How can you reduce the risk of cancer with a proper diet routine?

Cancer is one of the leading causes of death worldwide, with nearly 10 million people dying from cancer in 2022.

A 2008 study published in Pharmaceutical Research, the official journal of the American Association of Pharmaceutical Scientists, found that only 5 to 10 percent of all cancer cases are caused by genetic defects, while more than 90 percent of cases are related to environment and lifestyle—and 30 to 35 percent of all cancer deaths are diet-related.

Zhang Weijun, a nutritionist at Keji Nutrition Consultation Center, shared his insights on the relationship between cancer and diet and his recommendations for proper cooking routines and lifestyle habits to reduce cancer risk, on NTDTV’s “Health 1+1.”

Multiple Cancers Linked to Diet

Research has shown the effect that dietary choices can have on cancer risk, underscoring the importance of nutrition in disease prevention.​

1. Colorectal Cancer

Colorectal cancer is significantly affected by dietary habits. A diet lacking in fiber because of low intake of vegetables, fruits, and whole grains can lead to prolonged exposure of the intestines to toxic matter, increasing the risk of colorectal cancer.

Excessive intake of red and processed meat also increases colorectal cancer risk. Processed meat (including sausage, ham, bacon, corned beef, cured meat, and canned meat) has been classified as a Level 1 carcinogen by the World Health Organization’s International Agency for Research on Cancer (IARC). While processed meat is confirmed to cause colorectal cancer, its link to stomach cancer is still unclear.

Red meat (such as pork, beef, and mutton) is classified as a Class 2A carcinogen by the IARC. The classification is based on some studies linking high consumption of red meat to an increased risk of certain types of cancer, particularly colorectal cancer.

Class 1 carcinogens have well-established links to cancer in humans, whereas Class 2 carcinogens are based on varying levels of uncertainty, with 2A having stronger evidence than 2B.

Therefore, to reduce cancer risk, do not eat red meat every day, and when you do, remember to eat it with fiber-rich foods such as vegetables and fruits to reduce the risk of cancer.

2. Liver Cancer

In hot, humid environments, improper storage of cereals, nuts, and peanuts can lead to aflatoxin production. Classified as a Level 1 carcinogen by the IARC, aflatoxin, a highly poisonous substance, may increase liver cancer risk.

It’s recommended to store unconsumed nuts and grains in sealed containers in the refrigerator or dried at room temperature.

3. Gastric Cancer

Consuming excessive amounts of salted foods, such as cured meats, salted fish, and pickles, can damage the gastric mucosa and increase the risk of cell mutation leading to cancer. It also enhances the growth of Helicobacter pylori, a type of bacteria in the stomach, a major cause of gastric cancer.

A recent study, published in Gastric Cancer, following more than 470,000 people for about 11 years, found that those who regularly add extra salt to meals have a 41 percent higher risk of gastric cancer than those who rarely or never do so.

4. Breast Cancer

A study published in PNAS in May found that a high-fat diet is a significant risk factor for cancer progression because of its destructive effect on intestinal microbiota.

A separate comprehensive research found that a higher intake of total fat and saturated fat was associated with an increased risk of breast cancer.

5. Obesity-Related Cancers

An unrestrained diet leading to obesity increases the risk of more than 10 types of cancer, including esophageal, liver, kidney, gastric, colorectal, prostate, breast, gallbladder, and ovarian cancers.

Obesity not only contributes to cancer initiation and spread but also worsens the prognosis of many cancers.

4 Habits That Increase Cancer Risk

Zhang highlighted several habits that can significantly increase cancer risk:

1. Chewing Areca Nut (Oral Cancer Risk)

Areca nut, containing arecoline as its primary active ingredient, is classified as a Class 1 carcinogen by the IARC. Though chewed for its mild psychoactive effects, it continuously irritates and damages the oral mucosa, potentially causing cancer. Alternatives for a refreshing effect include drinking coffee, chewing gum, or using a peppermint stick.

2. Swallowing Very Hot Drinks (Esophageal Cancer Risk)

Drinks above 65 degrees Celsius (149 Fahrenheit) are classified as Class 2A carcinogens by the IARC.

Overheated beverages can damage and irritate esophageal cells, and repeated exposure can increase cancer risk. Always allow hot tea or soup to cool before consuming.

3. Eating Moldy Food (Liver Cancer Risk)

Moldy foods contain carcinogens such as mold and aflatoxins.

Avoid fruits with moldy skin, as the mold may penetrate the interior. It’s best to eat cooked food within one or two days to prevent mold growth.

4. Drinking Alcohol (Digestive Tract Cancer Risk)

Alcohol is classified as a Class 1 carcinogen by the IARC. Even small amounts consumed over long periods can increase cancer risk. Alcohol is a risk factor for several cancer types, including breast, colorectal, gastric, liver, pancreatic, and esophageal cancers.

Eat before and during alcohol consumption, particularly vegetables and fruits. Alternating with nonalcoholic drinks can also help reduce alcohol’s effect on the body.

Better Cooking Methods to Reduce Cancer Risk

Proper cooking techniques help maintain nutrition and reduce cancer risk. Zhang suggests:

1. Limit Stewing Time

Prolonged stewing can reduce nutrients. Ensure that the different ingredients are fully cooked but not excessively stewed by adding slow-cooking foods first, followed by items such as vegetables that cook quickly.

2. Avoid High-Heat Frying

Grease, when exposed to high temperatures, tends to produce oily fumes, which are also a Class 2A carcinogen and can increase the risk of lung cancer. It is recommended to opt for medium-low heat stir-frying, steaming, or boiling to reduce harmful substances.

3. Minimize Grilling and Deep Frying

High temperatures will overheat proteins and can produce Class 2B carcinogens such as polycyclic aromatic hydrocarbons.

Avoid burning meat, limit grilled meat consumption, and pair it with vegetables and fruits.

4. Be Cautious With Starchy Foods

Deep-frying or baking starchy foods at very high temperatures produces acrylamide, a Class 2A carcinogen.

Cancer Prevention Lifestyle Habits

To live a cancer-prevention lifestyle, Zhang suggests that one:

1. Maintain a Regular, Balanced Diet

Eat moderate portions regularly, emphasizing vegetables and fruits. Overeating burdens the digestive tract, potentially leading to gastroesophageal reflux or gastric ulcers, precursors to cancer.

2. Manage Body Weight

Obesity increases the risk for more than 10 cancer types. Reduce high-fat and high-sugar foods while increasing fruit and vegetable intake to control weight and minimize chronic, low-grade inflammation.

3. Limit Takeout Foods

Takeout meals often contain high calories, fats, and sugars, increasing obesity and cancer risks. Also, associated plastic tableware can be harmful to health.

4. Prioritize Physical and Mental Health

Adequate sleep, regular exercise, and maintaining a positive mood support proper immune function.

A 2020 meta-analysis found that a healthy lifestyle—including proper diet, weight management, physical activity, limited alcohol consumption, and avoiding smoking—was associated with a significantly lower risk of cancer incidence and mortality. The healthiest lifestyle choices can reduce risks for various cancers (including bladder, breast, colon, endometrial, esophageal, kidney, liver, lung, rectal, and stomach) by 17 to 58 percent.