According to a new study teenagers who have an unhealthy and unbalanced diet may be more prone to respiratory problems such as asthma.
The study suggests that a low dietary intake of certain nutrients increases the likelihood of respiratory symptoms such as asthma, and this is especially so in teenagers who smoke.
The researchers also say a lack of such nutrients may also affect lower lung function.
Lead study author Dr. Jane Burns of Harvard School of Public Health, says this study along with other research, suggests that higher intakes of antioxidant and anti-inflammatory micronutrients are linked to fewer reports of cough, respiratory infections, and less severe asthma-related symptoms.
Dr. Burns says teenagers who have low dietary intakes of fruit, vitamin E, and omega-3 fatty acids are at greater risk of having asthma; she says the study highlights the importance of a balanced diet, composed of whole foods.
For the study Dr. Burns and her colleagues from Health Canada, Brigham and Women's Hospital, and the Environmental Protection Agency (EPA) looked at 12th-grade students from 12 communities around the U.S. and Canada.
In order to examine the associations of low dietary nutrient intake with low pulmonary function and respiratory symptoms over the duration of one school year, 2,112 students completed a standardized respiratory questionnaire and a dietary questionnaire.
They also answered questions about medication use, smoking habits, and recent exercise, before participating in lung function testing.
Dr. Burns says the teenage years were chosen as the focus because it is the ideal time at which to test lung capacity and compare eating habits as most have reached their adult physical stature and lung growth closely parallels this growth.
Burns says although the diet survey targeted eating habits only during the past year, it did give an indication of the teenagers' past diet and it is suspected that current respiratory health may also be a reflection of diet during childhood.
In the study most of the teenagers were white, one third were overweight, and 72% did not consume multivitamins, while almost 25% reported smoking on a daily basis.
The study revealed that at least one third of the students' diets were below the recommended levels of fruit, vegetable, vitamins A and E, beta-carotene, and omega-3 fatty acid intake.
The results showed that low dietary intakes of fruit, vitamins C and E, and omega-3 fatty acids were linked to decreased lung function and a greater risk of chronic bronchitic symptoms, wheeze, and asthma.