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A new study suggests that restricting sugar intake during pregnancy and the first two years of a child’s life is associated with a reduced risk of developing asthma and chronic obstructive pulmonary disease in adulthood. The research, which also found a link to improved adult lung function, was published in The American Journal of Clinical Nutrition.
The period from conception to a child’s second birthday is a foundational window for lifelong health. Previous studies in animals and humans have suggested a connection between a mother’s high sugar intake during pregnancy and an increased risk of asthma and allergies in her children. However, the long-term consequences of early-life sugar exposure on respiratory health extending into adulthood remained largely unknown.
A team of researchers led by Jiazhen Zheng of The Hong Kong University of Science and Technology (Guangzhou) sought to investigate this long-term relationship. They took advantage of a unique historical event: the end of sugar rationing in the United Kingdom in September 1953. This event created a natural experiment. After rationing ended, national data shows that average daily sugar consumption for adults nearly doubled, while the intake of other foods remained relatively stable. This sharp change allowed the scientists to compare the health outcomes of people born during rationing with those born just after it was lifted.
The study utilized data from the UK Biobank, a large-scale biomedical database containing health information from over half a million participants. The researchers focused on 58,670 individuals born in the United Kingdom between 1951 and 1956. Based on their birth date, participants were categorized by their exposure to the national sugar rationing policy during their first 1,000 days of development. Those born before July 1954 were considered exposed to rationing for varying lengths of time, while those born after this date were considered unexposed.
The scientists then tracked the participants’ health records over many years to identify new cases of three respiratory diseases: asthma, chronic obstructive pulmonary disease, and idiopathic pulmonary fibrosis. They also analyzed results from spirometry tests, which measure lung function. These tests assess metrics like the total amount of air a person can exhale and how quickly they can exhale it. The analysis accounted for a wide range of factors, including age, sex, socioeconomic status, smoking history, parental health, and other medical conditions.
The results showed a clear association between being exposed to sugar rationing in early life and better respiratory health in adulthood. Individuals who experienced sugar restriction both in the womb and for one to two years after birth had a 25% lower risk of developing asthma and a 27% lower risk of developing chronic obstructive pulmonary disease compared to those who were not exposed to rationing.
The findings also revealed a dose-response relationship, meaning that longer periods of sugar restriction were associated with greater protection. The risk of respiratory disease gradually increased for groups born closer to the end of rationing, whose exposure was shorter. For those exposed to rationing for the longest period, the onset of asthma was delayed by an average of 3.6 years and chronic obstructive pulmonary disease by 2.8 years. The association with idiopathic pulmonary fibrosis, a rarer lung disease, showed a similar trend but did not reach statistical significance.
Beyond disease risk, the study found a link between early-life sugar rationing and improved lung capacity. Participants in the rationed group showed significantly better performance on lung function tests. Their measurements for forced expiratory volume in one second and forced vital capacity, which indicate how much air the lungs can forcefully exhale and hold, were higher than those in the non-rationed group.
To strengthen their conclusions, the researchers conducted several validation tests. They examined a control group of UK Biobank participants who were born outside the United Kingdom during the same years and found no association between their birth date and respiratory health. This suggests the effect was specific to the conditions in the United Kingdom. Similar analyses using data from large aging studies in the United States and England further supported the main findings.
The team also tested for associations with “placebo outcomes,” which are health conditions not expected to be linked to early-life diet, such as influenza and shingles. They found no connection between sugar rationing and the risk of these illnesses, reinforcing the idea that the observed effect on respiratory health was not a coincidence or due to general improvements in health over time. The researchers also explored potential pathways for the association. They found that conditions like type 2 diabetes and hypertension, which are related to sugar consumption, explained about 18% of the relationship, suggesting other biological mechanisms are also at play.
The study does have some limitations. Because it is based on a historical event, it identifies associations rather than proving direct causation. The analysis relied on birth dates as a proxy for sugar exposure, as individual dietary records from that time do not exist. Information about early-life factors like breastfeeding was self-reported by adults and may be subject to recall errors. Finally, the UK Biobank population is predominantly of White European ancestry, so the findings may not apply to other ethnic groups.
Despite these limitations, the study offers compelling evidence that limiting sugar intake during the critical developmental window of the first 1,000 days may have lasting benefits for respiratory health. The findings align with modern dietary guidelines that recommend reducing free sugar intake for pregnant women and avoiding added sugars for children under two. Future research, including randomized controlled trials, could help confirm these results and clarify the biological processes that connect early sugar consumption to adult lung disease.
The study, “Sugar restriction in the first 1000 days after conception, and long-term respiratory health: a quasi-experiment study,” was authored by Jiazhen Zheng, Chuang Yang, Zhen Zhou, Jinghan Huang, Qiang Tu, Haisheng Wu, Quan Yang, Wenbo Huang, Junchun Shen, and Feng Cao.
