Iron homeostasis in older adults: balancing nutritional requirements and health risks

Iron plays a crucial role in many physiological processes, including oxygen transport, bioenergetics, and immune function. Iron is assimilated from food and also recycled from senescent red blood cells. Iron exists in two dietary forms: heme (animal based) and non-heme (mostly plant based). The body uses iron for metabolic purposes, and stores the excess mainly in splenic and hepatic macrophages. Physiologically, iron excretion in humans is inefficient and not highly regulated, so regulation of intestinal absorption maintains iron homeostasis. Iron losses occur at a steady rate via turnover of the intestinal epithelium, blood loss, and exfoliation of dead skin cells, but overall iron homeostasis is tightly controlled at cellular and systemic levels. Aging can have a profound impact on iron homeostasis and induce a dyshomeostasis where iron deficiency or overload (sometimes both simultaneously) can occur, potentially leading to several disorders and pathologies. To maintain physiologically balanced iron levels, reduce risk of disease, and promote healthy aging, it is advisable for older adults to follow recommended daily intake guidelines and periodically assess iron levels. Clinicians can evaluate body iron status using different techniques but selecting an assessment method primarily depends on the condition being examined. This review provides a comprehensive overview of the forms, sources, and metabolism of dietary iron, associated disorders of iron dyshomeostasis, assessment of iron levels in older adults, and nutritional guidelines and strategies to maintain iron balance in older adults.

Abstract 557: Stretching With Ankle Dorsiflexion Splint Improves Measures Of Microvascular Reactivity And Oxygen Extraction In Patients With Peripheral Artery Disease

Peripheral Artery Disease (PAD) is a vascular disease that affects over 8 million Americans. PAD patients commonly have difficulty walking due to pain in the legs during physical exertion. Supervised walking therapy has been recommended to improve walking performance and attenuate disease progression; however, this therapy remains underutilized in PAD patients. Recently, there has been evidence to suggest that stretching accomplished via an ankle dorsiflexion splint may improve vascular health and walking performance in PAD; however, it is currently unknown how this protocol affects tissue oxygenation (StO 2 ). The purpose of this study was to determine the impact of 4 wks of ankle dorsiflexion stretching on measures of tissue oxygenation in patients with PAD. Thirteen PAD patients (67.7 ± 7.9 years) were randomized to a stretch (n = 9) or a non-stretch control (n = 4) group. Patients in the stretch were instructed to wear the splint for 30 min/day, 5 days/wk for 4 wks. A 5-min vascular occlusion test was administered before and after the intervention. Measures of StO 2 recovery were calculated following the vascular occlusion test and while completing a 6-minute walk test (6MWT). All measures of StO 2 were derived via Near-Infrared Spectroscopy. Repeated measures ANOVA was used to analyze data. There was a significant improvement in StO 2 recovery in the stretch group compared to the control (Stretch: 0.35 ± 0.25 %/sec vs 0.53 ± 0.29 %/sec; Control: 0.57 ± 0.43 %/sec vs 0.32 ± 0.19 %/sec; p = 0.002). During the 6MWT, patients completing the stretching protocol significantly improved oxygen extraction in the first minute of the test (-0.63 ± 0.05 StO 2 vs -0.73 ± 0.09 StO 2 ); however, this improvement was not significantly different compared to changes in the control group. These results indicate an improvement in microvascular reactivity and oxygen extraction following 4 wks of splint-based stretching. This stretching intervention holds potential therapeutic value for PAD patients and warrants further investigation.

"Functional pain," functional outcomes, and quality of life after hyaluronic acid intra-articular injection for knee osteoarthritis

OBJECTIVE

To compare the effect of hyaluronic acid (HA) intra-articular knee injections on pain and functional outcomes in persons with knee osteoarthritis (OA) over 6 months, and to determine whether or not changes in functional pain are related to improvements in quality of life.

DESIGN

A prospective cohort study.

SETTING

A research laboratory in an academic medical center.

PARTICIPANTS

Patients with knee OA (N = 53) who were receiving medical care for OA.

INTERVENTIONS

Intra-articular knee injections of HA (3 injections, each separated by 1 week) and a comparative noninjection group.

MAIN OUTCOME MEASUREMENTS

Functional pain and outcomes assessments during chair rise, stair climbing, and a 6-minute walking test (by using 0-10 point numerical pain ratings during each test); gait parameters; Medical Outcomes Short Form-36 (SF-36) scores and subscores; the Western Ontario McMaster University Osteoarthritis Index (WOMAC).

RESULTS

Six months after HA, the completion times for the chair rise and stair climb tasks, and the distance covered during the 6-minute walk were not different between the groups. However, functional pain ratings during stair climbing decreased in the HA-treated group (P = .05). Six-month changes in gait velocity, cadence, stride length, step length, and the percentage of the gait cycle spent in single support were all higher after HA injection at month 6 (all P < .05). Significant group-by-time interactions existed for total WOMAC scores. SF-36 Vitality subscores improved by 13%, and Role Physical scores were higher in patients treated with HA injection compared with participants in the noninjection group (P < .05). Regression analyses revealed that changes in the functional pain measures did not correspond with SF-36 scores.

CONCLUSIONS

HA is associated with lower functional pain severity, with minimal impact on functional test scores. We interpreted this finding to represent an increase in the quality of the movement and functional activity. The change in functional pain did not correspond to changes in SF-36 quality-of-life scores.