Written by Angeline A. De Leon, Staff Writer. Study results found a reduced cardiovascular risk associated with decreased LDL oxidation in the participating military personnel who supplemented with a single dose (200 mg proanthocyanidins) from dry Vitis vinifera extract during intense physical training.
Proanthocyanidins are a class of polyphenols with powerful antioxidant properties. Commonly sourced from grapes, apples, blueberries, and cranberries, proanthocyanidins have been tested in exercise studies for their beneficial effects on intense physical endurance training1 Studies show that the oxidative stress and energetic imbalance caused by strenuous exertion are associated with various metabolic changes in the endocrine system, specifically the release of adipokines (cytokines released by adipose tissue), leptin and adiponectin2 . Leptin (involved in appetite suppression and energy homeostasis) is thought to be a potential mediator of oxidative metabolism and shows sensitivity to exercise-induced stress 3,4, while adiponectin (involved in glucose and fatty acid metabolism) demonstrates an inverse correlation with metabolic imbalance and general inflammatory processes 5. Evidence suggests that circulating levels of leptin and adiponectin may fluctuate as a function of exercise 2. While the action of polyphenols on leptin and adiponectin secretion has been studied in various exercise studies, dose response remains unknown. A study published in the European Journal of Nutrition (2017) investigated how an acute dose of proanthocyanidins prior to intense, long-duration exercise might impact plasma levels of leptin and adiponectin, as well as electronegative low-density lipoprotein [LDL(-), a minor modified fraction of LDL with cytotoxic effects], an early marker of pre-oxidative events such as intense exercise 6,7.
A total of 54 healthy male army cadets (mean age = 22 +/- 2 years) were enrolled in a double-blind, randomized, placebo-controlled study. Subjects were randomly assigned to ingest a capsule of Vitis vinifera extract containing 200 mg of proanthocyanidin or an identical placebo immediately prior to the beginning of military exercise (training program consisted of 2 days of continuous exercise). Immediately before exercise, after the first day of exercise (consisting of an 8-hour, 24-km hike), after the second day (consisting of a combination of calisthenics, aerobics, strength, and resistance exercises), and after 24 hours of rest, blood samples were collected and fasting plasma levels of adiponectin, leptin, and LDL(-) were measured.
Results showed that plasma leptin concentration (ng/dL) in both groups significantly decreased (p = 0.001) with training (for proanthocyanidin group, leptin decreased from 6.0 +/- 1.4 before exercise to 0.8 +/- 0.1 after second day of exercise; for placebo, leptin decreased from 7.1 +/- 1.4 before exercise to 1.2 +/- 0.2 after second day of exercise). For the proanthocyanidin group, relative to the control group, a significant elevation in plasma adiponectin concentration (ng/dL) was reported after 24 hours of recovery (21.4 +/- 1.5 vs. 16.6 +/- 1.3, respectively; p = 0.02), along with a significant exercise x supplementation interaction (p = 0.033). After 24 and 48 hours of intense exercise and after 24 hours of rest, plasma LDL(-) concentration (U/L) in the proanthocyanidin group was found to be lower, in comparison to control (0.5 +/- 0.1 vs. 1.9 +/- 0.1, 1.3 +/- 0.1 vs. 3.4 +/- 0.3, 2.4 +/- 0.3 vs. 3.6 +/- 0.2, respectively; p < 0.001), and a significant interaction between exercise and supplementation was reported (p = 0.001). Furthermore, for the proanthocyanidin group only, a significant negative correlation was found between plasma LDL(-) and plasma adiponectin concentration in the period following 24 hours of rest (r = -0.41, p = 0.04).
Taken together, findings indicate that an acute dose of proanthocynaidin prior to exercise is sufficient to increase plasma adiponectin concentration and reduce the oxidative action of LDL(-) after 24 hours of post-training rest. Evidence suggests that the powerful antioxidant capacity of polyphenols may offer important cardioprotective effects for individuals involved in strenuous physical training. The unexpected decrease in leptin concentration may represent metabolic adaptation to intense physical activity, but this finding warrants further study.
Source: Goncalves MC, Passos MCF, de Oliveira CF, et al. Effects of proanthocyanidin on oxidative stress biomarkers and adipokines in army cadets: a placebo-controlled, double-blind study. Eur J Nutr. 2017; 56(2): 893-900. DOI: 10.1007/s00394-015-1137-1.
© Springer-Verlag Berlin Heidelberg 2015
Posted July 24, 2018.
References:
- Davison G. Antioxidant supplementation and immunoendocrine responses to prolonged exercise 2006.
- Roupas ND, Mamali I, Maragkos S, et al. The effect of prolonged aerobic exercise on serum adipokine levels during an ultra-marathon endurance race. Hormones (Athens). 2013;12(2):275-282.
- Rosenbaum M, Leibel RL. The role of leptin in energy homeostasis in humans. Journal of Endocrinology. 2014:JOE-14-0358.
- Mäestu J, Jürimäe J, Jürimäe T. Effect of heavy increase in training stress on the plasma leptin concentration in highly trained male rowers. Hormone Research in Paediatrics. 2003;59(2):91-94.
- Katsuki A, Suematsu M, Gabazza EC, et al. Increased oxidative stress is associated with decreased circulating levels of adiponectin in Japanese metabolically obese, normal-weight men with normal glucose tolerance. Diabetes research and clinical practice. 2006;73(3):310-314.
- Sanchez-Quesada JL, Benítez S, Ordóñez-Llanos J. Electronegative low-density lipoprotein. Current opinion in lipidology. 2004;15(3):329-335.
- Matsuura E, Hughes GR, Khamashta MA. Oxidation of LDL and its clinical implication. Autoimmunity reviews. 2008;7(7):558-566.
