Pro-inflammatory diet affects markers of iron metabolism in healthy older adults.

Background: Inflammation and inadequate nutrition are common in older age and known to affect iron homeostasis. However, it is not known whether a pro-inflammatory diet affects iron status in older adults. We investigated the diet quality of healthy older adults considering markers of iron homeostasis and inflammation compared to a younger control.

Methods: Serum markers of iron metabolism (iron, transferrin, ferritin, hepcidin, soluble transferrin receptor [sTfR]) and inflammation (interleukin-6 [IL-6], IL-10 high-sensitive C- reactive protein [hsCRP]) were quantified using immunosorbent assays. Insulin resistance was determined by calculating the homeostasis model assessment index (HOMA-IR). The Dietary Inflammatory Index® (DII) was computed based on dietary intake and inflammatory (ID) or less inflammatory diet (LID) groups were created by using median DII score specific to age group and sex.

Results: DII did not differ by age (p = 0.668, n = 80, F: 75 %, >65 years, n = 60, F: 72 %, ≤35 years). Iron and inflammation status were different between age groups in terms of higher transferrin saturation, sTfR, ferritin and IL-6 concentrations in the old (all p ≤ 0.001). Only in older adults, BMI, HOMA-IR, hsCRP, ferritin and hepcidin concentrations were significantly higher in ID compared to LID (all p < 0.01). In addition, a risk-factor adjusted regression analysis showed that ID was independently associated with higher ferritin and hepcidin concentrations in older adults.

Conclusion: In older age, a pro-inflammatory diet is associated with systemic inflammation and disturbed iron homeostasis.