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Diet can be an important key against cancer
Improper nutrition promotes cancer. However, proper nutrition can also suppress cancer cells. But what is the right diet in the fight against cancer?
Barbecue season, the meat sizzles on the grill, sometimes it chars at one point or another. Researchers have been warning about the risk of cancer in charred meat for 15 years, but barbecue lovers don't stop there. It would suffice to simply cut away the black areas.
With meat, it generally appears to be more difficult to influence the behavior of those at risk. In 2015, the International Agency for Research on Cancer, the cancer authority at its highest level, classified processed red meat as proven to be carcinogenic. Salami, sausage, ham made from pork, beef and lamb got into the twilight. They ended up in the same category as cigarettes and asbestos.
The data was not quite as clear for red meat that was not processed into sausage or ham. The cancer agency experts called this "probably carcinogenic". The panel's decision was based on an analysis of more than 800 studies. "There is no doubt that there is a connection between the consumption of processed red meat and certain types of cancer, especially colon, but also prostate and pancreatic cancer," says lead author Bernard Stewart, a cancer researcher at the University of New South Wales in Sydney. This is particularly important for the industrialized nations because a lot of sausage is eaten there. Globally, consuming these products accounts for 34,000 cancer deaths annually.
That's not a lot compared to a million cancer deaths from cigarettes. This is one of the reasons why Stewart immediately adds: “One is the clearly documented connection. The other is which nutritional recommendation you derive from it. I like to eat ham myself and continue to eat it, but I have curbed my consumption somewhat. ”
Unhealthy food is part of the culture
The German Nutrition Society (DGE) sticks to its advice to eat a maximum of 300 to 600 grams of meat per week, although with these amounts the risk of colon cancer would already be measurably increased. Weisswurst and Lyoner are just too popular. And not just them: "Bratwurst and ham have a centuries-old tradition and are part of the culture," explains meat critic Stewart. If you called for a waiver, you would mess with all lovers - and with industry. That's why he takes a gentle encouragement: Less liver sausage, cold cuts and corned beef is more.
Another cancer risk in food has hardly been discussed so far: Heidelberg Nobel laureate Harald zur Hausen recognized years ago that colon and breast cancer in particular are more common in regions where milk products and beef are consumed regularly. However, only if they come from the common breed of European-Asian cattle in this country. Cultures that feed on the descendants of the yak are less likely to suffer from such diseases.
After years of research, Zur Hausen and his team found an explanation: infectious agents in European-Asian cattle are responsible for the cancer accumulation. These pathogens are called "bovine meat and milk factors", or BMMF for short. After decades of silent infection, they apparently lead to chronic inflammation and cancer in some people. The number of all cancer cases due to a BMMF infection can not yet be given in numbers.
So is it best to avoid milk, cheese, butter and goulash? "No way," emphasizes Zur Hausen. Dairy products are an important source of calcium in bone-poor regions. Babies should not be given milk products before the first year of life, but breast milk, recommends zur Hausen. Breastfeeding is likely to protect against early infection.
Another germ from food can also cause cancer: the bacterium Helicobacter pilory can be transmitted through contaminated food and water and causes an estimated 60 percent of all gastric cancer cases. It causes inflammation of the stomach and thus promotes the formation of carcinoma.
After all, infections with Helicobacter are declining, so zur Hausen, "probably because people keep food frozen". The bacterium does not survive the cold. In addition, antibiotics work against the pathogen.
But there are other cancer triggers that are not easy to banish. In 2002, the discovery of the nerve poison acrylamide in biscuits, crispbread and french fries made headlines, especially in Germany: 10,000 deaths a year were caused by it, the horror reports at the time were.
The substance is created when cereals or potatoes are roasted, fried, baked, or heated to more than 120 degrees in another way. In the meantime, potato chips, fries and biscuits from factories contain less acrylamide than before. But "the substance cannot be avoided entirely," says Knut Franke from the German Institute for Food Technology in Quakenbrück. If you prepare fried potatoes or fries yourself, you should only let them turn golden brown and not eat them too often.
Rice has also been warned for three years. At that time, the Berlin Federal Institute for Risk Assessment announced that there was too much arsenic in the grain. Arsenic increases the risk of skin, lung, liver and kidney cancer. Infants and young children should never eat rice-containing foods on a daily basis.
At the end of January 2016, the German Society for Toxicology warned that toddlers in particular eat too much rice, since many baby porridge and crackers are based on rice or rice flour. Young children get an average of between 0.61 and 2.09 micrograms per kilogram of body weight of arsenic per day. But from 0.3 micrograms per kilogram of arsenic daily and lifelong exposure, the cancer risk increases by one percent, the experts warn.
Since then, consumers on rice crackers have been warned that children should not eat more than three to five pieces a day, depending on the size of the snack. "This is serious advice," says Potsdam toxicologist Tanja Schwerdtle, who has been on numerous EU bodies for the assessment of arsenic in the food chain for years. “We demanded ten lower limit values. But then there would be too little marketable rice. "
It is actually quite easy to reduce the risk of cancer with the right nutrition. Because there is food that is proven to work against the development of tumors. A study by the nutritional researcher Heiner Boeing from the German Institute for Nutritional Research in Potsdam-Rehbrücke identified some of these healthy foods. Boeing and his team have interviewed 27,548 men and women over 20 years about their eating habits and compared their diet to the incidence of cancer.
Through this EPIC Potsdam study, which ended in 2014, the researchers determined that the risk of colon cancer increased by 49 percent from just 100 grams of pork, beef or lamb a day. The increase in sausage was 70 percent. Those who ate the same amount of fish every day instead halved the risk. A very simple nutrition tip is: fish instead of bratwurst.
The protective effect of fiber was already proven in the EPIC study in 2003. Just 15 grams a day reduced the risk of colon cancer by 40 percent. Muesli, whole grain bread, lentils and beans can therefore be in the food every day because they are rich in fiber.
"Eating fruit and vegetables also lowers the risk of cancer a little," says Boeing, but warns against exaggerated expectations. Those who eat a lot of fresh food usually also eat less meat. The positive effect could also be due to this displacement effect. This suggests that men who eat a lot of fruit and vegetables are less likely to suffer from cancer of the mouth, throat, larynx or esophagus. But this is not the case with women who eat the same thing.
Fruit does not protect against every cancer
The once heavily advertised recommendation of the German Nutrition Society to eat fruit and vegetables five times a day to prevent cancer has not been confirmed in this clarity. For example, the EPIC study revealed that the frequent consumption of fruits and vegetables has no positive effect on the incidence of ovarian cancer in women.
The relationships are complex. This can be illustrated with the example of breast cancer in women. Alcohol increases the risk very much. Already more than 0.1 liters of wine per day increases the danger. A large amount of animal fats, i.e. a lot of sausage, butter, cheese and margarine, also harm. In addition, if little bread and fruit juices were consumed, the risk of breast cancer doubled over the course of six years compared to women who consumed a lot of bread, who often drank fruit juices but ate little animal fat, according to the EPIC study.
Researching nutritional effects on cancer risk is anything but trivial. Because usually a certain diet goes hand in hand with a certain lifestyle. Many vegetarians pay more attention to their health than omnivores. They exercise regularly and are more likely to see a doctor. It is not really possible to find out exactly what has reduced or increased the risk of cancer in a person through surveys and long-term observations. This would require seamless monitoring in the laboratory - and this, in turn, would only be of limited significance for normal life.
The healthy power of cabbage
But there are also foods with clearly positive effects: The laboratory shows that individual foods can suppress cancer cells. This is particularly well documented for cruciferous vegetables: Broccoli, cauliflower, radish, cabbage and arugula.
The Heidelberg cancer researcher Ingrid Herr was able to prove that it is primarily the sulfur-containing ingredient sulforaphane that directly suppresses the development of cancer cells. Canadian colleagues were able to help prostate cancer patients with three servings of broccoli or cauliflower per week. Her cancer spread less or less than in patients who did not eat cabbage.
Ingrid Herr emphasizes that nobody has to buy expensive broccoli sprout products. It was enough to regularly eat more broccoli, cauliflower, cabbage and arugula.
As intensive as oncologists are researching the bad and good effects of food: there will never be an anti-cancer diet. Because everyone has to find the right balance of healthy eating and fulfilling lifestyle for themselves. Grilling in summer is part of it for many.
Bernard Stewart of the International Cancer Agency therefore gives as a grill tip that meat and sausages should only be exposed to the concentrated heat in the middle of the grate at the beginning. Then they finish cooking healthier on the cooler edge. By the way, grilled meat has a decisive advantage over other foods: hardly anyone eats it all year round. On average, Germans grill twelve times a year - fortunately, the dose that makes the poison is rather low. (fs)