How eating more calories helps lower asthma risk in children

New research finds that kids who don’t eat enough calories face a higher risk of asthma — but piling on more food won’t keep cutting the risk. Here’s what parents and doctors need to know.

Study: The relationship between energy intake and asthma in Americans aged 1–18 years: a cross-sectional study. Image Credit: OnlyZoia / Shutterstock

In a recent article in the journal BMC Pediatrics, researchers explored how energy intake from the diet affects asthma in American children using a cross-sectional design.

Their findings indicate that the relationship between energy intake and asthma forms an L-shaped curve, a statistically significant association (p=0.001), suggesting that asthma risk drops significantly as energy intake increases. However, this protective association “saturates” after crossing an intake level of 56.442 kcal per kilogram of weight per day, beyond which further increases in energy intake do not provide additional benefits.

Background

Asthma is a highly prevalent chronic disease in children and can cause severe breathing difficulties. Estimates suggest that 4.67 million out of the 25 million Americans with asthma in 2021 were children, representing a significant healthcare burden.

Some studies suggest that diet plays a role in reducing asthma risk. For example, the Mediterranean diet, rich in healthy fats, whole grains, fish, vegetables, and fruit, may be protective, while Western diets, which are high in processed foods, may increase risk.

Obesity, often a result of high-calorie diets, may contribute to asthma, but few studies have investigated the association between calories consumed and asthma incidence.

About the study

Researchers used data collected between 2009 and 2018 from a national health survey to assess how different levels of calorie consumption affect the development of asthma and to improve strategies to prevent and manage this condition. This dataset, from the National Health and Nutrition Examination Survey, collects data through lab tests, physical exams, and interviews.

After excluding individuals with missing data, the sample of children under 18 comprised 12,070 individuals. Asthma diagnosis was based on whether they had ever been told that they had asthma by a health professional. Calorie intake was assessed using two 24-hour dietary recall surveys, based on which each participant was categorized into quartiles.

Comparisons between the groups were conducted using statistical tests, and the relationship between calorie intake and asthma prevalence was analyzed using logistic regression models, which accounted for blood markers, nutritional intake, lifestyle and health factors, and demographics.

Findings

Approximately 15.7% of the participants had asthma; slightly over half were male. The lowest quartile (or bottom 25%) of participants consumed less than 33.98 kcal per kg body weight each day; those in the second quartile consumed between 33.98 and 55.41, those in the third 55.41 and 81.6, and those in the highest quartile consumed more than 81.6 kcal per kg per day.

These four groups differed significantly in terms of sex, ethnicity and race, age, body mass index, birth weight, blood and dietary blood markers, maternal age at birth, and poverty-to-income ratio. They did not, however, differ in terms of maternal smoking during pregnancy.

The research team found that lower calorie intake was linked to a significantly higher risk of asthma. Specifically, compared to the lowest energy intake group, the second quartile had a 28% lower risk, the third had a 37% lower risk, and the fourth had a 45% lower risk.

However, there was a threshold beyond which asthma risk decreased by only 1.9%, and this threshold was precisely estimated at 56.442 kcal per kilogram body weight per day. Beyond this level, the association between energy intake and asthma was no longer statistically significant.

No significant differences were observed in this relationship based on poverty-to-income ratio, ethnicity, sex, and age. Removing outliers, or participants with very high energy intake, also did not affect the findings.

Conclusions

Higher dietary energy intake is linked to a lower risk of asthma in children and adolescents, but this protective effect reaches a saturation point after a certain level, estimated at 56.442 kcal for each kilogram of body weight per day.

Previous research on the link between diet and asthma has been inconsistent, with some studies suggesting that a high intake of sugar increases the risk of developing asthma, while fish or whole grains are protective.

While some reviews indicate that caloric restriction can improve symptoms for individuals with obesity, these are based on small sample sizes. Obesity could worsen symptoms as the accumulation of fat can trigger inflammatory cytokines.

Excess intake of sugar and fat could trigger chronic inflammation and cause obesity, increasing the risk of asthma, while moderate intake may support a more balanced immune response. Moderate energy intake may also help maintain immune system balance by reducing the release of pro-inflammatory cytokines such as interleukin-4 (IL-4) and interleukin-13 (IL-13), both of which are involved in asthma development.

Higher-energy diets can also disrupt the gut microbiome, affect airway sensitivity, and increase reactive oxygen species, while a lower sugar intake can decrease oxidative stress and support lung health.

While this study included a large sample size, data collected over 10 years, and robust methods of analysis, it has some limitations, including the use of self-reported dietary information, which may be biased. Also, energy requirements may change with age, which was not considered, and the study’s cross-sectional nature limits causal inference. Further studies are needed to confirm these findings.