Every time we eat something, whether it is a healthy green apple or a nice little cupcake, we chew and swallow it without any thought. We just enjoy our food and that is it. But what happens after the food gets into the mouth? Here our digestive system comes into the game. Food passes through the digestive tract and is mixed with digestive juices so that we can receive all the vitamins and minerals from it.
However, because of carelessness about what we put into our mouth our digestive system may suffer silently for years before we notice that something went wrong. Maybe if we thought twice about what to eat, fewer digestive illnesses would appear.
Gastrointestinal cancers (also called digestive cancers) are a global burden that is responsible for 35% of all cancer deaths. In 2018, there were 4.8 million new cases of digestive cancers (oesophagal, stomach, colorectum, liver, and pancreas cancers) and 3.4 million related deaths.
What is digestive cancer?
Digestive cancer is a disease that occurs when cells in one of the digestive system organs begin to grow abnormally and divide uncontrollably. The digestive system includes the mouth, oesophagus, stomach, small intestine, colon, rectum, and anus.
The most common digestive cancers are the next:
Oesophageal cancer affects the tube between your mouth and stomach.
Stomach cancer affects directly the stomach.
Colorectal cancer is cancer of the colon or rectum.
Pancreatic cancer affects the pancreas, a gland located behind the stomach that produces hormones and digestive enzymes.
Liver cancer affects directly the liver.
The main symptoms of digestive cancer
The biggest catch about digestive cancer is that it belongs to a group of silent diseases. The symptoms are either not present or they can be so benign that we do not take them seriously until it is too late. For example, colorectal cancer usually begins with small, benign (noncancerous) clusters of cells called polyps that form on the inner lining of the colon. In 10-15 years these polyps can develop into cancer. This is the main reason why we all have to be aware of the symptoms and risk factors of the very disease to get medical help and not let it go further.
The most general signs may include:
Unexpected weight loss
Belly pain or discomfort in the area above the belly button
Difficulty digesting food, heartburn, or vomiting
Decreased appetite or feeling full after eating small amounts of food
Weakness or tiredness
Vomiting blood or passing blood in the stool
Difficulty swallowing or the sensation of food getting stuck in the throat
The main risk factors of digestive cancer
Smoking is a major risk for various types of cancer and cancers of the digestive system do not drop off the very list. Current smoking is associated with a twofold risk of developing stomach and pancreatic cancer, while current smokers have a 59% greater risk of colorectal cancer.
Regularly eating foods high in salt has been linked to an increased risk of digestive cancer. This includes foods preserved by drying, smoking, salting, or pickling and foods high in added salt.
Eating a lot of salted fish may increase your risk of stomach cancer by 15%, according to a report from the World Cancer Research Fund in 2018. The report also found that eating 20 grams of pickled vegetables per day may increase your risk of stomach cancer by 9%.
Alcohol can damage the stomach cells and lead to inflammation and lesions. Heavy alcohol can delay stomach emptying, induce bacterial degradation of the food, and cause stomach discomfort.
Any type of drinking is associated with a higher risk of digestive cancer. A population-based study in South Korea showed that light drinking as well as moderate to heavy alcohol consumption significantly increased the risks of oesophagal, gastric or colorectal cancers.
Another study demonstrated that 150 millilitres of red wine (containing 42g of alcohol) a day increased the risk of stomach cancer risk by 42%.
Research studies show that being obese may cause up to 14% of tumours. Obesity is linked to many types of cancer, including pancreatic and oesophageal. According to the World Cancer Research Fund, up to 35% of these cancers may be caused by obesity. Obesity also makes cancer more deadly. Research shows that obesity may cause up to 14% of cancer deaths in men and 20% in women.
Cancers of the digestive system mostly appear in older people, aged 50 years and older.
Men are more likely to succumb to any type of digestive cancer. For instance, the lifetime risk of developing stomach cancer for men is about 1 in 96, while for women it is about 1 in 152.
H. pylori is a bacterium that can cause stomach problems like inflammation and ulcers. It can also lead to stomach cancer. If someone in your family has had stomach cancer and their doctor thinks H. pylori might be the cause, or if they know they have H. pylori, you should get tested for it too and treat the infection if you have it.
People with first-degree relatives who have a digestive cancer history are at a higher risk of succumbing to the very illness. This may be caused by mutated genes that can be passed from a parent to a child. For example, if you have a parent, sibling, or child with colon cancer, you are more likely to get it too. Your risk goes up from 5% to 15%. If a relative who had cancer is younger than 50, your risk is even higher. If you have more than one family member with colon or rectal cancer, your risk goes up even more.
People who have had stomach surgery, pernicious anaemia, or achlorhydria have a higher risk of cancer of the digestive system. Pernicious anaemia happens when the stomach cannot take in enough vitamin B12. This causes a severe decrease in red blood cells. Achlorhydria is when there is no hydrochloric acid in the gastric juices, which helps digest food.
Seven ways to drop the risk of digestive cancers
It is always the best decision to prevent the disease, especially such an unpleasant event as cancer. The good news is that the digestive system can be held in good ‘shape’ by lifestyle choices. A study showed that regardless of family history of various cancer types, a healthy lifestyle was associated with a lower risk of digestive cancer.
Thus, in order to maintain a healthy digestive system you should incorporate the following healthy habits:
1Eat a healthy diet
The food you eat can affect your cancer risk indirectly, such as by worsening acid reflux, a risk factor for oesophagal cancer, or through direct contact with the lining of your digestive tract.
A healthy diet is the number one habit you should incorporate into your daily life to maintain a healthy digestive system. A diet high in fruits, vegetables, and whole grains can help reduce your risk of digestive cancers. Studies have revealed that the high consumption of fruit is associated with a decreased gastric cancer risk. Fruit and citrus consumption per day decreased gastric cancer risk by 5% and cardia (part of the stomach where the oesophagus enters) cancer risk by 24%.
Women in the United States may have 10 times more colorectal cancer than women in India. Men in the United States appear to have 11 times more colorectal cancer than men in India. What is the reason for such a discrepancy? One possible explanation is the regular use of turmeric in Indian cooking.
A study of smokers showed that curcumin (the main compound of turmeric that gives it its yellow colour) significantly reduced cancer-associated structures in the rectums of the subjects by up to nearly 40% within 30 days. Thus, turmeric intake can ward off the odds of colorectal cancer.
Whole grains, seeds, legumes, nuts
Phytates or phytic acids are antioxidants that can be found in whole grains, legumes, nuts and seeds. Foods rich in phytates have been shown to have a protective effect against digestive cancer.
A study conducted by the National Cancer Institute found that a one-quarter cup (60 grams) increase in bean consumption a day could significantly reduce the risk of precancerous colorectal polyp recurrence by up to 65%.
Phytates may also help protect against colorectal cancer. The study of about 30,000 Californians for six years found a link between higher meat consumption and colon cancer risk. Beans, an excellent source of phytates, have been found to help reduce some of that risk, so your meat-to-vegetable ratio may determine your risk of developing colon cancer risk.
Berries can make polyps (a projecting growth of tissue from a surface in the body that may, later, turn into digestive cancer) retreat. After 9 months of daily intake of black raspberry, the number of rectal polyps of 14 patients was reduced by half.
Strawberry also demonstrated its positive effect in reversing cancer. In 80% of patients who consumed powdered strawberries (the equivalent of 450 grams of fresh berries) precancerous lesions of the oesophagus decreased. 50% of patients were disease-free after such a strawberry treatment.
2Say goodbye to harmful drinking and smoking habits
Alcohol consumption and smoking lead to heartburn – a disease in which acid from the stomach gurgles up into the oesophagus, burning the inner layer and causing inflammation that can eventually lead to cancer.
Thus in order to prevent cancer of the digestive system, especially of the oesophagus, these two unhealthy habits should be eliminated. Even a moderate alcohol intake seems to have a detrimental effect on the digestive system. Whereas smoking cessation will not give immediate results as former smokers are at a higher risk of digestive cancers for up to 25 years after quitting when compared to never-smokers. There’s no better time to quit binge drinking or smoking than now.
Based on the study, a low-risk lifestyle, which includes minimization of alcohol consumption and refusal of tobacco smoking, can result in a 50% lower risk of digestive cancers.
3Maintaining a healthy weight
Carrying excess weight, especially in the belly area, has been linked to an increased risk of several types of cancer, including cancer of the oesophagus, pancreas, colon, and rectum. This is thought to be due to the fact that excess fat leads to insulin resistance, chronic inflammation, and abnormal metabolism of sex hormones.
A higher body mass index (BMI) is linked with greater cancer risks and vice versa. For instance, according to cohort studies and meta-analyses, obesity (body mass index of 30 kg/m2 and more) increases the risk of colon cancer by up to 33% compared to anyone with a normal body mass index (18.5 to 24.9 kg/m2).
Thus, maintaining a healthy weight is vital for preventing various diseases including digestive cancer. This can be done through a balanced diet and regular physical activity.
4Pay attention to your iron levels
Overconsumption of meat (especially red) can increase cancer risks because meat includes heme iron that can generate free radicals that cause cancer.
Iron can be taken as a double-edged sword: too little can cause anaemia, and too much – rises cancer risks. This is why we have to be very careful about our iron levels so as not to put ourselves at risk. Blood donation can be a way of maintaining healthy iron levels. Research has shown that people who regularly donate blood to reduce their iron stores cut their risk of getting and dying from new gut cancers by about half.
You may also prevent iron overload by cutting down on meat consumption. Aim for no more than about three servings per week, which is equivalent to around 350-500 grams of cooked red meat. Plus, you may get iron from such plants as whole grains, legumes, nuts, seeds, dried fruits, and green, leafy vegetables. A plant food’s iron is not as effectively absorbed as meat’s heme iron. This can be beneficial in preventing iron overload.
5Eliminate acid reflux disease
Acid reflux or simply heartburn is one of the most common disorders of the digestive tract. Heartburn disease contributes to digestive cancer, especially oesophagal cancer. So in order to prevent cancer, acid reflux must be halted and this can be done by dietary changes. This can be done in two ways:
Reduce meat intake: Over the past 20 years, have investigated the relationship between diet and oesophagal cancer. The most consistently observed link to cancer has been the consumption of meat and high-fat meals.
Consume more plant fibre: Increasing fibre intake can reduce the incidence of oesophageal cancer by up to one-third by preventing acid reflux. Red, orange, and dark-green leafy vegetables, berries, apples, and citrus fruits seem to be the most protective foods for stomach and oesophagus cancers; however, all unprocessed plant foods are beneficial because of the fibre they contain.
6Be physically active
Being engaged in regular physical activity has an especially good effect on the digestive system. Through physical activity, more blood flows to the muscles of the digestive tract, which massage food along the digestive tract, resulting in faster digestion. What is more, regular exercise can drop digestive cancer risks.
The study showed that the risk of colon cancer was 50% lower for men who burned more than 2,500 kcal weekly (equal to approximately 4 hours of intensive training per week) than for those who burned less than 1,000. Other studies revealed that the odds of digestive cancer risks were lower by 20%, depending on the organ affected, in participants who were regularly engaged in physical activities.
Thus, to keep your digestion healthy and help it process food faster it is recommended to aim for at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity physical activity each week, or a combination of both.
7Start having annual check-ups for digestive health at age 50
Digestive cancer is a silent disease that may be asymptomatic for years. It is generally recommended to start seeing your doctor regularly from the age of 50 for checking your digestive system for the presence of some abnormal cell growth. Annual screenings can help doctors find and treat cancer early before it has a chance to spread. By catching cancer early, treatment is more likely to be successful.
How to prevent digestive cancer? Let’s summarise
Cancers of the digestive system are silent killers that may develop for years before being diagnosed. The truth is that we all sentence ourselves to the very conditions by eating too much meat, remaining sedentary, drinking, and smoking. Let’s try to do the opposite and maintain healthy digestion by taking on and practising health-beneficial lifestyle choices discussed in this article. Start as soon as possible and remain resilient to keep digestion healthy and prevent digestive cancers.
Not enough? Here is more from our colleagues
If you want to learn more about digestive cancer, we recommend you read the book ‘How not to die’ by Michael Greger. Not only does it provide insight into preventing and dealing with digestive system diseases and other severe conditions but also offers tips on having a healthy lifestyle that can protect you from premature death. This very article is inspired by this book. It is a must-read for anyone looking to improve their overall health and longevity.
In this video, a registered dietitian examines the relationship between colon cancer and diet and discusses the benefits of a cancer-preventive diet.
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