Dr. Liu Zhongping, a cardiologist, mentioned that he had two friends who had been vegetarians for more than two decades. However, both developed symptoms of colorectal cancer in their 50s and were diagnosed with terminal colorectal cancer, and one of them was a monk, who had been a vegetarian for more than 30 years. Eating red meat or processed meat, such as sausages and ham, can increase the risk of colorectal cancer. Nevertheless, why do some people still get colorectal cancer even though they follow a vegetarian diet?
The Journal of the American Medical Association – Internal Medicine published a large-scale medical study in 2015, which tracked the diets of more than 70,000 Christians with healthy habits and colorectal cancers over a seven-year period.
The study found that compared to non-vegetarians, vegans had a 16 percent lower risk of colorectal cancer and lacto-ovo-vegetarians (who consume dairy products and eggs) had an 18 percent lower risk. The other semi-vegetarians had only a 7 percent reduction in risk.
This study highlights the fact that a high intake of fruits and vegetables can reduce the risk of colorectal cancer. In recent years, there are also many concepts about being vegetarian for health reasons. However, some vegetarians still get colorectal cancer, such as Chadwick Boseman, the star of the movie Black Panther, who was on a vegetarian diet before his passing due to colorectal cancer.
Dr. Jianxian Wu of the Department of Hepatology and Gastroenterology at Taipei Hospital pointed out that diet is not the only cause of colorectal cancer. Exposure to environmental carcinogens, poor lifestyle habits, being over 40 years old, and a family history of colorectal cancer or colorectal polyps are all high risk factors for colorectal cancer.
However, in terms of diet alone, a “vegetarian diet” cannot be equated with a “healthy diet,” and the key is what is being eaten. Although many people eat vegetarian food, the ingredients and cooking methods may actually increase the risk of colorectal cancer.
Avoiding Two Major Vegetarian Minefields: Processed Vegetarian Products and High-Temperature Cooking
To prevent colorectal cancer, we should pay attention to two major vegetarian minefields: processed vegetarian products and high-temperature cooking.
There is a wide range of processed vegetarian products on the market, including vegetarian meat, vegetarian meatloaf, vegetarian ham, and vegetarian sausages… These are mostly imitations of meat, which seem to be more nutritious than real meat. However, in fact, just like processed meat, these products are all “processed” in a similar way.
Dr. Wu pointed out that processed meat is harmful to health, because of the high temperatures used to process the items, as well as the pickling, smoking, and other procedures used in the process, which is prone to producing carcinogens. For instance, the proteins in meat are denatured at high temperatures. Similarly, the raw materials of processed vegetarian products are mostly soybeans, which are plant-based proteins, and are also suspected of producing carcinogens after high-temperature processing.
Some processed vegetarian products have a lot of added fat, sugar, and/or soy sauce or have been smoked to add more flavor. However, high-fat, high-sugar, smoked or preserved foods can increase the risk of colorectal cancer.
Furthermore, foods high in salt can also increase the risk of cardiovascular diseases. In addition, some processed vegetarian foods contain a large number of chemical additives, such as pigments, flavor enhancers, preservatives, and bactericides.
Dr. Wu added that processed vegetarian products have their advantages, as they are more aromatic and tasty than unprocessed vegan foods, so they can be consumed in moderation. However, we should choose products made by qualified manufacturers and avoid excessive chemical additives listed in the ingredients list.
The American Cancer Society’s 2019 report on colorectal cancer published in the journal Gut showed that South Korea had the highest incidence of colorectal cancer among adults under the age of 50. Scholars believe that this is related to the Korean people’s love of barbecued meats.
High-temperature cooking methods, such as barbecuing and deep-frying, are not conducive to the prevention of colorectal cancer. The vegetables are particularly prone to scorching when grilling, and it is best not to eat the scorched parts.
In addition, some restaurants sell cooked vegetarian foods, which are made from processed vegetarian meat and again cooked again through high-temperature frying and deep-frying, adding another layer of risk.
6 Tips to Prevent Colorectal Cancer by Smart Vegetarian Eating
To prevent colorectal cancer through vegetarianism, there is a set of healthy dietary methods.
Eating a Lot of High-Fiber and Dark Green Vegetables
Eating high-fiber foods is the key to prevent colorectal cancer. Dr. Mingzhu Chen, director of the Department of Chinese Medicine at Taipei Hospital, pointed out that to reduce the incidence of colorectal cancer, the environment of the colon needs to be maintained in good condition. The dietary fiber can grab body waste and stimulate intestinal peristalsis, to make the bowel movement smooth, and then the waste is expelled from the body to reduce intestinal pathology.
Among all vegetables, the dark green ones are the best. According to Dr. Wu, these vegetables are rich in antioxidants, which are beneficial for fighting colon cancer.
Using Natural Food as Main Ingredients and Avoiding Over-Seasoning and High-Temperature Cooking
It is recommended to boil, stir-fry, braise, and stew food, while limiting the use of high-temperature cooking techniques, such as frying and deep-frying. And we should avoid heavy seasoning.
Dr. Lobsang Gyaltsen, renowned expert in preventive medicine and director of Lobsang Preventive Medicine Group, recommends eating more natural, unrefined foods, such as products made with whole-grain grains, and reducing the intake of refined starch foods.
Consuming High-Quality Plant-Based Proteins
For plant-based protein sources, choose natural legumes, such as soybeans, black beans, Edamame beans, and peas, or less processed vegetarian foods, such as tofu, dried beans, and soy milk.
At the same time, we should reduce our consumption of over-processed plant-based proteins with low nutritional value, such as fried vegetarian “meats.”
Keeping a Balanced Diet With Many Colors
We should eat a variety of fruits and vegetables of all colors, because different types of fruits and vegetables of different colors contain different phytochemicals, which can increase the body’s immunity and help prevent cancer.
The Formosa Cancer Foundation recommends adult women to eat seven servings of fruits and vegetables a day, including four servings of vegetables and three servings of fruits; and adult men should eat nine servings of fruits and vegetables a day, including five servings of vegetables and four servings of fruits.
Dr. Chen stressed that we cannot eat only a certain kind of fruits and vegetables. For example, we cannot consume an excess of spinach, precisely because it is very nutritious. If the body absorbs too much of the mineral contents of spinach, it may cause an imbalance in the body’s physiological responses.
Supplementing Fermented Foods to Improve the Intestinal Microbiome
Lacto-ovo-vegetarians can consume a lot of fermented dairy products, such as yogurt. Dr. Wu explained that fermented dairy products not only provide protein, calcium and other nutrients, but also contain a large number of good bacteria, which are beneficial to intestinal health. However, people with lactose intolerance are advised to consume small amounts of fermented dairy products to avoid problems such as bloating and diarrhea.
We can also consume other fermented foods, including miso, kimchi, and vinegar, all of which contain probiotics. However, commercially available kimchi should be consumed in moderation, because in addition to the possibility of excessive sodium intake, there might also be a lot of additives.
Consuming Foods High in Omega-3
Omega-3 polyunsaturated fatty acids are beneficial for reducing the occurrence, progress, and distant metastasis of colorectal cancer.
The general public can supplement omega-3 by eating fish, and vegetarians can get this nutrient from natural plant foods, such as sesame seeds, pumpkin seeds, sunflower seeds, walnuts, avocados, and chia seed oil.
Finally, in addition to a healthy diet, we should exercise moderately, avoid excessive alcohol consumption, stop smoking, and maintain a healthy weight. People over the age of 50 should undergo annual colon cancer stool screening tests and regular colonoscopy. If there are changes in bowel habits, blood-colored stools, as well as mucus, foul odor and/or shape changes in stool, they should seek medical attention.
Epoch Health articles are for informational purposes and are not a substitute for individualized medical advice. Please consult a trusted professional for personal medical advice, diagnoses, and treatment.