Cancer is a word that holds a lot gravity.
This is not surprising given that one in two Australian men and women will be diagnosed with cancer by the age of 85 (1). Of those cancers, the most common ones in Australia (which make up 60% of all cases) are prostate, breast, colorectal (bowel), melanoma and lung cancer.
In women, breast cancer is one of the most common cancers. A third of all cancers in women are diagnosed as breast cancer globally.
Breast cancer is defined as the abnormal growth of cells in the breast lobules or ducts. It is important to note that breast cancer can also develop in men, and those who are transgender.
Some symptoms of breast cancer might include (2) :
– New lumps in one breast
– Change in shape or appearance of the nipple
– Change in shape or size of the breast
– Discomfort, swelling or lumps in the armpits
– Ongoing pain in one or two breasts that is not cycle dependant.
For some, there are no symptoms of breast cancer, and it is found only upon routine screening (such as mammograms), or physical checks.
There are both genetic and lifestyle factors that can increase a person’s risk of developing breast cancer. Some of the “uncontrollable” factors include, a persons age, family history of breast cancer, inheritance of mutations in the genes BRCA2, BRCA1 and CHEK2, and having a previous history of breast cancer diagnosis, or other non cancerous breast conditions. When we speak about cancer, or any chronic illness, there are so many factors that feel outside our control. It can be helpful to focus on what we can control in these cases. Lifestyle factors are a common point of change for both individuals without cancer, and those who have gone through cancer treatments.
Some lifestyle related risk factors include: alcohol intake, low levels of physical activity and having a higher than average body fat percentage.
How might nutrition play a role in both preventing breast cancer, and in managing breast cancer?
Dietary fat
It seems the research can shed some light on the role of nutrition. A systematic review found that there was a correlation between intake of dietary fat and an increased risk of breast cancer development (3). This was luckily broken down into types of fats. The main types of fats in the diet are trans fats, saturated fats, monounsaturated fats and polyunsaturated fats. Both trans fats and saturated fats were shown to be one the strongest risk factors for development of breast cancer, as supported by various research and health reports (4,5).
The Mediterranean diet is high in fats such as olive oil, avocado, nuts and seeds, and fish. Interestingly, breast cancer risk was decreased in those following this type of diet, as well as overall cancer risk (6). Another study showed that overall deaths (non cancer related) were reduced in early-stage breast cancer survivors (7). A key fat involved in the prevention of breast cancer are omega-3 fatty acids. Omega 3’s have been shown to be protective of breast cancer, with one study showing that the risk is reduced by 5% for every 0.1g/day increase in consumption of fish and seafood (6). Omega 3’s are known as being anti-inflammatory. In another study, this was shown as omega 3’s were able to protect healthy body cells from chemotherapy drugs (8).
The systematic review that was done however found an interesting link between breast cancer prognosis and dietary fat.
The important “take home message” from these studies is that the quality and types of fats being consumed, is more important than the overall amount of dietary fat being consumed.
Fruits, vegetables and meat
Another large study was done that looked at the impact of multiple food items on breast cancer risk. The general conclusions were that increased intake of vegetables, some fruits, dairy and eggs reduce the risk of breast cancer. This same study showed that a high intake of meat was shown to increase risk of breast cancer. This is backed up by other research around high intake of red meat specifically and it’s link to increasing the risk of breast cancer. There is less clear consensus around the intake of poultry (e.g. chicken and turkey) and how this impacts breast cancer risk.
Fruits and vegetables are antioxidant rich. Antioxidants (in simple terms) protect our body cells, and fight against reactive oxygen species (ROS) such as free radicals. Free radicals are often referred to when discussing chronic disease, and play a role in increasing the rate of aging. It is no surprise then that a high intake of antioxidants helps in protecting against all types of cancer. Specific vegetables and fruit such as dark leafy green vegetables, carrots, tomatoes, cruciferous vegetables, and citrus fruits have strong evidence backing their role in prevention against breast cancer.
What about the relationship between soy and breast cancer?
The connection between soy consumption and breast cancer has been the subject of much debate and confusion. Some sources claim that soy is beneficial, while others suggest it might be harmful.
It’s important to understand what soy is and what it contains. Soy is a legume native to East Asia and is a staple in many traditional diets. It contains various nutrients and bioactive compounds, including, protein (soy is an excellent source of plant-based protein) and isoflavones. These are plant compounds found in soy, which are often referred to as phytoestrogens (plant estrogen) due to their structural similarity to the hormone estrogen.
The Concerns and Misconceptions:
There is a misconception that soy increases breast cancer risk: Some have raised concerns that the estrogen-like properties of soy isoflavones may increase the risk of hormone receptor-positive breast cancer. However, research does not support this claim
Numerous studies have failed to establish a clear link between soy consumption and an increased risk of breast cancer. In fact, some research suggests that soy consumption might even be associated with a reduced risk of breast cancer. This should of course be discussed with your healthcare team especially if you are on hormonal therapy as there can be some exceptions to this.
A benefit of soy, is that during menopause bone density halves (due to the drop in estrogen). Soy is a great source of calcium, which can support bone health. Another benefit of soy is it’s role in improving heart health by reducing LDL cholesterol levels. This could be based on the spread of protein. It’s likely that those who have higher amounts of plant based protein (like soy) will have lower amounts of other foods such as red meat which is higher in saturated fats. When choosing to include soy foods in your diet, you should opt for whole soy foods like tofu, tempeh, edamame, and soy milk, rather than highly processed soy products.
The bottom line:
Having a healthy and balanced diet is the main way to reduce all types of cancer, including breast cancer. A diet high in non starchy vegetables, fresh fruit, wholegrains, legumes and healthy fats. A person’s dietary intake can impact risk factors however, it is never anyone’s fault if they are diagnosed with cancer. It is important to always check in with your health team if you have any questions or concerns about what to eat during breast cancer treatment. For more information, head to BCNA (Breast Cancer Network Australia).
To make an appointment with a women’s health dietitian, book in here.
Until next time,
Big Sis x
