Chan said they decided to look for a link between diet and pulmonary hypertension when they observed that diseased cells called fibroblasts of the lung blood vessels in pulmonary hypertension are surprisingly “hungry” for the amino acids glutamine and serine.

“Our data later showed that this hunger comes from the need (for) fibroblasts to increase collagen production and deposition in and around the blood vessels to stiffen them in disease,” he continued.

“When we cut off that amino acid supply or prevented the use of these amino acids for collagen production, we could reduce collagen production, vessel stiffening, and worsening of pulmonary hypertension.”

Chan and his team used a mouse model to test their theory. When the mice were administered drugs that lowered their cellular uptake of glutamine and serine, the pulmonary hypertensive blood vessels were relieved of their craving.

Additionally, researchers found the lack of glutamine and serine stopped the production of excess collagen, which would lead to lung blood vessel stiffening and impaired function.

Through the research team’s findings regarding serine and glutamine, they were also able to develop a new diagnostic test for pulmonary hypertension.

The test uses positron emission tomography (PET) scan technology and a glutamine imaging tracer to track where glutamine goes in the body. Cells “hungry” for glutamine distinguish themselves on the PET scan, helping doctors with making a diagnosis.

“One of the crucial obstacles in managing pulmonary hypertension is that the diagnosis requires an invasive test called cardiac catheterization, where a long hollow tube is inserted into the blood vessels of the neck,” Chan detailed.

“That catheter is then threaded all the way down into the heart and lungs to measure pressure directly. Not every medical center has this capability, particularly those in more rural or isolated settings, and this limits the ability to appropriately identify and treat patients with this disease.”

“While we use some noninvasive imaging studies like MRI and ultrasound in managing the disease, they are not sufficient to make the diagnosis,” he continued. “Thus, accurate and early diagnosis of pulmonary hypertension is crucial, and there is a clear unmet need for developing better noninvasive diagnostic technology.”

“Our data was only performed in animals with experimental pulmonary hypertension,” Chan added. “We are actively recruiting for a clinical trial at our institution that is testing this new PET technology in patients with pulmonary hypertension.”

— Stephen Y. Chan, MD, PhD, co-senior study author

Chan said that for the first time, researchers have proof that specific dietary adjustments — reducing glutamine and serine consumption, in particular — may serve as an effective way of treating pulmonary hypertension.

“It opens up a new way that we could manage this disease, because now — instead of just relying on medications and transplantation — there are possibly effective lifestyle interventions,” he continued.

“For patients with pulmonary hypertension, avoiding foods rich in serine and glutamine, or eating foods with these amino acids depleted, might improve symptoms, reduce disease progression, or bolster the effectiveness of current medications,” Chan explained.

However, Chan did urge caution in over-interpreting their findings at this stage.

“Our work fully restricted all glutamine and serine from the rodent diets which led to improvement of pulmonary hypertension,” he said.

“We view this finding as (an) important proof-of-concept that dietary maneuvers can be effective as therapies in this deadly disease. However, this level of absolute restriction would not be feasible in a normal human diet, and we certainly do not recommend that our patients attempt to do so at this time.”

“More work is needed to determine if lower levels of amino acid restriction have the same therapeutic effect and/or if more feasible and safe dietary maneuvers could bolster current treatments to promote even better improvement of (the) disease,” Chan added.

After reviewing this study, Cheng-Han Chen, MD, a board certified interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, CA, told MNT that a dietary approach to improving pulmonary hypertension is a novel approach that could be more accessible to people with pulmonary hypertension as a form of treatment.

“Pulmonary hypertension is a complex disease that could have many different causes,” Chen explained.

“Many of the causes are not easily treatable with our current therapies. This type of research has the potential to provide new targets for medications that could improve the prospects for our patients with pulmonary hypertension.”

However, Chen said we are not yet at the point where people should adjust their diets specifically for glutamine and serine based on the results of this study.

“I advise all patients to eat a well-balanced, heart-healthy diet. The next step should be to see if these findings apply in humans, not just in mice. They probably will be looking at clinical studies to evaluate the effects of diet, specifically glutamine and serine intake, on pulmonary hypertension in those individuals.”

— Cheng-Han Chen, MD, cardiologist

MNT also spoke with Monique Richard, a registered dietitian nutritionist and owner of Nutrition-In-Sight, about this study.

Richard explained that amino acids are the building blocks of protein. Foods rich in amino acids include animal and plant proteins, grains, and legumes with the richest sources, most bioavailable — meaning the body can use efficiently.

“In practice, we often observe an excess intake of animal proteins from those who have hypertension, cardiovascular disease risk, chronic obstructive pulmonary disease (COPD), and other related conditions, as well as contributory factors related to lifestyle choices such as minimal activity, smoking, alcohol intake, poor sleep hygiene, (and) hydration status,” she said.

For those worried about their glutamine and serine intake, Richard advised meeting with a registered dietitian nutritionist (RDN) to fully assess diet composition and intake appropriate for an individual’s needs.