Vitamin C
Your body's most versatile antioxidant. It supports your immune system, builds collagen for skin and joints, and — crucially for Indian diets — helps you absorb iron from plant foods.
Vitamin C does a lot of heavy lifting in your body — from keeping your immune cells fuelled to building the collagen that holds your skin, joints, and gut together. For Indian vegetarians, it's especially important because it dramatically improves iron absorption from plant foods like dal and spinach.
Good for you if: You eat a vegetarian diet and need better iron absorption, want stronger immunity, take collagen supplements, live in a polluted city, or want antioxidant protection.
Dive deeper into the researchCommon side effects
- Diarrhoea or stomach cramps at doses above 1,000 mg at once
- Heartburn or nausea in some people on an empty stomach
- May increase kidney stone risk if you're prone to oxalate stones
What does vitamin C do?
Vitamin C is a water-soluble vitamin that your body can't make on its own — you need to get it from food or supplements every day. It does several things that matter:
Immune support: Your immune cells (neutrophils and lymphocytes) accumulate vitamin C at 80 times the concentration in your blood. They need it to fight infections effectively.
Collagen production: Vitamin C is essential for building collagen — the protein that holds your skin, joints, bones, and gut lining together. Without it, collagen literally falls apart.
Iron absorption: This is huge for India. Vegetarian diets provide mostly non-heme iron (from lentils, spinach, fortified foods), which is poorly absorbed — only 2–10%. Vitamin C converts it to a form your body can use, boosting absorption by 3–4x.
What can you expect?
- Better iron levels — if you're vegetarian, taking vitamin C with meals can significantly improve your ferritin over 4–8 weeks
- Fewer and shorter colds — regular vitamin C use reduces cold duration by about 8% in adults
- Healthier skin — improved collagen synthesis shows up as better skin texture over time
- Antioxidant protection — especially valuable if you live in a polluted city
- Better collagen supplement results — taking 50–100 mg vitamin C with collagen peptides maximises their effectiveness
How to take it
500 mg twice daily with meals — morning and evening. This keeps your blood levels consistently high and is well-absorbed without stomach issues.
For iron absorption specifically: take 100–200 mg with your iron-rich meals (dal, green leafy vegetables). This is the simplest nutrition intervention for iron deficiency in India.
During illness: You can increase to 1,000–2,000 mg per day in divided doses. Your body's tolerance goes up when you're sick.
When to be careful: If you have a history of oxalate kidney stones, keep your dose at 500 mg or below. Vitamin C is metabolised to oxalate, which can contribute to stone formation.
Which form to buy?
| Regular (Ascorbic Acid) | Liposomal | |
|---|---|---|
| Absorption | Good up to 200 mg, drops above 1 g | 3–5x higher blood levels |
| Best for | Daily maintenance | Therapeutic doses, anti-aging |
| Stomach issues | Common above 1 g | Much less likely |
| Price (India) | ₹200–400/month | ₹1,500–3,000/month |
For most people, regular ascorbic acid at 500 mg twice daily is the best value. Liposomal C is worth it if you need higher therapeutic doses or want to avoid GI side effects.
Want to see if vitamin C is actually working for you?
eterni tracks your ferritin, iron panel, and inflammatory markers before and after — so you're not just guessing.
Get early accessFrequently Asked Questions
How much vitamin C should I take daily?
For most people, 500 mg twice daily with meals is a good baseline. This is well-absorbed and cost-effective. If you're fighting a cold or under high stress, you can go up to 1,000–2,000 mg per day in divided doses. Above 1,000 mg at once, your body absorbs less and the excess can cause stomach upset.
Liposomal vitamin C vs regular — is it worth the cost?
Liposomal C achieves 3–5x higher blood levels than the same dose of regular vitamin C by bypassing absorption limits in your gut. For daily maintenance, regular ascorbic acid at 500 mg twice daily is cost-effective. For therapeutic needs — immune support, recovery, anti-aging — liposomal C at 500–1,000 mg justifies its higher cost.
Why is vitamin C important for vegetarians in India?
Indian vegetarian diets provide mostly non-heme iron from lentils and greens, which is poorly absorbed (only 2–10%). Vitamin C converts this iron into a form your body can actually use, boosting absorption by 3–4x. Taking 100–200 mg vitamin C with your dal or saag is one of the simplest ways to fight iron deficiency.
Can you take too much vitamin C?
The upper limit is 2,000 mg per day. Above that, most people get diarrhoea and stomach cramps. If you have a history of kidney stones (oxalate type), stick to 500 mg per day since vitamin C converts to oxalate. During illness, 1–2 g per day in divided doses is safe for most people.
How it works in your body
Vitamin C (ascorbic acid) is a cofactor for at least 15 enzymes. Its two most important roles involve collagen synthesis (as a cofactor for prolyl and lysyl hydroxylase — the enzymes that stabilise collagen's triple helix structure) and antioxidant defence (scavenging free radicals and regenerating oxidised vitamin E and glutathione).
It also plays a key role in neurotransmitter production — it's needed to convert dopamine to norepinephrine — and in carnitine synthesis, which is required for fat metabolism.
What the studies show
- Immune function: Neutrophils accumulate vitamin C at 80x plasma concentration. Supplementation enhances immune cell killing ability and shortens cold duration by ~8%
- Iron absorption: 100–200 mg vitamin C with meals increases non-heme iron absorption by 3–4x — critical for India's iron deficiency epidemic (affects ~50% of women, ~25% of men)
- Collagen: Vitamin C is mandatory for stable collagen formation. Taking it with collagen peptide supplements maximises synthesis
- Absorption curve: At 200 mg: ~70–80% absorbed. At 1,000 mg: ~50% absorbed. Above 1 g: diminishing returns plus GI side effects
- Antioxidant: Reduces oxidative stress markers, particularly important in high-pollution environments
Side effects & safety
Vitamin C is water-soluble and generally very safe — your body excretes what it doesn't need. But there are limits:
- Diarrhoea and cramps — The most common side effect above "bowel tolerance" (typically 1–3 g/day). This is your body saying it has enough. Split doses or switch to liposomal to avoid this.
- Kidney stones — Vitamin C is metabolised to oxalate. If you have a history of oxalate kidney stones, limit to 500 mg/day.
- Nausea — Can happen if taken on an empty stomach. Always take with food.
- Iron overload — Because vitamin C enhances iron absorption, people with haemochromatosis should avoid high doses.
Who should be careful: People with kidney disease, haemochromatosis, or G6PD deficiency should consult their doctor before high-dose supplementation (above 1 g/day).
Which labs to check
To track whether vitamin C supplementation is making a difference:
- Ferritin & iron panel — if you're taking it for iron absorption, this is the key marker
- hsCRP — inflammatory marker that may improve with consistent antioxidant support
- CBC — to monitor anaemia status if iron deficiency was the starting point
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