Dietary choices to help prevent breast cancer
Breast cancer is a complex disease with many contributing factors. Some of these factors, including age, family history, genetics, and gender, are not within a person's control.
However, a person can control other factors, such as smoking, physical activity levels, body weight, and diet. Some researchers have suggested that dietary factors could be responsible for 30–40% of all cancers.
Foods to eat
Fresh fruits and vegetables may help prevent breast cancer.
Breast cancer can start in different places, grow in different ways, and require different kinds of treatment. Just as particular types of cancer respond better to certain treatments, some cancers respond well to specific foods.
The following foods can play a role in a healthful diet in general, and they may also help prevent the development or progression of breast cancer:
- a variety of fruits and vegetables, including salad
- foods that are rich in fiber, such as whole grains, beans, and legumes
- low fat milk and dairy products
- soybean-based products
- foods rich in vitamin D and other vitamins
- foods, particularly spices, with anti-inflammatory properties
- foods — mainly plant based — that contain antioxidants
Dietary patterns that prioritize these foods include:
- A southern diet that is high in cooked greens, legumes, and sweet potatoes
- A Mediterranean diet, which emphasizes fresh fruits and vegetables and healthful oils
- Any "prudent" diet that contains plenty of fruit, vegetables, whole grains, and fish
Fruits and vegetables
A study of 91,779 women found that following a diet comprising mainly plants could cut the risk of developing breast cancer by 15%.
Along with their other benefits, fruits and vegetables are rich in flavonoids and carotenoids, which appear to have various medical benefits.
Studies have suggested that the following foods may help prevent breast cancer:
- dark, green, leafy vegetables, such as kale and broccoli
- fruits, especially berries and peaches
- beans, pulses, fish, eggs, and some meat
Researchers have associated beta carotene, which occurs naturally in vegetables such as carrots, with a lower risk of breast cancer. Scientists speculate that this may be because it interferes with the growth process of cancer cells.
The United States Department of Agriculture (USDA) recommend consuming between five and nine servings of fresh fruit and vegetables a day.
Dietary fiber and antioxidants
Research into dietary fiber and its effect on breast cancer is currently inconclusive, but several studies have suggested that it can help protect against the disease.
Excess estrogen can be a factor in the development and spread of some types of breast cancer. Some treatments aim to keep estrogen from interacting with breast cancer cells. Eating a high fiber diet can support this process and accelerate the elimination of estrogen.
Fiber supports the digestive system and the regular elimination of waste, including excess estrogen. It helps the body eliminate toxins and limits the damage that they can do.
The way that fiber binds to estrogen in the gut may also help prevent the body from absorbing too much estrogen. These factors may help reduce the risk of breast cancer.
Fruits, vegetables, whole grains, and legumes provide fiber, but they also contain antioxidants, including beta carotene and vitamins C and E.
Antioxidants can help prevent many diseases by reducing the numbers of free radicals, which are waste substances that the body naturally produces. A 2013 meta-analysis found that people who eat more whole grains may have a lower risk of breast cancer.
The Dietary Guidelines for Americans 2015–2020 recommend an intake of up to 33.6 grams of fiber a day, depending on a person's age and sex.
Dietary fiber supplements are available for purchase online.
Avocado is a good source of healthful fats.
Fatty foods can lead to obesity, and people with obesity appear to have a higher risk of developing cancer, including breast cancer.
Some dietary fat is necessary for the body to work properly, but it is important to consume the right type.
Polyunsaturated and monounsaturated fats can be beneficial in moderation. They are present in:
- olive oil
Cold water fish, such as salmon and herring, contain a healthful polyunsaturated fat called omega-3. This fat may also help reduce the risk of breast cancer.
Learn more here about healthful fats.
They also cited another study involving over 3,000 women, which showed that those who consumed high levels of omega-3 had a 25% lower risk of breast cancer recurrence over the next 7 years.
The health benefits of omega-3 fatty acids might be due to their ability to reduce inflammation. Inflammation may be a contributing factor for breast cancer.
Omega-3 supplements are available for purchase online.
Soy is a healthful food source that may help reduce the risk of breast cancer. It is a plant based product that is rich in protein, healthful fat, vitamins, and minerals but low in carbohydrates. It also contains antioxidants known as isoflavones.
The authors of a 2017 study that looked at data for 6,235 women concluded that, overall, "a higher dietary intake of isoflavone was associated with reduced all-cause mortality." The researchers were investigating whether soy consumption was a good idea for people with breast cancer.
Soy may also help reduce levels of low-density lipoprotein (LDL), or "bad," cholesterol and lower the risk of heart disease. Along with obesity, these conditions are risk factors that contribute to metabolic syndrome, which involves inflammation.
Inflammation may play a role in breast cancer, although the role that it plays remains uncertain.
Soy is present in foods such as:
- soy milk
- soy nuts
Some people question whether soy might increase the risk of breast cancer because it contains isoflavones, which resemble estrogen.
However, the author of a 2016 review article notes that estrogen is not the same as isoflavones and that the two are unlikely to behave in the same way. According to the author, the North American Menopause Society have concluded that isoflavones do not increase the risk of breast cancer.
Foods to avoid
Foods that may increase the risk of different kinds of cancer, including breast cancer, include:
- added sugar
- red meat
- processed foods
Studies have identified a link between regular alcohol consumption and an increased risk of breast cancer.
Breastcancer.org report that alcohol may increase estrogen levels and cause damage to DNA. They also note that women who drink three alcoholic beverages per week increase their risk of developing breast cancer by 15%.
According to estimates, the risk goes up by about 10% with each additional drink per day.
In research from 2016, mice that ate a diet that was as rich in sugar as the typical diet in the U.S. were more likely to develop mammary gland tumors similar to breast cancer in humans.
In addition, these tumors were more likely to spread, or metastasize.
Studies suggest that not all fats are bad. Although fat from processed foods appears to increase the risk of breast cancer, some plant based fats may help reduce it.
Trans fats are a type of fat that is common in processed and premade foods. Scientists have linked it with a higher risk of breast cancer. Trans fats most commonly occur in processed foods, such as fried foods, some crackers, donuts, and packaged cookies or pastries. People should limit their intake of trans fats where possible.
Some studies have found a link between red meat and an increased risk of breast cancer, especially if a person cooks the meat at high temperatures, which can trigger the release of toxins.
In addition, processed meats and cold cuts tend to be high in fat, salt, and preservatives. These may increase rather than reduce the risk of breast cancer. Overall, minimizing the processing of a food makes it more healthful.
Turmeric may have anti-inflammatory properties that help prevent breast cancer.
Vitamin D from foods and sunlight exposure may help protect against breast cancer. Vitamin D is present in eggs, cold water fish, and fortified products. A person can consult a doctor to check their vitamin D levels. If these are low, the doctor may recommend a supplement.
Green tea may have several beneficial health effects. It contains antioxidants, and these may help strengthen the immune system and reduce the risk of breast cancer.
Turmeric is a yellow spice that may have anti-inflammatory properties that could limit the growth of breast cancer cells.
Maintaining a healthy body weight is beneficial for well-being in general, but it is particularly important for people who wish to prevent the development or recurrence of breast cancer. Obesity is a known risk factor for the disease.
Exercise is also important. The National Cancer Institute report that women who exercise for 4 hours per week or longer have a lower risk of breast cancer.
Following a healthful diet that is rich in fruits and vegetables and low in added sugar and trans fats may reduce the risk of breast cancer.
It can also lower the risk of obesity, a condition that increases the likelihood of a person developing breast and other cancers.
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