Causal relationship between obesity and iron deficiency anemia: a two-sample Mendelian randomization study

Area of Science:

• Genetics
• Nutritional Science
• Epidemiology

Background:

• Observational studies suggest a link between obesity and iron deficiency anemia.
• Previous studies faced limitations like reverse causation and confounding.
• Mendelian randomization was employed to investigate causality.

Purpose of the Study:

• To determine if obesity causally contributes to iron deficiency anemia.
• To leverage genetic variants as instrumental variables for causal inference.

Main Methods:

• Utilized UK Biobank data for genome-wide association studies on obesity indicators and iron deficiency anemia.
• Employed various Mendelian randomization methods (e.g., inverse variance-weighted, weighted median) to assess causality.
• Assessed heterogeneity and horizontal pleiotropy using established statistical tests.

Main Results:

• A causal association was found between obesity indicators (BMI, waist circumference, body fat percentage) and iron deficiency anemia.
• Odds ratios ranged from 1.003 to 1.004, with P-values ≤ 0.001.
• Minimal heterogeneity and no significant horizontal pleiotropy were detected.

Conclusions:

• Mendelian randomization analysis supports a causal relationship where obesity leads to iron deficiency anemia.
• This finding provides robust genetic evidence for the impact of obesity on iron status.