Folic acid supplementation does not attenuate thermoregulatory or cardiovascular strain of older adults exposed to extreme heat and humidity

Daniel Gagnon, Steven Anthony Romero, Matthew N. Cramer, Ken Kouda, Paula Y.S. Poh, Hai Ngo, Ollie Jay, Craig G. Crandall

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

New Findings: What is the central question of this study? Does folic acid supplementation alleviate thermoregulatory and cardiovascular strain of older adults during exposure to extreme heat and humidity? What is the main finding and its importance? Folic acid supplementation for 6 weeks did not affect whole-limb blood flow/vasodilatation, core and skin temperatures, heart rate, blood pressure and cardiac output. Thus, 6 weeks of folic acid supplementation does not alleviate thermoregulatory or cardiovascular strain of healthy older adults exposed to extreme heat and humidity. Abstract: Folic acid supplementation reverses age-related reductions in cutaneous vasodilatation during passive heating. However, it is unknown if folic acid supplementation alleviates thermoregulatory and cardiovascular strain experienced by older adults during heat exposure. We evaluated the effect of folic acid supplementation on thermoregulatory and cardiovascular responses of nine healthy older adults (61–72 years, 3 males/6 females) exposed to extreme heat and humidity. Participants rested at 42°C while relative humidity was increased from 30% to 70% in 2% increments every 5 min. The protocol was performed before (CON) and after (FOLIC) 6 weeks of folic acid supplementation (5 mg day−1). Local cutaneous vascular conductance (CVC, laser-Doppler flowmetry), forearm vascular conductance (FVC, Doppler ultrasound), mean skin and oesophageal temperatures, heart rate, blood pressure and cardiac output were measured. Folic acid supplementation increased fasting serum folate concentrations (P < 0.01). Absolute CVC was greater throughout the protocol following supplementation (CON: 1.29 ± 0.16 units mmHg−1 vs. FOLIC: 1.65 ± 0.24 units mmHg−1, P < 0.01). However, normalized CVC (CON: 54 ± 8% vs. FOLIC: 59 ± 7%, P = 0.22), FVC (CON: 3.47 ± 0.76 ml mmHg−1 vs. FOLIC: 3.40 ± 0.56 ml mmHg−1, P = 0.93), mean skin (P = 0.81) and oesophageal (CON: 36.87 ± 0.28°C vs. folic: 36.90 ± 0.25°C, P = 0.98) temperatures, heart rate (CON: 83 ± 10 beats min−1 vs. FOLIC: 84 ± 8 beats min−1, P = 0.64), blood pressure (P = 0.71) and cardiac output (P = 0.20) were unaffected by folic acid supplementation. These results demonstrate that 6 weeks of folic acid supplementation does not alleviate thermoregulatory or cardiovascular strain of healthy older adults exposed to extreme heat and humidity.

Original languageEnglish
Pages (from-to)1123-1131
Number of pages9
JournalExperimental physiology
Volume103
Issue number8
DOIs
StatePublished - 1 Aug 2018

Fingerprint

Extreme Heat
Humidity
Folic Acid
Cardiac Output
Skin Temperature
Heart Rate
Blood Pressure
Vasodilation
Skin
Blood Vessels
Doppler Ultrasonography
Laser-Doppler Flowmetry
Forearm
Heating

Keywords

  • Age
  • core temperature
  • heart rate
  • heat wave
  • sweat
  • vasodilatation

Cite this

Gagnon, Daniel ; Romero, Steven Anthony ; Cramer, Matthew N. ; Kouda, Ken ; Poh, Paula Y.S. ; Ngo, Hai ; Jay, Ollie ; Crandall, Craig G. / Folic acid supplementation does not attenuate thermoregulatory or cardiovascular strain of older adults exposed to extreme heat and humidity. In: Experimental physiology. 2018 ; Vol. 103, No. 8. pp. 1123-1131.
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Folic acid supplementation does not attenuate thermoregulatory or cardiovascular strain of older adults exposed to extreme heat and humidity. / Gagnon, Daniel; Romero, Steven Anthony; Cramer, Matthew N.; Kouda, Ken; Poh, Paula Y.S.; Ngo, Hai; Jay, Ollie; Crandall, Craig G.

In: Experimental physiology, Vol. 103, No. 8, 01.08.2018, p. 1123-1131.

Research output: Contribution to journalArticle

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AU - Romero, Steven Anthony

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AU - Poh, Paula Y.S.

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KW - Age

KW - core temperature

KW - heart rate

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