Is Grilled Food Bad for You?

  • By Ari Daniel
  • Posted 08.08.18
  • NOVA

Summer holidays are rarely complete without eating grilled meat and vegetables. Explore the science of grilling including the difference between caramelization and the Maillard Reaction and how it could affect your health. While no direct link between grilling and cancer in humans has been shown, some compounds produced during grilling are dangerous to some rats and mice.

Running Time: 04:21


Is Grilled Food Bad for You?

Published: August 8, 2018

Onscreen: Time to fire up the grill!

Scott Jones: The steak. And we’ll throw an ear of corn on there too.

Onscreen: But is it safe?

Jones: Now that we have some room, a pork chop and a burger.

Onscreen: What happens to food on a grill?

Jones: There are two main reactions that take place during grilling.

Onscreen: The first is caramelization, which makes food sweeter and darker. Vegetables may not taste sweet but they’re mostly carbohydrate, which is sugar. Meat is mostly protein but contains a little sugar that once powered the muscle.

Jones: It’s just as if you took sugar in a pot and cooked it down and made caramel, those same reactions are taking place in food, where the sugars are developing and getting darker, and developing other flavors that we associate with caramel.

Onscreen: The second thing that happens is called the Maillard Reaction. Named after this guy. Louis-Camille Maillard.

Jones: Where sugars and proteins interact with each other. That begins a series of hundreds of reactions that create hundreds of different products and all of those are different flavor compounds. And those flavor compounds break down into hundreds of other flavors that you want to eat.

Roasting coffee beans, roasting chocolate, baking bread, when you fry French fries and they get brown on the outside, all of these are the Maillard reaction interactions between sugars and proteins.

Onscreen: The Maillard reaction demands a lot of energy. So it relies on a blast of sustained heat.

Jones: If I boiled a piece of meat, that temperature isn’t high enough to cause these reactions to take place.

Onscreen: But a grill jacks the temperature to at least 300˚ F to make the Maillard reaction possible.

Vegetables and meats behave differently on a grill.

Jones: Anything that you grill, all things go through the same reactions, it’s just in different amounts. It depends on how much sugar you have and how much protein you have.

Onscreen: Vegetables have more sugar than protein, so they experience more caramelization. Whereas meats are more protein than sugar, so they undergo more of the Maillard reaction.

Jones: The other flavors are coming from the smoke, from the flare, from the fat dripping down and hitting the grill. The flip side of that, all these things that I’ve said that you want for the flavor of grilling is where some of the compounds come from that some people will tell you are carcinogenic.

Onscreen: Here’s one of those people.

Colleen Doyle: We have seen animal studies that suggest cooking meats at these high temperatures, when you grill them, increase the risk of pancreatic cancer, colorectal cancer, breast cancer, stomach cancer potentially.

Onscreen: Doyle says no direct link between grilling and cancer in humans has been shown.

Doyle: We still need more research in humans on this.

Onscreen: But we do know which compounds are dangerous to some rats and mice.

Jones: If I cooked this pork chop too far, black on the outside, totally cooked on the inside. Some of the end results of the Maillard reaction, or if it goes for too long, is these heterocyclic amines. And those are thought to cause cancer. So people suggest don’t cook your meats too far.

Onscreen: Same thing goes for vegetables.

Jones: If you really charred your onion black, which is my favorite way to grill onions, you're still getting carcinogenic compounds.

Onscreen: And then there’s meat fat.

Doyle: Fat, when it burns at high temperatures, also produces some compounds that again in animal studies look to be carcinogenic. Those are called polycyclic aromatic hydrocarbons.

Jones: They’re multi-ringed carbons, they’re one of the earliest forms of carbon in the universe and are thought to be one of the building blocks for the earliest forms of life.

Onscreen: The American Cancer Society has a few ways to reduce your exposure to these possibly dangerous compounds.

Doyle: Number one. Precook some of that meat in your kitchen ahead of time so that the meat isn’t on the grill at that super high temperature for as long a period of time.

Cleaning your grill off before you put another hamburger or another steak on there. A lot of that charred compound might have some of these potential carcinogens.

Trimming excess fat off your meat.

Onscreen: But Chef Scott Jones is willing to take the risk.

Jones: If you are trying to avoid the health risks of grilling, it's not the grill that's going to hurt you. It's the meat. And so if you're really trying to eat healthier, eat less meat.

But it’s the season for grilling. And I think we all have to we make choices in this life and grilled meat is delicious.



Digital Producer
Ari Daniel
Production Assistance
Fatima Husain & Aparna Nathan
Editorial Review
Julia Cort
© WGBH Educational Foundation 2018


NASA's Goddard Space Flight Center/CI Lab


(main image: food plate)
© WGBH Educational Foundation 2018

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