Effects of Far Infrared Irradiation on Vascular Function in Healthy Subjects

  • Hala Abubaker Ali Bagabir

Student thesis: Doctoral ThesisDoctor of Philosophy


Introduction: far infrared (FIR) is an invisible electromagnetic wave and a source of heat. It is involved in a range of biological effects which includes improvement in clinical outcomes in many pathological diseases especially in patients with chronic heart failure. FIR was also employed in animal and cellular models to further explore their effects and to conclude an understanding of its mechanistic pathways. However, the mechanisms behind the beneficial effects induced by FIR is still unclear. Therefore, this pilot study aims to investigate the effects of FIR on the vascular function in healthy subjects. This study will also explore some of the mechanisms including anti-oxidation and an endothelium-related gene that might be explained by FIR effects.

Methods: in this thesis, 70 healthy, non-smoking volunteers (31.47 ± 11, mean ± SD) participated in this study. They received 4 sessions (40 minutes each) over 2 weeks of either FIR, heat or placebo. Vascular assessments were performed following two testing protocols. Protocol 1: at baseline, immediately after single session and 24-hour after the last session. Protocol 2: at baseline, 4-hours after single session and 4-hours after the last session. Participants were assigned blindly into 6 groups (n=10, except for the first two groups where n=15). Two groups received FIR to the back with two different testing protocols (protocol 1 or protocol 2), two groups received FIR to the forearm following testing protocol 1 and protocol 2, one group received heat and one placebo-receiving group. The latter two interventions were delivered to the back only following protocol 1. FIR was delivered using a FIR ray device, a heating pad set at 38°C was used for the heat group and for the placebo group a switched-off FIR device was used. Endothelial function was assessed using Laser Doppler imaging with the iontophoresis of an endothelium-dependent agent, acetylcholine (ACh) and endothelium-independent agent, sodium nitroprusside (SNP). Arterial stiffness was measured using pulse wave analysis to determine the augmentation index (AI@75%) using a Sphygmocor device. Blood was obtained to look at circulatory biomarkers including cytokines, adhesion molecules, and oxidative stress biomarkers. Furthermore, the expression of 9 genes regulated by the nuclear factor erythroid 2–related factor 2 (NRF2), NFE2L2 (gene name for NRF2), Kelch-like ECH-associated protein 1 (KEAP1) and endothelial nitric oxide synthase (NOS3) in peripheral blood mononuclear cells (PBMCs) was examined.

Results: in comparison with baseline, the ACh response was significantly improved with FIR treated back following both protocols 1 and 2. There was no change seen after a single session; however, greater responses were seen after repeated FIR sessions to the back in protocols 1 and 2 relative to baseline (mean (SD), 374064(11086) to 458390(129347) p-value= 0.017, and 328951(105075) to 409808(101317) p-value=0.023, respectively). Responses to SNP remained unchanged in both protocols following FIR to the back. AI@75% significantly improved after one session of FIR compared to baseline following protocols 1 and 2 (mean (SD), 4.8(16.1) to 2.7(16.3), p-value= 0.025, and -2.3(13.2) to -7.13(13.5), p-value = 0.00, respectively) and further improvements were seen after the last session in protocols 1 and 2 (mean (SD) 4.8(16.1) to 1(17.4), p-value < 0.001 and -2.3(13.2) to -9.6(12.9), p-value < 0.001, respectively). FIR treated forearm (protocol 2) showed a significant reduction in AI@75% after the last FIR session compared to baseline (mean (SD), 3.2(19.8) to -0.8(19.0), p=0.02). For gene expression, NFE2LE did not change following FIR treatment to the back; KEAP1, however, was significantly increased after the last session of FIR to the back (protocol 1) compared to the baseline level. Significant expression of NOS3, as well as some NRF2 related genes including GCLM, TXNRD1, HSP70 and PRDX1 following FIR, treated back (protocol 2). Forearm group showed a significant increase in KEAP1 4 hours after the last session (protocol2). Apart from that, forearm group, heat and placebo groups showed no change in endothelial function, arterial stiffness, or gene expression. Circulatory biomarkers showed no change in all the assigned groups.

Conclusion: FIR non-thermally improves vascular function in healthy subjects when repeatedly given possibly through the upregulation of NOS3 and NRF2, which might be a promising modality to promote vascular health
Date of Award2020
Original languageEnglish
SponsorsKing Abdulaziz University & Kingdom of Saudi Arabia
SupervisorFaisel Khan (Supervisor) & Chim Lang (Supervisor)

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