Does acrylamide in coffee really cause cancer? What other foods besides coffee also contain?

(screenshots are available on the The Guardian news website)

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The news about whether coffee causes cancer has caused a lot of discussion recently: "A court in California recently ruled that it is necessary to clearly label carcinogenic warnings on coffee products in the future against the sale of acrylamide coffee, which is a carcinogen."

Why did California rule in this way?

The Office of Environmental Health hazards (Environmental Health Hazard Assessment, OEHHA) of the California Environmental Protection Agency (Cal/EPA) identified acrylamide as a carcinogen in 1990.

A court in California ruled that because the coffee industry failed to prove that acrylamide in coffee was not significantly risky, the product must be warned that it contained acrylamide to warn consumers.

What is acrylamide (Acrylamide)?

At high temperature, the amino acids in the food react with reducing sugars by Mena reaction, giving the food a special flavor and color, but this reaction will also promote the formation of acrylamide, especially under the heating conditions of more than 120℃, the food contains "asparagine (asparagine)" and "reducing sugars" (glucose, fructose, lactose. Will form "acrylamide", which is more common in high-temperature fried or baked starchy foods.

(photo source: acrylamide lazybones arranged by the National Environmental Toxicology Research Center)

Do you know? In fact, there are too many foods in daily life that contain acrylamide!

More than 7000 kinds of food contain acrylamide, which is common in starchy foods fried or barbecued. Generally speaking, products such as potato chips, black sugar, almonds, Youtiao and French fries have higher levels of acrylamide when heated. According to the National Environmental Toxicology Research Center of the National Institutes of Health, the content of acrylamide is as follows:

Potato chips (1146 ±307 ppb), brown sugar (847 ±454 ppb), almond fruit (606 ±451 ppb), potato cake (554 ±138 ppb), Youtiao (307 ±82 ppb), French fries (284 ±78 ppb).

Does acrylamide really cause cancer?

At present, the International Agency for Research on Cancer (International Agency forResearch on Cancer, IARC) of the World Health Organization (WHO) classified acrylamide as 2A-a carcinogen that may cause cancer in humans in 1994, which means that the substance has been shown to be carcinogenic to experimental animals, but there is no sufficient evidence to increase the risk of cancer in humans.

At present, in the world, with the exception of California in the United States, other countries only remind the public and operators to pay attention to their intake, and there is no relevant limit standard, and Taiwan only adopts the recommended value and does not require additional warning measures. The biggest reason is that there are too many kinds of food, and the content of acrylamide will vary with the process conditions such as different food composition, heating temperature and time.

You can still drink coffee, but don't overdo it.

In the process of roasting and preparation of coffee, trace acrylamide will be produced due to chemical changes. In 2012, the Food and Drug Administration issued the "processing reference Manual for reducing the content of acrylamide in Foods", in which there are recommendations on limits for roasted coffee and instant coffee, respectively. Roasted coffee is 450ppb and instant coffee is 900ppb.

According to the human experimental study of the National Environmental Toxicology Research Center of the National Institutes of Health, after ingesting 0.94 mg of acrylamide, about 60% of the urine excreted within 72 hours can be absorbed and metabolized by the human body and excreted by urine in the form of acrylamide, metabolites of acrylamide and epoxy derivatives. The half-lives of these substances range from 2 to 26 hours.

Generally brewed coffee has a water content of more than 95%, so the content of acrylamide is so low that normal and healthy people can metabolize it. So you can still drink coffee, just be careful not to eat too much. The Department of Health recommends that the daily caffeine intake per person should not exceed 300 mg, which is equivalent to drinking 1 to 3 cups of caffeine a day.

In 2006, the Taiwan Consumer Insurance Association launched a "caffeine grading system for hand-made drinks," including espresso or other types, to remind consumers of the caffeine content of each cup of coffee according to the color differences of red, yellow and green. Among them, red is 200-300 mg or more, yellow is 100-200 mg, green is less than 100 mg.

Will it be okay if you eat it? How toxic is acrylamide?

As early as 1996, a research team used mice to prove that acrylamide and DNA molecules produce a Michael addition chemical reaction (Michael-type reactivity) with related proteins, which causes DNA mutation in mouse spermatozoa. Some scientists speculate that intracellular Pmur450 enzyme will cause acrylamide to produce a highly active epoxy structure (epoxide), which may destroy DNA or protein, leading to mutation. However, if a high dose of acrylamide is given to rats, it will cause neurotoxicity such as drowsiness and motor dyskinesia. after dissection, it is found that the peripheral ganglia of rats are damaged. Even the International Agency for Research on Cancer (IARC) of the World Health Organization lists acrylamide as a "2A carcinogen". It's horrible! However, acrylamide has been eaten since humans could barbecue meat and roast sweet potatoes. If this thing is really so poisonous, why haven't humans become extinct?.

First of all, let's figure out what "2A" is. 2A is defined as "there is no epidemiological evidence of carcinogenicity in humans, but only in animal experiments." after the cow shaking incident in Sweden, Nordic scientists have launched a number of epidemiological projects with high interest (or adequate funding) to study whether there is a correlation between human disease and acrylamide intake. A joint report by Sweden and the United States in 2003 tracked nearly 1,000 patients with colorectal, bladder and kidney cancer and concluded that acrylamide was not associated with the occurrence of the three cancers. Then, in 2005, Sweden, Norway and the United States published a study on breast cancer, which also concluded that there was no link between the two.

So why is there a difference between animal experiments and human epidemiology? First of all, the metabolic pathway, rodent animal experiments can not fully represent human metabolism, also in 2005, the Journal of toxic Science (Toxicological Sciences) published a paper, the research team recruited a group of human brave, using a variety of ways to ingest acrylamide, and finally found that humans and mice have slightly different metabolic pathways, and therefore the same substance into different animals. There may be a far cry from the results. Another possibility is that the animal environment in the laboratory is strictly restricted, while in the real human society, we have a variety of foods and colorful lives, and the differences in the living environment of the two have different results. There have been a lot of food and security troubles in Taiwan in recent years. I believe everyone has already developed the concept of risk-sharing, right? Therefore, if you are not addicted to certain kinds of food for a long time, you don't seem to have to worry too much.

In addition to coffee, acrylamide is also found in many foods in daily life, so a balanced diet and regular exercise to keep the body functioning normally is the fundamental way to be healthy! (extended Reading: what can I drink before exercise? In addition to boiled water, you have other options)