Can drinking coffee really cause cancer?

Drinking two cups of coffee a day is the work and living habit of many people nowadays. However, some time ago, an article entitled "you can't drink instant coffee, and there are more carcinogens than smoking" has brought a lot of trouble to everyone. I don't know if I want to continue to drink coffee for a while.

This article spread on major websites across the country, saying that the concentration of acrylamide, a carcinogen detected in instant coffee, is higher than that of potato chips, French fries, cakes and cigarettes, and that drinking instant coffee is far more harmful than smoking. "instead of quitting smoking, it's better to quit instant coffee."

The reporter then asked a number of nutrition and food experts for confirmation, and they unanimously recommended the reporter to find Professor Zhang Ying of the School of Food of Zhejiang University.

"in the past 10 years, the media all over the country have always asked me about the carcinogenicity of potato chips. If you ask about the risk of instant coffee, you are the first. " Professor Zhang Ying said bluntly on the phone yesterday that we undertake the national project of "effectively reducing hazards in hot-processed foods", which mainly refers to acrylamide. Last year, we drafted national standards for the content of acrylamide in fried foods such as potato chips and French fries. This year, the main research is to control the reduction of acrylamide in instant coffee.

Zhang Ying told the reporter that she also read the online article on "instant coffee is not drinkable". Some of the data are true, but the analogy and judgment conclusions are biased and wrong.

First of all, instant coffee does contain acrylamide. In 1994, the International Cancer Research Center listed acrylamide as a class 2A carcinogen, that is, it is potentially carcinogenic to human beings, but there is still a lack of epidemiological evidence.

So, where does acrylamide come from in instant coffee? She explained that raw green coffee is free, and when green coffee is roasted at high temperature into coffee beans, it contains about 300 micrograms of acrylamide per kilogram; when instant coffee is extracted from coffee beans, the amount of acrylamide per kilogram is as high as 700 to 1000 micrograms. In general, the acrylamide content of instant coffee is 2 to 3 times that of coffee beans.

"when the heating process of baking and frying exceeds 120 ℃, acrylamide will be produced in the food, and the higher the temperature and the longer the heating time, the more acrylamide will be formed." Therefore, including potato chips, French fries, mugi-cha, fried dishes, whether fried or non-fried, as long as the degree of heating is enough, and even cigarette burning, will produce acrylamide.

The reporter asked, which contains high concentration of acrylamide, instant coffee, potato chips or cigarettes? Zhang Ying replied, "Ten years ago, the content of acrylamide in potato chips was higher than that of instant coffee in the same unit. By improving the production process of potato chips that reduce acrylamide over the years, the contents of the two are now about the same. Relatively speaking, the release of acrylamide from cigarette combustion is the lowest. "

Although both instant coffee and cigarettes contain acrylamide, there is no simple analogy. She said that the former belongs to hot-processed food, while the latter belongs to tobacco products with different properties. If it has to be "compared", then smoking has the greatest risk of causing cancer, which has been confirmed by World Health Organization (WHO) earlier.

Cigarette smoke is known to contain more than 4000 chemicals, of which more than 400 are confirmed to be toxic to humans, and about 60 are carcinogens or synergistic carcinogens. As early as 2009, World Health Organization (WHO) listed cigarettes and arsenic as "high-risk carcinogens with the same lethal power." World Health Organization (WHO) banned not only smoking, but also "other forms of tobacco advertising, promotion and sponsorship". Acrylamide in instant coffee is at best a "potential carcinogen". In addition, most people drink instant coffee more frequently than smoking.

In a word, the argument that drinking instant coffee is more carcinogenic than smoking is not true. "you can drink instant coffee at ease!"

Of course, to say that instant coffee has a low risk of cancer does not advocate unrestrained drinking. Zhang Ying recalled that in April 2005, the then Ministry of Health issued a notice advising people to reduce the intake of foods containing acrylamide, followed by potato fried foods, cereal fried foods, cereal baked foods and other foods. "although the contents of instant coffee, mugi-cha and corn tea rank low, they should not be taken lightly."

"how much instant or freshly ground coffee should you drink every day?" The reporter asked. "this is exactly what we are studying." She said frankly that compared with potato chips, instant noodles and foreign fast food, the formation mechanism and pathway of acrylamide in instant coffee are not yet clear, and it is also a difficult problem in the world of hot processed food.

"whether instant coffee or freshly brewed coffee, the first is the right amount, the daily limit should not exceed 5 bags (cups)." Zhang Ying said that her advice refers to the 2015 edition of the Dietary guidelines for American residents, which states that "there is strong evidence that drinking 3 to 5 cups of coffee a day is a healthy diet." it can even reduce the risk of type 2 diabetes and heart disease. There is also some advice: don't get extra calories from cream, milk and sugar; oppose oversized energy drinks that are popular in supermarkets; and limit pregnant women to two cups of coffee a day. "

"if you drink coffee as water and consume too much caffeine, the brain will change from excitement to inhibition, and people are likely to become depressed." She warned.

Small knowledge points:

Coffee refreshing ≠ instant coffee also refreshing

When coffee was first discovered by indigenous Africans, people found that they were inexplicably excited when they ate coffee. After research, people understand that the reason why drinking coffee will be particularly excited, to achieve a refreshing effect, which is entirely due to the large amount of caffeine contained in coffee. Caffeine has a strong bitter taste and can stimulate the central nervous system, heart and respiratory system, making people forget fatigue and excitement.

However, according to a study in Japan, depending on people's physique, drinking more than five cups of instant coffee a day may not achieve a refreshing effect, because instant coffee has been separated from the original concentration of coffee beans. add other flavors such as cream, syrup, coffee companions, etc., in an instant coffee, the real coffee content is only about 1/4 to 1/3 of the original ground coffee. After the concentration of caffeine is reduced, the refreshing effect of instant coffee is greatly reduced. Just like drinking green tea can relieve fatigue, but the green tea drinks on the market have no effect. Of course, it cannot be denied that some people who are more sensitive to nerves can cheer up even after drinking instant coffee.

Refreshing tea is healthier than coffee.

Chinese people always like to drink tea, which also has a refreshing effect, because tea also contains the same ingredients as coffee-caffeine and polyphenols, but the concentration is different from that of coffee. Why tea is healthier than coffee is because natural coffee contains sugar and fat even without any manual processing. Every 100 grams of coffee beans contain 16 grams of fat and 46.7 grams of sugar, even if you buy fresh coffee beans to grind your own coffee, you will inevitably eat some sugar and fat. Tea, which does not contain any fat or carbohydrates, is a zero-energy drink. Since the refreshing effect is about the same, naturally the tea with lower energy is healthier, and of course, for people who are losing weight, the significance of choosing tea will be more obvious.

May there be no disease and no pain for mankind.