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Share on Pinterest Regular milk consumption may have a negative effect on heart health in women, but fermented milk products appear to be safe. Image credit: Tatjana Zlatkovic/Stocksy. Researchers recently studied how consuming fermented and nonfermented milk may impact heart disease in men and women. Fermented milk, also known as cultured milk, undergoes a process to add beneficial bacteria, yeast, or acids. The study found that taking in higher amounts of non-fermented milk is associated with a higher risk of ischemic heart disease (also called coronary heart disease) and myocardial infarction (heart attack) in women. While nonfermented milk was associated with a higher risk of these heart issues in women, the study did not find a negative impact on heart disease in men. A recent study involving around 100,000 Swedish women and men examined how milk consumption impacts cardiometabolic proteins. Doctors use these protein patterns to determine someone’s risk for cardiovascular disease. Karl Michaëlsson, MD, PhD, a professor of medical epidemiology in the Department of Surgical Sciences at Uppsala University, Sweden, led the study. The researchers analyzed two multidecade cohort studies that followed the participants’ diets and lifestyles. Through tracking various metrics and self-reported food and beverage intake, the researchers found that women who consumed 300 milliliters (mL) or more of nonfermented, or regular, milk had an association with a higher risk of ischemic heart disease and myocardial infarction (heart attack). While nonfermented milk showed a negative association with heart disease in women, fermented milk products —such as sour milk and yogurt — did not show an association with such a risk. Heart disease is the top cause of death in the United States, with statistics showing it was responsible for more than 700,000 deaths in 2022. While heart disease is more prevalent in men than in women, women die at higher rates from heart disease. A number of factors can contribute to developing heart disease such as genetics, diet and lifestyle, smoking, and drinking alcohol. The current study of Swedish men and women examined how milk consumption can contribute to heart disease. Even though milk has health benefits, such as providing vitamin D and protein, many scientists wonder how it impacts the heart. Both of these studies tracked lifestyle data from the participants, including food and drink consumption, body mass index (BMI), heart disease events, and heart attack events. Some participants also provided plasma samples that the researchers used to analyze the proteomics, which refers to the study of protein patterns . As part of the food and beverage reporting, participants reported their milk consumption. They listed how frequently they consumed milk, whether it was fermented or non-fermented, and the quantity of milk consumed. The blood plasma analysis measured 276 protein biomarkers. The goal was to see how the presence of biomarkers associated with ischemic heart disease and myocardial infarction compared to milk consumption. After analyzing the blood plasma and comparing that to the participants’ self-reported milk consumption, the researchers found no correlation between fermented milk and an increase in heart disease for men or women. When comparing the amount of nonfermented milk consumed, the scientists noted an increase in both ischemic heart disease and myocardial infarction in women who drank higher amounts of milk. There was no increase in this risk with men. Women who drank 100 mL (or half of a glass) of nonfermented milk daily saw lower rates of these diseases compared to women who consumed more than 300 mL (or 1.5 glasses) of nonfermented milk. The scientists found that consuming 4 glasses of nonfermented milk daily was associated with a 21% higher risk of developing ischemic heart disease compared to consuming half of a glass per day. The researchers noted that even when adjusting for lifestyle factors, the results were consistent at all milk fat percentages. Women who drank higher amounts of non-fermented milk had higher levels of angiotensin-converting enzyme 2 ( ACE-2 ) and lower levels of fibroblast growth factor 21 (FGF21). Both are markers that are associated with ischemic heart disease risk. People with elevated ACE-2 experience have shown higher cardiovascular mortality rates and elevated FGF21 levels may be associated with heart damage. 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, who was not involved in this study, spoke with Medical News Today about its findings. Reflecting on why there would be an association of an increased risk in women who consume nonfermented milk developing heart disease or heart attacks compared to men, Chen said it remains unclear. “It is possible that sex-specific differences in the metabolism of milk components such as lactose result in differences in degradation products, which can potentially cause differences in oxidative stress and inflammation,” he suggested. “This could then lead to increased risk of developing heart disease.” Chen also discussed how fermented milk could potentially offer heart-protective benefits. “Fermented milk products such as yogurt are rich in bacteria ([for example,] Lactobacillus) that influence the composition of our gut microbiome,” he explained. The beneficial effects of yogurt are likely related to its benefit to the microbiome.” Chen further noted that while more research is needed about the microbiome and heart health, “many studies have found that different compositions of the microbiome can help with decreasing the risk of high blood pressure, diabetes, and even heart disease.” John Higgins, MD, a cardiologist at UTHealth