Normal developmental changes during the teenage years leave young adult men at higher risk of heart disease than their female counterparts, researchers report in the journal Circulation.
“Women’s protective advantage against heart disease starts young,” says lead author Dr. Antoinette Moran, at the University of Minnesota Children’s Hospital.
In adults, a set of factors increases the risk of heart disease.
These factors include high blood pressure, smoking, obesity, physical inactivity, abnormal cholesterol levels, and insulin resistance (a pre-diabetic condition in which the body cannot use insulin effectively).
To track the risk factors, researchers followed 507 Minneapolis school children from ages 11 to 19, when they had all reached sexual maturity. Fifty-seven percent of the children were male, 80 percent were Caucasian, and 20 percent were African American.
During the study, the researchers made 996 observations on the group, noting blood pressure, insulin sensitivity (opposite to insulin resistance), body mass index (BMI) and other body composition measures, blood glucose, and cholesterol measurements.
“We wanted to see which risks emerge first and how they relate to one another in normal, healthy school kids without diabetes or other major illnesses,” says Dr. Moran.
At age 11, boys and girls were similar in their body composition, lipid levels, and blood pressure, the researchers say.
Boys and girls became heavier during adolescence, increasing in body mass index and waist size. As expected during puberty, changes in body composition differed sharply between genders, with percentage of body fat decreasing in boys and increasing in girls.
During the study, changes in several cardiovascular risk factors or risk markers differed significantly between boys and girls:
Researchers found no gender difference in two other cardiovascular risk factors, total cholesterol, and low-density lipoprotein (LDL or “bad”) cholesterol.
“By age 19, the boys were at greater cardiovascular risk,” notes Dr. Moran. “This is particularly surprising because we usually think of body fat as associated with cardiovascular risk, and the increasing risk in boys happened at the time in normal development when they were gaining muscle mass and losing fat.”
Although girls gained cardiovascular protection when their proportion of body fat was increasing, excess fat is still a cause for concern.
“Obesity trumps all of the other factors and erases any gender-protective effect,” says Dr. Moran. “Obese boys and girls and men and women all have higher cardiovascular risk.”
The researchers say further studies are needed to better understand the development of cardiovascular protection during adolescence.
“That the protection associated with female gender starts young is fascinating and something that we don’t understand very well,” explains Dr. Moran.
“That this protection emerges during puberty and disappears after menopause suggests that sex hormones give women a protective advantage,” he says.
“There’s still a lot that needs to be sorted out in future studies - estrogen may be protective or testosterone may be harmful,” says Dr. Moran.
Dr. Moran says that this is normal physiology and not something that is influenced by lifestyle factors.
Always consult your physician for more information.
The food guide pyramid is a guideline to help you eat a healthy diet.
The food guide pyramid can help you eat a variety of foods while encouraging the right amount of calories and fat.
The United States Department of Agriculture (USDA) and the US Department of Health and Human Services have prepared a food pyramid to guide you in selecting foods.
The food pyramid is divided into six colored bands representing the five food groups plus oils.
Orange represents grains: Make half the grains consumed each day whole grains.
Whole-grain foods include oatmeal, whole-wheat flour, whole cornmeal, brown rice, and whole-wheat bread. Check the food label on processed foods - the words “whole” or “whole grain” should be listed before the specific grain in the product.
Green represents vegetables: Vary your vegetables. Choose a variety of vegetables, including dark green- and orange-colored kinds, legumes (peas and beans), starchy vegetables, and other vegetables.
Red represents fruits: Focus on fruits. Any fruit or 100 percent fruit juice counts as part of the fruit group. Fruits may be fresh, canned, frozen, or dried, and may be whole, cut-up, or pureed.
Yellow represents oils: Know the limits on fats, sugars, and salt (sodium).
Make most of your fat sources from fish, nuts, and vegetable oils. Limit solid fats like butter, stick margarine, shortening, and lard, as well as foods that contain these.
Blue represents milk: Get your calcium-rich foods. Milk and milk products contain calcium and vitamin D, both important ingredients in building and maintaining bone tissue. Use low-fat or fat-free milk after the age of two years.
However, during the first year of life, infants should be fed breast milk or iron-fortified formula.
Whole cow’s milk may be introduced after an infant’s first birthday, but lower-fat or skim milk should not be used until the child is at least two years old.
Purple represents meat and beans: Go lean on protein. Choose low fat or lean meats and poultry. Vary your protein routine - choose more fish, nuts, seeds, peas, and beans.
Activity is also represented on the pyramid by the steps and the person climbing them, as a reminder of the importance of daily physical activity.
Always consult your physician for more information.
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