A large study that included data on more than 150,000 Veterans found that risk of coronary artery disease—a form of heart disease—rises based on the rate of fried food consumption.

Research has linked fried foods to chronic health conditions, such as diabetes, heart attack, obesity, and hypertension. Surprisingly, however, the findings have been mixed on whether fried foods are associated with coronary artery disease.

Coronary arteries are the blood vessels that transport oxygenated blood to the heart. A narrowing or blockage of a coronary artery can lead to chest pain, shortness of breath, or heart attack.

Jackie Honerlaw, who led the study while affiliated with the Massachusetts Veterans Epidemiology Research and Information Center at the VA Boston Healthcare System, says it’s the largest paper to date on the link between fried foods and heart disease.

The Veterans who participated in the study were enrolled in VA’s Million Veteran Program, which is aimed at learning how genes, lifestyle, and military exposures affect the health of former service members.

Researcher not surprised by main conclusion

“Our findings provide evidence for a dose-dependent association between fried food consumption and incidence [of coronary artery disease],” the researchers write. “The MVP cohort provides an ethnically diverse sample of Veterans from across the nation with sufficient [cases] for analysis. While a randomized controlled trial is needed to confirm these results, this may not be feasible given the evidence of cardiovascular disease risk related to fried food consumption.”

In other words, the researchers say it would be unethical to do a trial in which some participants eat a lot of fried foods, given what doctors already know about the harmful effects.

The study appeared online in the journal Clinical Nutrition in June 2019. Honerlaw didn’t find the main conclusion surprising because of a 2014 analysis that found eating fried food regularly is significantly associated with the risk of diabetes and moderately associated with coronary artery disease. The analysis, which appeared in the American Journal of Clinical Nutrition, pooled data from the Nurse’s Health Study and the Health Professionals Follow-Up Study.

With a combined cohort of nearly 112,000 participants, the analysis represented the largest cohort on the connection between fried foods and heart disease before Honerlaw’s study was published, she says. The participants were free of cardiovascular disease, diabetes, and cancer at baseline.

Study findings align with dietary recommendations

On the main finding in Honerlaw’s study, American Heart Association fellow Dr. Penny Kris-Etherton says: “It aligns with our current dietary recommendations, which say to typically use healthy food preparation techniques. There are many healthier ways to eat foods that are typically fried like french fries. It’s better to eat potatoes in other ways, like a plain baked potato or an oven-roasted potato, and to eat grilled chicken instead of fried chicken.”

Many Americans are frequent consumers of fried foods, such as french fries and fried chicken, which are both high in sodium, or salt. Too much salt can increase the risk of high blood pressure, stroke, heart disease, kidney disease, stomach cancer, and osteoporosis, a condition when bones become weak and brittle. The study didn’t control for the consumption of salt, so the conclusion doesn’t imply cause and effect, just an association. Plus, french fries and fried chicken are often rich in trans fats, which can raise bad (LDL) cholesterol levels and cause clogged or blocked arteries.

Frying can raise calorie count in foods

In addition, frying can raise the energy density of foods—basically, the calorie count—or the absorption of fats, and change the composition of nutrients. These factors can lead to obesity, elevated blood pressure, and diabetes.

There are several reasons, Honerlaw explains, that previous findings on fried foods and coronary artery disease have been mixed. For one, no large randomized trial has assessed the effects of fried foods on coronary artery disease, she says, noting that data from observational studies can be prone to error.

“Differences in how the studies were conducted, errors in the self-reporting of fried foods, and drastic improvements over time in the treatment of patients with heart disease, among other reasons, can partly explain such inconsistency,” she says. “For example, differences in calories between deep and sautéed fried foods and the type of oil used for frying, as well as portion sizes, are sources of error and not standardized across studies.”

To read more about this study, visit VA Research Currents.

To learn more about VA research on cardiovascular disease, visit the topic page section of the VA Research website.

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Published on Apr. 15, 2020

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