Dr. Kumar’s Take:
This study from Scotland in the early 1970s shows just how fast vitamin C in our white blood cells can drop during a cold, falling to scurvy-like levels within a single day of symptoms! The researchers found that keeping vitamin C intake high, both before and during a cold, helps your immune cells recover their vitamin C stores much faster. If you want to bounce back from a cold as quickly as possible, a higher-dose vitamin C regimen could help your immune system do its job.
Key Takeaways:
✔ White blood cell vitamin C (L.A.A.) drops to dangerously low levels within 24 hours of cold symptoms starting.
✔ Levels recover to normal as symptoms go away, usually by day 5.
✔ Regular vitamin C supplements (1g per day) keep immune cell levels up and may blunt this drop.
✔ A high-dose “therapeutic” regimen (6g/day for 3 days at symptom onset) prevented deficiency in a small test.
✔ No serious side effects, but mild digestive upset can happen at higher doses.
Actionable Tip:
To help your immune system recover from a cold, consider taking 1 gram of vitamin C daily for prevention. If you feel a cold coming on, increase to 6 grams per day (split into smaller doses) for the first 3 days, then return to 1 gram per day. Always check with your doctor before starting any new supplement routine.
Vitamin C and Immune Health: What This Study Found
Researchers followed seven healthy adults who caught the common cold and tracked their white blood cell vitamin C (called leucocyte ascorbic acid or L.A.A.). They found that L.A.A. levels dropped by more than half within one day of cold symptoms starting—well into the deficiency range. These levels returned to normal around day 5, just as people were feeling better.
They also tested how much vitamin C is needed to saturate white blood cells and serum. The “sweet spot” was about 1 gram per day for prevention, and 6 grams per day for therapy when sick. People who followed this regimen did not see their immune cell vitamin C drop below normal, and their symptoms tended to go away faster.
Study Design: How the Vitamin C Study Was Done
- Participants: 7 medical staff (2 men, 5 women) tracked through common cold episodes
- Measurements: White blood cell and serum vitamin C levels measured before, during, and after colds
- Supplement Trials:
- Stepped daily vitamin C doses (0.2g, 1g, 3g, 6g, and 10g) after recovery
- Prophylactic (preventive) dose: 1g/day
- Therapeutic (sick-day) dose: 6g/day, split over 3 days
- Outcomes: Changes in immune cell vitamin C levels, symptom duration, side effects
Results: What Happened to Vitamin C Levels?
- Before the cold: White blood cell vitamin C averaged 20 µg/10⁸ cells (normal range)
- Day 1 of symptoms: Dropped to 10 µg/10⁸ cells (scurvy range)
- Days 3–4: Began to recover
- Day 5: Back to normal as symptoms cleared
- 10 days later: Higher than before the cold
With supplementation:
- Taking 1g per day for prevention kept immune cell vitamin C at high-normal levels
- Increasing to 6g/day at the first sign of a cold prevented big drops
- Higher doses (above 6g/day) did not give much extra benefit
- Some people had mild stomach upset with high doses, which resolved with time
Why Vitamin C Needs Spike During Infection
Your white blood cells use up vitamin C rapidly when fighting off infections. This study is one of the clearest demonstrations: even healthy people can become temporarily “deficient” in vitamin C during acute illness. When intake is too low, your immune system may not work as well, and recovery can take longer.
Related Studies and Research
Vitamin C Deficiency: Clinical Signs, Risk Factors, and Treatment – Comprehensive overview of scurvy’s clinical features, causes, and evidence-based prevention and therapy.
Vitamin C Dosing, Plasma Saturation, and Urinary Loss – Detailed pharmacokinetic analysis showing how different oral doses affect blood levels and excretion patterns.
Vitamin C Physiology: The Goldilocks Review – Explores the optimal “just right” range of vitamin C for maintaining health without excess.
Plasma and Leucocyte Vitamin C Relationship: Insights from BMJ 1971 – Foundational study describing how plasma and white-cell ascorbate concentrations mirror overall vitamin C status.
Frequently Asked Questions
How fast do vitamin C levels drop when you get sick?
Vitamin C in white blood cells can fall by more than half within 24 hours of cold symptoms starting.
Is more vitamin C always better?
No. In this study, 1g per day was enough to saturate immune cells for most people, and 6g/day during a cold helped keep levels up. Higher doses did not add much benefit.
What about side effects?
Mild digestive upset (like loose stools) sometimes occurred at higher doses (above 3g/day), but this usually went away with time.
Can vitamin C prevent or cure a cold?
Vitamin C may help immune cells work better and recover faster during illness, but it does not prevent all colds. It can help reduce the severity and duration of symptoms for some people.
Conclusion
This study shows that your immune system uses up vitamin C rapidly during infection, dropping to “scurvy” levels even in healthy adults. Keeping up your intake—especially before and during a cold—helps your white blood cells recover and may speed up symptom resolution. A daily vitamin C supplement of 1g is enough for most people, but higher doses may be useful at the start of a cold.
For the full research details, you can read the study below.