Vitamin C

• Vitamin C keeps you from getting sick
• Vitamin C supports immune system
• Vitamin C helps prevent stress fractures
• Vitamin C prevents bruising
• Vitamin C speeds recovery
• Vitamin C helps supports hemoglobin production
• Vitamin C helps recovery of tendons
• Vitamin C helps reduce asthma

Vitamin C is a water-soluble, essential nutrient that is part of numerous biological functions in the body.  Vitamin C is also known as ascorbic acid aka ascorbate.  Vitamin C is the primary water-soluble, non-enzymatic antioxidant in your blood and in tissues. Your body cannot make vitamin C.  As a water-soluble vitamin, your body cannot store it, making it important to have vitamin C regularly in your diet or through a supplement. Antioxidant means that vitamin C may prevent or delay some types of cell damage.  It is a well-known supplement, particularly as an antidote to the common cold. 

Historically, the importance of vitamin C for health was established when it was discovered that fresh fruit and vegetables prevented and even cured scurvy, a disease that results from a deficiency in vitamin C (Sauberlich, 1997; Dresen et al, 2023).  Vitamin C deficiency is associated with a plethora of symptoms, including weakness, fatigue, irritability, weight loss, hair and tooth loss, bruising, anemia, rough skin, joint pain and swelling, slow wound healing, and respiratory infections (Banhegyi et al, 2014; Frei et al, 2012; Grosso et al, 2013). 

Even now, vitamin C deficiency (defined as <11 μmol/L) is the fourth leading nutrient deficiency in the United States (Schleicher et al, 2009; US Centers for Disease Control; Hemila, 2017; Carr & Maggini, 2017)

Vitamin C is particularly important to exercise metabolism and exercise immunology (Peake, 2003; Margaritis & Rousseau, 2008).  Beyond its role as a potent antioxidant, vitamin C is a required cofactor in the biosynthesis of collagen, elastin, and carnitine.  Carnitine is a molecule that helps transport fatty acids into the mitochondria for energy production (Arrigoni & De Tullio, 2002; Carlsohn et al, 2020; Brancaccio et al, 2022).

The organs with the highest concentration of ascorbate are the adrenal glands, the brain, the liver, and in terms of size, the skeletal muscle with a concentration of 35 mg/kg (Richelle et al, 2006).

Collagen

Collagen is the most abundant structural protein that supports skin and connective tissue such as tendons and ligaments.  Without collagen, blood vessels, tendons, and skin become fragile, which can lead to bleeding, and weakening of bones that can subsequently lead to fractures.  As an example, stress fractures may reflect a lack of vitamin C.  Vitamin C is required for the making of collagen in the body contributing to the strength and integrity of joints and muscles, which is essential for the success of any athlete. (Carlsohn et al, 2020; Brancaccio et al, 2022).  

Tendinopathy is the general term used for both tendinitis and tendinosis. The fundamental molecular component of tendons is type I collagen.  Tendinopathy is estimated to be about 30–50% of all sports injuries. Treatment with vitamin C accelerated Achilles tendon healing (Omeroglu et al, 2009) and significantly improved tendon resistance and reduced scarring after 6 weeks of treatment in an animal model with tendinopathy (Hung et al, 2013).

98 patients with tendinopathy, Achilles, patellar and lateral epicondyle tendon, were given Tendoactive^® containing 435 mg of mucopolysaccharides, 75 mg of collagen type i and 60 mg of vitamin C (equivalent to 2 capsules per day) for 90 consecutive days and were followed up monthly during the study period. There was a significant reduction in pain at rest and during activity for all three types of tendinopathy. On day 90, improvement from baseline was 38% for the Achilles group, 46% for the patellar group, and 77% for the epicondyle group.  Simultaneous to the clinical improvement, there was a reduction of the tendon thickness; 12% in Achilles, 10% in patellar tendon and 20% in the lateral epicondyle tendon (Arquer et al, 2014).

A recent review of the efficacy of vitamin C for tendinopathies showed that Vitamin C supplementation, alone or in combination with other products, increases collagen synthesis with a consequent improvement in the patient’s condition. On the other hand, vitamin C deficiency is associated with a decrease in collagen synthesis, hindering the tendon repair process (Noriega-Gonzalez et al, 2022).  Furthermore, vitamin C also enhances collagen gene expression in fibroblasts contributing to the strength and integrity of joints and muscles.

Healthy active male collegiate athletes were recruited from the University of California Davis football (n = 18) and rugby (n = 19) teams and Reserve Officer Training Corps (ROTC) elite training group (n = 13). They took vitamin C-enriched collagen, 20 grams of collagen with 50 mg of vitamin, or a placebo, daily one hour prior to training over a three-week period. Maximal isometric squats, countermovement jumps, and squat jumps were performed on a force plate at the same time each testing day (baseline, Tests 1, 2, and 3) to measure RFD (rate of force development) and maximal force development. The collagen and vitamn C supplementation improved RFD in the squat and countermovement jump demonstrating that consumption of 20 g of vitamin C-enriched collagen in conjunction with combined heavy strength and power training resulted in improved eccentric force capacity.  They concluded that HC + C augmented collagen synthesis resulted in improved matrix mechanics, creating stiffer, more dense muscle ECM and tendons that transmit force faster, a key factor for explosive muscle performance (Lis et al, 2021).   

Vitamin C also plays a vital role in wound healing, making it an important nutrient when recovering from injury (De Oliveira et al, 2019; Rossi, 2017) Wound healing necessitates the creation and build-up of collagen; in wounded tissue, new tensile strength is provided by subsequent cross-linking of the fibers. Studies evaluating the effects of vitamin C on fracture healing reported an acceleration in collagen synthesis when compared with control groups.  Duygulu  et al, 2007; Sarisozen et al, 2002; Yilmaz et al, 2001).  One study reported that there were no significant differences between the vitamin C and control groups for fracture healing (Giordano et al, 2012).

Aids Iron Absorption

We all know the importance of iron for athletes.  Often people eat enough iron but struggle to absorb the mineral.  Vitamin C is a powerful enhancer of the absorption of nonheme iron, the form of iron found in plant foods (Lynch & Cook, 1980; Lane & Richardson, 2014; O’Dwyer, 2023). This process is important for athletes as it reduces the chance of anemia, defined as a low level of hemoglobin (red blood cells) the vital blood cells needed to transport oxygen around the body. If an athlete is deficient in Vitamin C, common symptoms such as delayed wound healing, fatigue, weakness, aching joints, and impaired aerobic performance may show themselves as an effect of anemia. 

Asthma

Asthma is a chronic lung disease that makes it difficult to breathe.  The airways that connect your windpipe to your lungs are called bronchi.  Sometimes the muscles that line your bronchi tighten and cause your airways to narrow, which is called a bronchospasm. Asthma can be induced by exercise, referred to as EIB (Exercise Induced Bronchospasm). Vitamin C helps reduce the impact of asthma when exercising (Devereux et al, 2005; Gilliland et al, 2003).

One of the most important symptoms of asthma is airway hyperresponsiveness (AHR) to various stimuli. A deficiency in vitamin C leads to an increased AHR (Soutar et al, 1997]).  Supplementing with vitamin C decreases AHR (Trenca et al, 2001; Tecklenburg et al, 2007).

Asthmatic patients generally have a lower intake of vitamin C than other subjects (de Luis et al, 2006; Misso et al, 2005). Vitamin C intake is negatively associated with the risks of asthma (Huang & Pan, 2001)

A 2013 review identified three studies showing that vitamin C before exercise (a 0.5-g dose on two subsequent days in one trial, a single dose of 2 g in the second trial, and 1.5 g daily for two weeks in the third trial) significantly reduced the exercise-induced decline in FEV (Forced Expiratory Volume), which is a measure of lung function (Milan et al, 2013).  Both acute and chronic vitamin C supplementation for exercise-induced asthma improves respiration markers (Hemila, 2013;  Hemila, 2013).

Immune System Support

The immune system is a multifaceted and sophisticated network of specialized organs, tissues, cells, proteins, and chemicals, which has evolved in order to protect you from a range of pathogens, such as bacteria, viruses, fungi, and parasites, as well as cancer cells. A strong immune system defends against infections and diseases (Parkin & Cohen, 2001).

Nutrition plays a key role in the immune system.  All immune cells require a variety of vitamins and minerals and essential fatty acids to function. (Calder, 2020).  Vitamin C is a crucial vitamin for the immune system (Maggini, Wintergerst et al, 2007; Webb & Villamor, 2007; Pauling, 1970; Carr & Maggini, 2017; Li et al, 2022).  Vitamin C has been shown to stimulate both the production and function of leukocytes (white blood cells), especially neutrophils, lymphocytes, and phagocytes, which are critical immune system cells (Jariwalla & Harakeh, 1996; Kennes et al, 1983; Panush et al, 1982; Prinz et al, 1977; Vallance, 1977; Anderson et al, 1980; Levy et al, 1996; Evans et al, 1982). 

Prolonged and intensive exertion causes numerous changes in immunity. During and immediately following exercise, there is a rapid release of lymphocytes (a type of immune cell) into circulation, which gradually decrease (Nieman et al, 1995).  This response to exercise has been referred to as the ‘Open Window’ hypothesis, believing this represented a suppression of the immune system (Nieman, 1994; Kakanis et al, 2010).  This ‘Open Window’ was associated with an increased incidence of URTI (Upper Respiratory Tract Infections) symptoms following participation in ultramarathon events (Peters & Bateman, 1983; Peters et al, 1993; Peters et al, 1996).

Subsequent research has shown that those immune cells are not lost or destroyed, but have moved to sites in the body that are more likely to become infected ( xxxx).  And other research has shown that all forms of exercise, at the same duration, shows a similar pattern of immune response, indicating that it is not necessarily prolonged exercise that creates infection risk (Ekblom et al, 2006; Arroyo et al, 2022).

Upper Respiratory Tract Infection (URTI), the Common Cold

There has been interest in vitamin C for the common cold since the middle of the 20th century (Ruskin, 1938; Markwell, 1947; Miegl, 1958; Bessel-Lorck, 1959; Ritzel, 1961; Ritzel, 1976]. In 1971, Linus Pauling carried out a meta-analysis of vitamin C and the common cold and found very strong evidence that vitamin C decreased morbidity caused by the common cold (Pauling, 1971; Hemila, 1997; Hemila, 2006].

Extensive research has been completed showing that vitamin C reduces the length and severity of illness.  A meta-analysis of the effectiveness of vitamin C and childhood colds showed that children treated with vitamin C had fewer URTI, their length of illness was shorter and they were less contagious than the control group (Saeed & Abdelrahim, 2023).  Another meta-analysis showed that children under 6 years of age benefit from vitamin C supplementation associated with ear infections (Vorilhon et al, 2019). One trial found a 26% reduction in common cold duration after taking 2 grams/day of vitamin C regularly (Coulehan et al, 1974). 

A review of the research showed that 0.2 g/day found that vitamin C supplementation shortened the duration of colds by 9.4%.  If the infection has already begun, higher doses of 200-2000 mg/day to compensate for the increased metabolic demand were effective in reducing the duration of a cold by 8% and reduced the severity of symptoms (Hemila & Chalker, 2013). 

Vitamin C has been shown to reduce the severity of the common cold by about 60% (Ritzel, 1961; Sabiston et al, 1974; Hunt et al, 1994).   Supplementation of individuals who had an inadequate vitamin C status (i.e., <45 μmol/L) also decreased the incidence of the common cold (Johnson et al, 2014)

Long-term bias against vitamin C and other vitamins has been documented (Hemila & Chalker, 2022; Louhiala & Hemila, 2014; Goodwin & Tangum, 1998).  Two influential reviews on vitamin C and the common cold in the 1970s concluded that vitamin C is useless for colds, and those reviews were extensively cited (Chalmers et al, 1975; Dykes & Meiers, 1975; Truswell, 1986). However, the reviews were shown to be seriously flawed and have been debunked (Hemila, 1996; Hemila & Herman, 1995; Hemila, 1996). 

The most recent review of vitamin C found that it has a significant benefit for the common cold.  Compared to a placebo, vitamin C significantly decreased the severity of the common cold by 15%.  Given the low cost and safety of vitamin C, the 15–26% decrease in cold severity may justify regular vitamin C administration (Hemila & Chalker, 2023). 

Tip – You have to take enough vitamin C based on your body, your diet and your athletic effort.

Athletes and URTI

The immune system is very responsive to exercise, and physical activity can prevent and reduce the severity of respiratory infection symptoms (Nieman & Sakaguchi, 2022). 

Regular moderate exercise training stimulates the innate immune system and decreases URTI risk, while sustained and intense exertion increases URTI risk by inducing immune dysregulation, inflammation, and oxidative stress (Nieman, 2009; Shephard et al, 1995; Davis et al, 1997; Matthews et al, 2002; Kostka & Praczko, 2007; Fondell et al, 2011; Nieman et al, 1990; Nieman et al, 1993).

A 1-year epidemiological study of 547 adults showed a 23% reduction in URTI risk in those engaging in regular versus irregular moderate-to-vigorous physical activity (Matthews et al, 2002). Active Swedish people aged 20-60 were followed for fifteen weeks in the winter/spring.  Physical activity was associated with an 18% reduced risk of an URTI for both men and women (Fondell et al, 2010).  Adults, aged 18-85, men and women were followed for twelve weeks in Wisconsin during the fall and winter.  Those who were active more than 5 days per week with aerobic exercise showed 32% to 41% reduced severity of URTI (Nieman et al, 2011).  A high frequency of leisure-time exercise (≥3 days/week) was associated with a 26% reduced risk of having at least one episode of the common cold (OR, 0.74; 95% CI, 0.55–0.98) compared with a low frequency group (< 4 days/month). A review of data bases showed that exercise reduced the severity of respiratory infection symptoms (Grande et al, 2020).

However intense and prolonged exercise such as marathon and ultramarathon races can create acute physiological stress that negatively impacts immunity for several days. During exercise, our muscles produce increased amounts of ROS and RNS (Reactive Oxygen Species and Reactive Nitrogen Species). Excess ROS and RNS can promote damage to proteins, lipids, and DNA, and potentially impair physical performance, recovery, and immune function. Thus, athletes may become susceptible to infections after rigorous training or competitive events (Nieman & Wentz, 2019; Northoff & Berg, 1991; Nieman, 1985; Peake et al, 2015; Peake et al, 1985). The tissue recovery process has a high energy demand and therefore the immune system cannot be physiologically effective (Spirandelli et al, 2020).

Numerous studies document the impact of intense exercise on infection risk.  Ultra-marathoners often suffer from upper respiratory infections after a race. In the “Two Oceans Marathon” held in Cape Town, South Africa, more than 30% of runners suffered from upper respiratory tract infections, mainly affecting the faster runners (Peters and Bateman, 1983; Peters et al, 1993). It has been demonstrated that ultra-marathoners are more likely to suffer from an infection than runners over shorter distances (Castell, 1996). Research on adolescents showed that 24 weeks of high-intensity exercise reduced the number of essential immune cells, while low-intensity exercise did not (Tenorio et al, 2018). An ultra-marathon seems to lead to a depression of the immune function with an increased prevalence of infections of the upper respiratory tract. (Nieman et al, 2005; Nieman et al, 2011; Knechtle & Nikolaidis, 2018).

The wealth of acute illness epidemiologic data collected during international competition events has revealed that 2%–18% of elite athletes experience illness episodes, with higher proportions for females and those engaging in endurance events (Nieman, Dumke et al, 2005; Pacque et al, 2007; Nieman, 2007; Alonso  et al, 2012; Palmer-Green & Elliott, 2015; Svendson et al, 2015; Nieman & Wentz, 2019). 

Studies of athletes have shown that vitamin C improves their immunity and would protect from illness.  Studies on physically active people, in a skiing camp, in long-distance running and in military camp, found that vitamin C supplementation halved the incidence of colds in those groups (Ritzel et al, 1961; Sabiston & Radomski, 1974; Peters et al, 1993; Hemila, 1996b; (Hemila & Chalker, 2013).  Peters et al. (1993) showed that 600 mg/day of vitamin C for three weeks prior and two weeks after a 90 km ultramarathon reduced the incidence of URI symptoms.  68% of those who took the placebo reported symptoms, while only 33% of those who took vitamin C reported symptoms.  In a study of adolescent competitive swimmers who took 1 g/day of vitamin c, there was a significant decrease in the duration and severity of URI episodes in the male swimmers where the illness duration was halved, but not for the female swimmers (Constantini et al, 2011).  Some evidence from randomized controlled trials indicates that vitamin C supplementation (500-2000 mg per day) can prevent exercise-induced bronchoconstriction (Hemila, 2014).

Runners were randomly assigned to received either received ascorbic acid 250 mg/day, beta-carotene 4.5 mg/day or a placebo for the six weeks prior to a 90 km ultra marathon footrace, and for two weeks after the event.  The non-running control with which the runner was paired received the identical supplement.  The athletes, who took ascorbic acid (vitamin C) supplementation experienced significantly fewer URTI's than those on placebo supplementation. All of the controls (100%) and 80% of the athletes who developed severe URTI's were on placebo medication (Moolla, 1996).

Some studies have found no benefit from supplementing with vitamin C and immunity. A study of marathon runners and sedentary subjects were randomly assigned to receive either 1,000 mg vitamin C or a placebo daily for two months before and one month after a marathon race.  No treatment differences were found for URTI incidence.  Training, such as pace and number of competitive events, and female gender were more influential than vitamin C supplementation in explaining the incidence of URTIs. (Himmelstein et al, 1998).  Ultramarathon runners took 1500 mg/day of vitamin C for 7 days before the race and there were no differences in the oxidative and their immunity markers when compared to the placebo group (Nieman et al, 2002). 

More recently, Kim et al (2022) carried out a large randomized, double-blind, placebo-controlled trial in 1,444 Korean soldiers, 695 of whom received vitamin C (6 g/day) for 30 days. They showed that the vitamin C group had a 0.80-fold lower risk of getting the common cold compared to the placebo group (n = 749).

In summary, moderate physical activity itself can prevent and reduce the severity of respiratory infection symptoms (Nieman & Sakaguchi, 2022) but prolonged and intense training and competition can reduce immunity, leading to an increased risk of upper respiratory tract infections ((Nieman et al, 2005; Nieman, Henson et al, 2011; Knechtle & Nikolaidis, 2018). There is robust research showing that vitamin C helps reduce the severity and duration of respiratory infections in general (Hemila & Chalker, 2023), and specifically the research shows that vitamin C helps improve immunity in endurance athletes, reducing how sick they will get.

 

Performance

Intense exercise can increase the production of free radicals or reactive oxygen species (ROS) and nitrogen species (RONS), which can hinder muscular contractions and cause muscle fatigue and reduced performance (Teixeira et al, 2014; Merry & Ristow, 2016; McLean et al, 2022).  This inflammatory state often results in the presence of muscle soreness and decreased functionality (Powers  et al, 2011) which can impact the performance (Peternelj & Coombes, 2011), and lead to the abandonment of regular exercise practice by beginners (Howatson & Van Someren, 2008).

To combat muscle damage and fatigue and enhance performance, athletes often consume antioxidant supplements, on the assumption that the RONS represents a “biochemical accident” that can be prevented by antioxidants, and that RONS fulfill no beneficial physiological functions.  Indeed, the American College of Sports Medicine suggests that around half of athletes use vitamin supplements to maintain fitness and boost stamina (Viitala et al, 2004) yet, from this percentage, another 50% of elite endurance and male collegiate athletes consumed doses of antioxidant supplements daily that were higher than the recommended daily allowance (RDA) (Li et al, 2022).

Vitamin C supplementation has been suggested to improve athletic performance due to its antioxidant effects, its ability to regenerate other antioxidants, and its potential to improve immune function (Peternelj & Coombes, 2011; Higgins et al, 2020).  Some studies have found that vitamin C supplementation may improve antioxidant capacity, reduce muscle damage, and reduce inflammation in athletes (Poulab et al, 2015; Davison & Gleeson, 2007; Thompson et al, 2001; Righi et al, 2020 ).  However, these markers were not affected by vitamin C supplementation in other study (Bahlooli et al, 2012).

However, while vitamin C improves immunity, it has not been found to improve performance. 

Senturk et al, (2005) supplemented athletes with 0.8 g of VC daily for 2 months and found no significant change in cycle time to fatigue.  In another study 36 male PE students, average age 22.48, were sorted into three groups, taking 500 mg of vitamin C, 1000 mg of vitamin C or a placebo for three weeks.  They took the supplements between 11-1:00 every day. They were evaluated at the end of three weeks, between 5 and 8 pm. There was no improvement in those who took the vitamin C in either anaerobic or aerobic power (Jourkesh et al, 2011).

Another study concluded that vitamin C may have a positive antioxidant effect but does not directly improve athletic performance in marathon runners.  Female runners were given vitamin C (1 g), blackcurrant juice (15 mg VC, 300 mg anthocyanins) and placebo to determine the impact on training progression, incremental running test and a 5-km time-trial performance over 3 weeks and 3 days, separated by a washout.  There was a likely harmful effect on mean running speed during training when taking vitamin C (Braakhuis et al, 2014; Braakhuis et al, 2015).

100 male volunteers were measured for their vitamin C levels and their V02Max performance.  Those with low intake of vitamin C had significantly lower V02Max levels at baseline.  After 30 days of supplementing with 999 mg of vitamin C, their V02Max levels improved and their levels of oxidative stress significantly improved. This study showed for the first time that low vitamin C concentration is linked with decreased physical performance and increased oxidative stress and that vitamin C supplementation decreases oxidative stress and might increase exercise performance only in those with low initial concentration of vitamin C (Paschalis et al, 2016).

What the research has concluded is that oxidative stress is actually important and necessary for regulating physiological signaling pathways, protein synthesis, and it improves the antioxidant system, all of which promote training adaptation. (Powers et al. 2010; Handayaningsih et al. 2011; Azizbeigi et al. 2013).  Indeed, it appears that oxidative stress is necessary to initiate and regulate the body’s adaptive responses to exercise (Powers & Schrager, 2022; Bouviere et al, 2021].  It is likely that the negative effects of high doses of antioxidant supplementation exceed their potential benefits (Reid, 2016).  When the inflammation is dampened too much, performance is impaired.

It is now understood that the oxidative stress serves to regulate both acute exercise-induced responses, such as muscle contractile function, glucose uptake, blood flow and bioenergetics as well as exercise-induced adaptations (mitochondrial biogenesis, muscle hypertrophy, angiogenesis and redox homeostasis) Margaritelis, Pasxhalis et al, 2020).  Additionally, ROS generated by exercise also signal for improvements to the larger antioxidant system (Powers et al. 2010; Handayaningsih et al. 2011; Azizbeigi et al. 2013).

Reactive species are essential for normal force production in skeletal muscle (Powers & Jackson, 2008; Reid, 2008), for the development of training-induced adaptation in endurance performance (Ristow et al, 2009; Wray et al, 2009), and for the induction of endogenous antioxidant systems (Gomez-Cabrera et al, 2005; Gomez-Cabrera, et al, 2008; Powers et al, 2010; Handayaningsih et al,  2011; Azizbeigi et al, 2013).

Research shows that the degree of physiological adaptation (i.e., maximal oxygen uptake (VO₂ max), time trials, and Wingate tests) was greater in the groups with  “moderate” and “high” levels of inflammation groups than in the “low” exercise-induced oxidative stress group (Margaritelis et al, 2017). , the greater production of RONS leads to an increase in the endogenous antioxidant system capacity (Yavari et al, 201516), which results in adaptations and muscle remodeling (Coffey & Hawleey, 2007). 

Khassaf et al. indicated that chronic vitamin C supplementation attenuated protective adaptations in response to exercise-induced RONS at a dose of 500 mg per day (Khassaf et al, 2003).

A double-blind randomized controlled trial by Gomez-Cabrera et al. compared the effectiveness of eight weeks of endurance training in a group that was supplemented with an oral dose of 1 g of vitamin C as compared to a placebo treated group. Athletes not supplemented with vitamin C had an eleven percent greater improvement in VO_2max, suggesting that vitamin C supplementation prevented crucial cellular adaptations to exercise.  It is possible high doses of single antioxidant nutrients may be detrimental to athletic performance, interfering with mitochondrial biogenesis and hampering muscle force generation and exercise recovery overall (Gomez-Cabrera et al., 2008).  By and large the research indicates that vitamin C does not enhance performance (Senturk et al, 2005; Jourkesh et al, 2011; Braakhuis et al, 2014; Paschalis et al, 2016) though one study found no impairment (Roberts et al, 2011).

The goal for any athlete now is to determine the amount of anti-oxidant, such as vitamin C to take for immune protection, while not hindering the training adaptations that lead to improved performance (Vargas-Mendoze et al, 2021; Ji et al, 2020; Reid, 2016).

Dose

With the new understanding of the role of RONS (Reactive Oxygen and Nitrogen Species) in helping training adaptations, there is an ongoing discussion as to how much vitamin C would be beneficial.  The most commonly used marker of vitamin C status is plasma ascorbate concentrations – how much is measured in a blood test.

Based on the available data it appears that a plasma concentration of vitamin C of about 70 μmol/L appears to be optimal for health (Lykkesfeldt & Poulsen, 2010) and the vitamin C status of muscle tissue (Carr et al, 2013).  This means that a daily intake of about 200 mg of vitamin C should achieve this status (Frei et al, 2012) and might serve as an appropriate ‘guidance’ for athletes.

Tip-When you take vitamin C, it only lasts 4-6 hours in your system.  So if you are going to test for your vitamin C levels, do so approximately after you have ingested it.

Vitamin C, being a small water-soluble molecule, is readily filtered by the kidneys; therefore, any excess not required by the body is readily excreted in urine (Lykkesfeldt & Tveden-Nyborg, 2019). Thus, vitamin C has no known upper limit (UL) for toxicity, although some authorities have set ULs of 1–2 g/day (Carr & Lykkesfeldt, 2021). Adverse side effects are mostly related to gastrointestinal disturbance due to unabsorbed vitamin C from high gram doses passing through the gastrointestinal tract (Scientific Committee, 2006).

Tip – For extensive detailed reading on the topic of Vitamin C, suggest you go to https://lpi.oregonstate.edu/mic/vitamins/vitamin-C

If you are very ill such as with covid, recent research suggests mega dose of 3-4 grams of vitamin C per kg body weight, over a period of 7 hours or .5 grams per hour.   Your body can tolerate 3 grams per hour without bowel distress.

Adults

The suggested recommended daily allowance (RDI) of vitamin C for adults is based on the intake necessary for a 70 kg/154 pounds individual to obtain a plasma concentration of about 50 µmol/L, that is, an RDI of 90 mg/day. If you weigh more or less than 70kg/154 pounds, then add or subtract 10 mg/per day of intake per 10 kg/22 pounds to your RDI to obtain the vitamin C necessary to achieve the target plasma concentration of 50 µmol/L (Carr & Lykkesfeldt, 2023).

A plasma concentration below 50 µmol/L indicates that tissues will also be depleted (Carr et al, 2013).  The plasma concentration will not rise until the tissues are no longer depleted, as vitamin C is preferentially loaded into depleted tissue first (Lindblad et al, 2013p; Lykkesfeldt & Tveden-Nyborg, 2019).

 

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