Did you know that eating a handful of blackcurrants could improve your speed, endurance and recovery?
New Zealand blackcurrants have gained attention because they appear to have unique health and performance properties not found in other fruits. Specific running and cycling benefits have been observed following blackcurrant ingestion, whereas performance improvements following intake of other fruits, like cherries and berries, have not been found to the same extent.
Fruits and vegetables are given their vibrant colours by phytonutrients which are of special interest to health professionals because they have functional benefits such as antioxidants, anti-inflammatories and detoxification. Phytonutrients get their colours from pigments. For example, carrots, pumpkin and apricots contain the yellow-orange hues of carotenoids; berries, cherries and red grapes contain the red-blue hues of anthocyanins.
Researchers still don’t know why NZ blackcurrants are in a class of their own – however it’s not related to their antioxidant capacity. It is speculated that their anthocyanin content is the key, because they have a distinct purple colour which isn’t found in other common fruits and berries. This intense purple comes from the high amount of two specific compounds in these blackcurrants: cyanidins, which have a red pigment, and delphinidins, which have a blue pigment.
Research has shown that NZ blackcurrants have a range of health promoting properties, including:
- Reducing oxidative stress and inflammation
- Enhancing immune response
- Increasing peripheral blood flow and reducing muscle stiffness, cramp and fatigue symptoms in stressed muscle tissue
- Improving glucose response and insulin control.
For an athlete, this is really interesting. An increased peripheral blood flow may affect lactate clearance, cardiovascular response, VO2 max and muscle repair. There’s a fine balance between training load and recovery, and if you get it wrong you know all about it: lactic acid build-up, exercise-induced muscle damage, impaired performance, and often an opportunistic infection (like the common cold). Clinical trials with runners and cyclists have been flush with exciting results. NZ blackcurrant appears to:
- Decrease lactate accumulation and improve lactate tolerance (performance), and increase lactate clearance (recovery) in both running and cycling
- Reduce oxidative stress and muscle damage, and increase tissue repair (recovery)
- Improve fat oxidation in cycling (performance)
- Maintain high intensity/sprint running for longer (performance)
- Improve time trial results in cycling (performance)
- Increase resistance to fatigue in slow twitch fibres of endurance athletes (performance)
- Maintain healthy immune function and defences immediately after exercise (recovery).
It’s hypothesised that improved exercise performance results from increased blood flow, and training adaptations from faster recovery via antioxidant and anti-inflammatory pathways.
However, it’s important to be aware of the limitations of these trials. Most have been very short-term (many were only conducted over 7 days), have usually tested only male subjects, and there is still no definitive guide as to the appropriate dose and duration for different exercise groups, such as elite versus moderately trained athletes. The anthocyanin dosage used in studies has ranged from 100mg to 300mg. Some trials used pre- and post-exercise ingestion, while others only used pre-exercise ingestion. Therefore, it’s difficult to know how valid these findings are for general daily use by the average athlete.
To put these doses in perspective, one blackcurrant weighs around one gram and contains about six milligrams anthocyanin. So, to get a 100mg dose of anthocyanin from fresh berries, you’d need to eat about 17 berries. Fresh blackcurrants aren’t easy to source, so frozen blackcurrants and freeze-dried powder are good options.
Another key factor is the recognised ‘blunting’ effect of antioxidant supplementation on muscle recovery and repair. If you don’t know anything about this, read my post ‘What you need to know about antioxidants and exercise’ here. While these short-term studies don’t show any detriment to immediate training responses and performance from the antioxidant properties in blackcurrants, the effect of longer-term daily dosing on recovery and performance gains is unknown, and shouldn’t be ignored, as blackcurrants are very high in vitamin C.
I was intrigued by the latest study which suggested that consuming 1.6mg NZ blackcurrant extract per kilogram of bodyweight, one hour before exercise, assists with recovery from exercise-induced oxidative stress and preserves immunity. I’ve just started training towards my second Ironman in March 2020 (IMNZ Taupo), and I’m looking for those nutritional tweaks that may boost my training and recovery. I’ve always been a big fan of blueberries, so I was very interested to see if blackcurrants would make a noticeable difference to my training performance and 24-hour recovery. It was my intention to trial a pre- and post-exercise dose of blackcurrant powder for seven days. Unfortunately my gut didn’t tolerate the pre-exercise dose very well, giving me stomach cramps about halfway into each training session, so I didn’t continue after the 3rd day. I’m still keen to trial it again, this time as a post-exercise recovery supplement in the near future.
The goal then with adding blackcurrant into your nutritional strategy would be to find the dose which is tolerable and produces a noticeable performance and recovery benefit, yet doesn’t negatively affect circulating antioxidant levels. This is still speculative science.
Image by Pezibear of Pixabay
Key References for those of you who like to read all the science stuff:
Effects of blackcurrant anthocyanin intake on peripheral muscle circulation during typing work in humans. EUROPEAN JOURNAL APPLIED PHYSIOLOGY 2005, 94: 36-45.
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.
Blackcurrant nectar reduces muscle damage and inflammation following a bout of high-intensity eccentric contractions. Journal of Dietary Supplements, 1-15 2014.
Effects of dietary antioxidants on training and performance in female runners. Eur J Sport Sci. 2014;14(2):160-8.
Beneficial physiological effects with blackcurrant intake in endurance athletes. Int J Sport Nutr Exerc Metab. 2015 Aug;25(4):367-74.
New Zealand Blackcurrant Extract Improves Cycling Performance and Fat Oxidation in Cyclists. European Journal of Applied Physiology, Nov. 2015, 115, 11, p2357-2365.
Beneficial physiological effects with blackcurrant intake in endurance athletes. International Journal of Sports Nutrition and Exercise Metabolism, 2015, Vol 25, Issue 4.
New Zealand Blackcurrant Extract Improves High-intensity Intermittent Running. International Journal of Sports Nutrition and Exercise Metabolism, 2015, 25, p.487 – 493.
Beneficial Effects of New Zealand Blackcurrant Extract on Maximal Sprint Speed during the Longborough Intermittent Shuttle Test. Sports, 2016, 4, 42.
Cardiovascular Function during Supine Rest in Endurance Trained Males with New Zealand Blackcurrant: A Dose-Response Study. European Journal of Applied Physiology. 2016 pp. 1-8.
Blackcurrant alters physiological responses and femoral artery diameter during sustained isometric contraction. Nutrients, 2017, vol 9, issue 6.
Consumption of an Anthocyanin-Rich Extract Made From New Zealand Blackcurrants Prior to Exercise May Assist Recovery From Oxidative Stress and Maintains Circulating Neutrophil Function: A Pilot Study. Front Nutr. 2019 May 29; 6:73.
Dietary Anthocyanins: A Review of the Exercise Performance Effects and Related Physiological Responses. Int J Sport Nutr Exerc Metab. 2019 May 1;29(3):322-330.