Vitamins
Vitamin C — timing, dose & interactions
Water-soluble antioxidant required for collagen synthesis and immune function. Enhances absorption of non-heme (plant/supplement) iron.
Also known as Ascorbic acid
Timing
When to take it
Any time. Split large doses — absorption falls above ~1 g per dose.
Dose note. Adult UL. Higher doses commonly cause GI upset.
Interactions
Vitamin C with other supplements
Safety
Medications & health conditions
Antioxidants may interfere with cancer treatment. Some chemotherapy and radiation work partly through oxidative damage; high-dose antioxidants could reduce their effect. Discuss every supplement with your oncology team.
High-dose vitamin C raises oxalate. Vitamin C is partly converted to oxalate, which can contribute to kidney stones.
Vitamin C increases iron absorption. Avoid vitamin C supplements with meals if you have iron overload.
Buying guide
What to look for on the label
Vitamin C
- Ascorbic acid
- Buffered vitamin C if acid bothers your stomach
FAQ
Common questions
When is the best time to take Vitamin C?
Breakfast. Any time. Split large doses — absorption falls above ~1 g per dose.
Should Vitamin C be taken with food?
It can be taken with or without food. Any time. Split large doses — absorption falls above ~1 g per dose.
Can you take Vitamin C with Iron?
Yes — taking them together can increase absorption, though it isn't required for iron supplements to work. Optional: take them together. More important for plant-based diets than for iron supplements.
Can you take Vitamin C with Vitamin E?
Yes — they are complementary antioxidants. No special timing needed.
Can you take Vitamin C with Collagen Peptides?
Yes — taking them together is a sensible pairing. Take together, e.g. in a morning smoothie.
Sources