Table 4 Findings from acute studies, including reported outcome measures for placebo and cocoa interventions and the direction of effect

Cutaneous

(b) Heiss 2015 [72]

Laser doppler perfusion imaging (LDPI)

Rest

(b1) 42 ± 4.69/42.1 ± 4.69 PU

(b2) 41 ± 4.47/44 ± 0.44 PU

(b1) 38 ± 4.69/40 ± 4.69 PU

(b2) 38 ± 4.47/39 ± 4.47 PU

1

0

Low risk

RH peak

(b1) 259 ± 70.4/270 ± 79.7 PU

(b2) 186 ± 35.8/186 ± 35.8 PU

(b1) 257 ± 65.7/292 ± 70.4 PU

(b2) 184 ± 67.1/200 ± 62.6 PU

p < 0.05

p < 0.05

1

1

(c) Neukam 2007 [45]

Laser Doppler (cutaneous blood flow)

Rest

22 ± 15/22 ± 10 AU

30 ± 10/50 ± 8 AU

p < 0.05

1

Some concerns

(a) Bapir 2022 [56]

OCT (hands/ feet,

mean vessel diameters)

Resting

Foot: 46 ± 4/43 ± 4 μm

Hand: 57 ± 4/49 ± 9 μm

Foot: 44 ± 4/44 ± 4 μm

Hand: 48 ± 4/48 ± 4 μm

p < 0.001

p = 0.371

1

1

Some concerns

RH peak

Foot: 49 ± 4/47 ± 4 μm

Hand: 57 ± 4/55 ± 4 μm

Foot: 51 ± 9/50 ± 4 μm

Hand: 57 ± 4/57 ± 4 μm

p = 0.751

p = 0.120

1

1

(d) Kim 2020 [62]

Laser Doppler (forearm)

Rest (%CVC max)

(d₁) 11.15 ± 1.44

(d₂) 8.16 ± 2.56

(d₁) 9.73 ± 1.3

(d₂) 9.99 ± 2.31

0

1

Some concerns

Local heating (flux/mmHg)

(d₁) 3.21 ± 0.43

(d₂) 2.85 ± 0.17

(d₁) 3.03 ± 0.25

(d₂) 3.04 ± 0.26

p = 0.4

p < 0.01

0

1

(e) Hammer 2015 [61]

Laser Doppler (forearm)

Median (IQR)

Rest

0.22(0.13–0.47)/0.41(0.24–0.51) AU

0.32(0.18–0.60)/0.31(0.25–0.55) AU

p = 0.78

0

Some concerns

RH peak

0.89(0.58–1.49)/1.24(0.85–1.79) AU

1.22(0.84–1.87)/1.18(0.7–2.27) AU

p = 0.69

0

Skeletal

(f) Baynham 2021 [55]

VOP (forearm, % change pre-post)

Rest

-0.38 ± 0.28%

0.34 ± 0.83%

p < 0.001

1

Low risk

Stress

0.26 ± 0.66%

1.46 ± 1.81%

P = 0.002

1

(b) Heiss 2015 [72]

VOP (forearm)

Rest

(b₁) 1.5 ± 0.47/1.5 ± 0.47

(b₂) 1.1 ± 0.45/0.9 ± 0.45

(b₁) 1.7 ± 0.47/1.6 ± 0.47

(b₂) 1.5 ± 0.45/1.2 ± 0.45

0

0

Low risk

RH peak

(b₁) 13.7 ± 7.50/14.3 ± 8.44

(b₂) 11.3 ± 5.36/10.8 ± 6.71

(all ml/100 ml*min)

(b₁) 13.2 ± 2.81/16.2 ± 4.69

(b₂) 10.9 ± 5.36/12.3 ± 6.71

(all ml/100 ml*min)

p < 0.05

p < 0.05

1

1

(g) Santos 2023 [63]

NIRS-derived SO₂ (forearm)

Vascular occlusion test post-exercise

Reperfusion rate (%/s):

2.03 ± 0.46/ 2.02 ± 0.59

Reperfusion rate (%/s):

2.14 ± 0.58/ 2.35 ± 0.92

p = 0.488

1

Low risk

Retinal

(h) Scuderi 2020 [64]

OCT-A (change from baseline @2hrs, SCP whole density)

Rest

0.586 ± 2.67%

0.739 ± 1.816%

p = 0.317

1

Some concerns

(i) Siedlecki 2019 [65]

OCT-A (superficial retinal plexus)

Rest (vessel density)

47.5 ± 2.6%

48.0 ± 2.7%

p = 0.56

1

Some concerns

Cerebral

(j) Decroix 2018a [59]

fNIRS (oxyHb, right PFC)

Stroop task

1.2 ± 1.5 AU

1 ± 1.5 AU

0

Low risk

(k) Decroix 2016 [58]

fNIRS (oxyHb)

Cognitive task

1.5 ± 0.3 AU

2 ± 0.3 AU

p = 0.02

1

Low risk

Exercise

12 ± 1.5 AU

12.5 ± 1.5 AU

1

(l) Gratton 2020 [60]

fNIRS (change in oxyHb, at 3–4)

Hypercapnia

18 ± 41.2/11 ± 24.7 AU

17 ± 33.0/36 ± 33.0 AU

p = 0.03

1

Low risk

(m) Bloomfield 2023 [57]

fNIRS (oxyHb, normalised to normoxic baseline)

Rest

0.8 ± 1.0 µmol

1.7 ± 2.3 µmol

p = 0.005

1

Some concerns

Hypoxia

-4.0 ± 3.6 µmol

-1.3 ± 2.7 µmol

1