Vitamin C (Ascorbic Acid)
Vitamin C is a water-soluble vitamin that acts as a potent antioxidant, protecting cells from oxidative stress. It is primarily used to boost immune function, enhance collagen synthesis, and improve iron absorption. Key caveats include its water solubility, which limits storage in the body, necessitating regular intake.
Evidence last reviewed: 29 Apr 2026
The evidence supports Vitamin C's role in enhancing immune function, collagen synthesis, and iron absorption, with moderate to high-quality studies backing these claims. However, gaps exist in its effectiveness for cardiovascular outcomes and high-dose applications.
Immune function / cold durationAdults with common cold · Randomized Controlled TrialModerate
Vitamin C supplementation was associated with a reduction in the duration of cold symptoms by approximately 8% in adults.
Collagen synthesis / skin agingMiddle-aged women · Randomized Controlled TrialHigh
Supplementation with Vitamin C improved skin elasticity and reduced wrinkles, likely due to enhanced collagen synthesis.
Iron absorption enhancementIron-deficient individuals · Randomized Controlled TrialHigh
Vitamin C significantly increased iron absorption from plant-based sources, improving iron status in deficient individuals.
Antioxidant / oxidative stressAdults under oxidative stress · Randomized Controlled TrialModerate
Vitamin C supplementation reduced markers of oxidative stress, such as malondialdehyde, in adults exposed to oxidative stress.
Cardiovascular outcomesAdults with hypertension · Meta-analysis of RCTsLow
Vitamin C supplementation resulted in a modest reduction in systolic blood pressure by approximately 3.7 mmHg.
Cancer adjuvant (high-dose IV)Patients undergoing stem cell transplantation · Randomized Controlled TrialLow
High-dose intravenous Vitamin C improved plasma levels and showed trends toward reduced complications in stem cell transplant patients.
Hair + Nails Reality Check Stack
Minimalist approach that focuses on likely gaps & avoids mega-dosing trends.
Longevity Mix (Bryan Johnson)
Bryan Johnson's Blueprint Longevity Mix is the core daily powder from his self-quantified anti-aging protocol. It combines NAD+ pathway support (CaAKG), collagen precursors (Glycine, Lysine, Vitamin C), joint protection (Glucosamine, Sodium Hyaluronate), mitochondrial support (Creatine, CoQ10-adjacent), and antioxidant defence (Glutathione, Taurine). Every ingredient is dosed at clinically relevant levels validated through continuous biomarker tracking.
My Sample Stack
Built from your selected goals, constraints, diet, & the supplement evidence library. You can edit doses & timing.
Immune Support and Antioxidant Defense
Combining Sea Buckthorn with Vitamin C can enhance immune function and provide antioxidant defense. Sea Buckthorn is known for its immune-boosting and antioxidant properties, while Vitamin C supports immune health and reduces oxidative stress.
Forms & usage▾
Take 500-1000 mg daily, preferably with meals.
Safety & trade-offs2▾
Gastrointestinal Tolerance
Context: High doses of Vitamin C can cause gastrointestinal discomfort, including diarrhea.
Kidney Stones
Context: Excessive intake of Vitamin C may increase the risk of kidney stones in susceptible individuals.
●High ●Moderate ● Low / note