The new 25 year study – published in Nutrition Journal – claims to be the first to show that regional and national dietary interventions to reduce fat intake do lead to decreased cholesterol levels, whilst switches to popular low carbohydrate diets are paralleled by in an increase in cholesterol levels.
Led by commented Professor Ingegerd Johansson from Umea University, Sweden, the researchers noted that people selected to take part in an intervention programme in northern Sweden decreased reported fat intake over a seven year period from 1986 to 1992.
Fat intake then increased again after 2004, coinciding with widespread media support for low carbohydrate-high-fat (LCHF) diets, they said.
The team reported that whilst the initial intervention – based on better food labelling, improved health information, and cooking demonstrations – reduced levels of cholesterol in the population. The widespread popularity of the LCHF diet several years later was matched with rises in cholesterol levels.
“The decrease and following increase in cholesterol levels occurred simultaneously with the time trends in food selection, whereas a constant increase in BMI remained unaltered,” reported Johansson and his colleagues.
“These changes in risk factors may have important effects on primary and secondary prevention of cardiovascular disease (CVD).”
Johansson commented that while low carbohydrate/high fat diets may help short term weight loss, the results of his current study “demonstrate that long term weight loss is not maintained and that this diet increases blood cholesterol which has a major impact on risk of cardiovascular disease.”