MONDAY, Jan. 14 (HealthDay News) -- Kids who eat fast food three or more times a week are likely to have more severe allergic reactions, a large new international study suggests.

These include bouts of asthma, eczema and hay fever (rhinitis). And although the study doesn't prove that those burgers, chicken snacks and fries cause these problems, the evidence of an association is compelling, researchers say.

"The study adds to a growing body of evidence of the possible harms of fast foods," said study co-author Hywel Williams, a professor of dermato-epidemiology at the University of Nottingham, in England.

"Whether the evidence we have found is strong enough to recommend a reduction of fast food intake for those with allergies is a matter of debate," he added.

These finding are important, Williams said, because this is the largest study to date on allergies in young people across the world and the findings are remarkably consistent globally for both boys and girls and regardless of family income.

"If true, the findings have big public health implications given that these allergic disorders appear to be on the increase and because fast food is so popular," he said.

However, Williams cautioned that fast food might not be causing these problems. "It could be due to other factors linked to behavior that we have not measured, or it could be due to biases that occur in studies that measure disease and ask about previous food intake," he said.

In addition, this association between fast foods and severe allergies does not necessarily mean that eating less fast food will reduce the severity of disease of asthma, hay fever or eczema (an itchy skin disorder), Williams said.

The report was published in the Jan. 14 online issue of Thorax.

Williams and colleagues collected data on more than 319,000 teens aged 13 and 14 from 51 countries and more than 181,000 kids aged 6 and 7 from 31 countries. All of the children were part of a single study on child asthma and allergies.

Kids and their parents were asked about whether they suffered from asthma or runny or blocked nose along with itchy and watery eyes and eczema. Participants also described in detail what they ate during the week.

Fast food was linked to those conditions in both older and younger children.

Consuming three or more weekly fast food meals was associated with a 39 percent increased risk of severe asthma among teens And three such meals for younger children was associated with a 27 percent increased risk of severe asthma, as well higher risk of rhinitis and eczema.

Fruit, however, appeared to reduce the incidence and severity of these conditions for all the children, and for incidence and severity of wheeze and rhinitis among the teens.

According to Williams, three or more weekly servings of fruit reduced the severity of symptoms 11 percent among the teens and 14 percent among the children.

When looked at closely, the data among children was not as convincing as among teens. However, fast food meals were still associated with symptoms except for current eczema, and in poorer countries, except for current and severe asthma.

"Eating fast food is not healthy for a multitude of reasons," said Samantha Heller, an exercise physiologist and clinical nutrition coordinator at the Center for Cancer Care at Griffin Hospital in Derby, Conn.

It's notorious for being high in sodium, saturated fat, trans fats and refined and processed carbohydrates, and low in essential healthy nutrients such as vitamins, minerals, healthy unsaturated fats and fiber, she said.

"I cannot imagine any parent would choose the convenience of fast food over their child's health if they fully understood how deleterious a diet of fast and junk food is to children," Heller added.

Healthy compounds like vitamins, minerals, antioxidants and healthy fats are essential players in whole-body immunity. Kids eating fast food regularly are subject not only to the disease-promoting and inflammatory effects of trans and saturated fats, excess sodium and refined carbohydrates but also likely to suffer from deficiencies of essential health-promoting compounds, Heller said.

"This can lead to chronic diseases such as cardiovascular disease, diabetes, obesity, behavior problems, and as this study suggests, possibly asthma, eczema and colds," she said.

Eating at home more often not only saves money but also keeps families healthier, Heller said.

"For example, you can make healthy fast-food dishes in your own kitchen, such as black bean veggie burgers on whole-wheat buns with tomato and avocado, mashed potatoes with low-fat milk and olive oil or roasted sweet potato fries," she suggested.

More information

For more about healthy eating for children, visit the Nemours Foundation.