How much vitamin C do I need?

The adult RDA is 90 mg a day for men and 75 mg for women. Smokers need 35 mg more. The upper limit is 2,000 mg a day (US National Academies).

Does vitamin C prevent colds?

No, not in the general population. A Cochrane review of community trials (10,708 participants) found a pooled risk ratio of 0.97 (95% CI 0.94 to 1.00). Regular vitamin C shortened colds by about 8% in adults and 14% in children.

Should I take vitamin C with iron?

Vitamin C increases absorption of non-heme (plant) iron, so it is not a reason to keep them apart. If you have a condition that causes iron overload, ask your doctor before taking supplements.

What happens if I take too much vitamin C?

Above the 2,000 mg a day upper limit, osmotic diarrhea and stomach upset are the main effects, and rarely kidney stones (National Academies; MedlinePlus). Absorption also falls to about 50% or less at doses above 1 g a day.

Can vitamin C interact with medicines?

Check with your doctor or pharmacist if you take prescription medicines. Large doses are not recommended in pregnancy.

Supplement guide Vitamins

Vitamin C

Vitamin C is needed for collagen, wound healing and iron absorption. See the RDA and upper limit, what the Cochrane review found on colds, and why extra vitamin C has no convincing effect on immunity.

At a glance

Snapshot

Primary goal: Meeting daily vitamin C needs
Dosage range: RDA 90 mg (men) or 75 mg (women) a day; upper limit 2,000 mg a day
Best time to take: Not established in studies
Time to effect: Not established
Common stacks: Not studied
Intake notes: Smokers need 35 mg more a day. Above 2,000 mg a day, osmotic diarrhea, stomach upset and, rarely, kidney stones can occur. Large doses are not recommended in pregnancy (MedlinePlus).

Ranked picks

Top 3 Best Vitamin C Supplements

#1 NootroScore9.1

Nature's Bounty

Nature's Bounty Vitamin C + Rose HIPS, Immune Support, 1000mg, Coated Caplets, 100 Ct

CapletVitamin C + Rose HIPSImmune Support

Quantity: 100 count
Potency: 1000mg

$6.65$0.07/count

View product

#2 NootroScore9.0

Emergen-C

Emergen-C 1000mg Vitamin C Powder for Daily Immune Support Caffeine Free Vitamin C Supplements with Zinc and Manganese, B Vitamins and Electrolytes, Super Orange Flavor - 30 Count

PowderCaffeine Freewith Zinc and Manganese

Quantity: 30 count
Potency: 1000mg

$8.35$0.28/count

View product

#3 NootroScore9.0

Nature Made

Nature Made Extra Strength Vitamin C 1000 mg, Dietary Supplement for Immune Support, 100 Tablets, 100 Day Supply

Tablet

Quantity: 100 count
Potency: 1000 mg

$8.26$0.08/count

View product

Top 10 Vitamin C Supplements

Nature's Bounty

Nature's Bounty Vitamin C + Rose HIPS, Immune Support, 1000mg, Coated Caplets, 100 Ct

CapletVitamin C + Rose HIPSImmune Support

Quantity: 100 count
Potency: 1000mg
NootroScore: 9.1
Price: $6.65$0.07/count

Buy

Emergen-C

Emergen-C 1000mg Vitamin C Powder for Daily Immune Support Caffeine Free Vitamin C Supplements with Zinc and Manganese, B Vitamins and Electrolytes, Super Orange Flavor - 30 Count

PowderCaffeine Freewith Zinc and Manganese

Quantity: 30 count
Potency: 1000mg
NootroScore: 9.0
Price: $8.35$0.28/count

Buy

Nature Made

Nature Made Extra Strength Vitamin C 1000 mg, Dietary Supplement for Immune Support, 100 Tablets, 100 Day Supply

Tablet

Quantity: 100 count
Potency: 1000 mg
NootroScore: 9.0
Price: $8.26$0.08/count

Buy

NOW Foods

NOW Foods Supplements, Vitamin C-1,000 with 100 mg of Bioflavonoids, Antioxidant protection*, 100 Veg Capsules

CapsuleAntioxidant protectionVegetarian

Quantity: 100 count
Potency: 1,000 mg
NootroScore: 8.9
Price: $8.56$0.09/count

Buy

American Health

American Health Ester-C with Citrus Bioflavonoids Capsules - Gentle On Stomach, Non-Acidic Vitamin C - 500 mg, 60 Servings, 120 Count

CapsuleEster-C with Citrus BioflavonoidsGentle On Stomach

Quantity: 120 count
Potency: 500 mg
NootroScore: 8.6
Price: $13.99$0.12/count

Buy

Solgar

Solgar Vitamin C 1000 mg, 100 Vegetable Capsules - Antioxidant & Immune Support - Overall Health - Healthy Skin & Joints - Bioflavonoids Supplement - Non-GMO, Vegan, Gluten Free, Kosher - 100 Servings

CapsuleAntioxidant & Immune SupportOverall Health

Quantity: 100 count
Potency: 1000 mg
NootroScore: 8.5
Price: $14.51$0.15/count

Buy

NOW Foods

NOW Foods Supplements, Vitamin C-1,000 with 100 mg of Bioflavonoids, Antioxidant Protection*, 250 Veg Capsules

CapsuleVegetarian

Quantity: 250 count
Potency: 1,000 mg
NootroScore: 8.4
Price: $15.99$0.06/count

Buy

Emergen-C

Emergen-C 1000mg Vitamin C Powder for Daily Immune Support Caffeine Free Vitamin C Supplements with Zinc and Manganese, B Vitamins and Electrolytes, Super Orange Flavor -60 Count(Pack of 1)

PowderCaffeine Freewith Zinc and Manganese

Quantity: 60 count
Potency: 1000mg
NootroScore: 8.0
Price: $22.48$2.34/Ounce

Buy

Sports Research

Sports Research Vitamin C 1000mg - Non-GMO Project Verified Ascorbic Acid Vitamin C Supplement for Immune Support & Antioxidant Protection | Vegan Friendly, 8 Month Supply (240 Count)

CapsuleNon-GMO Project VerifiedVegan Friendly

Quantity: 240 count
Potency: 1000mg
NootroScore: 7.9
Price: $22.95$0.10/count

Buy

#10

SOLARAY

SOLARAY Vitamin C 1000mg Timed Release Capsules with Rose HIPS & Acerola Bioflavonoids, Two-Stage for High Absorption & All Day Immune Function Support, 60 Day Guarantee, 275 Servings, 275 VegCaps

CapsuleTimed ReleaseRose HIPS & Acerola Bioflavonoids

Quantity: 275 count
Potency: 1000mg
NootroScore: 7.1
Price: $35.27$0.13/count

Buy

Affiliate disclosure: NootroWorld may earn a commission from qualifying purchases made through these links, at no extra cost to you. Rankings are calculated independently of any affiliate relationship. How we make money.

Use and selection

Buying Guide

Everything you need to know to make an informed decision about Vitamin C

Why It Matters

The body cannot make vitamin C and does not store it, so it must come from food or supplements regularly. Most people who eat fruit and vegetables get enough. Deficiency (scurvy) mainly affects older, malnourished adults.

How Vitamin C Helps You

Collagen and wound healing

Vitamin C is needed to form collagen, a protein used to make skin, and to heal wounds and form scar tissue.

Iron absorption

Vitamin C increases absorption of non-heme (plant) iron when taken in the same meal.

Colds

In a Cochrane review, regular vitamin C shortened colds by about 8% in adults and 14% in children. It did not reduce how often colds occurred (pooled RR 0.97, 95% CI 0.94 to 1.00).

Immune function

Vitamin C deficiency impairs immune function. In people who already get enough, the National Academies found no convincing evidence that extra vitamin C has a significant effect on immune function.

Frequently Asked Questions

Common questions about Vitamin C answered by our experts

How much vitamin C do I need?: The adult RDA is 90 mg a day for men and 75 mg for women. Smokers need 35 mg more. The upper limit is 2,000 mg a day (US National Academies).
Does vitamin C prevent colds?: No, not in the general population. A Cochrane review of community trials (10,708 participants) found a pooled risk ratio of 0.97 (95% CI 0.94 to 1.00). Regular vitamin C shortened colds by about 8% in adults and 14% in children.
Does vitamin C boost the immune system?: Deficiency impairs immunity, but in people who already get enough, the National Academies found no convincing evidence that extra vitamin C has a significant effect on immune function.
Should I take vitamin C with iron?: Vitamin C increases absorption of non-heme (plant) iron, so it is not a reason to keep them apart. If you have a condition that causes iron overload, ask your doctor before taking supplements.
What happens if I take too much vitamin C?: Above the 2,000 mg a day upper limit, osmotic diarrhea and stomach upset are the main effects, and rarely kidney stones (National Academies; MedlinePlus). Absorption also falls to about 50% or less at doses above 1 g a day.
Can vitamin C interact with medicines?: Check with your doctor or pharmacist if you take prescription medicines. Large doses are not recommended in pregnancy.