Vitamin C gets marketed as "immune boosting," but that oversimplifies what it actually does. Your immune system doesn't need boosting—it needs the raw materials to function properly. Vitamin C is one of those essential inputs.
Beyond immunity, vitamin C supports collagen formation, antioxidant defense, and stress resilience. If you're dealing with chronic stress, frequent infections, or slow recovery from physical strain, adequate vitamin C intake becomes non-negotiable.
Most people get enough to avoid scurvy (the RDA is 90mg for men, 75mg for women). But that's a far cry from the 1,000-2,000mg daily that supports optimal function under modern stress loads.
WHY VITAMIN C MATTERS FOR IMMUNITY
Your immune system concentrates vitamin C in white blood cells at levels 10-100 times higher than in your blood. This tells you how critical it is for immune function.
Specifically, vitamin C:
- Enhances neutrophil chemotaxis (immune cells' ability to reach infection sites)
- Supports phagocytosis (immune cells engulfing and destroying pathogens)
- Protects immune cells from oxidative damage during immune responses
- Supports antibody production and T-cell function
When vitamin C is deficient, these processes slow down. You get sick more frequently, infections last longer, and recovery drags.
Supplementation doesn't "boost" immunity in some superhuman way—it ensures your immune system has what it needs to respond effectively when challenged.
THE STRESS-VITAMIN C CONNECTION
Your adrenal glands—which produce cortisol and other stress hormones—contain the highest concentrations of vitamin C in your body. During stress, cortisol production rapidly depletes these stores.
Chronic stress without adequate vitamin C replenishment creates a vicious cycle:
- Stress depletes vitamin C
- Low vitamin C impairs cortisol regulation
- Dysregulated cortisol creates more stress
The result? Erratic energy, mood instability, weakened immunity, and slower recovery from both physical and psychological strain.
Supplementing 1,000-2,000mg daily maintains adrenal vitamin C reserves, buffering the oxidative stress from chronic cortisol elevation and supporting more stable stress responses.
COLLAGEN FORMATION AND TISSUE REPAIR
Collagen is the most abundant protein in your body, forming the structural matrix for:
- Skin (elasticity, wound healing)
- Blood vessels (vascular integrity)
- Bones and cartilage (skeletal support)
- Tendons and ligaments (joint stability)
Vitamin C is a required cofactor for the enzymes that stabilize collagen structure. Without adequate vitamin C, collagen synthesis slows, leading to:
- Poor wound healing
- Fragile blood vessels (easy bruising)
- Joint and connective tissue weakness
- Skin degradation
If you're recovering from injury, training intensely, or simply aging (collagen production declines with age), vitamin C supports the ongoing repair and maintenance your body requires.
ANTIOXIDANT DEFENSE
Cellular metabolism generates reactive oxygen species (ROS) as byproducts. In small amounts, ROS serve as signaling molecules. In excess, they damage proteins, lipids, and DNA—a state called oxidative stress.
Vitamin C is a potent antioxidant that:
- Directly neutralizes free radicals
- Regenerates other antioxidants (vitamin E, glutathione)
- Protects mitochondria from oxidative damage
Oxidative stress accelerates when you're:
- Under chronic psychological stress
- Training intensely or working physically demanding jobs
- Ill or dealing with inflammation
- Exposed to environmental toxins (pollution, chemicals)
Vitamin C buffers this oxidative load, protecting cellular structures and supporting long-term health.
HOW MUCH DO YOU NEED?
The RDA (90mg for men, 75mg for women) prevents scurvy but doesn't define optimal intake for someone under chronic stress or high physical demand.
Research suggests:
- 200-500mg daily for baseline health maintenance
- 1,000-2,000mg daily for those under chronic stress, training regularly, or frequently ill
- Higher doses (2,000-3,000mg) during acute illness may modestly reduce symptom duration
Vitamin C is water-soluble, so excess is excreted in urine. Doses above 2,000mg may cause GI distress (diarrhea, cramping) due to osmotic effects in the intestine, but toxicity is extremely rare.
WHY SPLIT DOSING WORKS BETTER
Vitamin C has a short half-life in the bloodstream (~30 minutes). Taking 2,000mg at once means much of it is excreted before your cells can use it.
Splitting the dose—1,000mg in the morning, 1,000mg in the evening—maintains more stable blood levels throughout the day, improving overall absorption and utilization.
Absorption efficiency also decreases as dose size increases:
- ~90% absorbed at 200mg
- ~50% absorbed at 1,000mg
- <50% absorbed at 2,000mg+
This is another reason why split dosing (2x 1,000mg) is more effective than a single large dose.
WHO BENEFITS MOST
**Chronically stressed individuals**: High cortisol output depletes vitamin C rapidly. Daily supplementation supports adrenal function and stress resilience.
**Smokers**: Require an additional 35mg/day due to increased oxidative stress from smoking.
**Athletes**: Higher oxidative burden from training. 500-1,000mg daily supports recovery without blunting beneficial training adaptations.
**People who get sick frequently**: Consistent vitamin C intake maintains immune readiness and may reduce infection duration modestly.
**Anyone recovering from injury or surgery**: Vitamin C supports collagen synthesis and tissue repair.
FOOD VS. SUPPLEMENTS
Whole food sources—citrus fruits, berries, bell peppers, leafy greens—provide vitamin C along with other beneficial compounds (bioflavonoids, fiber, antioxidants).
But reaching 1,000-2,000mg daily through food alone is challenging. You'd need to eat:
- 10-15 oranges
- 2-3 pounds of bell peppers
- Large quantities of berries daily
Supplementation fills the gap efficiently, especially during high-stress periods when needs exceed what's practical to get from food.
THE BOTTOM LINE
Vitamin C isn't a cure-all, but it's foundational for immune function, stress resilience, collagen formation, and antioxidant defense—all of which decline when intake is inadequate.
If you're dealing with chronic stress, frequent illness, or high physical demands, 1,000-2,000mg daily (split into two doses) provides the support your body needs to maintain function rather than just avoid deficiency.
Simple, well-researched, effective. This is what daily care looks like.
