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Primary care providers are accustomed to talking with their patients about how diet and nutrition influence health conditions like diabetes and cardiovascular health. But their effect on lung health?

“It’s not always at the forefront of our recommendations for lung health,” said Christina M. Eckhardt, MD, MS, a pulmonologist and assistant professor of medicine and environmental health sciences at the Columbia University Vagelos College of Physicians and Surgeons, New York City.

However, she suggested that nutrition does play an important protective role and deserves a greater focus. Here’s what primary care providers might keep in mind when they raise the issue with their patients.

Obesity’s Impact on Lung Health

There’s a tendency to focus on environmental factors when it comes to lung conditions, especially those that are triggered by smoke and pollution.

But Allen J. Dozor, MD, professor of pediatrics and the division chief of Pulmonology, Allergy, and Sleep Medicine at New York Medical College in New York City, suggested that physicians remember a key point: “More than half of your environment is what you eat,” he said. “The other half is what you breathe in.”

“Nutrition does play a role in keeping our lungs healthy for sure,” said Amy Bragagnini, MS, RD, clinical oncology dietitian at Trinity Health Lacks Cancer Center in Grand Rapids, Michigan, and a spokesperson for the Academy of Nutrition and Dietetics.

For example, good nutrition and a healthy diet are key to helping people achieve and maintain a healthy weight, which can also influence lung health.

“We shouldn’t forget that obesity is, in and of itself, a risk factor for countless lung diseases,” said Dozor. “Obesity makes asthma worse, and asthma makes obesity worse.”

Excess adipose tissue can put pressure on the lungs, which in turn can reduce functional residual capacity. In fact, some research shows that oxygen levels decrease as body mass index (BMI) goes up in patients with obesity, which can lead to hypoxemia. Lung disease like chronic obstructive pulmonary disease (COPD) can complicate the management of obesity in some patients, too, because it can make it harder for them to exercise.

Extra adipose tissue can also increase the production of inflammatory cytokines that contribute to disease.

“It should be known that your weight has very clear effects on your breathing,” said Edward Len, MD, a pulmonologist with Mid-Atlantic Permanente Medical Group in Largo, Maryland.

And given that more than 41% of adults in the United States, or 100 million people, are considered obese, which is defined as having a BMI ≥ 30, that could affect a significant number of patients in any primary care practice.

Other Effects of Diet on Lung Health

Primary care providers may also want to watch for disease progression in patients with lung disease with an eye toward making sure they’re eating the right foods.

Julia Zumpano, RD, a registered dietitian with the Cleveland Clinic Center for Human Nutrition, Cleveland, said lung disorders can alter a patient’s nutritional needs. Patients with lung conditions, such as asthma, emphysema, COPD, and lung cancer, often use a lot of extra energy to breathe, and as their condition progresses, their body’s needs increase too.

“Therefore, it is very important that they receive adequate macronutrients and micronutrients to support their needs to prevent weight loss, muscle loss, or nutrient deficiencies,” she said. 

Len also suggested that primary care providers ask their patients if they’re experiencing any symptoms of gastroesophageal reflux disease (GERD), which often coexists with asthma. Research is ongoing into the exact relationship between GERD and asthma, but treating GERD may help reduce some asthma exacerbations, thus improving lung function and quality of life. Untreated reflux can also be problematic for patients with interstitial lung disease, Len added.

While diagnosing GERD may require an upper gastrointestinal endoscopy or other tests, a basic screen doesn’t have to take a lot of time. Physicians can ask a few simple questions about indigestion, heartburn, or pain after eating. The patient’s answers can determine whether they need additional evaluation. Providers can also advise patients on dietary and lifestyle changes that may help reduce the incidence of reflux.

The Virtues of a Plant-Based Diet

Experts are increasingly suggesting that a plant-based diet is the way to go.

Research suggested that plant-based dietary patterns may improve outcomes for cancer survivors and possibly even reduce the overall risk of developing cancer, including lung cancer. A 2023 study in the journal Antioxidants (Basel) found that consuming certain antioxidants from food sources seemed to have a protective effect against lung cancer. The nutrients with the most favorable effects included alpha-carotene, magnesium, vitamin C, vitamin E, lycopene, selenium, lutein and zeaxanthin, and beta-carotene.

A growing body of research suggested that eating a plant-based diet could also optimize lung health. For example, a 2023 study in Nutrients found that patients who ate a healthful version of a plant-based diet had a lower risk of developing COPD.

Eating a plant-based diet — or a mostly plant-based diet — may require patients to pay a little extra attention to certain nutritional requirements. For example, they may need to be more deliberate about consuming adequate amounts of plant-based protein to make sure they receive enough of the amino acids not synthesized by the body. Bragagnini suggested recommending sources such as quinoa, nuts and seeds, nut butters, beans, peas, lentils, and whole soy foods such as tofu, tempeh, and soy milk.

Helping Patients Make Positive Changes

“It is worth emphasizing to patients in general the importance of a balanced diet and not having too much of certain things in excess, specifically fried, fatty, greasy foods, and red meat,” said Len. “I think everyone would agree that moderation of those things would be very reasonable.”

But primary care providers don’t have to take on the entire task of teaching their patients about the fine details of a plant-based diet — or other nutritional changes that can enhance lung health in general. They can refer patients to registered dietitians to get more personalized information on making dietary changes.

“To me, referring a patient to a dietitian is just as important, if not more important than, referring a patient to a specialist for a disease,” said Dozor.

Dietitians can connect with patients, learn more about potential barriers to making changes, and then make recommendations to help them make meaningful and sustainable improvements.

“I think it makes people feel empowered that there are decisions that they can make in their day-to-day lives to improve their lung health in addition to using the medication that we prescribe,” said Eckhardt.

Bragagnini also recommended that primary care providers make sure they’re aware of their patients’ socioeconomic status when discussing diet and nutrition. They may need to connect some patients with resources in the community that can help them gain access to healthy food. Just because one patient has a well-stocked grocery store nearby doesn’t mean that everyone does.

“Just be aware that a lot of people don’t, and a lot of people are undeserved,” she said.

She suggested that physicians remember to be kind when approaching patients who may need to lose some weight or adjust their diet. They may be worried they’ll be scolded or shamed.

“Education begins with kindness, and it begins with a lack of shame,” said Bragagnini.