
A healthy lifestyle offers protection now. What changes can you make to reduce your breast cancer risk or ease your treatment? According to research or other evidence, the following self-care steps may be helpful:

These recommendations are not comprehensive and are not intended to replace the advice of your doctor or pharmacist. Continue reading the full breast cancer article for more in-depth, fully-referenced information on medicines, vitamins, herbs, and dietary and lifestyle changes that may be helpful.
Breast cancer is a malignancy of the breast that is common in women and rare in men. It is characterized by unregulated replication of cells creating tumors, with the possibility of some of the cells spreading to other sites (metastasis).
This article includes a discussion of studies that have assessed whether certain vitamins, minerals, herbs, or other dietary ingredients offered in dietary or herbal supplements may be beneficial in connection with the reduction of risk of developing breast cancer, or of signs and symptoms in people who have this condition.
This information is provided solely to aid consumers in discussing supplements with their healthcare providers. It is not advised, nor is this information intended to advocate, promote, or encourage self prescription of these supplements for cancer risk reduction or treatment. Furthermore, none of this information should be misconstrued to suggest that dietary or herbal supplements can or should be used in place of conventional anticancer approaches or treatments.
It should be noted that certain studies referenced below, indicating the potential usefulness of a particular dietary ingredient or dietary or herbal supplement in connection with the reduction of risk of breast cancer, are preliminary evidence only. Some studies suggest an association between high blood or dietary levels of a particular dietary ingredient with a reduced risk of developing breast cancer. Even if such an association were established, this does not mean that dietary supplements containing large amounts of the dietary ingredient will necessarily have a cancer risk reduction effect.
Most breast cancer is not hereditary, although a small percentage of women have a genetic weakness that dramatically increases their risk. Women with a strong family history of breast cancer may choose to explore the possibility of genetic testing with a geneticist, found on the staff of many major hospitals.
The incidence of postmenopausal breast cancer varies dramatically from one part of the world to the other, and those who move from one country to another will, on average, over time, begin to take on the risk of the new society to which they have moved. This evidence strongly suggests that most, though not all, breast cancer is preventable. However, great controversy exists about which factors are most responsible for the large differences in breast cancer incidence that separate high-risk populations from low-risk populations.
A few factors that affect the risk of having breast cancer are widely accepted:
Several other factors may affect a woman’s risk of getting breast cancer. Many researchers and some doctors believe that long-term (greater than five years) use of oral contraceptives increases the risk of premenopausal breast cancer, but not the risk of postmenopausal breast cancer. Also, being overweight appears to slightly reduce the risk of premenopausal breast cancer, even though it increases the risk of postmenopausal breast cancer.
Almost all women with noninvasive breast cancer (ductal carcinoma in situ), along with a majority of women diagnosed with node-negative invasive breast cancer, are cured with appropriate conventional treatment. Even when breast cancer is diagnosed after it has spread to lymph nodes, many patients are curable. Once breast cancer has spread to a distant part of the body, conventional treatment sometimes extends life but cannot provide a cure.
Product ratings for breast cancer
| Science Ratings | Nutritional Supplements | Herbs |
|---|---|---|
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Folic acid (reduces risk in women who consume alcohol) |
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Vitamin D (reduces risk) |
Coriolus versicolor Green tea (reduces risk) |
Reliable
and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies
suggesting a health benefit or minimal health benefit. For an herb, supported by traditional use but minimal
or no scientific evidence. For a supplement, little scientific support and/or minimal health
benefit. |
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The diagnosis of breast cancer is usually begun at the time a painless one-sided lump is discovered by the woman or her physician. In recent years, the diagnosis of breast cancer often begins with suspicious findings from a routine screening mammogram accompanied by no symptoms. In more advanced cases, changes to the contour of the affected breast may occur, and the lump may eventually become immovable.
If breast cancer spreads to a distant part of the body (distal metastasis), symptoms are determined by the location to which the cancer has spread. For example, if breast cancer spreads to bone, it frequently causes bone pain; if it spreads to the brain, it generally causes neurological symptoms, such as headaches that do not respond to aspirin. When it has spread to a distant part of the body, breast cancer also eventually causes severe weight loss, untreatable fatigue-inducing anemia, and finally death.
The following dietary changes have been studied in connection with breast cancer.
Avoidance of alcohol
An analysis of studies using the best available methodology found that women who drink alcohol
have a higher risk of breast cancer compared with teetotalers.1 Alcohol consumption
during early adulthood may be more of a risk factor than alcohol consumption at a later
age.2
Some,3 4 though not all,5 studies have reported that alcohol increases estrogen levels. Increased estrogen levels might explain the increase in risk.
In a preliminary report, drinkers with low intake of folic acid had a 32% increased risk of breast cancer compared with nondrinkers; however, the excess risk was only 5% in those drinkers who consumed adequate levels of folic acid.6 In the same report, women taking multivitamins containing folic acid and having at least 1.5 drinks per day had a 26% lower risk of being diagnosed with breast cancer compared with women drinking the same amount of alcohol but not taking folic acid-containing vitamins.7
Fiber
Insoluble fiber from grains delays the onset
of mammary (breast) cancer in animals.8 In an analysis of the data from many
studies, people who eat relatively high amounts of whole grains were reported to be at low
risk for breast cancer.9
In some studies, the protective effect of fiber against the risk of breast cancer has been stronger in young women than in older women.10 This finding might occur because fiber has been reported to lower estrogen levels in premenopausal women but not in postmenopausal women.11 12 Other researchers, however, report that fiber appears to equally reduce the risk of breast cancer in women of all ages.13 One leading researcher has suggested the active components in fiber may be phytate and isoflavones, substances that may provide protection even in the absence of a decrease in estrogen levels.14 If these substances do protect against breast cancer, they might be as helpful in older women as in younger women.
Consuming a diet high in insoluble fiber is best achieved by switching from white rice to brown rice and from bakery goods made with white flour or mixed flours to 100% whole wheat bread, whole rye crackers, and whole grain pancake mixes. Refined white flour is generally listed on food packaging labels as “flour,”“enriched flour,”“unbleached flour,”“durum wheat,”“semolina,” or “white flour.” Breads containing only whole wheat are usually labeled “100% whole wheat.”
Vegetarianism
Compared with meat eaters, most,15 but not all,16 studies have found
that vegetarians are less likely to be diagnosed with cancer. Vegetarians have also been shown
to have stronger immune functioning, possibly
explaining why vegetarians may be partially protected against cancer.17 Female
vegetarians have been reported to have lower estrogen levels compared with meat-eating women,
possibly explaining a lower incidence of breast cancer that has been reported in vegetarian
women.18
Fruits and vegetables
An analysis of 17 studies on breast cancer risk and diet found that high consumption of
vegetables was associated with a 25% decreased risk of breast cancer compared with low
consumption.19 The same report analyzed 12 studies that found high consumption of
fruit was associated with a 6% reduction of breast cancer incidence compared with low
consumption. However, when data from only the eight largest and best studies were combined,
high intake of fruits and/or vegetables did not correlate with protection from breast
cancer.20 Therefore, the protective effect of fruit and vegetable consumption
against breast cancer remains unproven.21
Tomatoes
Tomatoes contain lycopene—an antioxidant similar in structure to beta-carotene. Most lycopene in our diet comes from
tomatoes, though traces of lycopene exist in other foods. Lycopene has been reported to
inhibit the proliferation of cancer cells in test tube research.22
A review of published research found that higher intake of tomatoes or higher blood levels of lycopene correlated with a reduced risk of a variety of cancers in 57 of 72 studies. Findings in 35 of these studies were statistically significant.23 Evidence of a protective effect for tomato consumption was strongest for cancers other than breast cancer (prostate, lung, and stomach cancer), but some evidence of a protective effect also appeared for breast cancer.
Meat and how it
is cooked
Most,24 25 but not all,26 studies show that consumption of
meat is associated with an increased risk of breast cancer. This association probably depends
in part on how well the meat is cooked. Well-done meat contains more carcinogenic material
than does lightly cooked meat.27 Evidence from preliminary studies shows that women
who eat well-done meat have a high risk of breast cancer.28 Genetic factors may
determine which women increase their risk of breast cancer by eating well-done
meat.29
Fish
Fish eaters have been reported to have a low risk of breast cancer.30 The omega-3 fatty acids found in fish are thought by some
researchers to be the components of fish responsible for protection against
cancer.31
Coffee, unrelated
to risk
Coffee drinking has been reported to increase breast pain associated with noncancerous lumps
in the breast—a group of conditions commonly called fibrocystic breast disease. The presence of some forms
of fibrocystic breast disease have been reported by some researchers to increase the risk of
breast cancer.32 As a result of these separate findings, some women may be
concerned coffee drinking might increase the risk of breast cancer. However, most research has
shown that coffee drinkers are at no higher risk of breast cancer than are women who do not
drink coffee.33 34 35
Olive
oil
Olive oil consumption has been associated with a reduced risk of breast cancer in several
preliminary reports.36 37 38 Oleic acid, the main fatty acid
found in olive oil, does not appear to be the cause of this protective effect,39
and scientists now guess that some as-yet undiscovered substance in olive oil might be
responsible for the apparent protective effect of olive oil consumption.40
The dilemma over dietary fat
Olive oil and fish are two sources of dietary
fat considered potentially helpful in protecting against breast cancer.41
42 43 44 Each has been discussed separately above. The information
below discusses fat sources that some researchers are concerned might increase the
risk of cancer.
High-fat diets increase the risk of mammary cancer in animals.45 From country to country, breast cancer risk in women is proportionate to the level of total fat consumed in the diet.46 Estrogen levels, body weight, and breast density have all been reported to decrease when women are put on low-fat diets—all changes that are thought to reduce the risk of breast cancer.47 48 49 50 Moreover, breast cancer patients have been reported to reduce their chances of survival by eating a diet high in saturated fat.51 (Saturated fat is found mostly in meat and dairy fat.) Similarly, breast cancer patients have been reported to be at increased risk of suffering a recurrence if they eat higher levels of fatty foods, such as butter, margarine, red meat, and bacon.52
Analysis of human trials, using a research design dependent on the memories of subjects, also has shown women consuming high-fat diets to be at high risk of breast cancer.53 In some cases, the correlation has been quite strong.54 However, most,55 56 57 but not all,58 “prospective” studies—which avoid problems caused by faulty memories—have not found any association between fat intake and the risk of breast cancer.
Why do some research findings suggest that fat increases the risk of cancer and other studies find no association? Some studies finding dietary fat unrelated to cancer risks have not factored out the effects of olive oil or fish fat; both may protect against cancer.59 60 61 62 Adding them to the total dietary fat intake and then studying whether “more fat causes more cancer” is therefore misleading. Some studies finding no association between fat intake and breast cancer have made one or both of these errors.63 64
Scientists know cancers caused by diet most likely occur many years after the causative foods are regularly consumed. When one group of researchers compared dietary intakes to cancer rates occurring ten years after the consumption of food, and also eliminated from consideration the effect of fat from fish consumption, they found a high degree of correlation between consumption of animal fat (other than from fish) and the risk of breast cancer death rates for women at least 50 years of age.65
In the debate over whether dietary fat increases breast cancer risks, only one fact is indisputable: women in countries that consume high amounts of meat and dairy fat have a high risk of breast cancer, while women in countries that mostly consume rice, soy, vegetables, and fish (instead of dairy fat and meat) have a low risk of breast cancer.66
The complex relationship between soy consumption and risk
Asian countries in which soy consumption is high generally have a low incidence of breast
cancer. However, the dietary habits in these countries are so different from diets in
high-risk countries that attributing protection from breast cancer specifically to soy foods
on the basis of this evidence alone is premature.67 Similarly, within a
society, women who frequently consume tofu
have been reported to be at low risk of breast cancer.68 Consumption of tofu might
only be a marker for other dietary or lifestyle factors that are responsible for protection
against breast cancer.
Genistein, one of the isoflavones found in many soy foods, inhibits proliferation of breast cancer cells in test tube studies. Most animal studies report that soybeans and soy isoflavones protect against mammary cancer.69 However, the protective effect in animals have occurred primarily when soy has been administered before puberty.70 If the same holds true in humans, consuming soy products in adulthood might provide little, if any, protection against breast cancer.
The findings of several recent studies suggest that consuming soy might, under some circumstances, increase the risk of breast cancer.71 72 73 74 75 When ovaries were removed from animals—a situation related to the condition of women who have had a total hysterectomy—dietary genistein was reported to increase the proliferation of breast cancer cells.76 When pregnant rats were given genistein injections, their female offspring were reported to be at greater risk of breast cancer.77 Although premenopausal women have shown decreases in estrogen levels in response to soy consumption,78 79 proestrogenic effects have also been reported.80 When premenopausal women were given soy isoflavones, an increase in breast secretions resulted—an effect thought to elevate the risk of breast cancer.81 In yet another trial, healthy breast cells from women previously given soy supplements containing isoflavones showed an increase in proliferation rates—an effect that might also increase the risk of breast cancer.82
The commonly held belief that consuming soybeans or isoflavones such as genistein will protect against breast cancer is, therefore, far from proven.83 84 85 86 87 Possibly, consuming soybeans in childhood may ultimately be proven to have a protective effect.88 Doing the same in adulthood, however, may have very different effects.89 90 91 92 93
Some scientists, at least under some circumstances, remain hopeful about the potential for soy to protect against breast cancer. These scientists recommend consumption of foods made from soy (such as tofu), as opposed to taking isoflavone supplements. Several substances in soybeans other than isoflavones have shown anticancer activity in preliminary research.94
Reduction in
sugar
Preliminary studies have reported associations between an increased intake of sugar or
sugar-containing foods and an increased risk of breast cancer,95 though this link
does not appear consistently in published research.96 Whether these associations
exist because sugar directly promotes cancer or because sugar consumption is only a marker for
some other dietary or lifestyle factor remains unknown.
The following lifestyle changes have been studied in connection with breast cancer.
Exercise and prevention
Girls who engage in a significant amount of exercise have been reported to be less likely to
get breast cancer as adults.97 Although some doctors speculate that exercise in
preadolescent girls might reduce the risk of eventually getting breast cancer by reducing the
number of menstrual cycles and therefore exposure to estrogen, these effects may occur only in
girls engaging in very strenuous exercise.98
Most,99 100 but not all,101 studies find that adult women who exercise are less likely to get breast cancer. Women who exercise have also been reported to have a reduced risk of high-risk mammography patterns compared with inactive women.102
Exercise in adulthood might help protect against breast cancer by lowering blood levels of estrogen or by helping maintain ideal body weight. In addition to the preventive effects of exercise, aerobic exercise has been reported to reduce depression and anxiety in women already diagnosed with breast cancer.103
Smoking and risk
Some studies have found an association between smoking and an increased risk of breast cancer,
including exposure to secondhand smoke.104 However, several reports have either
found no association105 or have reported an association between smoking and an
apparent protection against breast cancer.106 Some of the studies
reporting that smoking is detrimental have found that exposure to cigarette smoke during
childhood appears to be most likely to increase the risk of breast cancer.107
The mind-body connection
In some studies, the risk of breast cancer has been reported to be higher in women who have
experienced major (though not minor)
depression in the years preceding diagnosis.108 Some,109
110 but not all,111 studies have found that exposure to severely stressful
events increases a woman’s chance of developing breast cancer. In one study, breast
cancer patients exposed to severely stressful events, such as death of a spouse or divorce,
had more than five times the risk of suffering a recurrence compared with women not exposed to
such stressors.112 Although stress has long been considered as a possible risk
factor, some studies have not found significant correlations between psychological stressors
and breast cancer risk113 or the risk of breast cancer recurrence.114
Similarly, experiencing psychological distress (independent of external stressors) has, in
some reports, not been associated with a reduction in survival or the risk of suffering a
breast cancer recurrence.115
Exposure to psychological stress has been reported to weaken the immune system of breast cancer patients.116 Strong social support has been reported to increase immune function in breast cancer patients.117 These findings suggest a possible way in which the mind might play a role in affecting the risk of a breast cancer recurrence.118 119
In one study, breast cancer patients with strong social support in the months following surgery had only half the risk of dying from the disease during a seven-year period compared with patients who lacked anyone to confide in.120 After 10121 and 15 years,122 breast cancer patients with a helpless and hopeless attitude or with an attitude of stoicism were much less likely to survive compared with women who had what the researchers called a “fighting spirit.” In a five-year study, the same helpless/hopeless attitude correlated with an increased risk of recurrence or death in breast cancer patients, but a “fighting spirit” did not correlate with special protection against recurrence or death.123 One trial reported that psychological therapy for hopeless/helpless breast cancer patients was capable of changing these attitudes and reducing psychological distress in only eight weeks.124
Several trials using a variety of psychological interventions have reported increased life expectancy in women receiving counseling or psychotherapy compared with women who did not receive psychological intervention125 —even in women with late-stage disease.126 In a now-famous trial, late-stage breast cancer patients in a year-long, 90-minute-per-week support group lived on average twice as long as a group of similar patients who did not receive such support.127
Finally, relaxation training has been reported to reduce psychological distress in breast cancer patients,128 and group therapy and hypnosis have reduced pain in late-stage breast cancer patients.129
Even extensive psychological support (weekly peer support, family therapy, individual counseling, and use of positive mental imagery) has not led to a clear increase in breast cancer survival in every study.130 Why some studies clearly find mind-body connections in regard to breast cancer risk, recurrence, or survival, while other studies find no such connection, remains unclear.
Overweight and
risk
Being overweight increases the risk of postmenopausal breast cancer, a fact widely accepted by
the research community. Overweight does not increase the risk of premenopausal breast
cancer and even may be associated with a slightly reduced risk of breast cancer in young
women.131
Increasingly, women with noninvasive breast cancer (ductal carcinoma in situ) are treated with a variety of surgical and radiation options depending upon several factors (called Van Nuys criteria) that determine their risk of developing invasive (potentially life-threatening) breast cancer. Lobular carcinoma in situ is generally not considered to be breast cancer, only a risk factor for developing breast cancer. Most women with invasive breast cancer are initially offered one of two options: either removal of the lump (lumpectomy) combined with removal of axillary (arm pit) lymph nodes followed by radiation, or removal of the breast (mastectomy) combined with removal of axillary lymph nodes. In a minority of cases, patients receiving mastectomy are advised to receive radiation after the mastectomy.
The following nutritional supplements have been studied in connection with breast cancer.
Folic
acid
Among women who drink alcohol, those who consume relatively high amounts of folate from their
diet have been reported to be at reduced risk of breast cancer, compared with women who drink
alcohol but consumed less folate, according to a preliminary study.132 In a similar
report, consumption of folic acid-containing supplements was associated with a lower risk of
breast cancer in women who drank alcohol, compared with women who drank alcohol but did not
take such supplements.133
The damaging effect alcohol has on DNA—the material responsible for normal replication of cells—is partially reversed by folic acid. Therefore, a potential association between both dietary folate and folic acid supplements and protection against breast cancer in women who drink alcohol is consistent with our understanding of the biochemical effects of these substances. A combined intake from food and supplements of at least 600 mcg per day was associated with a 43% reduced risk of breast cancer in women who consumed 1.5 drinks per day or more, compared with women who drank the same amount but did not take folic acid-containing supplements.134
No research has yet explored the effect of folic acid supplementation in people who have already been diagnosed with cancer. Cancer patients taking the chemotherapy drug methotrexate must not take folic acid supplements without the direction of their oncologist.
Selenium
The association between relatively higher blood levels of selenium and lower risks of cancer
in men has been fairly consistent.135 136 137 However,
most,138 139 140 141 though not all,142
studies have found selenium status to be unrelated to cancer risk in women, particularly in
relation to cancers that strike only women. In fact, a few studies have reported that exposure
to higher amounts of selenium143 —including selenium from
supplements144 —is associated with a higher risk of several cancers
in women, though these studies have been criticized.145
In a famous double-blind trial that reported dramatic reductions in the incidence of lung, colon, and prostate cancers as a result of selenium supplementation, of the few women who got breast cancer during the trial, more were taking selenium than were taking placebo, though this difference may well have been due to chance.146 Thus, the findings of this famous trial also do not support the idea that selenium supplementation protects against breast cancer.147
In contrast, animal studies generally find that selenium helps protect against mammary cancer,148 149 and associations between higher selenium status and decreased risk of breast cancer in women have also occasionally been reported.150 151 Despite these hopeful findings, most studies suggest that higher selenium status confers no protection against breast cancer.152 153 154 155 156 157 158
Vitamin
E
Although some preliminary evidence suggests that vitamin E may protect against breast
cancer,159 160 most research does not suggest a protective
effect.161 162 163 In a preliminary study, women taking
vitamin E supplements had the same risk of breast cancer as did other women.164
However, in one study, women with of low blood levels of bothselenium and vitamin E had a tenfold
higher risk of breast cancer compared with women having higher levels of both
nutrients.165 Although vitamin E and selenium function together in the body, the
meaning of this dramatic finding is not clear;most studies examining the effects of vitamin E
or selenium separately have suggested that neither protects against breast cancer.
Although one form of vitamin E—alpha tocopheryl succinate—has been touted as a potential treatment for women with breast cancer, only test tube studies suggest that it may have anticancer activity,166 and no trials have been conducted in breast cancer patients.
Vitamin
D
Breast cancer rates have been reported to be relatively high in areas of low exposure to
sunlight.167 Sunlight triggers the formation of vitamin D in the skin, which can be
activated in the liver and kidneys into a hormone with great activity. This activated form of
vitamin D causes “cellular differentiation”—essentially the opposite of
cancer.
The following evidence indicates that vitamin D might have a protective role against breast cancer:
Activated vitamin D
Activated vitamin D comes in several forms. One of them—1,25
dihydroxycholecalciferol—is an exact duplicate of the hormone made in the human
body.
The following preliminary, non-clinical evidence supports the idea that activated vitamin D may be of help to some breast cancer patients:
In a preliminary trial, activated vitamin D was applied topically to the breast, once per day for six weeks, in 19 patients with breast cancer.176 Of the 14 patients who completed the trial, three showed a large reduction in tumor size, and one showed a minor improvement. Those who responded had tumors that contained receptors for activated vitamin D. However, other preliminary reports have not found that high levels of these receptors consistently correlate with a better outcome.177 178 179
With a doctor’s prescription, compounding pharmacists can put activated vitamin D, a hormone, into a topical ointment. Due to potential toxicity, use of this hormone, even topically, requires careful monitoring by a physician. Standard vitamin D supplements are unlikely to duplicate the effects of activated vitamin D in women with breast cancer. The patients in the breast cancer trial all had locally advanced disease.
Melatonin
Melatonin has been reported to have anticancer activity against breast cancer cells in
most180 181 though not all182 test tube studies. In a
preliminary trial, breast cancer patients were studied who previously had responded either not
at all or only temporarily to treatment with the drug tamoxifen.183 During the trial, these women
were given tamoxifen again, this time with added melatonin. Blood levels of IGF-1, a marker
for progression of breast cancer, declined significantly. Of fourteen patients, four showed
evidence of tumor shrinkage that lasted an average of eight months.
Most cancer trials studying the effects of melatonin have used 20 mg of melatonin per 24 hours, all taken at bedtime.184 185 186 187 188 189 190 191 192 193 194 195 No one should take such a high amount of this hormone without the supervision of a healthcare professional.
Coenzyme Q10
(CoQ10)
French researchers have reported that the lower the blood level of CoQ10 in breast cancer
patients, the worse the chance of remaining free of disease.196 For several years,
researchers from Denmark and the United States have been studying the effects CoQ10 in a group
of 32 breast cancer patients who were either at high risk of suffering a recurrence or had
already been diagnosed with advanced disease.197 After 18 months, only one patient
had suffered a recurrence, all were still alive, those who did not have advanced disease at
the beginning of the trial had not progressed to advanced disease, one patient with advanced
disease had stabilized, and two patients with advanced disease had significantly
improved.198 Patients continued to do well after two years of
supplementation,199 and after three to five years, surprising improvements were
reported in two patients who had had advanced disease at the beginning of the
trial.200
At first, 90 mg of CoQ10 per day was used. In subsequent reports, the amount of CoQ10 was increased until some women were receiving 390 mg per day.201 Initially, the CoQ10 was accompanied by the use of many other supplements.202 The researchers of this trial have attributed the therapeutic effects observed primarily to CoQ10 and, in later reports, no further mention of other supplements was made.203 204 205
This preliminary investigation has been conducted with no control group, and published reports have provided only sketchy details about the conditions of most of the women being studied. Some of the patients were given conventional treatments along with CoQ10. Therefore, CoQ10 remains unproven as a cancer treatment.
Fiber
Although fiber is available in supplement form (such as Metamucil®), most fiber
consumption results from eating food. Preliminary evidence suggests that high fiber
consumption may reduce the risk of breast cancer. See the discussion of fiber and possible
prevention of breast cancer in Dietary changes, above.
Indole-3-carbinol
Cruciferous vegetables—broccoli, Brussels sprouts, cauliflower, and cabbage—contain a substance called
indole-3-carbinol (I3C). In preliminary research, I3C has been reported to affect the
metabolism of estrogen in a way that might protect against breast cancer,206 an
idea supported by animal207 and test tube research.208 No research
trials have yet investigated the effects of I3C supplementation in women with breast
cancer.
Diindolylmethane
Diindolylmethane is a substance also found in cruciferous vegetables. Test tube209
and animal studies210 suggest that it may help protect against breast cancer.
However, no clinical trials with cancer patients given diindolylmethane have yet been
published.
Calcium
D-glucarate (D-Glucaric acid)
Calcium D-glucarate is available as a supplement, and it is also found in fruits and vegetables in a slightly altered form—D-glucaric
acid.211 Preliminary evidence suggests that calcium D-glucarate indirectly helps
the body lower its burden of estrogen, an effect that may reduce the risk of breast
cancer.212 Although animal research supports such a possibility,213 no
human trials have been published to evaluate whether calcium D-glucarate has a therapeutic or
preventive effect.
IP-6
IP-6 (also called inositol hexaphosphate, phytate, or phytic acid) is found in many foods,
particularly oat bran, wheat bran, and unleavened (flat) bread. Until recently, most IP-6
research focused on interference with the absorption of minerals—a side effect of
consuming IP-6. More recently, however, animal studies have found that IP-6 has anticancer
activity.214 No human trials using IP-6 supplements to prevent or treat breast
cancer have yet been published.
Soy isoflavones,
including genistein
No research has directly investigated whether soy isoflavone supplements prevent breast cancer
or help people already diagnosed with this disease. Nonetheless, considerable preliminary
information has been gathered about the relationship between soy isoflavones and breast
cancer. For more information, see the discussion about soy in Dietary changes, above.
Conjugated linoleic
acid
Preliminary animal and test tube research suggests that CLA might reduce the risk of cancers at several sites, including breast,
prostate, colorectal, lung, skin, and stomach.215 216
217 218 Whether CLA will have a similar protective effect for people has
yet to be demonstrated in human research.
The following herbs have been studied in connection with breast cancer.
Garlic and onion
Preliminary studies hunting for associations between consumption of garlic (Allium
sativum) and onion(Allium cepa)
and a reduced risk of breast cancer have produced only mixed results;219
220 thus, there is no proof that consumption of either food helps prevent the risk of
breast cancer.
Cloud mushroom (Coriolus versicolor)
Coriolus is a Chinese mushroom that has been reported to improve parameters of immune function.221 A Japanese extract from
this mushroom called Polysaccharide Krestin (PSK) has been studied in many trials with cancer
patients, often in conjunction with conventional treatment.222 223
224 225 226 227 228 229
230 PSK’s effects in women with breast cancer have been somewhat inconsistent. One
double-blind trial reported that some groups of women with breast cancer, given PSK along with
chemotherapy, had better outcomes than those who took chemotherapy alone.231
Another double-blind trial reported 81% survival in breast cancer patients given PSK plus
chemotherapy, compared with 65% in those given chemotherapy alone, though this difference did
not quite reach statistical significance.232 A third double-blind trial did not
find PSK to be beneficial for women with breast cancer.233
PSK is not readily available in the United States and is available in Japan only by prescription. Although hot water-extracted products made from Coriolus versicolor are available in the United States without prescription, the extent to which these herbal products produce the effects of Japanese PSK remains unknown.
Eleuthero (Eleutherococcus senticosus, Acanthopanax s.)
Also known as Siberian ginseng, eleuthero has been shown to enhance immune function in preliminary Russian trials studying
people with cancer, particularly breast cancer.234 235 These trials
typically used 1to 2 ml of a fluid extract taken three times per day for at least one month.
Most of the people in these trials were also treated with chemotherapy, radiation therapy,
and/or surgery.236 237 Several of the Russian trials showed fewer side
effects from conventional therapies among those who also took eleuthero extracts. No
information is available on the ability of eleuthero to prevent cancer, nor have clinical
trials yet explored whether eleuthero extracts affect either recurrence of breast cancer or
survival in women with breast cancer.
European
mistletoe (Viscum album)
Special extracts of European mistletoe injected under the skin has been studied in several
positive and negative double-blind trials with cancer patients.238 239
240 241 242 A double-blind trial of women with breast cancer
(all treated with chemotherapy) found that
those who received mistletoe injections had improved immunity and quality of life compared
with those who took placebo.243 The use of oral mistletoe preparations has not been
studied in breast cancer patients. Mistletoe injections (usually of a product called
Iscador®) are available only through physicians and are not readily available in the
United States. It is unknown if American mistletoe (Phoradendron leucarpum) would
provide the same effect as European mistletoe.
Green
tea
In one Japanese study, green tea consumption was associated with increased survival time and
decreased spread of cancer to lymph nodes in women with early stages of breast cancer, but not
in breast cancer patients with more advanced disease.244 Recurrence rates were
found to be lowest in those who drank at least five cups per day.245 Despite these
associations, however, no proof yet exists that green tea consumption helps breast cancer
patients or helps healthy women prevent breast cancer.
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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires February 2010.