Teens, particularly overweight teens, who are exposed to tobacco smoke are at increased risk of the metabolic syndrome, according to a study published in Circulation: Journal of the American Heart Association.
The study is the first to discover a link between tobacco exposure and the metabolic syndrome in this age group.
The metabolic syndrome is a cluster of conditions that increase cardiovascular risk. The syndrome often develops in childhood and is associated with insulin resistance, a metabolic disorder in which the body can’t use insulin efficiently.
“Tobacco and obesity are the two leading causes of preventable death in the United States, so our findings may have profound implications for the future health of the public,” said lead author Michael Weitzman, M.D., executive director of the American Academy of Pediatrics Center for Child Health Research and professor and associate chair at the University of Rochester School of Medicine and Dentistry, both in Rochester, N.Y.
In teens, the metabolic syndrome primarily strikes those who are overweight or at-risk for overweight, a group that has tripled during the last two decades. This makes “a growing segment of the nation’s youth uniquely vulnerable to the development of this syndrome and to subsequent premature cardiovascular disease and type II diabetes,” the researchers said.
Due to the lack of a universally accepted definition of the metabolic syndrome in adolescents, this study defined it as having at least three of these conditions: waist circumference at least in the 90th percentile for age and sex; blood pressure at or above the 90th percentile for age, sex and height; hypertriglyceridemia; low high-density lipoprotein (HDL or “good” cholesterol); and elevated fasting glucose.
The U.S. Centers for Disease Control (CDC) uses body mass index (BMI), a ratio of height to weight, for classifying weight. At-risk for overweight is defined as at least the 85th percentile for age and gender. Overweight is a BMI of at least the 95th percentile.
The researchers studied 2,273 adolescents ages 12 to 19 using data from the CDC’s National Health and Nutrition Examination Survey III (NHANES III 1988 to 1994). The teens and their parents were asked whether they or anyone in the household smoked, and the teens received physical exams with laboratory blood and urine testing.
This is the first study in any age group to use self-reported tobacco exposure along with measurements of cotinine, a biomarker of nicotine breakdown in the liver. Two-thirds of the teens who abstained from smoking had cotinine levels between .05 and 15 nanograms per milliliter, indicating exposure to secondhand smoke.
The researchers found:
Overall, 5.6 percent of all adolescents had the metabolic syndrome;
1.2 percent of those unexposed to smoke had the metabolic syndrome;
5.4 percent of those with cotinine levels indicating smoke exposure had the disorder; and
8.7 percent of those who actively smoked had the metabolic syndrome.
“All things equal, you are almost five times more likely to develop the metabolic syndrome if you are exposed to secondhand smoke,” Weitzman said. “Active smoking increases the risk to at least six times that of a non-exposed individual.”
The strength of the dose-response relationship was a surprise, Weitzman said.
“We were expecting to find something, but in terms of epidemiologic phenomena those are huge differences,” he said.
An even more dramatic effect was found in overweight and at-risk for overweight teens:
5.6 percent of non-exposed individuals had the metabolic syndrome;
19.6 percent of exposed teens had the metabolic syndrome; and
23.6 percent of the active smokers had the metabolic syndrome.
Other subgroups associated with higher risk of the metabolic syndrome included:
8.1 percent of males had the disorder compared to 2.9 percent of females, and
6.7 percent of Mexican Americans and 6.5 percent of whites had the disorder compared to 3.1 percent of blacks.
Weitzman said the research group will replicate the study when sufficient data has been collected from the most recent NHANES survey. However, he said there is no reason to believe the implications will be any less important since the obesity epidemic continues.
About 16 percent of all children and teens in the United States are overweight, according to the American Heart Association. “This is a group in which it is profoundly important to reduce secondhand smoke exposure and active smoking,” Weitzman said.
Coauthors are Stephen Cook, M.D.; Peggy Auinger, M.S.; Todd A. Florin, B.A.; Stephen Daniels, M.D., Ph.D.; Michael Nguyen, M.D.; and Jonathan P. Winickoff, M.D., M.P.H.
The American Legacy Foundation, Health Resources and Services Administration and the American Academy of Pediatrics Center for Child Health Research funded the research.
From American Heart Association
I thought over-weight children and teens was being caused primarily by inactivity. Thousands, Hundreds of Thousands most likely Millions of children and teens in my generation (1960’s) were exposed to tobacco smoke throughout there childhood and these problems are now just showing up?