AICR's Cancer Research Update

Issue 39 — March 24, 2010

Also in this issue:

  1. Health Behaviors of American Adults: Not So Healthy
  2. Gut Bacteria May Link to Heartier Appetite and Weight
  3. Portion Growth
  4. In Brief: Post Those Calories
3d diagram of human lungs in situ

Science in the Spotlight: Lowering Lung Cancer Risk

Lung cancer is the leading cause of cancer death. There is no doubt that cigarette smoking is the primary cause of lung cancer, accounting for approximately 90 percent of cases. But a growing body of evidence indicates that diet and physical activity can influence lung cancer risk for both smokers and non-smokers.

Pointing in the Healthy Direction

AICR’s expert report found that high amounts of fruits and foods containing carotenoids decrease the risk of lung cancer. These foods contain many antioxidant compounds, which may mitigate the oxidative stress cigarette smoking may cause. The report found limited evidence for physical activity and non-starchy vegetables lowering risk.

With your gernerous support, AICR funds reserach in diet, physical activity and weight management. Please donate now.“This is a very active area of research and the studies tend to be pointing in the same direction as the report’s [conclusions],” said Anthony J. Alberg, PhD, an epidemiologist at the Medical University of South Carolina who led the literature review on lung cancer for AICR’s expert report.

Evidence continues to suggest healthy eating and activity habits may play a role in lung cancer protection. For example, a recent study examining fruit and vegetable intake from almost 50,000 participants found that total consumption was unrelated to risk. But among men, high intake of several food groups that included apples, peaches and sweet potatoes was significantly linked with lung cancer protection.

Foods containing carotenoids include tomatoes, carrots and other orange-colored plant-based foods. Earlier evidence pointed to the carotenoid beta carotene as protective against lung cancer. Research now suggests that high doses of beta carotene supplements do not decrease risk and even may cause smokers harm (see sidebar).

In the 1990s, two large, well-designed clinical trials both reached the same conclusion: high amounts of beta-carotene supplements increased the risk of lung cancer among smokers. A third study involving approximately 22,000 physicians showed neither benefit nor harm.

AICR’s expert report also concluded that high doses of beta-carotene supplements convincingly increased the risk of lung cancer in smokers. At this time, AICR does not recommend relying on any supplements to prevent cancer.

A 2008 review study by Alberg investigating carotenoids’ influence on lung cancer found that total carotenoid intake was most strongly linked to lung cancer protection. The carotenoid lycopene also was consistently linked with protection.

Preventing or Delaying

Another carotenoid linked with lower risk is beta-cryptoxanthin, a phytochemical found in red peppers, peaches and oranges. In an AICR-supported study, Chun Liu, MD, a researcher at the Human Nutrition Research Center on Aging at Tufts University, studied how beta-cryptoxanthin influences lung cancer risk in ferrets (ferrets absorb smoke and carotenoids in a similar way to humans). Preliminary findings suggest that both a low and high dose of beta-cryptoxanthin significantly reduced inflammation in precancerous lung cancer lesions, a condition strongly linked to increased cancer risk. “That was really exciting, “ said Liu. “The next step is to find out why.”

The results of this study only apply to smoking-induced lung cancer, says Liu, but he is planning on continuing this research to better understand if it will prevent or delay lung cancer in smokers and non-smokers.

All agree that the most important way to prevent lung cancer is to stop smoking. “But no matter what, a lot of people still smoke,” Liu said. “If you have to smoke, if you can have a healthy diet and lifestyle, then maybe, you can somewhat reduce your risk.”

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In Brief

Drive Thru Neon SignPost Those Calories

Consumers across the country will soon be able to track their calories when eating at a fast food restaurant, due to the new health bill passed this week. The bill requires that restaurants with 20 or more outlets -- along with vending machines -- clearly post calorie counts of their foods.

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Man Jumping Rope on BeachResearch Roundup

Health Behaviors of American Adults: Not So Healthy

Approximately one-third of adults say they are regularly engaging in physical activity and close to two-thirds consider themselves drinkers, according to the latest National Health Interview Survey. The report, released this week by the Centers for Disease Control and Prevention, also found that adults with higher levels of education are less likely to smoke, to be obese and to sleep less than six hours.

The CDC report, Health Behaviors of Adults: United States, 2005-2007, is based on survey data collected from 79,096 interviews with adults between 2005-2007. This is the fourth report since 1997, when the annual interviews began. Since that time, rates of cigarette smoking have declined a few percentage points, rates of obesity have climbed, and rates of alcohol use, and leisure-time physical activity have remained relatively unchanged.

Overall, the latest report found:

  • About 6 in 10 (61.2%) U.S. adults were current drinkers
  • About 1 in 4 adults (24.6%) were lifetime abstainers
  • About 1 in 5 adults (20.4%) were current smokers
  • About 6 in 10 adults engaged in at least some leisure-time physical activity
  • About 3 in 10 adults regularly engaged in leisure-time physical activity
  • About 6 in 10 adults were overweight or obese
  • About 6 in 10 adults usually slept 7 to 8 hours in a 24-hour period

Visit the CDC for the full report. (pdf file)

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Gut Bacteria May Link to Heartier Appetite and Weight

BacteriaThe mix of healthy bacteria that help digest food may play a role in contributing to obesity, if research from an animal study carries to humans. The study, published online in Science also suggests that gut bacteria – called microbiota – may contribute to metabolic disease.

Study researchers began with mice lacking a gene that made them unable to recognize and control bacteria in their intestines. These animals developed obesity and insulin resistance along with other features of metabolic syndrome. The metabolic changes correlated with changes in their gut microbiota.

And when researchers transferred the intestinal microbiota of the genetically-deficient mice into the intestines of healthy mice, it appeared to promote unhealthy characteristics of metabolic syndrome. The healthy mice began exhibiting characteristics of metabolic syndrome, including increased appetite, obesity, elevated blood sugar, and insulin resistance.

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da Vinci LastS upper sectionPortion Growth

Portion and plate sizes shown in the most famous depictions of the Last Supper have gradually increased over time, according to a release on a new study scheduled for publication in the April issue of the International Journal of Obesity. The findings suggest that the modern-day trend of serving bigger portions on bigger plates has occurred over the last thousand years.

In 52 paintings of the Last Supper, researchers analyzed the size of the entrees, bread and plates relative to the size of the average head in the paintings. The result was that the size of the entrées progressively increased 69 percent; plate size increased 66 percent and bread size by about 23 percent.

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