Cancer is one of the leading causes of death worldwide. According to GLOBOCAN, an international agency that collects and reports data on cancer, about 14.9 million new cases of cancer were diagnosed in 2012 and 8.2 million people died from the disease worldwide (13). This makes it the number 1 cause of death for both men and women. In the U.S., cancer claims the lives of more than 600,000 people each year (7% of the population). Most people who get cancer are over 50, and one-quarter of all cancer cases are projected to be diagnosed in people over 65 (14).
While there is still no known cure for cancer, there are several elements that can help prevent it. The most well-known example is the ‘5-a-day’ diet, which helps prevent certain kinds of cancer. Other examples include avoiding tobacco and alcohol, which are both known carcinogens, and maintaining a healthy weight, which is also associated with a lowered risk of cancer (2, 7, 15-17).
A diet rich in nutrients may also be an important ingredient in preventing cancer. The National Cancer Institute (NCI) states that “nutrients play a critical role in protecting the human body against cancer and other diseases” (4). Specifically, vegetables, fruit, and nuts—all of which have anti-cancer properties —have been proven to reduce the risk of cancer (18, 19).
A diet rich in foods with anti-cancer properties may help prevent cancer.
What is nutrition?
“Nutrition” is the study of the nutrients in food and how these nutrients are used by the body. There are many different types of nutrition, such as medical nutrition, dietary nutrition, and organic nutrition. When discussing nutrition and cancer prevention, the focus is often on the role that diet plays in preventing cancer. Thus, this article will review the evidence for the link between nutrition and cancer as well as give some tips on modifying someone’s diet if they want to reduce their risk of developing the disease.
The Role of Nutrition in Cancer Prevention
A large number of nutritional studies have focused on the question of whether certain foods are linked to an increased or decreased risk of cancer. The results of these studies have consistently shown that a diet rich in vegetables, fruit, and nuts is related to a significantly lowered risk of cancer (18, 19).
The nutrients in vegetables, fruit, and nuts may help protect the body and prevent cancer.
A diet rich in nutrients may help prevent cancer.
It is thought that the anti-cancer properties of vegetables, fruit, and nuts are due to the presence of antioxidants (such as vitamins C and E, and the antioxidants specific to tomatoes, strawberries, and raspberries) and bioactive compounds (nutrients that work in a similar way to conventional drugs, such as aspirin, tamoxifen, and cyclosporin) (20).
The antioxidants and bioactive compounds in vegetables, fruit, and nuts may neutralize harmful substances (such as free radicals) that are produced by internal body processes (such as metabolism) or external factors (such as tobacco and alcohol) and may prevent cancer (18, 19, 20).
If you want to reduce your risk of cancer, you should eat more vegetables, fruit, and nuts.
How is nutrition studied?
Most nutrition studies are designed to test specific dietary hypotheses or to establish the relation between nutrition and particular health outcomes. One of the most well-known studies in this area is the ‘Cornell Medical Study’, which was designed to investigate the relationship between nutrition and cancer (21).
In the study, over 9000 men and women participated and were followed for more than 20 years. During this time, 758 of the participants developed cancer and 338 died from the disease. After adjusting for age, sex, and other risk factors, the data showed that those who ate the most vegetable compared to those who ate the least amount of vegetables had a 23% lowered risk of cancer. Further analysis showed that vitamin C-rich fruit and vitamin E-rich fruit & nuts lowered cancer risk by 25% and 18%, respectively. The data from this study suggested that eating vegetables, fruit, and nuts may help reduce the risk of cancer.
Other notable studies in this area include the ‘PREDIMED’ study, which looked at the effects of a diet low in fat and high in vegetables and fruits compared to a diet high in fat and low in vegetables and fruits on the incidence of cardiovascular disease and cancer in people with type 2 diabetes (22).
The study, which was conducted in Spain and published in 2013, involved 7,287 participants with type 2 diabetes. After an average follow-up of 4.8 years, 815 cases of cancer and 1,041 cases of cardiovascular disease were recorded. The results showed that a diet rich in vegetables and fruits was associated with a 29% lowered risk of cancer and a 22% lowered risk of cardiovascular disease. The study provided evidence that a diet high in vegetables and fruits may help to prevent cancer and cardiovascular disease in people with type 2 diabetes.
What types of cancer can be prevented by nutrition?
The nutrients in vegetables, fruit, and nuts may help to prevent a number of different cancers (18, 19). According to a research review published in 2018, there is strong evidence that a diet rich in vegetables, fruit, and nuts significantly lowers the risk of cancer, including:
- Colon cancer
- Breast cancer
- Lung cancer
- Prostate cancer
- Esophageal cancer
- Gastric cancer
- Hepatitis C virus-associated hepatocellular carcinoma
In addition to having an impact on cancer risk, nutrition may also influence the course of the disease once it is established. There is some evidence to suggest that nutrition may alter the effect of chemotherapy drugs (23, 24). A clinical trial published in 2018 evaluated the impact of a diet high in vegetables versus a diet low in vegetables on the effectiveness of neoadjuvant chemotherapy in breast cancer patients. The focus of the study was to determine whether a diet modified in advance of chemotherapy would influence the response to the treatment. The results showed that those who consumed the highest amounts of vegetables and fruit after the diagnosis of breast cancer experienced a greater reduction in the size of their tumors after undergoing chemotherapy compared to those who ate the least amount of vegetables (25). More research in this area is needed to determine how much dietary modification is necessary before chemotherapy and whether nutrition plays an important role in drug response.
The evidence clearly shows that a diet rich in vegetables, fruit, and nuts can help to prevent cancer. Further, there is some evidence that a diet high in vegetables and fruits may alter the effectiveness of certain chemotherapy drugs. More research in this area is needed to understand whether nutrition plays a role in drug response and whether specific diets can maximize this response.
The data do not suggest that any particular diet can establish as superior or inferior in preventing cancer. Instead, the data consistently show that a diet rich in vegetables, fruit, and nuts is associated with a lowered risk of cancer. In addition, the American Institute for Cancer Research (AICR) suggests that everyone should eat plenty of vegetables and fruits and avoid foods that are high in saturated fat and sugar, to reduce their risk of cancer (26).