Vitamin C
The body cannot make it. Has to come from food or a supplement, every single day.
Vitamin C is water-soluble and not stored, so the body uses what it needs and excretes the rest within hours. It supports collagen production, immune function, and acts as an antioxidant that helps protect cells from oxidative damage. It also significantly boosts the absorption of non-haem iron, which is why pairing Vitamin C with iron-rich meals or iron supplements is a well-documented practical strategy. Higher doses (above around 200mg) offer diminishing returns on absorption, though they remain safe for most people.
Reference values
Daily reference values from official nutrition authorities. These are population reference figures, not personal recommendations.
| RDA | Upper limit | Source |
|---|---|---|
| 40 mg | No UL set | UK SACN DRVs (1991); EFSA found insufficient evidence to set UL (2013) |
Forms and bioavailability
Not all forms are absorbed equally. The form on your supplement label affects how much your body can actually use.
| Form | Absorption | With food | Timing | Evidence |
|---|---|---|---|---|
| liposomal vitamin C | Higher | Either | Either | Possible |
| ascorbic acid | Typical | Either | Either | Strong |
How it pairs with other supplements
Works well with
Vitamin C (50-100 mg) taken with non-haem iron enhances absorption by reducing ferric to ferrous form. Stronger effect on plant-source iron.
Stack Almanac surfaces the Vitamin C and iron pairing automatically and tracks your daily total across multivitamins and standalone supplements so you can see whether you are meeting the SACN reference intake.
Track your Vitamin C in Stack Almanac
Last reviewed: 2026-05-21. Reference values are adult-general RDAs from UK. Individual needs may vary. This page is for informational purposes only and is not a substitute for professional medical advice.