Quick Hit Summary
Vitamin C is a popular antioxidant that many athletes take to assist athletic performance/recovery. However, very little evidence supports this practice. In most studies involving endurance athletes, Vitamin C has not been shown to positively influence inflammation, muscle damage or oxidative damage. In fact, the reverse has been shown; high doses of vitamin C (1g/day) have actually been shown to enhance post workout inflammation. With respect to resistance training, lower doses (200-400 mg/day) may attenuate loss of strength 24 hours post workout. However, larger doses appear to have no effect. Based off current research, I cannot recommend taking high dose Vitamin C supplements. Rather, I recommend receiving it from whole food sources and as part of a balanced multi-vitamin.
Dietary Antioxidants- Vitamin C
Figure 1 The chemical structure of vitamin C11.
Previously, I’ve discussed what antioxidants are and how they function in the body (Understanding Antioxidants, Free Radicals & Oxidative Damage). Additionally I discussed the main lipid soluble antioxidant that we obtain from our diet, Vitamin E (Vitamin E- Athletic Performance/Recovery & Vitamin E- General Health Issues). Now, I’d like to shift our attention and focus on another dietary antioxidant, Vitamin C.
About Vitamin C
In contrast to vitamin E, vitamin C is a water soluble vitamin and is therefore not found in lipids. Vitamin C works not only to deactivate free radicals, but also to “recharge” vitamin E that has already used up its antioxidant capabilities1.
Vitamin C & Athletic Performance/Recovery
Similar to vitamin E, researchers have looked at vitamin C’s ability to aid physical performance. As mentioned in my article on vitamin E, many studies have already focused on the combinatorial effect of taking these two antioxidants (along with beta-carotene) together. Thus, I will focus on studies involving only vitamin C or studies where vitamin C was used in large relative quantities compared to the other antioxidants.
Endurance Training
Various aerobic based trials involving vitamin C supplementation have been conducted. Nakhostin-Roohi et al. investigated the effects of taking a single dose of vitamin C (1000 mg), 2 hours before completing a 30 minutes treadmill run completed at 75% VO2max2. The study included 16 untrained college aged men. Results indicated that no differences were present in lipid oxidation, muscle damage, and inflammatory markers at any point (measured pre-exercise, immediate post exercise, 2 and 4 hours post exercise) between those taking the vitamin C supplementation vs. the placebo. In contrast to the work completed by Nakhostin-Roohi et al., other researchers have studied the effects of vitamin C supplementation in conjunction with more extreme endurance running. Using a sample of 28 trained runners, covering a large age range (20-70 years old; mean ages in 40’s), Palmer et al. examined the effects of taking vitamin C (500mg, 3x/day) 7 days prior to and during an ultramarathon event3. One of the key variables measured was the effect that vitamin C had on oxidative damage. Upon obtaining and measuring lipid hydroperoxide (marker of oxidative stress), it was determined that vitamin C had no protective effect on oxidative damage.
More alarming than having no effect, within the past 10 years, multiple studies have been published indicating that high doses of vitamin C supplementation may actually increase oxidative and inflammatory damage in endurance athletes. In a study involving 7 trained cyclists, Bryant et al. examined how a vitamin C supplement (1g/day) influenced lipid oxidation and lactic acid concentration following a 90 minute cycling protocol (60 minutes steady state riding, immediately followed by a 30 minute performance test)4. Participants served as their own controls, taking a placebo for 2 weeks followed by a cycling test. Upon completion, they started taking the vitamin C supplements (1g/day) for another 2 weeks before completing a 2nd cycling test. In comparison to their results obtained while taking the placebo, vitamin C supplementation did not improve post exercise lactic acid concentrations. Furthermore, following the vitamin C trial, athletes had significantly higher levels of oxidative damage.
Similar results of oxidative and inflammatory damage have been obtained following extreme endurance events. Peters et al. reported that vitamin C dampens the rise in anti-inflammatory cytokines in those running a ~55 mile ultramarathon5. In the study, 29 runners were randomly assigned to 1 of 3 groups:
- Group A- 3 Placebo pills
- Group B- 2 placebo pills & 1 vitamin C pill (500 mg)
- Group C- 3 vitamin C pills (1500mg)
Each group took their assigned tablets for a total of 10 days (7 days prior to, day of race, 2 days after race). Blood levels of anti-inflammatory cytokines (chemicals that regulate inflammation) were measured 30-60 minutes after the completion of the race. Results indicated that participants receiving 1500 mg of vitamin C had significantly lower amounts of anti-inflammatory cytokines than individuals receiving < 500mg vitamin C. In other words, those taking 1500 mg of vitamin C had greater potential for inflammation due to a lack of anti-inflammatory chemical messengers.
In a 2nd study published by Peters et al., the effect of vitamin C on pro-inflammatory markers (ie-inflammatory provoking agents) was examined in a different set of ultramarathon runners6. Results indicated that supplementing 16 ultramarathon runners with vitamin C (500mg; 2x/day) or placebo for 10 days (same protocol as above) actually increased pro-inflammatory markers. In addition, C-reactive protein (an acute phase marker of inflammation) was significantly higher in the vitamin C group vs. placebo at 0.5. 24 and 48 hours post race.
Resistance Training
In contrast to aerobic exercise which primarily generates free radicals via respiration (breaking down fat/carbs for energy), eccentric based training causes free radical damage in a slightly different way. With eccentric training, small tears are created in muscle tissue. In turn, free radicals are produced by various cells responsible for cleaning up and repairing the damaged muscle fibers7. Jakeman & Maxwell randomly assigned 24 physically active college aged individuals into groups that received a placebo, 400 mg vitamin E, or 400 mg vitamin C8. The researchers sought to find out if taking either of the antioxidants impacted muscle recovery following an eccentric based exercise session involving box stepping (box set at height equal to that of knee cap). Each group took their assigned supplement for 21 days prior to and 7 days following a bout of box stepping. In comparison to both the placebo and vitamin E, results indicated that supplementing with vitamin C significantly attenuated the loss in muscle strength during the first 24 hours following the exercise session.
In a more recent study, researchers at the University of Florida, measured the effects of giving a vitamin C and NAC (another antioxidant) supplement to 14 untrained males (mean age 24.4) following the completion of eccentric arm curls (3×10; 80% of eccentric 1RM)9. The supplements were individualized such that each participant (in the experimental group) received 5.7 mg vitamin C and 4.53 mg of NAC per pound of bodyweight. For reference, a 150 lb person would consume 855 mg vitamin C and 680 mg NAC. Individuals consumed their respective supplement immediately after exercise and during ensuing 7 days. Upon examining the data, researchers noted that those taking antioxidants had significantly increased unbound iron (which is a source of free radical generation) levels in their blood on days 2, 3, and 4 vs. those in the placebo. They hypothesized that the antioxidants directly interacted with circulating proteins that store iron (ie- ferritin), allowing it to be freely released into the serum (blood). Likewise, in comparison to those taking the placebo, the vitamin C + NAC group had significantly higher lipid oxidation levels on day 2. Although greater oxidative damage was seen in the antioxidant group, it should be noted that both groups had similar decreases in range of motion and increased muscle soreness when compared to pre-exercise values.
Bryer & Goldfarb reported that taking 3g vitamin C/day (vs. placebo) for 2 weeks prior and 4 days following eccentric resistance training (70 eccentric elbow extensions) significantly reduced muscle soreness in 18 previously untrained men10. This decrease was present during the first 24 hours following the session, after which time the muscle soreness was the same between the groups. Despite having decreased muscle soreness during the first 24 hours, there was no difference in loss of muscle force or range of motion at any point of time in those taking a placebo vs. vitamin C.
The exact reason as to why Vitamin C did not attenuate the loss of muscle strength in Bryer & Goldfarb’s study10 as seen in Jakeman & Maxwell’s study8 is not completely understood. This may be indicative of an “upside down, U-shaped” curve with respect to vitamin C and muscle recovery. For example, small amounts of vitamin C (ie-placebo) result in the normal slow, recovery of muscle strength. When taking larger doses (400 mg) muscle strength recovery could be enhanced. However, once one reaches a certain level, performance decreases with increasing amounts of supplemental vitamin C.
Bottom Line
Overall, results obtained from studies involving vitamin C supplementation and exercise have been inconsistent. Many studies examining this relationship have indicated that vitamin C supplementation does not significantly reduce oxidative and inflammatory damage. In fact, larger doses may even enhance post-exercise oxidative damage. On the other hand, various evidence exist indicating that lower doses (200-400mg) or extremely large doses (3g) may provide some short term benefit following eccentric based exercise. However, more research is still needed to confirm this effect.
To my knowledge, there hasn’t been any research studying the long term effectiveness (>1-2 months) of vitamin C on muscle recovery and oxidative damage in athletic populations. As mentioned in my article on vitamin E, there has been one study indicating that vitamin C as part of an “antioxidant soup” improves aerobic metabolism in endurance trained athletes11. However, I haven’t read any study that has studied this phenomena using vitamin C alone.
Based off the research to date, I do not see a need to take high dose vitamin C supplements (please do not confuse this with taking a balanced multi vitamin-mineral complex that contains > 100% RDA value for vitamin C). Rather, I suggest receiving vitamin C from eating a wide variety of vitamin C containing foods (citrus, etc) and as part of a balanced multi vitamin-mineral complex.
Stay tuned for the conclusion of this article when we examine the potential role that vitamin C has on heart health, cancer, and those pesky common colds.
1 Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes: Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press, 2000.
2 Nakhostin-Roohi B, Babaei P, Rahmani-Nia F, Bohlooli S. Effect of vitamin C supplementation on lipid peroxidation, muscle damage and inflammation after 30-min exercise at 75% VO2max. J Sports Med Phys Fitness. 2008 Jun;48(2):217-24.
3 Palmer FM, Nieman DC, Henson DA, McAnulty SR, McAnulty L, Swick NS, Utter AC, Vinci DM, Morrow JD. Influence of vitamin C supplementation on oxidative and salivary IgA changes following an ultramarathon. Eur J Appl Physiol. 2003 Mar;89(1):100-7. Epub 2003 Jan 21.
4 Bryant RJ, Ryder J, Martino P, Kim J, Craig BW. Effects of vitamin E and C supplementation either alone or in combination on exercise-induced lipid peroxidation in trained cyclists. J Strength Cond Res. 2003 Nov;17(4):792-800.
5 Peters EM, Anderson R, Nieman DC, Fickl H, Jogessar V. Vitamin C supplementation attenuates the increases in circulating cortisol, adrenaline and anti-inflammatory polypeptides following ultramarathon running. Int J Sports Med. 2001 Oct;22(7):537-43.
6 Peters EM, Anderson R, Theron AJ. Attenuation of increase in circulating cortisol and enhancement of the acute phase protein response in vitamin C-supplemented ultramarathoners. Int J Sports Med. 2001 Feb;22(2):120-6.
7 Peake JM, Suzuki K, Coombes JS.The influence of antioxidant supplementation on markers of inflammation and the relationship to oxidative stress after exercise. Journal of Nutritional Biochemistry 18 (2007) 357–371.
8 Jakeman P, Maxwell S. Effect of antioxidant vitamin supplementation on muscle function after eccentric exercise.J Appl Physiol Occup Physiol. 1993;67(5):426-30.
9 Childs, A., et al. Supplementation with vitamin C and N-acetyl-cysteine increases oxidative stress in humans after an acute muscle injury induced by eccentric exercise. Free Radic Biol Med. 2001 Sep 15;31(6):745-53.
10 Bryer SC, Goldfarb AH. Effect of high dose vitamin C supplementation on muscle soreness, damage, function, and oxidative stress to eccentric exercise. Int J Sport Nutr Exerc Metab. 2006 Jun;16(3):270-80.
11 Accessed June 14, 2010 from: http://en.wikipedia.org/wiki/File:Ascorbic_acid_structure.png