Breast cancer is a complex disease, and many things contribute to it. The following points explain some other things you can do to help prevent breast cancer.
• Vitamin D
• Bra wearing habits
• Low GI (glycemic index) carbohydrates
• Omega-3 fats
• Flaxseed and cruciferous vegetables
• Vitamin E
Bra wearing habits
In a study by Singer and Grismaijer in 1995, 3 out of 4 women studied who wore a bra for 24 hours a day developed breast cancer compared to 1 out of 168 who wore a bra rarely or never.
• That is a huge difference, and the implication is clear. Your first line of defence in preventing breast cancer is to severely limit how many hours a day you wear a bra.
Bras do NOT cause the cancer initially but they restrict the flow of lymph within breast tissue, thereby hindering the normal cleansing process of the breast tissue. Many environmental toxins and pesticides that cause and promote cancer are "fat-loving" and so tend to reside in the breast tissue. Lymph fluid carries away waste products, dead cells, and toxins.
Vitamin D and sunlight
Breast cancer mortality rates in the U.S. vary according to the geographic region so that the highest rates are in the northeast and urban areas, and lowest rates in the south and rural areas. This is explained by the variation in sunlight and the subsequent vitamin D production. According to William B. Grant's analysis, breast cancer risk could be cut in half by sufficient vitamin D levels - or in other words, by sufficient sun exposure.
Adult humans need much more vitamin D than the amount that used to be recommended (400 IU) — probably somewhere around 3000-5000 IU daily. So you cannot get enough vitamin D from the diet alone. Sun exposure without sunscreens is the preferred source of vitamin D. If you need vitamin D supplementation, blood testing of vitamin D level is recommended to know how much supplements to take and not to overdose. Dr. Mercola's article on vitamin D deficiency explains the testing, as well as how much sun exposure is adequate. Just remember, don't burn!
Carbohydrates, obesity, and breast cancer
Obesity has long been recognized as a risk factor for breast cancer. Recent reasearch is starting to unveil a bigger picture where obesity, a condition called insulin resistance/hyperinsulinemia, higher estrogen levels, and insulin-like growth factor I are all connected, and act synergistically. The exact causal mechanism is yet uncertain and under study.
People with insulin resistance or hyperinsulinemia (also called syndrome X) have high levels of insulin in their blood because the cells in their body are resisting insulin and so the body produces lots of it to counteract the resistance. This condition is caused by eating too much carbohydrates that digest rapidly, like bread, potatoes, rice, corn, baked goods, pop and other sugary drinks, cakes, cookies, most desserts, and some sweet fruits. These foods have high glycemic index (GI). Carbohydrate foods with low glycemic index (those which digest slowly) would be lentils, beans, barley, most vegetables, and some fruits. And some foods have a medium glycemic index, for example pasta and certain kinds of breads.
The mechanism of insulin resistance is as follows:
When you eat lots of carbohydrates with high glycemic index, the pancreas produces lots of insulin so that the energy from those carbohydrates (in form of glucose) could be used in the cells all around the body. Insuling is like a 'key' that opens the door to the cells so that energy (glucose) can enter the cells from the bloodstream. When there is lots of insulin in the bloodstream, the cells start resisting insulin's action. Insulin-resistant cells resist the 'key', so therefore they don't get the glucose (energy). Instead, all the extra glucose ends up stored as body fat (that's why obesity is a symptom), while the person can still feel hungry.
Almost all people with type 2 diabetes and many with high blood pressure, cardiovascular disease, and overweight people are insulin resistant. But multitudes of apparently healthy Americans also are have this condition without knowing it, because their pancreas is (still) compensating for the resistance by putting out lots and lots of insulin. You can suspect insulin resistance if you suffer from fatigue, brain fogginess, low blood sugar, obesity, high triglycerides, and high blood pressure. A glucose tolerance test can determine if a person is insulin resistant.
The remedy to hyperinsulinemia is to change the diet towards foods with low glycemic index, protein foods, and vegetables. Also exercise works wonders in lowering insulin levels. Since the typical western diet contains lots of the high GI foods, this is one more factor explaining why breast cancer has become the disease of the affluent modern western world.
Another player in this synergistic play (besides insulin) is the insulin-like growth factor I (IGF-1) that is normally present in humans. Consuming flaxseed has been found to reduce the IGF-I levels. Note also that milk from cows injected with the genetically engineered bovine growth hormone rBGH contains much higher levels of IGF-1 than normal cow's milk. We do not know if this has much of an effect on breast cancer incidence, but breast cancer patients can consider using organic dairy products or cutting off dairy while trying to recover from cancer.
Omega-3 fats and breast cancer
The evidence is very compelling that consuming omega-3 fatty acids helps prevent breast cancer, and that the ratio of omega-6 to omega-3 fats in diet is important. One should not consume too much of omega-6 fats in relation to omega-3 fats. The typical western diet contains up to 20 times as much omega-6 fats as it does omega-3s; the optimum ratio for health is more like 4:1. The beneficial omega-3 fats won't work nearly as well in protecting you from cancer if the diet contains lots of omega-6 fats. This fat issue is also a major factor in heart disease.
Omega-6 fats are found in refined supermarket cooking oils such as soy oil, corn oil, sunflower, safflower oil, in margarine, and in all processed foods that use these. Omega-3 fats are found in flaxseed, walnuts, and in oily fish, like sardines, salmon, trout, and mackerel. To limit your intake of omega-6 fats, you can use olive oil for cooking and butter for (occasional) frying.
Flaxseed and cruciferous vegetables - connection with estrogen
Certain forms of the female hormone estrogen promote cancer growth. This explains why early puberty, short menstrual cycle, and not having children are risk factors - the more menstrual cycles you go through, the more estrogen you are exposed to.
The man-made hormones used in birth control pills and hormone replacement therapies have proven not to be totally safe. Man simply does not understand the complexities of the human body enough to be able to know all the effects of synthetic hormones. The hormone replacement therapy (HRT) that combines estrogen with synthetic progestin increases the breast cancer risk substantially. Women using birth control pills possibly have a slightly increased risk of breast cancer.
You can't stop your body from producing estrogen (and you wouldn't want to) but there are some plant substances that can alter the way your body processes estrogen (estrogen metabolism).
The body metabolizes estrogen in two ways. In one pathway, it is converted into 16alpha-hydroxyestrone (16alpha-OHE1) and 4-hydroxyestrone (4-OH), both of which promote tissue proliferation, breast cancer, and estrogen dominance. Obesity, alcohol consumption, and toxic exposure can increase the levels of 16alpha-OHE1, and high levels of it are connected with increased risk and poorer prognosis of breast cancer.
The other possibility for estrogen breakdown is a safer metabolite, 2-hydroxyestrone (2-OHE1) with weak estrogenic activity. You want to have a proper balance between these two metabolitess, 2-OHE1 and 16alpha-OHE1.
Lignans in flaxseed, isoflavonoids in soy (but see note below), indole-3 carbinols in the cruciferous vegetables like cabbage, cauliflower, broccoli, brussel sprouts, etc. and omega-3 fatty acids (flax, fatty fish) reduce the amount of the carcinogenic estrogen metabolite (16a-hydroxyestrone), and increase the neutral-to-favorable estrogen (2-hydroxyestrone), thereby increasing the 2-OH:16 alpha-OH ratio. Consuming flaxseed has been even shown to reduce breast cancer tumor size in rats.
Flax or flax oil should be part of everybody's diet anyway, because it is among the few good sources of the essential omega-3 fatty acid ALA. The lignans that are so helpful against breast cancer are found mainly in flax seed and not in the oil. Remember to grind flaxseed before use because if unground, it won't digest too well. You can add it to breads, muffins, or other baked goods, or sprinkle on oatmeal or salad.
Also, any excess estrogen produced by ovaries is sent to be eliminated in the feces, but if the bowel transit time is long, it can be reabsorbed. Fiber, vegetables, fruits, exercise and anything that keeps the bowels moving well will therefore lessen breast cancer risk.
Some studies have found vitamin E to have any protective effect against breast cancer, and many have not, but more recent studies are now finding that it is the form of vitamin E that makes the difference. It appears that the common form of vitamin E that you find in supplements and in most food sources, alpha tocopherol, is not protective against breast cancer (though it certainly is a very powerful antioxidant and needed nutrient). But women consuming other forms of vitamin E called tocotrienols have been found to have dramatically lower risk of contracting breast cancer - 50% less risk for women without family history of breast cancer, and as much as 90% for premenopausal women with family history.
The food sources of tocotrienols are rice bran, barley, and wheat germ. This is yet another piece of evidence about the benefits of whole grains (brown rice, whole wheat, barley) versus the refined counterparts. Actually palm oil is the best source of tocotrienols but palm oil sold in the U.S. is refined and as usual, refining removes the good stuff.
Research on soy and breast cancer presents a conflicting picture. Many studies have shown a protective effect, many have not. One study found that the major phytoestrogens in soy, genistein and daidzein, stimulated breast tumor growth in laboratory and in animals at low concentrations but had the opposite effect at high concentrations. In yet another study, soy and curcumin together produced a 100% effect in stopping tumor growth.
The fact that Japanese consume soy and have very low breast cancer rates is often used to 'prove' that soy can help prevent breast cancer. But traditional Japanese diets differ from typical Western diets in many ways so it could be something else that is causing that. For example, they eat lots of fish and seaweed. Also, Japanese consume soy in fermented form, and usually only as side dishes, in small amounts, and not as main staple. So more research is needed on soy.
Sources & Resources for further study
National Breast Cancer Prevention Project Lots of information about preventing breast cancer.