Exercise Performance, Diet & Immune Response                                                 

Clinical trials with blackcurrants

AUGMENTS BENEFITS OF EXERCISE and enhances immume response

This New Zealand study looked at the effectiveness of blackcurrant to augment the ability of regular exercise to enhance the immune responsiveness of the body.

Subjects consumed New Zealand blackcurrant capsules, pre and post exercise equivalent to about 1/3 cup berries (240mg anthocyanin), for three weeks. The results showed:
- Significantly lower levels of bio markers of oxidative stress in plasma.
- Significantly increased ability of plasma to suppress inflammatory responses.

The researchers concluded that blackcurrant extracts taken at the appropriate time and amount can augment the ability of regular exercise to enhance the immune responsiveness of the body.

This research found that blackcurrants boost the natural benefits of exercise, by reducing muscle damage and soreness and assisting immune protection.  These benefits are backed by scientific data showing speedier tissue repair, recovery and performance in exercise. Therefore, this study suggests that at the appropriate time and amounts, New Zealand blackcurrants enable those involved in physical fitness to train harder, for longer periods.

Improves cycling performance and fat oxidation

In this study 14 experienced cyclists consumed 300mg of New Zealand blackcurrant extract containing 105mg of anthocyanins or a placebo for seven days  prior to completing 30 mins of cycling at three different intensities, followed by a 16.1 km time trial.

The results showed that the blackcurrant extract:
- Increased whole body fat oxidation of the cyclists at both low and moderate cycling intensities (45%, 55% and 65% VO2 max) of 15%, 13%  and 27% respectively.
- Improved performance shown by faster times for 16.1km time trial, by an average of 2.4% compared to the placebo, with the highest result showing a time reduction of 8.6%.

The study showed that cycling performance could be significantly improved by intake of New Zealand blackcurrant extract. 

IMPROVED PERFORMANCE AND RECOVERY FOR ENDURANCE ATHLETES

This clinical trial with 13 experienced triathletes showed that cyclists consuming 7 days of New Zealand blackcurrant powder, showed performance effects for endurance athletes and improved recovery.
The results showed:
- Lower lactate accumulation during exercise indicating improved recovery
- Improved cycling intensity or power -  6% higher compared to the placebo at the onset of lactate in the blood
- Improved cardiovascular function at rest and increased blood flow, which could enhance recovery from exercise and may influence the delivery of nutrients and the clearance of metabolites.

 Improves High-intensity Intermittent Running

In this study 13 active males consumed 300mg of New Zealand blackcurrant extract containing 105mg of anthocyanins or a placebo for seven days  prior to performing high intensity intermittent running to exhaustion. The study design was used to mimic the high intensity repeated sprints often seen in team sports such as soccer and rugby.
The results showed that the blackcurrant extract:
- Enhanced  running performance, showing an increase in total running distance of 10.6%
Allowed for 15% higher lactate levels to be achieved at the point of exhaustion
- Improved post-exercise recovery, shown by larger changes in lactate clearance from the blood during the early recovery period compared to the placebo.

Beneficial effects on maximal sprint speed

This study examined 13 athletes completing an intermittent shuttle run test and a subsequent run to exhaustion, while consuming 7 days of New Zealand blackcurrant extract powder  containing 105mg blackcurrant anthocyanins or a placebo.

The results showed New Zealand blackcurrant anthocyanins reduced the slowing of the fastest sprint period of the test, which may indicate that the participants experienced less fatigue.The study concluded that New Zealand blackcurrant extract may enhance performance in team sport with repeated maximal sprints, such as soccer or rugby.

Improved cycling performance and recovery in triathletes

Nine experienced triathletes took part in a study of 10 mile/16.1km time trial, after 7 days of New Zealand blackcurrant powder containing 300mg anthocyanin per day. The blackcurrant powder showed improved cycling performance and recovery.
Results showed:
- Improved time trial performance by 3.6%
- Higher lactate tolerance during time trial performance.
-  Increased lactate clearance after exercise indicating improved recovery. 

IMPROVED CARDIOVASCULAR FUNCTION OF ATHLETES AT REST is DOSE RESPONDENT

In a previous study, New Zealand blackcurrant powder showed an effect on resting cardiovascular function of athletes. In this study fifteen experienced cyclists consumed  differing doses  (105mg, 210mg and 315mg anthocyanins) of New Zealand blackcurrant extract or a placebo for seven days  to show there was a dose effect on resting cardiovascular function.   

The results showed that the blackcurrant powder enabled the hearts of the participants to pump more blood (cardiac output increased by 27.5% at the highest dose, without an increase in heart rate), increased blood flow and increased stroke volume.The higher the dose the greater the effect on stroke volume and cardiac output at rest. New Zealand blackcurrant extract also had a dose -response effect on total peripheral resistance. 

The effect of New Zealand blackcurrant on resting cardiovascular function may support the recovery of endurance athletes. 

INSIGHT INTO THE MECHANISM FOR IMPROVED PHYSICAL PERFORMANCE

Blood flow to the muscles is critical for oxygen delivery for sustained muscular activity, so dietary interventions that can enhance blood flow to the muscles are of interest to athletes.

Previous studies show that consumption of blackcurrant anthocyanins improve sports performance and sports recovery and this study aimed to determine the mechanism for this enhanced effect.

In this study changes were measured with blackcurrant consumption, such as an increase in the diameter of the femoral (thigh) artery, decrease in thigh muscle oxygen saturation, increase in total haemoglobin, and cardiovascular changes, which, taken together, would indicate an increase in peripheral blood flow as the potential mechanism for enhanced exercise performance with blackcurrant.

REDUCED MUSCLE DAMAGE AND INFLAMMATION FOLLOWING EXERCISE

This study of 16 untrained participants showed that the consumption of blackcurrant juice twice a day for 8 days reduced muscle damage and inflammation that resulted from a series of high intensity leg contraction exercises. In addition, antioxidant capacity was maintained, compared to reduced antioxidant capacity measured for the placebo group. While leg muscle soreness scores were not reduced with blackcurrant consumption, the blackcurrant group did return to baseline values a full day before the placebo group.

Consumption of blackcurrant may represent a natural food alternative to taking analgesic and anti-inflammatory drugs following high intensity eccentric exercise.

reduces muscle stiffening

A.) Blackcurrants reduce muscle stiffness by increasing peripheral blood flow and reducing muscle fatigue. Subjects consumed anthocyanin (50mg) equivalent to one tablespoon of blackcurrant berries and carried out keyboard work for 30 minutes.
- Total haemoglobin was significantly higher (about 40%) in the blackcurrant intake group. Oxygenated haemoglobin was significantly higher in the blackcurrant intake group.
- There was significant stiffening of the trapezius (shoulder) muscle during typing in the placebo but not the blackcurrant intake group. However, final stiffness was not significantly different between the two.

B.) In another study anthocyanins from berry and grape extracts had a positive effect on chronic musculo-skeletal pain (fibromyalgia). Subjects consumed anthocyanin powders for three months with the following significant effects:
- Reduced fatigue
- Reduced sleep disturbance
- Increased general health.

The authors concluded that anthocyanins were beneficial for people suffering from this difficult chronic condition.

diet and inflammatory response

A direct effect of diet on inflammatory response, as measured by IL-17 in the blood, has been shown for the first time. IL-17 is a biomarker of inflammatory response.
- Healthy overweight subjects given a high fat meal showed production of IL-17 after 1 hour, which remained high for up to 8 hours.
- A similar meal and with a fruit juice drink containing blackcurrants plus other fruit, showed a significant inhibition of IL-17 production.

glycaemic control

Diets with a high glycaemic index may be associated with increased risk of obesity, type 2 diabetes and cardiovascular disorder.

Two recent clinical trials of sucrose taken with and without a berry meal (of 37.5g blackcurrants and similar amounts of three other berries), showed that the meal with berries slowed the absorption of sucrose and reduced the level of insulin and Glucagon-Like Peptide 1 (GLP-1) in the blood.

These results show that berries rich in polyphenols decrease the postprandial (after a meal) glucose response of sucrose in healthy subjects.

beneficial effects for patients with type 2 diabetes

In this study 58 patients with type 2 diabetes consumed 320mg per day of anthocyanins from blackcurrants and billberries, or a placebo, for 24 weeks.

The results showed significant beneficial metabolic effects with improved blood lipid levels (reducing elevated total cholesterol levels), enhanced antioxidant capacity by activating the body’s antioxidant defence system and scavenging excess damage-causing free radicals and also significantly reducing insulin resistance.

This study is the first human study to show the beneficial effects of anthocyanins on patients with type 2 diabetes. 

Scientific Literature

1. Lyall, K. A., Hurst, S.M.,Cooney, J.,Jensen, D.,Lo, K., Hurst, R.D., Stevenson L. M. Short-term blackcurrant extract consumption modulates exercise-induced oxidative stress and lipopolysaccharide-stimulated inflammatory responses. AM J PHYSIOL REGUL INTEGR COMP PHYSIOL 2009, 297: 70-81.
2. Cook, M., New Zealand Blackcurrant Extract Improves Cycling Performance and Fat Oxidation in Cyclists. European Journal of Applied Physiology, Nov. 2015, 115, 11, p2357-2365.
3. Willems, M.E., Beneficial physiological effects with blackcurrant intake in endurance athletes. International Journal of Sports Nutrition and Exercise Metabolism, 2015, Vol 25, Issue 4. 
4. 
Perkins, I., New Zealand Blackcurrant Extract Improves High-intensity Intermittent Running. International Journal of Sports Nutrition and Exercise Metabolism, 2015, 25, p.487 – 493.
5. Willems, M.E., Beneficial Effects of New Zealand Blackcurrant Extract on Maximal Sprint Speed during the Longborough Intermittent Shuttle Test. Sports, 2016, 4, 42.
6. Willems, M.E., University of Chichester, Department of Sport and Exercise Sciences, UK. Research study presented at the 11th Annual International Society of Sports Nutrition Conference and Expo, 20-21 June 2014 Clearwater Beach, FL, USA. Not yet published. Conference poster available. Click here to see research summary and results
7. Cook, Matthew D., Myers, Stephen D., Gault, Mandy L., Edwards, Victoria and Willems, Mark E. T. (2016) Cardiovascular Function during Supine Rest in Endurance Trained Males with New Zealand Blackcurrant: A Dose-Response Study. European Journal of Applied Physiology. pp. 1-8. ISSN 1439-6319
8. Cook, M., Meyers, S., Gault, M., Willems, M., Blackcurrant alters physiological responses and femoral artery diameter during sustained isometric contraction. Nutrients, 2017, vol 9, issue 6.
9. Hutchison, A., Flieller, E., Dillon, K., Leverett, B., Blackcurrant nectar reduces muscle damage and inflammation following a bout of high-intensity eccentric contractions.  Journal of Dietary Supplements, early online release. 1-15 2014.
10. Matsumoto, H., Takenami, E., Iwasaki-Kurashige, K., Osada, T., Katsumura, T., Hamaoka, T. Effects of blackcurrant anthocyanin intake on peripheral muscle circulation during typing work in humans. EUROPEAN JOURNAL APPLIED PHYSIOLOGY 2005, 94: 36-45.
11. Edwards, A.M., Blackburn, L., Townsend, S., David, J. Food supplements in the treatment of primary fibromyalgia: a double-blind, crossover trial of anthocyanidins and placebo. JOURNAL OF NUTRITIONAL & ENVIRONMENTAL MEDICINE 2000, 10: 189-199.
12.Peluso, IlariaRaguzzini, Anna Villano, Debora V Cesqui, EleonoraToti, ElisabettaCatasta, GiovinaSerafini, Mauro. High Fat Meal Increase of IL-17 is Prevented by Ingestion of Fruit Juice Drink in Healthy Overweight Subjects. CURRENT PHARMACEUTICAL DESIGN 2012, 18: 85-90.
13.Torronen, RiittaSarkkinen, EssiTapola, NiinHautaniemi, ElinaKilpi, KyllikkiNiskanen, Leo. Berries modify the postprandial plasma glucose response to sucrose in healthy subjects. BRITISH JOURNAL OF NUTRITION 2010, 103: 1094-1097.
14. Torronen, RiittaSarkkinen, EssiNiskanen, TarjaTapola, Niinakilpi, KyllikkiNiskanen, Leo. Postprandial glucose, insulin and glucagon-like peptide 1 responses to sucrose ingested with berries in healthy subjects. BRITISH JOURNAL OF NUTRITION 2012, 107: 1445-1451.
15. Li, D. Purified anthocyanin supplementation reduces dyslipidemia, enhances antioxidant capacity and prevents insulin resistance in diabetic patients. The Journal of Nutrition. Published ahead of print, February 2015.