Low-carbohydrate diets, often adopted to manage blood sugar and weight, could lead to a significant increase in cholesterol for a subset of the population, potentially raising the risk of heart disease, heart attack, and stroke, according to new research.
While these diets are popular for their perceived benefits, the study indicates that they are not universally beneficial and may pose risks for individuals with specific genetic predispositions. Approximately half of adults in the UK have high cholesterol, a condition where fatty plaque builds up in arteries, contributing to a substantial number of annual deaths.
Low-carb diets typically consist of about 75% fat, 20% protein, and 10% carbohydrates. Historically, such diets have been associated with an increase in "good" cholesterol, which aids in clearing arterial deposits. However, the latest findings suggest a potential increase in "bad" LDL cholesterol, particularly in individuals who are genetically susceptible, due to the high fat content inherent in these eating plans.
"Diet advice can sometimes be presented as one-size fits all," said Alexa Barad, lead author of the study from Stanford University School of Medicine. "While some people find a low-carb diet raises their cholesterol, others see no effect."
The research team sought to determine if genetic factors could identify individuals who might benefit from reduced carbohydrate intake versus those who could experience a dangerous spike in cholesterol. The study analyzed data from a trial involving over 600 adults who followed either a healthy low-carb or a healthy low-fat diet for one year. Initial findings showed no significant difference in weight loss between the two diets.
Focusing further on 431 participants with available genetic data, researchers examined their genetic makeup, saturated fat consumption, and changes in LDL cholesterol over six months. The results indicated that among those on a low-carb diet, individuals with a genetic predisposition to higher LDL cholesterol levels were more likely to experience a concerning increase. This effect was linked to the dietary practice of replacing carbohydrate-rich foods with high-fat options like red meat and cheese.
Participants with the highest genetic risk factor showed the most substantial increases in LDL cholesterol when their saturated fat intake was higher. The researchers hope this approach could eventually help healthcare professionals identify individuals at greater risk of adverse cholesterol changes from specific diets.
Saturated fats, commonly found in animal products such as meat and dairy, as well as in palm oil, are a key concern. Current UK guidelines recommend that saturated fat intake should not exceed 10% of daily calories, translating to a maximum of 30 grams for men and 20 grams for women. The National Health Service advises reducing saturated fat and replacing it with unsaturated fats, like omega-3, to mitigate heart disease risk. For those on low-carb diets, this means prioritizing foods like nuts, seeds, and olive oil over butter, fatty meats, and processed meats.
Cardiovascular disease is a leading cause of death in the UK, with around 200,000 people experiencing a heart attack or stroke annually. An estimated eight million people live with cardiovascular conditions, and approximately 100,000 strokes occur each year, claiming around 34,000 lives.