Fruit Derived Polyphenols

Polyphenols are a class of organic compounds primarily found in plants that can be classified into four main families: lignans, phenolic acids, stilbenes and flavonoids. They play a number of critical roles including growth, pigmentation, pollination and resistance to pathogens of plants.¹ Polyphenols also influence the taste and colour characteristics of fruit and vegetables. Brightly coloured fruit including cherries, blackcurrants, blueberries, blackberries and pomegranate are particularly good sources of polyphenols, which have been investigated for their healthpromoting, anti-oxidant and anti-inflammatory properties.

• The promotion of fruit and vegetable intake to support general health has been advocated for years. A greater understanding of the emerging role of polyphenols in favourable health, exercise performance and recovery outcomes further strengthens the public health message to maintain a high intake of fruit and vegetables. A summary of emerging research on outcomes relating to exercise performance and recovery from polyphenol ingestion follows below. Polyphenols appear to mimic some aspects of exercise training and may have an additive effect alongside exercise.²
• Polyphenols, by virtue of their antioxidant and anti-inflammatory properties, may reduce oxidative stress, inflammation and muscle pain associated with muscle damage induced by exercise, thereby enabling an earlier return to normal muscle strength/force.^{2, 3, 4, 5, 6}
• Early studies on quercetin (a type of flavonoid) supplementation promoted reduced perception of exercise effort, perhaps related to improved blood flow, including cerebral.⁷
• A meta-analysis of studies on blackcurrants showed an overall improvement to performance of high intensity prolonged exercise, predominantly cycling, with a greater effect in higher level athletes than sub-elite.9 Polyphenols may also reduce muscle soreness and improved recovery post exercise.^{4, 5, 6}
• Flavonoids may reduce the incidence of upper respiratory tract infections in healthy adults.⁸
• Anthocyanins (a type of flavonoid) may enhance nitric oxide production, facilitating blood flow during exercise.⁷
• Tart cherries contain melatonin which may aid sleep.⁵

• In addition to whole fruit and vegetables, there are a number of supplemental forms in which fruit polyphenols may appear. These forms are summarised in Table 1.
• There are a number of products on the market, however many do not state the exact content of active compounds, which makes it difficult to determine an effective dose.

Table 1: Fruit-derived polyphenols and sport performance >

• The absorption and metabolism of most polyphenols is thought to be slow and incomplete. However, the benefits to gastrointestinal health and gut bacteria are likely to play an important role in the mechanism of action of polyphenols, but at this stage have been poorly investigated.
• Apart from quercetin, cherries and blackcurrant, there is insufficient human data to recommend an effective dosing strategy of other polyphenols.
  • Quercetin: 1000 mg/day for at least 7 days prior to competition.³ Effects of chronic intake uncertain but probably best avoided.
  • Blackcurrant: 105-210 mg blackcurrant anthocyanins/day for 7 days prior to competition.6 Effects of chronic intake uncertain but likely ill advised. The majority of research has been conducted on New Zealand black currant, however provided the anthocyanin dose is achieved, there is no indication that other products would not have equal efficacy.
  • Tart Cherries: 90-200 cherries (in the form of cherry juice, cherry juice concentrate or capsulated powder) in a split dose for 4-7 days before and 2-4 days after eccentric exercise or endurance exercise that induces inflammation (such as a marathon). This includes competition which must be repeated multiple times within one day or multiple times over consecutive days.
• Approximately 150g blueberries or 300g mixed berries is sufficient to achieve the polyphenol content provided in many research studies.

1. There remains little consensus on specific doses of most of these fruit polyphenols.
   • Athletes are encouraged to consume a wide range of fruits and vegetables within a well-chosen diet to supply a variety of phytochemicals.
   • Furthermore, there may be variations in anthocyanin content of different variants of berries according to the conditions they’re grown in.
   • Further research is required to compare different variants of berries, including their bio-availability.
2. The research may only be relevant to specific variants of the fruit – such as New Zealand blackcurrants, Montmorency cherries
   • It is important to check the source / variant of the fruit in any supplement.
3. Gastrointestinal distress in those with sensitive gastrointestinal tracts
   • Cherries are known to have a laxative effect, and high doses of other berries may also cause gastrointestinal distress in those with sensitive gastrointestinal tracts. This may be particularly of concern in athletes with physical impairments that limit voluntary bowel control. As such, increasing berry/ cherry intake or the use of berry/ cherry juices (or derived products) should be trialled outside of exercise first.
4. The role of flavonoids on upper respiratory tract infections in athletes is yet to be fully researched.
5. Research indicates consuming high doses of antioxidants and anti-inflammatory compounds reduce the adaptive response to exercise training.
   • While consuming a wide range of fruits is strongly supported in the daily diet of athletes, supplementation of high doses of these fruit-derived polyphenols is NOT recommended during day to day training periods.

Gatorade Sport Science Institute www.gssiweb.org/docs/default-source/sse-docs/bowtell_sse_195-v3_final.pdf?sfvrsn=2, opens in a new tab

Supplement safety information and batch tested product list www.sportintegrity.gov.au/what-we-do/anti-doping/supplements-sport, opens in a new tab

1. Bowtell, J., & Kelly, V. (2019). Fruit-derived polyphenol supplementation for athlete recovery and performance. Sports Med, 49, 3-23.
2. Somerville, V., Bringans, C., & Braakhuis, A. (2017). Polyphenols and performance: A systematic review and meta-analysis. Sports Med, 47, 1589-1599.
3. Bowtell, J., Kelly, V. (2019). Fruit-derived polyphenol supplementation for athlete recovery and performance. Sports Med, 49, S3-S23.
4. Kashi, D.S., Shabir, A., Da Boit, M., Bailey, S.J., Higgins, M.F. (2019). The efficacy of administering fruit-derived polyphenols to improve health biomarkers, exercise performance and related physiological responses. Nutrients, 11, 2389.
5. Vitale, K.C., Hueglin, S., Broad, E. (2017). Tart cherry juice and athletes: A literature review and commentary. Curr Sports Med Rep, 16, 230-239.
6. Cook, M.D., Willems, M.E. (2019). Dietary anthocyanins: A review of the exercise performance effects and related physiological responses. Int J Sport Nutr Exerc Metab. 29:, 322-30.
7. Kressler, J., Millard-Stafford, M., & Warren, G. L. (2011). Quercetin and endurance exercise capacity: a systematic review and meta-analysis. Med Sci Sports Exerc, 43: 2396-2404.
8. Somerville, V.S., Braakhuis, A.J., Hopkins, W.G. (2016). Effect of flavonoids on upper respiratory tract infections and immune function: A systematic review and meta-analysis. Adv Nutr, 7, 488-497.
9. Braakhuis, A. J., Somerville, V. X., & Hurst, R. D. (2020). The effect of New Zealand blackcurrant on sport performance and related biomarkers: a systematic review and meta-analysis. J Int Soc Sports Nutr, 17, 1-10.
10. Levers K, Dalton R, Galvan E, O’Connor A, Goodenough C, Simbo S, Mertens-Talcott SU, Rasmussen C, Greenwood M, Riechman S, Crouse S, Kreider RB. (2016). Effects of powdered Montmorency tart cherry supplementation on acute endurance exercise performance in aerobically trained individuals. J Int Soc Sports Nutr, 26, 13:22.
11. Howatson G, Bell PG, Tallent J, Middleton B, McHugh MP, Ellis J. (2012). Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality. Eur J Nutr, 51(8), 909-16.
12. Ammar, A., Bailey, S.J., Chtourou, H., Trabelsi, K., Turki, M., Hökelmann, A., Souissi, N. (2018). Effects of pomegranate supplementation on exercise performance and post-exercise recovery in healthy adults: a systematic review. Br J Nutr, 120, 1201-16.