Spotlight on UPFs: NIH explores link between ultra-processed foods and heart disease

Spotlight on UPFs: NIH explores link between ultra-processed foods and heart disease
Studies show some UPFs may carry higher risks than others; knowledge gaps remain

From hot dogs and potato chips to chicken nuggets and sugary sodas, Americans are eating more ultra-processed foods (UPFs) than ever. Researchers estimate that up to 70% of the U.S. diet is composed of foods that are ultra-processed – meaning an excess number of substances have been added during manufacturing to help them taste better, look better, and last longer.

Yet, while research has been limited, UPFs are increasingly being linked to cardiovascular disease and other health problems. “There’s a lot of overlap between ultra-processed foods and those that are high in saturated fat, added sugar, and sodium, which are already known contributors to heart disease,” said Alison Brown, Ph.D., RDN, a program director in the Division of Cardiovascular Sciences at the National Heart, Lung, Blood Institute (NHLBI). 

While there’s been some progress, Brown said, the research remains complex, challenging, and incomplete – which is why researchers at the National Institutes of Health (NIH), including the NHLBI, are starting to take a closer look at both the health effects of UPFs and the mechanisms that may make them harmful.

Last year, NHLBI-funded researchers published one of the largest, most comprehensive studies to date linking UPFs to cardiovascular disease, the leading cause of death in the U.S. and worldwide. That observational study included a prospective U.S. cohort study of over 200,000 participants and a meta-analysis of health data from 1.2 million people. It showed that high consumption of UPFs was linked to an increased risk of heart disease and stroke in U.S. adults. In particular, it found that study participants with the highest UPF intake showed a 17% greater cardiovascular disease risk, 23% greater coronary heart disease risk, and 9% greater stroke risk compared with those with the lowest intake.

“Our study provides strong evidence that UPFs are linked to cardiovascular disease,” said study co-author JoAnn Manson, M.D., DrPH, professor of medicine at Harvard Medical School and NHLBI grantee. “But we also found that not all UPFs are equal. Some UPFs appear to be worse for your heart than others.”

The researchers showed, for example, that the UPFs that were associated with the highest risk for heart disease included sugar-sweetened beverages and processed meats such as hot dogs and deli meat. UPFs associated with the lowest risk of heart disease included breakfast cereals, yogurt, and some whole grain products. Examples of additives commonly used in UPFs include high-fructose corn syrup, hydrogenated oils, sodium nitrite, and artificial dyes.

While observational studies linking UPFs to cardiovascular disease are growing, rigorous clinical trials – the gold standard of scientific research – are largely lacking. An exception is a small NIH-supported clinical trial conducted in 2019 that linked UPFs to obesity, a risk factor for heart disease.

The study found that when people were given the high UPF diet they ate more calories and gained significantly more weight than when the same people were given a minimally processed diet, even though both diets contained the same number of calories.

“Our lab focuses on what it is about UPFs that causes people to overconsume calories, and I think that’s likely to be the most important UPF pathway to cardiovascular disease,” said Kevin D. Hall, Ph.D., a senior investigator at the National Institute of Diabetes and Digestive and Kidney Diseases and the study’s lead author. “If we understood that process, we might be able to reduce UPFs that cause overeating and perhaps reduce the risk of cardiovascular disease.”

Other possible mechanisms that may explain how UPFs are linked to heart disease are independent of calorie consumption, Hall said. They include inflammation, immune system dysregulation, and changes in the gut microbiome – the collection of bacteria and other microorganisms that live in our intestines. He and other researchers, including NIH-funded scientists, plan to explore these mechanisms and conduct additional clinical trials in the future.

“It could be just a handful of really bad players or UPF components acting through a handful of mechanisms,” Hall said. “If we can understand those mechanisms, we can better inform consumers, manufacturers, and policymakers.”

The list of health problems tied to UPFs, meanwhile, continues to grow. In addition to heart disease, studies have linked UPFs to weight gain, hypertension, type 2 diabetes, chronic obstructive pulmonary disease, cancer, and other problems.

Studies show that UPFs are also linked to health disparities, as populations with low socioeconomic status tend to eat higher amounts of these foods. Factors include limited access to healthier foods and higher costs of fresh produce.

NHLBI’s Brown agreed that there’s an urgent need to better understand the mechanisms linking UPF consumption and chronic diseases, particularly heart disease. “Although it’s challenging to completely eliminate ultra-processed foods, people should consider eating fewer of them,” she said. “Unfortunately, the consumption is going in the wrong direction, and that’s not good for a nation with high rates of heart disease.”

For now, Brown said, some of the best ways to avoid or reduce UPFs are to read food labels closely; choose meals that emphasize whole grains, fruits, and vegetables; and limit foods high in saturated fats, added sugars, and salt. The Dietary Approaches to Stop Hypertension (DASH) eating plan helps achieve this goal, she said. It was recently named the “Best Heart-Healthy Diet” by U.S. News & World Report.

EDITOR'S NOTE: For a look at recent news coverage of UPFs, click here