the inflammation that may contribute to ductal carcinoma.10
Antioxidants and oleic acid in extra-virgin olive oil inhibit malignant cell growth.
The apigenin in parsley is capable of inhibiting cancer cell growth.
Drinking black coffee may lower your risk of estrogen-receptor negative breast cancer.11
Walnuts, which contain the anti-inflammatory omega-3 fat linolenic acid.
Curcumin in turmeric makes this spice a potent adversary against breast cancer.12
Lycopene for Breast Cancer Prevention
Lycopene — a carotenoid antioxidant that gives fruits and vegetables like tomatoes and watermelon a pink or red color — has long been identified as a cancer fighter, although most often it's mentioned in relation to prostate cancer.
Research shows, however, that lycopene may reduce breast cancer risk as well and may be particularly promising for those with difficult-to-treat estrogen receptor (ER)–negative tumors.
Lycopene's antioxidant activity has long been suggested to be more powerful than other carotenoids such as beta-carotene, and research published in the Journal of the National Cancer Institute also found lycopene to be the most effective carotenoid in reducing breast cancer risk.13
The meta-analysis, which comprised more than 80 percent of the world's published data on blood levels of carotenoids and breast cancer, revealed women with the highest level of total carotenoids had a 19 percent lower breast cancer risk compared to those with the lowest levels.
It's clearly beneficial to consume a wide variety of vegetables that contain various carotenoids, but if you're looking for the one with the greatest cancer-fighting potential of all, lycopene came out on top.
Other Factors May Be Significant
In examining factors influencing why apples, bananas, grapes, oranges and kale were categorized as most significant in the featured study, several powerful phytonutrients, such as flavonoids, and vitamin C were identified as having cancer-killing potential.
Fiber was also an important factor, as were foods with high alpha-carotene content. Alpha carotene is a carotenoid and carotenoids have been recognized for their cancer-preventive capabilities. As the National Health Service14 explained:
One example of a carotenoid is beta-carotene, which can be orange, dark green or red in color. Just 3 to 6 milligrams per day can reduce breast cancer risk, according to the Institute of Medicine. Some of the best sources of carotenoids include spinach, carrots, kale, collard greens, Swiss chard, red bell peppers, mustard greens, tomatoes, sweet potatoes, winter squash, apricots, mangoes, pumpkin and cantaloupe.
Another study specified that vegetables, but not fruits, were associated with reduced breast cancer risk:
"We observed no association between total fruit and vegetable intake and risk of overall breast cancer. However, vegetable consumption was inversely associated with risk of ER(-) (estrogen receptive) breast cancer in our large pooled analyses."15
Another significant British Medical Journal study16 found that post-menopausal women who increased their alcohol intake by two or more drinks per day incurred a 30 percent increased breast cancer risk.
A Johns Hopkins Breast Center newsletter revealed that cancer prevention is not completely off every hospital's radar. Some experts are examining less toxic approaches to breast cancer prevention, such as the compound sulforaphane in broccoli sprouts, as opposed to resorting to drugs.17
The Fiber Link
One article noted: "Eating high-fiber foods is also associated with the prevention of cancer, such as raspberries, barley, broccoli, cauliflower, turnip greens, beans and legumes."18 One of those was a large-scale review,19 conducted by researchers at Harvard T.H. Chan School of Public Health, which determined that eating high-fiber foods brought similar results:
"Breast cancer risk was 12 percent to 19 percent lower among women who ate more dietary fiber in early adulthood, depending on how much more they ate. High intake of fiber during adolescence was also associated with 16 percent lower risk of overall breast cancer and 24 percent lower risk of breast cancer before menopause."
Notably, there was "a strong inverse association" between fiber intake and breast cancer among all the women in the study, possibly due to reduced estrogen levels in the blood, strongly linked with breast cancer development.
For each additional 10 grams of daily fiber intake consisting of (as an example) an apple, one-half cup of cooked kidney beans, cauliflower or squash consumed in early adulthood, breast cancer risk dropped by 13 percent. It's likely that some of the reduced cancer risk associated with fruit consumption in the featured study was also due to the fiber content of the fruit.
The Lignan Link
One of the most dramatic game-changers in regard to combating breast cancer are flaxseeds, which possess 100 times more cancer-fighting lignans than any other known plant-based food! Lignans in flaxseeds exert strong anti-estrogenic effects on estrogen receptor–positive breast cancer.20 Women Living Naturally21 listed several anti-cancer measures of lignans:
Helps breast tissue resist damage from environmental toxins
Comparable to Tamoxifen (drug) in blocking the estrogen receptor
Helps lower the production of estrogen
Creates an improved type of estrogen
Helps lower chances of cancer metastasizing (spreading)
Helps halt tumor cell growth
May block blood vessel growth in tumors
Lengthens the menstrual cycle
Additionally, it's extremely compelling to note this article's pithy statement that while women with high lignan levels have fewer incidences of breast cancer, women with low lignin levels have a high rate of breast cancer!
Fruit, Fructose and Cautions
No doubt about it — eating excess fructose stimulates weight gain and may increase your risk of cancer. If it's canned or otherwise not recognizable as fresh, fruit has very likely been packaged with syrup to be sweeter, and while fruits are better options than processed foods due to fiber and nutrient content, consuming excess fructose is still an issue for most people. It's metabolized to fat by your liver far more rapidly than any other sugar.
So, as mentioned, using this study to justify unlimited fruit intake for sedentary adults who are not eating healthy is simply a prescription for disaster.
Fruits Are Sweeter and Less Nutritious Than They Used to Be
The wild fruits consumed by our ancestors were smaller and resembled most closely what a blueberry is today. Modern cultivated fruits are much larger, which means they have a lot more sweet pulp inside and less skin. The sweet "pulp" or "flesh" of the fruit is where most of the fructose is, whereas the skin holds the antioxidants.
Since wild fruits were much smaller than today's fruits and thus had a much larger proportion of their volume as skin and seeds, they provided a healthy source of powerful antioxidants with limited amounts of fructose. Unfortunately, overeating modern fruits can easily push your fructose consumption into dangerous territory.
As a general guideline, I recommend limiting your total fructose consumption to 25 grams of fructose per day. If you suffer with any fructose-related health issues, such as insulin resistance, metabolic syndrome, heart disease, obesity or cancer, you would be wise to limit your total fructose consumption to 15 grams of fructose per day. This includes fructose from ALL sources, including whole fruit.
Sadly, Conventional Medicine Focuses Primarily on Treatment, Not Prevention
It's unfortunate that conventional medicine focuses primarily on treating cancer instead of exploring ways to prevent it. Alternative holistic site Women Living Naturally22 contends that:
"Breast cancer strikes fear in most American women — and for good reason. In this country, this deadly disease has hit epidemic proportions. Western medicine advises us to get yearly mammograms and to do monthly self-breast exams in an effort to catch the disease at a relatively early stage.
Tragically, Western medicine has not made prevention a priority, so few women and doctors are aware of the measures that can offer effective protection. Given these facts, it is not surprising that most women feel powerless in their ability to lower their risk."
That's why it's so important to arm yourself with the information you need to take control of your health, and as early as possible. As always, however, consuming real food, including organic vegetables, is the way to go whenever possible.