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Eating cured meats frequently can lead to lower lung function and potential COPD

Frequent consumption of cured meats results in lower lung function test scores and increases the odds of developing chronic obstructive pulmonary disease (COPD), according to a large cross-sectional survey of adults in the U.S.

The study results appear in the second issue for April 2007 of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.

Rui Jiang, M.D., Dr.P.H., of Columbia University Medical Center in New York, and three associates showed that the "odds ratio" for developing COPD among individuals who consumed cured meat products 14 times or more per month was 1.93, as compared with those who did not consume cured meats. An odds ratio greater than 1 implies that the event is more likely to occur within that group.

"Cured meats, such as bacon, sausage, luncheon meats and cured hams, are high in nitrites, which are added to meat products as a preservative, an anti-microbial agent, and a color fixative," said Dr. Jiang. "Nitrates generate reactive nitrogen species that may cause damage to the lungs, producing structural changes resembling emphysema."

Although certain rodent studies suggest that inhalation of nitrogen dioxide may contribute to emphysema, no other human studies to date have examined the relationship between consumption of cured meats and COPD, which is the fourth leading cause of death in the U.S.

In 2004, more than 11 million U.S. adults were estimated to suffer from COPD, which results from chronic bronchitis and emphysema, two inflammatory lung diseases that frequently co-exist and interfere with breathing.

The study cohort consisted of 7,352 individuals who participated in the Third National Health and Nutrition Examination Survey, conducted from 1988 to 1994 by the National Center for Health Statistics. The average age of participants was 64.5 years, and 48 percent were male.

"Individuals who consumed cured meats frequently were more likely to be male, of lower socioeconomic status, to be tobacco users, and were less likely to report physician-diagnosed asthma than individuals who never consumed cured meats," said Dr. Jiang. "Those who consumed cured meats more frequently had lower intakes of vitamin C, beta-carotene, fish, fruits, vegetables, and vitamin or mineral supplements. They also had higher intakes of vitamin E and total energy."

The hazard ratio from cured meats associated with lower lung function test results and increased odds for COPD did not change after researchers made adjustments for multiple dietary and other risk factors.

"Adjustment for these factors in our analyses did not appreciably change our findings, suggesting that the observed association between cured meats and lung function was unlikely to be explained by potential dietary confounding factors reported in previous studies," said Dr. Jiang.

The researchers noted that high dietary nitrite intake warrants further evaluation in prospective longitudinal studies as a novel risk factor for COPD.

Breastfeeding reduces risk of breast cancer for women who delay childbirth

Study presented at AACR meeting suggests that breastfeeding has protective benefit for both receptor positive and negative tumors

Breastfeeding can offset the increased risk of invasive breast cancer for women who had their first full-term pregnancy after the age of 25, a study led by researchers at the University of Southern California (USC) suggests.

The findings of the study were presented at a news conference on Monday, April 16 at the 2007 annual meeting of the American Association for Cancer Research held in Los Angeles.

"Breastfeeding may have a protective effect that negates the increased risk of breast cancer associated with late pregnancies," says Giske Ursin, M.D., Ph.D, associate professor of preventive medicine at the Keck School of Medicine of the University of Southern California. "As more women may choose to delay pregnancy until after 25, it is important to note that breastfeeding provides protection against both estrogen and progesterone receptor positive and negative tumors."

While having a first full-term pregnancy before the age of 25 and having many children protect against the type of breast cancers that express estrogen and progesterone receptors, these factors do not protect against the rarer tumors that do not have these receptors. Breastfeeding, however, appears to protect against both types of breast tumors, Ursin says.

Researchers analyzed data for women aged 55 and older—including 995 invasive breast cancer patients–who participated in the Women's Contraceptive and Reproductive Experiences (CARE) Study. The women varied by their age at first birth, their breastfeeding history and hormone receptor status.

Previous results from the Women's CARE Study have shown that early age at first pregnancy (younger than 25) and having many children (defined as four or more) are associated with a lower risk of breast cancer, Ursin says. Researchers sought to gain a better understanding of the associations between reproductive factors and breast cancer risk in women with a late age at first birth, she says.

Breastfeeding appears to have a protective effect regardless of when women started giving birth, Ursin says. This is important since having many children was only protective among women who gave birth early, she says. Giving birth after age 25—the average age that women in the U.S. first give birth, according to Census data—was associated with increased risk of hormone receptor negative breast cancer.

"Evidence suggests that women who have children after age 25 can reduce their risk of breast cancer by choosing to breastfeed," Ursin says.

While mellowing with age has often been thought to have positive effects, a Purdue University researcher has shown that doing so could also help you live longer.
Dan Mroczek (pronounced Mro-ZAK), an associate professor of child development and family studies at Purdue University, compared neurotic and non-neurotic men over time and tied change in the trait with mortality.

"We found that neurotic men whose levels dropped over time had a better chance at living longer," Mroczek said. "They seemed to recover from any damage high levels of the trait may have caused. On the flip side, neurotic men whose neuroticism increased over time died much sooner than their peers."

A neurotic personality was defined as a person with the tendency to worry, feel excessive amounts of anxiety or depression and to react to stressful life events more negatively than people with low levels of the trait. Neuroticism levels were measured using a standardized personality test.

Results of the study will be published in the print edition of the journal Psychological Science in late May. The study is available online at http://www.psychologicalscience.org.

In the study, researchers tracked the change in neuroticism levels of 1,663 aging men over a 12-year period. Using the data gathered in the first analysis, researchers calculated the men's mortality risk over an 18-year period using the average levels and rates of change.

By the end of the study, half of those men classified as highly neurotic with increasing levels of neuroticism had died while those whose levels decreased or were classified as less neurotic had between a 75 percent and 85 percent survival rate.

Even small increases in neuroticism were shown to have negative effects. Participants with as little as a one-unit increase in neuroticism over the course of the study were shown to have a 40 percent higher chance of death than a participant who showed no change.

Data was taken from the Veterans Affairs Normative Aging Study, a longitudinal investigation of aging in men founded at the Boston Veterans Affairs Outpatient Clinic in 1963. In 1988, the beginning of this study, the men ranged in age from 43 to 91.

Mroczek and Avron Spiro, an associate professor of epidemiology at Boston University's School of Public Health, also controlled the data for age, depression levels and both subjective and objective ratings of overall health.

"We found that neuroticism levels are a clear indicator of how long one can expect to live," Mroczek said. "The link between mortality and the rate of change in neuroticism is similar to the way we think about change in high blood pressure and risk of heart attack. If you have high blood pressure but make sure to lower it, you are likely to reduce your heart attack risk."

While those who were very neurotic and grew worse over time had a higher death rate, those who were the least neurotic and improved over time did not die at a significantly lower rate.

Mroczek said the anomaly could be traced to how these types of attitudes affect personal choices.

"It's possible that the key with neuroticism is having just the right amount," Mroczek said. "If you are too laid back, you may not be taking your health seriously enough. These folks might be engaging in more risky behaviors like smoking or drinking to excess because they don't believe anything bad will happen to them."

Mroczek, a member of Purdue's Center on Aging and the Life Course, said he sees a future in which doctors and other health practitioners include some form of personality assessments with routine medical screenings. Learning to deal with some of the potentially negative aspects of human personalities in a positive way could become part of a balanced and healthy lifestyle.

"For example, very neurotic people can work toward dealing better with stress," he said. "They can seek therapy, take up yoga, schedule daily walks to help themselves unwind, listen to calming music or even meditate."

While participants in the study were male and more than 90 percent Caucasian, Mroczek said there is little reason to believe that results for women or other ethnicities would show vastly different results.

"You can find the full range of personalities in any ethnic or gender group," Mroczek said. "There are those who are laid back and then there are those who worry, who react very poorly to stress, who are always on edge."

Mroczek will begin testing later this year to determine why higher levels of neuroticism increase mortality. He plans a study which tests cortisol levels in neurotic men to determine if they have higher levels of the damaging stress hormone that could contribute to early death. Other possible contributing factors might include unhealthy coping techniques, such as overeating or drinking to excess.

The first phase of a caloric restriction study in human subjects at the Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts University found evidence suggesting that calorie-restricted diets differing substantially in glycemic load can result in comparable long-term weight loss. The study, part of the multi-center Comprehensive Assessment of Long-term Effects of Restricting Intake of Energy (CALERIE) trial, funded by the National Institute on Aging, accounted for dietary factors that affect hunger and satiety, used laboratory techniques to measure adherence, and was the first of its kind to provide a complete set of meals and snacks to its participants. Recruitment is currently underway for participation in the second phase of the CALERIE study at Tufts, which will examine the relationship between calorie-restricted diets, aging, and age-related disease.

"Participants in our pilot study achieved and maintained comparable weight loss after one year, regardless of whether they were on a low-glycemic-load or a high-glycemic-load diet," says corresponding author Susan Roberts, PhD, director of the USDA HNRCA's Energy Metabolism Laboratory. "The goal was for both groups to restrict calories by 30 percent and, after one year, both groups had lost an average of 8 percent of their original body weight. We found that the two groups did not differ significantly in their average body fat loss, energy intake, metabolic rate, or reports of hunger and satiety."

The two study diets were carefully matched for factors known to influence food intake during weight-loss efforts, such as palatability, dietary variety, and fiber. "Because there was careful attention to factors that influence hunger and satiety, participants were generally satisfied on a calorie-restricted diet," says Roberts, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts.

Thirty-four overweight but otherwise healthy men and women were assigned randomly to a low-glycemic-load (LG) or high-glycemic-load (HG) diet. At six months, the LG group had lost an average of 10.4 percent body weight, while the HG group had lost an average of 9 percent body weight. By 12 months, participants in both the LG and HG groups had lost an average of 8 percent of their starting body weight.

"Unlike several other long-term studies, which have reported greater weight loss with low GL diets at six months but no differences by 12 months, our data show no significant short-term or long-term differences," notes Sai Das, PhD, scientist at the USDA HNRCA and first author of the study. "However, we did detect a greater tendency for weight and body-fat regain among LG participants. This finding suggests that reduced calorie intake may be harder to sustain on LG diets over time."

The LG diet contained 40 percent carbohydrate, 30 percent fat, and 30 percent protein; while the HG diet contained 60 percent carbohydrate, 20 percent fat, and 20 percent protein. A food's glycemic load is a relative measure of how much carbohydrate is in the food and how quickly that food is converted in the body to blood sugar. Examples of foods provided as part of the LG diet include bean and barley stew, low-fat cottage cheese, and pumpernickel bread. The HG diet included foods like bagels, candied sweet potatoes and shepherd's pie with mashed potatoes.

Both diets were designed to restrict calories by 30 percent, relative to a person's baseline energy requirements, while providing the recommended amounts of vitamins, minerals, and essential fatty acids. All participants attended weekly behavioral support groups and met individually with a dietitian.

To measure objectively actual dietary intakes, the researchers used a laboratory technique involving doubly labeled water. They determined that both groups ate more calories than study foods provided; at six months the HG group averaged a 16 percent calorie-restricted diet and the LG group averaged a 17 percent calorie-restricted diet. Although participants did consume additional calories, the degree of non-adherence was not significantly different between the LG and HG groups when measured at various points throughout the study.

"An important difference between our study and other weight-loss trials is that we did not rely on self-reported intakes," says Das, who is also an assistant professor at the Friedman School. "Underreporting of caloric intake can vary between 5 and 50 percent. By providing the study food for the first six months, we did not have to worry as much about lifestyle factors like shopping and cooking habits interfering with dietary change."

Roberts previously conducted a pilot study showing that a diet's overall glycemic load may be an important determinant of weight loss for people with high levels of insulin secretion, such as people with diabetes. "We have observed that for some groups, glycemic load may impact weight loss. However, in terms of calorie-restricted diets, we see little difference among diets of varying glycemic load when we account for factors that affect dietary adherence."