Allergies linked to obesity and heart risks

Sometimes, the body’s immune system goes into overdrive. It’s meant to fight disease and foreign microbes. But at times it may inappropriately fight against healthy parts of its own body. This is known as autoimmune disease. Common examples include asthma and allergies. Children with such diseases face a higher than normal risk of becoming overweight and developing conditions that could lead to heart disease, a study now finds.

Asthma is a  disease affecting the lungs’ airways. It  can make it hard to breathe. Eczema (EX-eh-mah) is an autoimmune disease that makes the skin rough, itchy and red. Allergies act up when the body thinks something harmless in the environment is actually dangerous and then tries to fight it.

Jonathan Silverberg looked for people with any of these conditions who had been interviewed as part of a major U.S. health survey. Silverberg works at Northwestern University’s Feinberg School of Medicine in Chicago, Ill. As a dermatologist there, he treats skin disorders, such as eczema.

For the new study, he reviewed data from interviews of more than 13,000 U.S. children and teens (and their families). Some 14 percent of children up to age 17 had asthma. Another 12 percent had eczema. And 17 percent had seasonal allergies, also known as hay fever. Then Silverberg looked beyond the autoimmune symptoms in these kids for signs of other underlying diseases. And he found them.

“Children with allergic disease have higher odds of obesity, high blood pressure and high cholesterol than those without allergic disease,” Silverberg now reports.

Obesity has been ruled a disease. And children with eczema were slightly more likely to be overweight or obese, he found. Children who had asthma or hay fever were too.

High blood pressure makes the heart work harder to push blood through its vessels and arteries. Cholesterol (Ko-LES-tur-oll) is a soft, waxy substance in the blood. Although it helps the body function, too much of it can clog the arteries. Both high blood pressure and high cholesterol can raise chances of serious heart problems, such as a heart attack. Children with asthma and hay fever were about twice as likely to have high blood pressure or cholesterol, Silverberg found.

Their overall risk of high blood pressure or high cholesterol was fairly small. And Silverberg can’t say whether asthma or allergies caused the high blood pressure or cholesterol. But it’s certainly possible, he notes.

Silverberg described his new findings December 8 in the Journal of Allergy and Clinical Immunology.

What to make of the findings

Kelvin MacDonald is a pulmonologist. He treats people with lung problems, such as asthma, at Oregon Health & Science University in Portland. MacDonald says that he and other doctors have been worried about a recent rise in childhood obesity and asthma. They’re also concerned that the two appear to be linked.

“It’s a chicken and an egg question,” MacDonald says. By that he means it is unclear which one comes first: the chicken or its egg. It’s possible, he says, that “you have asthma and you become obese because you’re inactive. Or,” he notes, it’s possible that “you start becoming obese because you’re being sedentary and that causes the asthma.” In the same way, scientists don’t know if asthma or allergies might cause high blood pressure and cholesterol or if it could be the other way round. For now, MacDonald says, nobody knows which is true.

Silverberg thinks there are several ways that having asthma or allergies might boost blood pressure or cholesterol. Inflammation, for instance, is the immune system’s response to injury or disease. And children with asthma and allergies usually have more of it. During inflammation, immune cells release proteins and hormones that cause changes in the body. For example, they can temporarily narrow blood vessels or irritate nerves. Scientists are still trying to understand how this might boost blood pressure.

Some children don’t get much exercise because it makes their asthma or allergies worse. They often take medicines. Silverberg points out that this medicine, the lack of exercise — or both — might affect blood pressure and cholesterol. But he adds that more research is needed to be sure.

MacDonald notes that different types of inflammation can occur. But the data used in this study did not identify which types of inflammation the sick children had. That makes it harder to understand what’s happening in their bodies.

“That’s the problem with all these types of investigations” that show provocative links between one thing and another, MacDonald says. They can find an association, but can’t show how it causes the problem.

But the study does suggest that allergic diseases and conditions like obesity are not separate problems. Indeed, MacDonald says, “It is interesting to think that the obesity epidemic and the allergy epidemic could be related.”

Meanwhile, for children and teens with asthma or allergies, it’s important to treat those diseases, Silverberg says. And to promote health, he adds, it’s also important to eat a healthy diet, to sit less and to move more.

Power Words

(for more about Power Words, click here)

allergen  A substance that causes an allergic reaction.

allergy  (adj. allergic) The inappropriate reaction by the body’s immune system to a normally harmless substance. Untreated, a particularly severe reaction can lead to death.

artery  Part of the body’s circulation system, these tubes carry blood from the heart to all parts of the body.

asthma  A disease affecting the body’s airways,which are the tubes through which animals breathe. Asthma obstructs these airways through swelling, the production of too much mucus or a tightening of the tubes. As a result, the body can expand to breathe in air, but loses the ability to exhale appropriately. The most common cause of asthma is an allergy. It is a leading cause of hospitalization and the top chronic disease responsible for kids missing school.

autoimmunity   (adj. autoimmune) A process whereby the immune system turns against its host. This inappropriate reaction can cause disease instead of curing it. Autoimmune diseases can be quite severe and hard for doctors to treat. They include rheumatoid arthritis (affecting joints, such as knees), multiple sclerosis (targeting nerves and muscles), Crohn’s disease (affecting the gut), psoriasis and lupus (affecting skin) and the type of diabetes that typically develops in young children. In all of these cases, the immune system generates out-of-control inflammation.

cholesterol    A fatty material in animals that forms a part of cell walls. In vertebrate animals, it travels through the blood in little vessels known as lipoproteins. Excessive levels in the blood can signal risks to the blood vessels and heart.

eczema    An allergic disease that causes an itchy red rash — or inflammation — on the skin. The term comes from a Greek word, which means to bubble up or boil over.

epidemic  A widespread outbreak of an infectious disease that sickens many people (or other organisms) in a community at the same time. The term also may be applied to non-infectious diseases or conditions that have spread in a similar way.

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

hormone   (in zoology and medicine)  A chemical produced in a gland and then carried in the bloodstream to another part of the body. Hormones control many important body activities, such as growth. Hormones act by triggering or regulating chemical reactions in the body. (in botany) A chemical that serves as a signaling compound that tells cells of a plant when and how to develop, or when to grow old and die.

inflammation  The body’s response to cellular injury and obesity; it often involves swelling, redness, heat and pain. It is also an underlying feature responsible for the development and aggravation of many diseases, especially heart disease and diabetes.

immune system  The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.

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

proteins      Compounds made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. The hemoglobin in blood and the antibodies that attempt to fight infections are among the better-known, stand-alone proteins. Medicines frequently work by latching onto proteins.

sedentary   Not physically active; an adjective for activities done largely while sitting.