Association between Adiposity and Iron Status in Women of Reproductive Age: Data from the UK National Diet and Nutrition Survey (NDNS) 2008-2019

Background: Overweight/obesity and iron deficiency (ID) are highly prevalent in women of reproductive age (WRA), impacting on women's health. Obesity is a risk factor for nutritional deficiencies but its association with ID is unclear.

Objectives: To determine the association between adiposity and markers of iron status and ID prevalence in WRA.

Methods: This cross-sectional study analyzed the National Diet and Nutrition Survey (2008-2019) data, focusing on women aged 18-49 y with body mass index (BMI) ≥18.5 kg/m². Prevalence of anemia, iron deficiency anemia (IDA), and ID were analyzed. Ferritin was adjusted for C-reactive protein. Iron status was assessed across high and low BMI, waist circumference (WC), waist-to-height ratio (WHtR), and waist-to-hip ratio (WHR). χ², linear and logistic regressions were performed adjusting for covariates.

Results: Among 1098 WRA, 496 normal weight and 602 overweight/obesity, prevalence rates were: anemia 9.2% and IDA 6.8%. Anemia was more prevalent in those with higher WHtR and WHR (11.9% compared with 5.9% and 16.7% compared with 6.5%, both P < 0.001). WRA with increased WC, WHtR, and WHR had higher IDA prevalence than those with lower adiposity (8.5% compared with 4.3%, P = 0.005; 9.4% compared with 3.3%, P < 0.001; 12.1% compared with 4.9%, P < 0.001). ID prevalence was 49.7% (ferritin cutoff 30 μg/L) and 19.6% (ferritin cutoff 15 μg/L), showing similar rates across adiposity groups. ID prevalence defined by soluble transferrin receptor (sTfR) was higher in women with increased WHR (P = 0.001). Higher WHR predicted ID categorized by sTfR (adjusted odds ratio [aOR]: 2.104, P = 0.004), and WHtR and WHR predicted anemia and IDA (anemia: WHtR aOR: 2.006, P = 0.036; WHR aOR: 4.489, P < 0.001 and IDA: WHtR aOR: 2.942, P = 0.012; WHR aOR: 4.142, P < 0.001).

Conclusions: At least 1 in 5 WRA in the UK are iron deficient, highlighting the need to revise current policies. Greater central adiposity was strongly associated with impaired iron status and the development of anemia, IDA, and ID.