Blood pressure rises as kids become overweight

The impacts of extra pounds don’t always need years or decades to show up. Some appear almost immediately. And that’s true even for children and teens, a new study finds. Their blood pressure can spike as they gain too much weight.

Blood pressure refers to how strongly blood pushes against the inside of blood vessels. High blood pressure can cause headaches, blurred vision and shortness of breath. Over many years, it also can damage blood vessels and the heart.

About one-third of U.S. kids who are 6- to 17-years old are overweight or obese. Scientists knew there was a link between high blood pressure and being overweight. Data also had shown that many youth have high blood pressure. But earlier studies had not tracked both weight and blood pressure in young people over long periods using data collected by doctors. A new study did just that.

Emily Parker is an epidemiologist at Health Partners Institute for Education and Research in Minneapolis, Minn. Epidemiologists search for the causes of disease. Her team collected data on 101,606 kids between the ages of three and 17. The researchers didn’t meet with each child. Instead they used medical records from health-care systems in Colorado, Minnesota and northern California. They sifted through data from kids who had seen their doctor at least three times over an average of three years.

Doctors had recorded a patient’s weight, height and blood pressure at each of those visits. Parker’s team then used the weight and height data to calculate each child’s body mass index, or BMI. BMI is one measure scientists use to determine whether someone’s weight is healthy. Parker and her team then looked at BMI and blood pressure for each kid, focusing on how those measures might have changed over time.

At the start of the study, 22 percent of the kids — slightly more than one in every five — had a BMI that marked them as overweight, obese or severely obese. Those who were obese and severely obese also had high blood pressure. Parker’s team then found that 343 patients developed their high blood pressure (the medical term is hypertension) just during the study’s three-year time frame.

Blood pressure increased significantly among kids and teens who shifted from a healthy weight to overweight, Parker says. It rose even more for those moving into the obese category. Severely obese kids and teens were almost 4.5 times as likely to have developed high blood pressure as their healthy-weight peers. Teen girls experienced the biggest increase in blood pressure as they turned overweight.

Parker’s team shared its findings online February 19 in Pediatrics.

“Maintaining a healthy weight and preventing weight gain can reduce the likelihood of increases in blood pressure at a young age,” Parker says. “The good news is that kids who moved to a lower BMI category saw significant reductions in blood pressure.”

This is a solid study using real-world data, says Bonita Falkner, who was not involved in the new research. Falkner is a hypertension and obesity researcher. She works at Thomas Jefferson University in Philadelphia, Penn. “The message to children and teens is first to avoid becoming overweight,” she says. That’s important, she explains, because those who are already overweight face a greater risk of becoming obese.

Falkner and Parker both recommend lifestyle changes to help overweight kids return to a normal weight. But this may not be as simple as just eating healthier or exercising more, a second study notes.

In it, girls who had a gene linked with obesity tended to eat more fatty foods. This study was conducted by researchers in Canada and Brazil. The preference for fatty foods held true only for girls living in poorer areas. Wealthier girls with the same gene ate less fat. The authors say this shows that both genes and the environment can affect weight gain, especially in girls. This second study appeared online February 1 in JAMA Pediatrics.

Power Words

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average   (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.

blood pressure   The force exerted against vessel walls by blood moving through the body. Usually this pressure refers to blood moving specifically through the body’s arteries. That pressure allows blood to circulate to our heads and keeps the fluid moving so that it can deliver oxygen to all tissues. Blood pressure can vary based on physical activity and the body’s position. High blood pressure can put someone at risk for heart attacks or stroke. Low blood pressure may leave people dizzy, or faint, as the pressure becomes too low to supply enough blood to the brain.

body mass index (BMI)    A person’s weight in kilograms divided by the square of his or her height in meters. BMI can be used to evaluate if someone is overweight or obese. However, because BMI does not account for how much muscle or fat a person has, it is not an accurate measure.

cardiovascular    An adjective that refers to things that affect or are part of the heart and the system of vessels and arteries that move blood through the heart and tissues of the body.

DNA    (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

environment   The sum of all of the things that exist around some organism or the process and the condition those things create for that organism or process. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature, humidity and placement of components in some electronics system or product.

epidemiologist    Like health detectives, these researchers figure out what causes a particular illness and how to limit its spread.

gene    A segment of DNA that codes, or holds instructions, for producing a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.

high blood pressure    The common term for a medical condition known as hypertension. It puts a strain on blood vessels and the heart.

hypertension    The medical term for high blood pressure. It can put a strain on blood vessels and the heart.

obesity    Extremely overweight. Obesity is associated with a wide range of health problems, including type 2 diabetes and high blood pressure.

overweight    A medical condition where the body has accumulated too much body fat. People are not considered overweight if they weigh more than is normal for their age and height, but that extra weight comes from bone or muscle.