Can Diet Slow the Decline of Lung Function?

 

Lung function can be measured by the amount of air expelled from the lungs in one second or the Forced Exhaled Volume in one second (FEV1), and by the Forced Vital Capacity (FVC), which is the total amount of air a person can inhale in six seconds. Lower values of FEV1 and FVC have long been known to be reduced by lung diseases including chronic bronchitis, pneumonia, emphysema, and asthma. Air pollution, infections, allergens, and especially tobacco smoke are all known to contribute to reduced lung function. Tobacco smoke is by far the most serious cause of a disabling loss of lung function leading to emphysema. While most of these lung insults lowered lung function they did not appear to cause a more rapid decline in lung function over time than what was seen in people without those ills. However, current smoking was associated with significantly more rapid rates of decline in FVC and FEV1 over time (1). Poor lung function has been linked with mortality risks from all diseases, including heart disease, lung cancer, and especially chronic obstructive pulmonary disease (COPD). This suggests that finding ways to slow the loss of lung function, particularly in former smokers, is important to reducing mortality risks. COPD is now the #3 cause of death in the USA with only heart disease and cancer responsible for more deaths each year (2).

Compared to smoking and other established causes of lung disease and declining lung function over time, the impact of diet on lung function has received relatively little research interest. There was one study of healthy subjects about 20 years ago that found that in both children and adults those whose fruit intake declined were significantly more likely to also see a decline in their lung function over time (3). But can what we eat impact the decline of lung function seen in lungs damaged by years of smoking?

Can Diet Slow Decline in Lung Function in Smokers?

Researchers at Johns Hopkins Bloomberg School of Public Health found that the natural decline in lung function over a 10-year period was slower among former smokers whose diets were much higher in tomatoes and fruits (especially apples). This data suggests there is something in these foods that may slow or even help restore some of the lung damage caused by even years of tobacco smoke.

The researchers found that adults who averaged 3 or more servings of tomatoes or 3 or more servings of fresh fruit daily had a slower decline in lung function compared to those who consumed fewer than one serving of fresh tomatoes or consumed less than a single fresh fruit serving daily, respectively. Interestingly, the protective effect of fruits and tomatoes was only observed with higher intakes of fresh fruit and vegetables and not with things like cooked tomato sauce.

The paper was part of the Aging Lungs in European Cohorts (ALEC) Study, led by Imperial College London. The study also found a slower decline in lung function among all adults, including those who had never smoked or had stopped smoking, among those with the highest tomato intake. The findings appear in the December issue of the European Respiratory Journal.

“This study shows that diet might help repair lung damage in people who have stopped smoking. It also suggests that a diet rich in fruits can slow down the lung’s natural aging process even if you have never smoked,” says Vanessa Garcia-Larsen, assistant professor in the Bloomberg School’s Department of International Health and the study’s lead author. “The findings support the need for dietary recommendations, especially for people at risk of developing respiratory diseases such as COPD.”

For the study, the research team assessed diet and lung function of more than 650 adults in 2002, and then repeated lung function tests on the same group of participants 10 years later. Participants from three European countries -- Germany, Norway and the United Kingdom -- completed questionnaires assessing their diets and overall nutritional intake. They also underwent spirometry, a procedure that measures the capacity of lungs to take in oxygen.

The test collects two standard measurements of lung function: FEV1 and FVC. The study controlled for factors such as age, height, sex, body mass index (an indicator of obesity), socio-economic status, physical activity, and total energy intake.

Among former smokers, the diet-lung-function connection was even more striking. Ex-smokers who ate a diet high in tomatoes and fruits had around 80 ml slower decline over the 10-year period. This suggests that nutrients in their diets are helping to repair damage done by smoking.

Bottom Line: “Lung function starts to decline at around age 30 at variable speed depending on the general and specific health of individuals,” stated Dr. Garcia-Larsen. “Our study suggests that eating more fruits on a regular basis can help attenuate the decline as people age, and might even help repair damage caused by smoking. Diet could become one way of combating rising diagnosis of COPD around the world” (4).

By James J. Kenney, PhD, FACN

References:

  1.  http://www.atsjournals.org/doi/full/10.1164/ajrccm.163.1.9906089
  2.   https://www.medicalnewstoday.com/articles/282929.php
  3.  http://www.atsjournals.org/doi/abs/10.1164/ajrccm.158.3.9712065
  4. Garcia-Larsen V, Potts JF, Omenaas E, et. al. Dietary antioxidants and 10-year lung function decline in adults from the ECRHS survey. Eur Respir J. 201750:1602286 or https://doi.org/10.1183/13993003.02286-2016
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