Fats and Hormones: A Link to Clarify?

The Insulin-like Growth Factor 1 (IGF-1) and its binding proteins (IGFBPs) play a key role in regulating cellular growth, apoptosis, and metabolic homeostasis. Imbalances in their concentrations have been associated with serious conditions such as cancer, cardiovascular diseases, and metabolic disorders. Identifying modifiable factors influencing these biomarkers could provide new perspectives in prevention strategies.  

Among potential determinants, the role of low-fat diets remains controversial. While some studies suggest a decrease in IGF-1 and IGFBPs levels with reduced fat intake, others have observed no effect or even increases. These inconsistencies highlight an urgent need for a comprehensive synthesis and global analysis of existing data. This study explores the impact of low-fat diets on IGF-1 and IGFBP concentrations.  

Low-Fat Diets: Do They Really Affect Our Hormones?

This study, conducted on adults aged ≥18 years, compares the effects of low-fat diets (≤30% of energy intake) to standard or high-fat diets (>30%). The effects of these various diets were assessed by measuring IGF-1 and IGFBP concentrations before and after the intervention. Results were consolidated using a random-effects model, estimating weighted mean differences (WMDs) and their confidence intervals (CIs).  

Low-fat diets showed no significant effect on IGF-1 levels, with a weighted mean difference (WMD) of 1.63 ng/ml. Analyses detected no heterogeneity among the included studies (I² = 0%), ensuring some consistency in the findings. Similarly, IGFBP-3 concentrations were not significantly influenced by these diets, with no heterogeneity observed (I² = 0%). However, data on IGFBP-1, limited to only two studies, yielded contradictory results, making any conclusions about this biomarker impossible.  

Low-Fat Diets: The Expected Effect Falls Short!

Biomarkers such as IGF-1 and IGFBPs play a central role in regulating cell growth and metabolic processes. Strongly associated with an increased risk of cancers (breast, prostate, colon) and higher overall mortality, these markers are also major targets in strategies for preventing severe diseases. This study aimed to assess whether low-fat diets could influence the expression of these biomarkers.  

The results indicate that low-fat diets are insufficient to effectively modulate these biomarkers to reduce the risk of severe diseases. However, interpreting the results is hindered by several limitations. Disparities among the analyzed studies (proportions and sources of macronutrients) complicate the establishment of clear links between diet and health. Other factors, such as body composition, age, physical activity, or micronutrient intake, may also influence the results.  

This study underscores the need for more rigorous research that controls for confounding variables and explores underlying biological mechanisms to provide more targeted and scientifically substantiated nutritional recommendations.