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

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.

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.

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.

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