“Let food be thy medicine and medicine be thy food” – Hippocrates
Despite widespread research and treatment options, cancer remains a leading cause of death worldwide. Cancer is still considered a largely preventable disease with estimates of 90-95% of the risk rooted in environmental and lifestyle factors (Cancer Management and Research, 2011).
- Dietary factors are estimated to be responsible for 30-35% of all cancers in the US.
- Diet is linked to as many as 50% of breast cancer cases.
At the 2012 American Association for Cancer Research’s (AACR) annual meeting, researchers from the Vanderbilt Epidemiology Center and Shanghai Centers for Disease Control and Prevention presented data from more than 4,800 female breast cancer survivors in China. They had been diagnosed with breast cancer, ranging from stage 1 to stage 4, between 2002 and 2006.
They found that higher consumption of cruciferous vegetables (broccoli, cauliflower, brussels spouts, kale and cabbage) during the first 36 months of diagnosis was associated with a reduced risk for total mortality, breast cancer-specific mortality and the recurrence of breast cancer.
Cruciferous vegetable consumption was measured in quartiles. There was an inverse relationship between women who ate more cruciferous vegetables with a decreased risk for mortality (non- and breast cancer-specific) and recurrence. Women that ate the most reduced their risk by 62% for both overall mortality and breast cancer-specific mortality, while 35% reduced their risk of breast cancer recurrence.
Overall, this study points to the positive role that all cruciferous vegetables can play in preventing (to a degree) and improving survival and recurrence rates associated with breast cancer. Limitations include an understanding of the chemical properties of cruciferous vegetables that protect from breast cancer development, but also the relative quantities in which these beneficial effects are derived.
Researchers at the Sprecher Institute for Comparative Cancer Research at Cornell University have identified and isolated many natural chemicals (phytochemicals) in fruits and vegetables that affect cancer risk and survival. Many other cancer preventing properties of these fruit and vegetable-derived chemicals are preliminary, but include:
- Isothiocyanates and thiocyanates (brussels sprouts)
- Flavonoids (berries)
- Coumarins (citrus fruits)
- Phenols (almost all fruits and vegetables)
- Protease inhibitors (legumes)
- Plant sterols (vegetables)
- Isoflavones, saponins, inositol hexaphophate (soybeans)
- Allium compounds (garlic)
- Limonene (citrus fruit oils)
- Resveratrol (grapes- aka: WINE!)
The Sprecher Institute at Cornell has a specific program that focuses their research on breast cancer and environmental risk factors. They have defined some of the mechanisms by which the natural chemicals in fruits and vegetables might biologically help reduce the risk of breast cancer and other cancers. These include:
- Stimulate cell differentiation and stop cell proliferation
- Cancer occurs more frequently from proliferating cells that are not differentiated. Fruit and vegetable compounds promote cell differentiation and potentially protect from cancer cell formation.
- Act as antioxidants
- Fruits and vegetables contain many antioxidants that reduce the oxidation of DNA leading to potential cancer cell formation.
- Increase activity of protective detoxifying enzymes
- Toxins in the body can be deactivated and eliminated by protective enzyme systems, a property of many fruits and vegetables, especially broccoli.
- Enhance immune function
- Fruits and vegetables strengthen the body’s defense against cancer and other diseases.
- Alter estrogen level
- Higher lifetime exposure to estrogen is related to a higher risk of breast cancer. Compounds in fruits and vegetables, especially broccoli, help the body increase the metabolism of estrogen into weaker forms.
Admittedly, the current evidence regarding the actual significance of the relationship between vegetarian eating patterns and the incidence of specific types of cancers are weak. However, a broad body of evidence does link specific plant foods such as fruits and vegetables, plant constituents such as antioxidants and fiber, and achieving and maintaining a healthy weight, as preventative methods to reduce the risk of cancer diagnosis and recurrence.
In the meantime, following a vegetarian diet naturally increases consumption of these beneficial plant constituents. Abiding by a plant-based lifestyle will aid in achieving and maintaining a healthy weight, which is currently the strongest evidence for primary prevention and for improving outcomes after a cancer diagnosis. In fact, vegetarians on average weigh 3-20% less and have lower rates of obesity than omnivores (Cancer Management and Research, 2011). Adopting a low-fat vegetarian diet and regular physical activity will likely lead to a healthy weight and therefore a reduced risk for cancer.
Lanou, A., Svenson, B. (2010). Reduced cancer risk in vegetarians: an analysis of recent reports. Cancer Management and Research, 3, 1-8. doi: 10.2147/CMR.S6910