Vitamin C
Content by: OpenSupplement Editorial Team | Medical review: pending | Last updated: April 13, 2026
TL;DR
The most famous antioxidant; essential for collagen and immune function
High evidence for slowing the progression of Macular Degeneration (AREDS2)
Low evidence for heart health
Critical for 'recycling' Vitamin E
Excellent safety; high doses may cause diarrhea
Very cheap: ~$5-8/month
Best for: Macular degeneration (in a formula), immune support, skin health
What it is
Vitamin C (ascorbic acid) is a 'master antioxidant' that humans cannot produce ourselves. It's essential for the synthesis of collagen (skin, joints, and blood vessels) and the function of white blood cells.
In the context of age-related disease, Vitamin C acts as a 'sacrificial lamb,' neutralizing free radicals before they can damage delicate tissues like the retina or the arterial walls.
What the research says
Vitamin C is a core component of the AREDS formula. Evidence. The original AREDS and AREDS2 trials showed that 500mg of Vitamin C, as part of an antioxidant cocktail, significantly reduced the risk of 'dry' AMD progressing to the 'wet' (vision-loss) stage. Why? The retina is under constant oxidative stress from light; Vitamin C is the first line of defense in the fluid surrounding the eye cells. [1][3]
Vitamin C is 'good for the heart' in theory, but pills aren't a cure. Evidence. Large trials have failed to show that Vitamin C supplements prevent heart attacks or strokes in the general population. Endothelial Health. It may modestly improve the 'stretchiness' of blood vessels in smokers or those with high oxidative stress, but its heart benefits are mostly seen in those with very low fruit and vegetable intake. [2]
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Vitamin C on Amazon
Safety
Extremely safe. High doses (2,000mg+) can cause 'osmotic diarrhea' and stomach cramps. Long-term high doses may slightly increase the risk of kidney stones in susceptible men.
Interactions
- Aluminum: May increase aluminum absorption from antacids.
- Chemotherapy: Some concern that antioxidants may protect cancer cells from treatment; consult an oncologist.
Dosing
Standard Dose: 500-1,000 mg daily. Form: Ascorbic acid is the standard. Liposomal forms are better absorbed but much more expensive.
Cost
Dirt cheap. $5-8 per month.
The bottom line
Vitamin C is a foundational antioxidant. If you have AMD, it's a mandatory part of your formula. For everyone else, it's a cheap and safe way to support your collagen and immune system.
References
- Age-Related Eye Disease Study 2 Research Group. Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. JAMA. 2013;309(19):2005-2015.
- Juraschek SP, Guallar E, Appel LJ, Miller ER 3rd. Effects of vitamin C supplementation on blood pressure: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2012;95(5):1079-1088.
- Office of Dietary Supplements - Vitamin C. National Institutes of Health.
Sources for this page include published meta-analyses, systematic reviews, and NIH dietary supplement fact sheets. All claims reflect the evidence as of early 2026.
This is not medical advice. Consult your healthcare provider before starting any supplement, especially if you take medications.