TKF Science Writing

In a new study published in the Archives of Internal Medicine, scientists have hypothesized that increasing red meat intake leads to higher overall mortality.

The study included people aged 50-71 and were recruited from 6 states (California, Florida, New Jersey, North Carolina, and Pennsylvania).  Atlanta and Detroit were the two main metro areas studied from the above list.  For baseline purposes, the participants were asked to fill out a questionairre outlining the foods they normally ate over the last year. 

Sources of red meat included bacon, beef, cold cuts, ham, hamburger, hotdogs, liver, pork, sausage, steak, and meats in foods such as pizza, chili, lasagna, and stew.  White meat included chicken, fish, turkey, poultry cold cuts, canned tuna, as well as low fat sausages and hot dogs.  The scientists did point out that there was some overlap in the food items as there is red meat in some of the low fat options.  Their statistical models accounted for this fact as the data was analyzed.

High, medium, and low risk type diets were created based on the results of the questionairre.  Over 600,000 respondents returned the questionairre form and after excluding people for various reasons (moved away, incomplete forms, very high or very low intake of red meat), the scientists came back with almost 550,000 samples with a 60/40 ratio of men to women respectively.  The researchers found that the higher the intake of red meat, mortality rates would increase modestly.  Conversely, with a higher white meat diet, there was a small decrease in total mortality.

There were some interesting correlations that the scientists also found.  For example, they found a positive association between smokers, or former smokers, and the intake of processed meats, as it relates to cancer.  They hypothesized that it could be due to the N-nitroso compounds and carcinogens found in cigarettes. 

The N-Nitroso compounds, as you may have guessed, are derived from nitrogen and are found in bacon, fermented sausage, hot dogs, bologna, salami, corned beef, ham, and other smoked or cured meat, fish, and poultry.  They are formed from nitrogen compounds (amines and amides) as bacteria break off the acid portion of amino acid compounds.  In chemistry terms, this is known as decarboxylation.

Prior studies have shown that cooked red meat intake can create chemicals that are not present in raw meat.  These chemicals are carcinogens.  This is due to the presence of heterocyclic amines and polycyclic aromatic hydrocarbons.  Easy enough to understand right?   

Heterocyclic amines (HCAs) are found in muscle meats such as beef, pork, fowl, and fish.  These compounds are formed at high temperatures as amino acids react with creatine, a chemical found in animal muscle tissue.  Four factors come into play when dealing with heterocyclic amines; type of food, cooking method, temperature, and time.  Of the four, temperature is the most important factor.  When cooking meats, the highest temperatures occur when we barbecue on a grill, broil in the oven, or fry in oil.  Oven roasting and baking are done at lower temperatures so the formation of HCA’s is less  Cooking meats low and slow and as a friend told me, with its best days before it (instead of well done), may be the best bet for someone who is concerned about HCA formation.  Also, take it easy on the drippings on the bottom of the pan as that gravy contains substantial amounts of HCA’s as well.  

Polycyclic aromatic hydrocarbons (PAH’s) are found on the surface of meat after cooking it at high temperatures.  They are also present due to incomplete burning of coal, oil and gas, garbage, or other organic substances like tobacco.  These compounds are more prevalent when grilling whereas the heterocyclic amines usually form when pan fried.