Cancer-meat study based on 'guesses' | Article

HERE we go again: A new study -- much like many old studies -- has come out linking cancer and heart disease to consumption of red meat and processed meat and a lowered risk to consumption of white meat.

The study was published in last week's Archives of Internal Medicine, an archive of the Journal of the American Medical Assn.

Like the other studies, it failed to consider several additional factors that can contribute to chronic disease, including participants' behavior as to alcohol and tobacco use, exercise, weight and access to health care, according to meat organization sources.

It also failed to recognize the role of beef, pork and other red meat in providing essential and under-consumed nutrients, they said.

Poor, unwise tool

The study, conducted by Dr. Rashmi Sinha and colleagues at the National Cancer Institute in Rockville, Md., assessed the association between consumption of red meat and the risk of death -- specifically the risk of death from cancer or heart disease -- in more than 500,000 individuals who were part of the National Institutes of Health Diet & Health Study.

Participants were 50-71 years old at the onset of the study in 1995 and completed food frequency questionnaires as to their consumption of red, white and processed meats, completing the questionnaires three times -- at the beginning of the study, five years later and at the end of the study in 2005. They were asked to recall what they ate during the previous five years.

Point one: Many scientists consider food frequency questionnaires unreliable because they expect people to remember how much of what they ate during a previous period, according to Ceci Snyder, a registered dietician for the National Pork Board.

Indeed, she noted that scientists in a recent article in the Journal of the National Cancer Institute called a food frequency questionnaire "a very poor tool" for assessing diets that "has proven so inaccurate that drawing conclusions about cancer and diet from studies using it is unwise."

Point two: The questionnaire was a 35-page questionnaire that instructed participants to answer every question, estimating as necessary, and stated that "a guess is better than leaving a blank," according to James H. Hodges, executive vice president of the American Meat Institute.

Many participants, racing to complete 35 pages of questions and remember their diets for the previous 10 years, likely "guessed extensively," he said, which is no way for health conclusions and public policy to be made.

Extraordinary diets

Sinha's study found that 47,976 of the men and 23,276 of the women in the study died during the 10 years from 1995 to 2005 and that the one-fifth of those who ate the most red meat and the one-fifth who ate the most processed meat had a higher risk of death and death from cancer and heart disease than the one-fifth who ate the least red and processed meat.

At a midpoint, Sinha said, the higher-risk participants ate 62.5 g (2.2 oz.) of red meat and 22.6 g (0.8 oz.) of processed meat per 1,000 calories, compared with lower-risk participants who ate 9.8 g (0.3 oz.) of red meat and 1.6 g (0.1 oz.) of processed meat per 1,000 calories.

Furthermore, Sinha said the one-fifth of participants who ate the most white meat were at lower risk of chronic disease than the one-fifth who consumed the least white meat.

Point three: According to U.S. government data, the actual daily intake of red meat is 2.7 oz. for men and 1.5 oz. for women on 2,000-calorie diets, Snyder said, while Sinha's study drew its conclusions from participants who consumed 4.8 oz. of red meat per 2,000 calories -- "far in excess of the average American diet."

Bare and fragile

Sinha said the study complements findings of and recommendations by the American Institute for Cancer Research (AICR) and World Cancer Research Fund (WCRF) from their epidemiological study that drew similar links between cancer and consuming red and processed meats (Feedstuffs, Nov. 5, 2007).

Point four: However, the AICR-WCRF report has been largely discredited, Hodges said, citing, in particular, an article by doctors with the U.N. International Agency for Cancer Research, published in the Annals of Oncology last year, stating that a "substantial review" of the AICR-WCRF report demonstrates "no discernable association" between specific dietary practices and the many forms of cancer.

"The AICR-WCRF conclusions were based on "fragile grounds," the article said. "The cupboard is bare."

Point five: Moreover, nutrition specialists told Feedstuffs last year that epidemiological studies themselves always are questionable because they are based on observational evidence that relies on human recall, which is subject to error, if not outright manipulation (Feedstuffs, Feb. 25, 2008).

Point six: The American Council on Science & Health last year listed the AICR-WCRF report as the third "most unfounded health scare of 2007" (Feedstuffs, Jan. 7, 2008).

Nutrition whiplash

In an editorial accompanying Sinha's article, Dr. Barry M. Popkin, a nutrition professor at the University of North Carolina, said "animal-sourced foods" are linked to cancer and cardiovascular disease, but because there are health benefits from eating "some red and white -- but not processed -- meats," recommendations should not be made "for a complete shift" to vegetarian diets.

Rather, he said, there is a need for "a major reduction" in meat consumption, especially in the consumption of processed meat "and other highly processed and salted animal-sourced food."

Point seven: What can be concluded from Sinha's study is that a balanced diet and healthy lifestyle are important in preventing chronic disease, noted Dr. Shalene McNeill, a registered dietitian and executive director for human nutrition research at the National Cattlemen's Beef Assn.

"Avoid smoking, use alcohol responsibly, be physically active, maintain a healthy weight and eat a balanced and nutrient-rich diet of fruits, vegetables, whole grains, low- and non-fat dairy products and lean meats," she said.

Snyder agreed: "The bottom line is that Americans are not eating enough fruits and vegetables, are eating too many calories and not getting enough physical activity for optimal health."

Studies that attempt to connect one food to increased mortality -- "even if the association is weak" -- should be viewed with skepticism, she said.

Consumers should set "this latest study of the week aside," added Hodges, "or they may experience another case of nutrition whiplash."

Additional information: To read studies about meat's role in the diet, go to www.meatsafety.org/ht/d/sp/i/41421/pid/41421. To view a video about processed meat, go to www.youtube.com/meatnewsnetwork.

To read Feedstuffs' reports on diet/health studies, go to www.FeedstuffsFoodLink.com and click on parts 1 and 2 of "Meat-cancer link discussed" and on "Diet-health studies need caution."

Daily Commentary provided by Farm Futures, a sister publication of Feedstuffs