Blackcurrants: A Nutrient-Rich Source for the Development of Functional Foods for Improved Athletic Performance

Figures & data

Figure 1. Chemical structures of phytonutrients present in blackcurrant fruit. The components of this figure are not associated with any copyrights (public domain).

Figure 2. Fatty acid content of blackcurrant pomace.

Table 1. Amino acid profile of blackcurrant pomace.

Amino acid	Content (wt. % of total amino acids)
Tryptophan	2
Arginine	8
Histidine	2
Lysine	5
Phenylalanine	4
Tyrosine	3
Leucine	7
Isoleucine	5
Methionine	2
Cysteine	2
Valine	4
Alanine	5
Glycine	6
Proline	4
Glutamic acid	21
Serine	4
Threonine	4
Aspartic acid	10

Figure 3. Proposed sites and mechanism of the production of reactive oxygen species in contracting skeletal muscles. CAT, catalase; SOD, superoxide dismutase; GPX, glutathione peroxidase; O₂.−, superoxide; ·oh, hydroxyl radical; H₂O₂, hydrogen peroxide; NOX, NADPH oxidase; PLA₂, phospholipase A₂. Adapted from ^[51] under the licences of (CC BY-NC-ND 4.0).

Figure 4. Physiological impact of blackcurrant anthocyanins and vitamin C on the oxidative stress in athletes.

Figure 5. Mechanism of activation of cellular stress-related signalling pathways by polyphenols resulting in the mobilisation of nuclear factor-erythroid factor 2-related factor 2 (Nrf2) and the activation of the nuclear antioxidant response element (ARE). Activation of the ARE promotes the production of Phase II enzymes and antioxidants (such as glutathione (GSH)). Abbreviations: PI3K - Phosphoinositide 3-kinase, Akt – protein kinase B, PKC – protein kinase C, Grb2 - growth factor receptor-bound protein 2, ERK 1/2 - extracellular signal-regulated kinase 1/2, P – phosphate, and bZIP – basic region-leucine zipper.

Table 2. Summary of clinical studies investigating the effect of blackcurrant supplementation on sports performance.

	Study Topic	Study Type	Sample Group	Intervention	Main Findings	References
1	Muscle damage and inflammation during high-intensity eccentric contractions	Double-blind, randomized, parallel	Undergraduate university students (n = 24), 6 males, 18 females, ages 18-40	Blackcurrant nectar CurrantC© 16 oz drink. Two bottles a day, one with breakfast and one with dinner for 8 consecutive days.	Supplementation attenuated muscle damage and inflammation. Reduced creatine kinase (CK) at 48 h and 96 h post-exercise. Change in Interleukin-6 (IL-6) was higher in placebo subjects at 24 h post-exercise. Increase in oxygen radical absorbance capacity (ORAC) at 48 h post-exercise.	^Citation70
2	Sport climbing performance between 3 intermittent climbing bouts	Double-blind, randomised, crossover	Sport climbers, males (n = 18) Age 24 ± 6 years, height 179 ± 6 cm, mass 71.4 ± 7.8 kg, French climbing grade 6a-8b.	New Zealand Blackcurrant (NZBC) extract in capsules. 600 mg day ^−1 of CurraNZ®, 2 capsules a day for 7 days. Final dose on the same morning of testing.	Higher Hang Time (HT) with Total Climbing Time (TCT) significantly improved (+23%). Accumulative fatigue regardless of supplement.	^Citation60
3	Muscle oxygenation during repeated intermittent forearm muscle contractions	Double-blind, randomized, crossover	Rock Climbers, Male. (n = 12; 6 boulderers, 6 sport climbers). Age 25 ± 4 years, height 178 ± 6 cm, weight 67.9 ± 5.7 kg, IRCRA grade 23.41.9.	NZBC Extract in capsules. 600 mg day ^−1 of CurraNZ®. Two capsules a day for 7 days. Final dose 2 hours before testing. Trial repeated twice with 2 week wash out period in between.	Greater Muscle oxidative capacity with NZBC. During trial two, there was a greater level of oxygen extraction. Between trial 1 and 2, there was a decrease in time to exhaustion as well as impulse with NZBC and placebo.	^Citation62
4	Exercise-Induced Muscle Damage (EIMD) recovery upon strenuous isokinetic resistance exercise	Double-blind, randomized, parallel	Non-resistance trained. (n = 14; 4 men, 10 women). Age 24 ± 2 years, Height 170 ± 9 cm, Weight 67.9 ± 15.7 kg, BMI 23.4 ± 3.5 kg/m^2.	NZBC extract in capsules, 300 mg day^−1 of CurraNZ®, 1 capsule a day for 8 days prior to strenuous muscle damage exercise and continued treatment for 4 days post-exercise.	NZBC Extract treatment showed faster recovery of baseline maximal voluntary contraction (MVC) NZBC extract attenuated muscle soreness at 24 and 48 h. NZBC Extract greatly reduced serum creatine kinase (CK) at 96 h.	^Citation69
5	Muscle oxygenation during forearm exercise in rock climbers	Double-blind, randomized, crossover	Intermediate level Rock Climbers. (n = 12 males). Age 26 ± 5 years, Height 179 ± 5 cm, Weight 78.3 ± 13.4 kg, IRCRA grade 17.2 ± 1.02.	NZBC Extract in capsules, 600 mg day ^−1 of CurraNZ®, 2 capsules a day for 7 days. Final dose 2 hours before testing.	Minimum TSI% (TSI%) was lower and time to half recovery was faster with NZBC followed by exhaustive contractions. NZBC extract seems to improve muscle oxygenation during and after contractions, while causing no changes in arterial blood flow or forearm endurance performance.	^Citation66
6	Fat oxidation in the heat during submaximal exercise	Double-blind, randomized, crossover	Recreationally active (n = 12; 12 males, 6 females). Age 27 ± 6 years, Height 176 ± 10 cm, Weight 74 ± 12 kg.	NZBC Extract in capsules, 600 mg day ^−1 of CurraNZ®, 2 capsules a day for 7 days, after 2 days of maximal exercise test and familiarization trial. Placebo trial commenced after a 2 week wash out period for males, or evenly spaced from proceeding mid luteal cycle phase for women.	Carbohydrate oxidation was decreased by 0.24 gmin^−1 and fat oxidation was increased by 0.12 gmin^−1 with NZBC extract compared to placebo. NZBC did not influence rectal temperature, body temperature, skin temperature, heart rate or physiological strain index during exercise.	^Citation65
7	Post-exercise lactate responses after high-intensity intermittent running	Double-blind, randomized, crossover	Recreationally active, sports experience with high-intensity intermittent exercise and treadmill (n = 13 males). Age 25 ± 4 years, Height 182 ± 7 cm, Weight 81 ± 14 kg.	NZBC Extract in capsules, 300 mg day ^−1 of CurraNZ®, 3 sessions over 5 weeks, 1 capsule a day for 7 days, after an initial rapid ramp test to exhaustion and high-intensity intermittent treadmill test. Sessions two and three included continuous/intermittent warm up protocol prior to running test. Sessions separated to allow a 14-day wash out period and 7 days of supplementation.	Total running distance and distance during sprints were increased by 10.6% and 10.8% with NZBC respectively. Blood lactate was higher for NZBC and had larger changes in lactate 15 minutes into passive recovery.	^Citation67
8	Fat oxidation during prolonged cycling	Double-blind, randomized, crossover	Endurance-trained females (n = 16). Age 28 ± 8 years, 167 ± 6 cm, Weight 59.5 ± 8.4 kg, BMI 21.3 ± 2.1 kg·m ^−2.	NZBC Extract in capsules, 600 mg day ^−1 of CurraNZ®, 1 capsule with breakfast, 1 capsule with dinner, for 6 days. On the morning of the 7th day, 2 capsules were taken with a standardised breakfast. Wash out period between trials was approx. 28 days, all experimental trials took place on day 9–11 of the follicular phase of the menstrual cycle.	Fat oxidation was increased by 27% during 120 min moderate intensity cycling with NZBC. Mean carbohydrate oxidation was lower with NZBC. Pre-exercise plasma NEFA and glycerol concentrations were greater with NZBC indicating higher lipolytic rates.	^Citation64
9	Physiological and cardiovascular responses at rest and during incremental cycling in endurance athletes	Double-blind, randomized, crossover	Trained Triathletes (n = 13; 8 males, 5 females). Age 38 ± 8 years, Height 174 ± 5 cm, Weight 71 ± 9 kg, BMI 23 ± 2 kg·m ^−2.	Sujon NZBC powder (6 g day^−1) as a drink, for 7 days. One familiarization session, and tw experimental testing sessions. The final dose was taken with breakfast, 2–3 hours before the experimental visit. A wash-out period of 4 weeks between sessions.	With NZBC: Intensity was 6% high at 4 mmol∙L^−1. Plasma lactate was lower by 27%, 22%, 17% and 13% at 40%, 50%, 60% and 70% of maximum power. At rest, NZBC increased cardiac output and stroke volume by 26% and 25% respectively and decreased total peripheral resistance by 16%. Maximum oxygen uptake, heart rate, power, blood pressure and cardiovascular responses at 40%, 50%, 60%, 70% and 80% intensity remained unaffected.	^Citation68
10	Physiological Responses and Femoral Artery Diameter during Sustained Isometric Contraction	Double-blind, randomized, crossover	Physically active males (n = 13). Age 25 ± 4 years, Height 182 ± 6 cm, Weight 82 ± 9 kg, BMI 25 ± 3 kg·m ^−2.	NZBC Extract in capsules, 600 mg day ^−1 of CurraNZ®, 2 capsules a day with breakfast, for 7 days, 2 experimental trials with a washout period of 14 days in between.	Total peripheral resistance, systolic, diastolic and mean arterial pressure were lower with increased cardiac output and stroke volume, as well as femoral artery diameter during the 30%iMVC with supplementation. Seven days of supplementation resulted in altered muscle oxygen saturation, muscle activity, cardiovascular responses and femoral artery diameter during 120 mins 30%iMVC of the quadriceps.	^Citation71
11	Physiological responses and substrate oxidation during prolonged cycling	Latin-square, randomized, counter-balanced	Endurance-trained male cyclists (n = 15). Age 38 ± 12 years, Height 187 ± 5 cm, Weight 76 ± 10 kg.	NZBC Extract in capsules, 300 mg day ^−1 per capsule, CurraNZ®.Four 120-min cycling trials with no dose, 300, 600 or 900 mg day ^−1 evenly spaced for 7 days, with a 14-day washout period between dosing trials.	With 600 and 900 mg day^−1 of NZBC, a change in mean fat oxidation of 21.5% and 24.1%, respectively was observed with no effect on heart rate, VO2, VCO2, plasma lactate and glucose.	^Citation61
12	Cardiovascular function during supine rest	Latin-square, randomized, counter-balanced	Endurance-trained male cyclists (n = 15). Age 38 ± 12 years, Height 187 ± 5 cm, Weight 76 ± 10 kg.	NZBC Extract in capsules, 300 mg day ^−1 per capsule, CurraNZ®.Four 120-min cycling trials with no dose, 300, 600 or 900 mg day ^−1 evenly spaced for 7 days, with a 14-day washout period between dosing trials.	During supine rest, 600 and 900 mg day^−1 of NZBC increased stroke volume by 5 ± 8 mL (7%) and 6 ± 17 mL (18%) and cardiac output by 0.6 ± 0.6 L min^−1 (15%) and 1.0 ± 1.0 L min^−1 (28%), respectively compared to control. Total peripheral resistance was decreased by 4 ± 3 mmHg L^−1 min^−1 (20%) and 5 ± 9 mmHg L^−1 min^−1 (20%) for 600 and 900 mg day^−1 of NZBC, respectively, during supine rest. Systolic and diastolic blood pressure, ejection time and heart rate were unaffected.	^Citation72
13	Fat oxidation and cycling performance	Double-blind, randomized, crossover	Cycling and triathlon males (n = 14). Age 38 ± 13 years, Height 178 ± 4 cm, Weight 77 ± 9 kg.	NZBC Extract in capsules, 300 mg day ^−1 per capsule, CurraNZ®, 1 capsule a day with breakfast, for 7 days, 2 experimental trials with a 14-day washout period in between exercise trials.	NZBC supplementation: Improved 16.1 km time-trial performance by 2.4% Increased fat oxidation by 27% at 65% VO2max Had higher levels of plasma lactate immediately after the time trial.	^Citation58
14	Force Steadiness of the Quadriceps Femoris Muscle during sustained submaximal isometric contraction	Placebo-controlled, randomized, crossover	Physically active males (n = 13). Age 25 ± 4 years, Height 178 ± 6 cm, Weight 80 ± 6 kg.	Study one: NZBC Extract in capsules, 300 mg day ^−1 per capsule, CurraNZ®, 2 capsules a day for 7 days. A washout period of 14 days between NZBC and placebo conditions. Study two: NZBC Extract in capsules, 300 mg day ^−1 per capsule, CurraNZ®. 2 capsules a day for 1, 4 and 7 days, as well as no intake as control. Capsules were taken 2 hours before the exercise trial postprandial.	Study one: NZBC enhanced isometric force steadiness of the quadriceps femoris muscle in the third (60–89 s) and fourth (90–120 s) quartiles during the 120 s contraction. Study two: NZBC did not cause any changes in 1 or 4 days, but enhanced isometric force steadiness following the 7-day intake in the second (30–59 s), third (60–89 s) and fourth (90–120 s) quartiles.	^Citation59
15	Walking-induced and body composition-dependent fat oxidation in females	Double-blind, randomized, cross-over	Female endurance athletes (n = 12). Age 21 ± 2 years, Height 166 ± 7 cm, Weight 65 ± 11 kg, BMI 23.7 ± 3.1 kg·m ^−2	NZBC extract in capsules, 300 mg day ^−1 per capsule, CurraNZ®, 2 capsules a day for 7 days. Final dose 2 hours before testing.	No changes in walking-induced heart rate, minute ventilation, oxygen uptake and carbon dioxide production. Significant correlation for changes in fat oxidation with body mass index, body fat% and fat oxidation at rest. Walking-induced fat oxidation is body composition-dependent and higher when body fat% is higher in young-adult females.	^Citation63

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