Episode 29 – Vitamin C

Key Topic Covered

Random Fact: Human’s cannot make their own vitamin C


  • Vitamin C (vit C) will stay in our system for up to 24 hours.
  • It’s a water-soluble vitamin; absorbed and extreted through water molecules.
  • Humans lose vit C through sweating and urination. Therefore, it’s important to consistently consume.


  • Immune function: Neutrophils require vit C to help fight bacteria.
  • Decrease cold/ flu duration up to 25%.
    • For those dosing daily, then consuming higher amounts at the beginning of a cold.
  • Endurance athletes: 50% reduction in cold and flu symptoms, when supplementing with vit C.
  • Reduce inflammation: Vit C helps stabilise molecules (reactive oxygen species), by donating one of its chemical groups. This then reduces oxidation and inflammation in the body.
  • Endurance athletes are more likely to get sick. This is a concern at a professional level, as taking time off can significantly hinder performance in the long run.


  • RDI – 45mg/ day for both men and women; to prevent deficiency.
  • Vitamin C deficiency can result in a disease state called Scurvy.
  • The dose does depend on the individual’s lifestyle and how much inflammation they have. ie. Smokers and athletes will have high amounts of inflammation.
  • The average person will have between 70-85mmol of blood vit C.


  • Orange ~ 70mg
  • Therefore, by consuming 1 orange per day you’ll meet/ exceed requirements.
  • However, the research shows that only 6% of the population consumes their fruit and vegetable requirements.
  • Upper Limit – Orally consuming 1000mg/ day for both men and women.
  • 200mg/day will increase blood vit C to 90mmol.
  • 1200mg/day will increase blood vit C to 180mmol.
  • 3000mg/day will increase blood vit C to 220mmol.
  • Consuming more than 3000mg/day orally makes no difference to blood plasma concentration.

Down side too consuming above the upper limit?

  • There’s no research showing that it’s dangerous to consume more than the upper limit.
  • We’ve experimented consuming 3g, every 4 hours whilst sick and had no negative side effects.
  • Some people report GI upset, such as diarrhea. This is likely due to rapid consumption on the background of minimal intake.


  • Some studies have experimented with injecting 40,000mg IV to prevent cancer growth.
  • Mechanism: Once vit C donates some of its compounds, it establishes a structure similar to glucose. It starts to interrupt glucose uptake into cancer cells (cancer needs glucose to grow). As well as the anti-inflammatory role it plays.
  • In saying this, the research is mixed. Some suggest that vit C protects all the cells in the body (including cancerous) making chemotherapy less effective?!

Sport and Exercise

  • The body does produce reactive oxygen species during exercise. It uses this as a signalling pathway to recover and improve for next time.
  • The research shows that it can improve VO2 max by blocking the mitochondrial adaptations. However, additional antioxidants were used during these studies. So, it’s unclear whether vit C alone has these same benefits.
  • Reduce DOMS – This can allow one to train more, which can improve metabolic adaptations, outside of VO2 max.
  • Promote collagen synthesis – This can support tendon and ligament repair when adhering to the protocol.

Is Supplementing Just Making “Expensive Urine”?

  • There are transporters in the small intestine that transport vit C from small intestine into the blood. There can become “maxed out”.
  • It’s essentially an exponential curve that demonstrates how much vit C will be absorbed.
  • Yes, if you’re consuming higher dosages you will excrete some. However, your body does require supplementation to reach the max blood saturation levels.

Overall, we are lifters and will continue to supplement vitamin C daily as the benefits outweigh the consequences.

Relevant Links/ Resource

Studies Mentioned

Relevant Blog Posts