01 09 10 Tweet Dietitians Eat Chocolate Too: Grillin' and Chillin'

Thursday, April 10, 2008

Grillin' and Chillin'

For many of us, there's nothing better than a juicy steak, chicken or fresh fish cooked out over the grill. Smoke wafting up, that nice crust forming on the outside.

Hold that thought. Go back to the the "nice crust." It looks good, and tastes good, but is it good for you?

For more than a decade, scientists have been researching the link between mutagens that can be formed in charred meats and cancer--this includes colon cancer, lung cancer and even breast cancer.

We all worry about making sure our meat is adequately cooked in order to avoid bacterial infection (E. Coli....Salmonella...etc.). However, some research is pointing right to our favorite backyard past time, apparently, cooking meat -beef, poultry and fish- at high temperatures for long periods of time can also be dangerous to your health? A growing number of studies suggest a relationship between methods of cooking meat and various cancers. But how affecting us?

Recent studies have further evaluated the relationship associated with methods of cooking meat and the development of specific types of cancer. One study conducted by researchers from NCI's Division of Cancer Epidemiology and Genetics found a link between individuals with stomach cancer and the consumption of cooked meats. The researchers assessed the diets and cooking habits of 176 people diagnosed with stomach cancer and 503 people without cancer.

The researchers found that those who ate their beef medium-well or well-done had more than three times the risk of stomach cancer than those who ate their beef rare or medium-rare. They also found that people who ate beef four or more times a week had more than twice the risk of stomach cancer than those consuming beef less frequently. Additional studies have shown that an increased risk of developing colorectal, pancreatic, and breast cancer is associated with high intakes of well-done, fried, or barbecued meats.

What’s causing the problem?

Heterocyclic Amines and PhIP are by products that are found in “muscle” meats that are cooked at high temperatures for specific periods of time (e.g. a hamburger, well done, grilled chicken, etc). PhIP (other wise known as 2-AMINO-1-METHYL-6-PHENYLIMIDAZO [4,5-b] PYRIDINE)
Some of these chemicals are not present in raw meats and may increase cancer risk. HAs are created when amino acids (the “building blocks” of proteins) and creatine (a chemical that is found in muscles, man and beast, alike) react at a high temperature. There are currently 17 different HAs that come from cooking muscle meats that may pose human cancer risk.

Over twenty years ago, HAs were found to be potent mutagens (about 80% of mutagens can cause cancer in laboratory animal studies). When HAs are isolated from muscle meats and fed and very high levels to rats and other animal models, they can cause cancer in several tissues or organs. This is what caused concern.

Am I at risk because I ate hamburger on the grill?

Probably not. Studies only show this in animals in a laboratory setting.

However, it is important to note that it may lead to cancer; consumers can decrease their exposure to PhIP and HAs in food through selection of cooking techniques and temperatures. Second, some dietary components can inhibit the formation of PhIP and HAs. The amounts of the different HAs in food vary with the type of food and the method of cooking. In general, broiling and frying produce high levels of HAs and steaming, boiling and stewing of meats produce little or no formation of HAs . Specifically, it is the burning of meat juices that generates these compounds. Most fast-food hamburgers do not have high amounts of HAs. Third, scientists have estimated that Americans have about a one in 10,000 or a 0.01% chance of getting cancer from exposure to HAs in foods over a lifetime. This risk is lower than the probability of getting any form of cancer.

What has the least amount of HAs on the grill?

Grilled vegetables, veggie/soy burgers, and meat substitutes are going to have the fewest HAs since they are not “muscle” meats and do not contain creatine which is present in meat. That isn’t to say that they don’t have any HAs. Also, just remember it’s really the “burnt juices” that come off the meat that are the greatest cause for concern.

How often can I grill, fry, or broil?

There are no set guidelines for how often you can fire up the grill, so it is best in moderation until guidelines are officially set up. Also consider other options such as baking or poaching. If you have to grill frequently, consider partially cooking food in the microwave then finishing on the grill. This still gives the meat some of the visual grill marks and a good crust without the excessive exposure of long term cooking at a high temperature.

Are there certain levels that are “safe”?

The content of heterocyclic amines vary greatly with cooking conditions, it is difficult to obtain an accurate estimate of the exposure. Plus different cuts and types of meats are going to have varying portions. There is no way to guarantee that organic or free range meat is better in terms of HA production.

What is it doing in my body?

In humans, the major part of PhIP and HAs are excreted in urine within 24–48 hours following a meal. A few percent is excreted as parent compounds, whereas the major part is metabolites. Urinary level of parent HA reflects only recent exposure. However, the pattern of excreted metabolites might indicate the capacity to activate or detoxify HAs.

How to avoid PhIP and HAs

There is no accurate estimate of the risk to humans from heterocyclic amines and PhIP in our diets but it is no doubt very low for most people. Nevertheless, consumers can control and minimize exposure to HAs—and potential risks associated with them:

Avoid overcooking poultry and beef when grilling, broiling, and pan-frying.
Choose moderate temperatures when cooking.
Microwave meats to partially cook them before you “finish grilling” and discarding the liquid after microwaving.
Eat a variety of foods in moderate portions.
Fiber may bind HAs and PhIP. One study showed that fiber can bind HAs and PhIP in the intestine.
Grilled vegetables, soy or veggie burgers, and portabella mushrooms have the lowest levels of PhIP since they are non-meat sources.