The Case Against Charred Foods

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Editor’s note: This article is a reprint. The first edition was published on February 8, 2017 in his.

In 2002, researchers discovered that when carbohydrate-rich foods are baked, fried, roasted, grilled, or toasted at high temperatures, they contain a carcinogenic and potentially neurotoxic compound called acrylamide. discovered that certain chemical substances are produced.

Acrylamide is a byproduct of a chemical reaction between sugar and the amino acid asparagine that occurs at high temperatures. This chemical can occur in many foods cooked or processed at temperatures above 250 degrees F (120 degrees C), but foods rich in carbohydrates are the most vulnerable.

Generally, acrylamide is formed when plant-based foods are heated sufficiently so that the surface becomes sufficiently dry and “brown” or burnt.1,2 Therefore, it is most easily found in:3

  • potato – chips, fries, and other roasted or fried foods
  • Cereals – Various processed snacks such as bread ears, toast, crispbread, roasted breakfast cereals, crackers and cookies
  • coffee; roasted Coffee beans and ground coffee powder. Surprisingly, chicory-based coffee substitutes actually contain two to three times more acrylamide than real coffee.
  • cacao products

Acrylamide is commonly found in the standard American diet

In November 2013, the U.S. Food and Drug Administration (FDA) issued an update for consumers.Four He advised people to reduce their intake of foods rich in acrylamide, noting that this toxic byproduct is found in 40 percent of the calories consumed by the average American.

To reduce acrylamide in your diet, the agency recommends avoiding fried foods and toasting or cooking foods such as bread and potatoes until they’re a light golden brown rather than dark brown or dark. Also, avoid storing potatoes in the refrigerator, as cooling during cooking actually increases acrylamide levels.Five

This effect is because starch converts to sugar more quickly when potatoes are exposed to lower temperatures. It can also negatively affect the taste of potatoes for the same reason. (Frozen foods, on the other hand, don’t have this risk because their sugars don’t break down at subzero temperatures.)

Store potatoes in a dark, dry closet or pantry. You can further reduce acrylamide formation by soaking potatoes in water for 15 to 30 minutes before cooking.

The FDA doesn’t mention avoiding processed foods in general, including potatoes and grains, which makes sense since many processed foods are processed at high temperatures and therefore may contain acrylamide. That’s true.

Acrylamide is linked to cancer in animals

Animal studies have shown that acrylamide increases the risk of several types of cancer, and the International Agency for Research on Cancer (IARC) considers acrylamide to be a “probable human carcinogen.” . According to a 1988 study:6

“Data show that acrylamide can induce genotoxic, carcinogenic, developmental and reproductive effects in tested organisms. Therefore, acrylamide is more than neurotoxic for exposed humans. It may pose a health hazard.”

Acrylamide is a small organic molecule that is highly water soluble. These properties likely facilitate rapid absorption and distribution throughout the body.

After absorption, acrylamide is rapidly metabolized, mainly by glutathione binding, and most of the applied substance is excreted within 24 hours…Acrylamide can bind to DNA…this is due to its genotoxic and carcinogenic properties. affect the possibility of ”

Human cancer research shows mixed results

For humans, the results look even more complex.the study7 A paper published in 2007 linked increased dietary intake of acrylamide to an increased risk of endometrial and ovarian cancer in postmenopausal women, especially nonsmokers.

2009 survey8 They also found that high intakes of acrylamide were associated with a higher risk of certain types of breast cancer, especially estrogen and progesterone receptor-positive breast cancers, compared to lower intakes. .

However, the association was small and no association was found for overall breast cancer risk or receptor-negative breast cancer. Acrylamide has also been associated with other neurotoxic effects, including nerve damage and neurological problems in workers who work with the substance.

On the other hand, in the 2015 review,9 They concluded that dietary acrylamide was unrelated to cancer risk for most common cancers, with the exception of kidney cancer, for which a “moderate association” was found. It’s being served.

They also noted that among nonsmokers, “dietary acrylamide also appears to slightly increase the risk of endometrial and ovarian cancer.” Still, concerns about acrylamide in the diet seem to be growing, not subsiding.

UK Food Standards Agency (FSA) launches ‘Go for Gold’ campaignTen,11 It aims to reduce dietary exposure to acrylamide, noting that “the scientific consensus is that acrylamide can cause cancer in humans.”

And Dr. George Alekseef, deputy director for science at the Office of Environmental Health Hazard Assessment (OEHHA), which oversees implementation of California’s Proposition 65.

“We believe that acrylamide is a chemical of concern. Our general assumption is that, unless there is some other evidence, if something causes cancer in animals, That means they think it can cause cancer in humans as well.”

Acrylamide levels in food often exceed legal limits for water

The federal limit for acrylamide in drinking water is 0.5 parts per billion (ppb), or about 0.12 micrograms (mcg) in an 8-ounce glass of water. On the other hand, 6 ounces of French fries can contain 60 micrograms of acrylamide.

This is approximately 500 times the permissible limit for drinking water. It seems a little strange that something that is toxic in drinking water suddenly becomes harmless in food.

Unfortunately, while the Environmental Protection Agency (EPA) regulates acrylamide in drinking water and the FDA regulates acrylamide residue levels in materials that may come into contact with food, the chemical in the food itself There are currently no guidelines restricting this. should.

2002 food analysis published in the Journal of Agriculture and Food Chemistry12 Moderate levels (5-50 mcg/kg) of acrylamide are found in cooked protein-rich foods and higher levels (150-4,000 mcg/kg) in carbohydrate-rich foods. it was done.

Undetectable levels (<5 mcg/kg) of acrylamide were found in uncooked and boiled foods, leading the researchers to conclude: "Consumption habits Acrylamide levels in the heated foods of interest indicate that they can lead to daily intakes of tens of micrograms."

Although little is yet known about whether such levels are safe, I vote in favor of taking a precautionary approach and limiting exposure as much as possible. Ingesting known toxins, even in trace amounts, is really not a good idea.

Worst offender: potato chips

Potato chips are by far one of the worst offenders.13 So much so that the state of California filed a lawsuit in 2005.14 A potato chip maker was accused of failing to warn California consumers about the health risks of acrylamide in its products. A 2005 report, “How Potato Chips Stack Up: Levels of Carcinogenic Acrylamide in Popular Brands of Potato Chips,” published by the California-based Environmental Law Foundation (ELF), found that this popular snack The risks are detailed.

According to their analysis, all potato chip products tested exceeded the legal limit for acrylamide by at least 39 times and up to 910 times. Interestingly, FDA data reveals that baked chips, which are often promoted as healthier chips, can contain levels of acrylamide more than three times higher than regular chips. I am.15

In 2008, a settlement was reached between the state of California and the potato chip manufacturer.16 When Frito-Lay and several other companies agreed to reduce acrylamide levels in chips to 275 parts per billion by 2011, low enough to not require Prop. 65 cancer warning labels.

How to make safer potato dishes

French fries are one of the most popular potato dishes, but they’re probably one of the worst ways to eat potatoes. Not only do you have to fight acrylamide, but unless you fry them in coconut oil or lard, you’re also ingesting lots of harmful vegetable oils. However, that doesn’t mean you need to avoid potatoes completely. When stored and cooked correctly, potatoes can be a healthy addition to your diet.

The key is to cook the potatoes in a way that increases their resistant starch. (As mentioned above, store potatoes in a cool, dry place, such as the pantry, not the refrigerator. Storing potatoes in the refrigerator produces large amounts of acrylamide during cooking.)

Digestion-resistant starch — found in unripe fruits such as banana,papaya, mangowhite beans, lentils, seeds, tapioca starch, brown rice flour, cold cooked potatoes, and even cold cooked pasta.17 — Fiber resists digestion in the small intestine, ferments slowly in the large intestine, and acts as a prebiotic that feeds healthy bacteria.18,19

Importantly, resistant starch is not digested and therefore does not cause a spike in blood sugar levels. In fact, research suggests that resistant starch can help improve insulin regulation and reduce the risk of insulin resistance.20,twenty one,twenty two,twenty three Resistant starch may also promote weight loss and is associated with a lower risk of colorectal cancer.twenty four

One of the most obvious dishes that comes to mind here is potato salad.twenty five,26 However, bean salads, pasta salads, and quinoa salads also contain resistant starch. The total amount of resistant starch in the final dish depends on many factors, including the amount of resistant starch in the raw food and the cooking method.

For example, roasted and cooled potatoes contain 19 grams of resistant starch per 100 grams, while steamed and cooled potatoes have 6 grams and boiled and cooled potatoes have only 0.8 grams. Contains only27,28

You can also use sweet potatoes, but regular potatoes are naturally high in resistant starch and produce more retrograde starch (resistant starch that is formed when potatoes are cooled after cooking). Masu. Cooked, cooled, and reheated potatoes contain 1.07 grams of resistant starch per 100 grams. Warm potatoes (not chilled) contain just under 0.6 grams, while sweet potatoes contain just 0.08 grams of resistant starch.29

One root vegetable that has the best of both worlds is the yam. Overall nutritious,30 When cooked and cooled, they produce more retrograde starch than sweet potatoes or regular potatoes.31 has an easy recipe for yam salad.32 To reduce net carbs, I omit the sweet relish. We also recommend replacing vegetable oil with avocado oil.

To learn how to properly roast potatoes and enjoy their benefits, read my article titled “.How to bake potatoes. ”

How to minimize exposure to acrylamide

Acrylamide is so far only found in foods heated above 250 degrees Celsius/120 degrees Celsius, which includes most processed foods. Eating a diet based on whole foods is one of the best ways to avoid this carcinogenic byproduct. When preparing meals, keep these tips in mind.

  • Frying, baking, and broiling seem to have the worst risks, while boiling and steaming seem to be safer.
  • Longer cooking times increase acrylamide, so the shorter the cooking time, the better.
  • Be careful not to overcook food, as the darker or blacker the food, the more acrylamide it contains.
  • Acrylamide is primarily found in plant-based, carbohydrate-rich foods such as potatoes and grain products (and is typically absent from meat, dairy products, and seafood).

If you would like to learn more about acrylamide, we recommend reading the online report Thermogenic Food Toxicity: Identification, Characterization, and Risk Minimization.33

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