Cancer and diet: How does everyday diet affect your risk of cancer?

Dietary factors that can increase the risk of cancer development

Evidence suggests that an unhealthy diet can significantly increase the risk of cancer development [, ]. Different types of food, as well as diet habits, have been found to be linked with cancer development. Some examples include:

1. Carcinogens

Carcinogens are any substances, agents, or organisms that can induce DNA damage and mutations that lead to cancer development, such as ultraviolet rays or certain viruses []. Different types of carcinogens have been identified in food.

One example is nitrosamines, which are chemical compounds formed during food processing and cooking and are derived from chemical reactions between nitrites and nitrates. Food manufacturers often add nitrites and nitrates as food additives to preserve the food, prevent the growth of bacteria, and improve the taste and the appearance of food products. Processed meats, such as bacon, ham, and sausage, are some examples of food that contain nitrites and nitrates and have been linked with increased risk of stomach, colorectal, and other types of cancer [, ]. Interestingly, a 10-year study showed that consumption of ultra-processed foods can increase the risk of developing different types of cancer by 2%, as well as increase mortality rates [].

Other examples of carcinogens are heterocyclic amines and polycyclic aromatic hydrocarbons which result from the smoking and grilling of meat at high temperatures and have been correlated with colorectal, stomach, and lung cancer [, ].

2. Lack of essential nutrients

Poor nutrition and lack of essential nutrients such as vitamins and minerals can contribute to cancer development [, ]. In addition, lack of antioxidant nutrients such as Vitamins C and E can increase the oxidative damage that occurs in our bodies and promote cancer progression. This is because antioxidants, which are substances that can prevent or delay certain types of cell damage, will not be able to neutralise the free radicals leading to oxidative stress, DNA damage, and ultimately cancer development [, ].

3. Excessive dietary fat intake

A high-fat diet has also been linked with cancer. Studies have shown that a diet high in fat can lead to oxidative stress, the accumulation of free radicals that can lead to mutations in the DNA, and accelerated cancer progression [, ].

4. Alcohol consumption

According to , in 2020 about 4% of diagnosed cancers were due to alcohol uptake []. Although the exact mechanisms of how alcohol can lead to cancer are not clearly understood, there are different ways in which alcohol is thought to contribute to cancer development. For example, alcohol can generate reactive oxidative species—small, highly reactive molecules—that can damage the DNA []. Drinking alcohol can also stop the body from absorbing nutrients whose lack is associated with cancer, such as vitamins and carotenoids []. Additionally, metabolizing alcoholic drinks can lead to the production of acetaldehyde, which is a toxic chemical leading to DNA mutations. Some of the most common types of cancer that are associated with alcohol uptake are head and neck cancer, esophageal, liver, breast, colorectal cancer [].

Types of cancer associated with unhealthy diet

There are several types of cancer that are associated with poor diet and consumption of unhealthy food [, , ]. Some examples include:

• Lung cancer
• Pancreatic cancer
• Prostate cancer
• Colorectal cancer
• Stomach cancer
• Breast cancer
• Liver cancer
• Esophageal cancer
• Head and neck cancer

Types of food that can reduce the risk of cancer development

Multiple studies demonstrate that certain types of food might reduce the risk of cancer. For example, fruits and vegetables such as red apples, tomatoes, oranges, bananas, broccoli, spinach, blueberries, and others have been found to be associated with reduced cancer risk including head and neck, esophageal, stomach, lung, pancreatic, and prostate cancer [, ]. Indeed, plant-based food contains phytochemicals (also known as phytonutrients) that can play a major role in cancer prevention by blocking cellular pathways that lead to cancer development []. Interestingly, phytochemicals have been used in anticancer drugs and are considered a promising tool for treating different types of cancers [, ]. Examples of phytochemicals include:

• Capsaicin found in chili peppers []
• Catechins found in green tea and other beverages []
• Lycopene found in tomatoes, papaya, pink grapefruit []
• Isoflavone found in soy, lentils, beans []

Additionally, foods that contain antioxidants such as beta-carotene, selenium, vitamins, and minerals including calcium and iodine can help the cells of the body repair themselves, neutralise free radicals that can cause DNA damage, and reduce the risk of cancer []. Furthermore, garlic and onions are other examples of food that have anti-cancer properties as they can block the formation of nitrosamines and the rapid growth of cancer, also known as proliferation [].

Everyday dietary habits that can reduce the risk of developing cancer

The recommends a balanced diet that is rich in vegetables, fruit, beans, and whole grains to reduce the risk of developing cancer. Therefore, increasing the amount of vegetable servings per day, especially vegetables of different colour-types, such as dark green, red, and orange, fiber-rich legumes as well as fruits in a variety of colours, can minimise the risk of cancer development []. Further recommendations include a diet that is low in red and processed meats, and low in sugar and sweetened drinks [, ]. The (WCRF) and the (AICR), also recommend reducing alcohol uptake [].

Conclusion

Our diet plays an essential role not only in cancer development but also in cancer prevention. It is always advisable to maintain a healthy lifestyle and a balanced diet to reduce cancer risk. This is particularly important for individuals with a positive family history of cancer, who can also benefit from hereditary genetic testing to identify predisposing germline (inherited) mutations, thereby maximizing the opportunities for better clinical management. Diet may not be the only factor contributing to cancer risk, but it is one that we can control.

The content of the above article is for informational purposes only and should not be treated as professional medical advice or counselling.