Vitamin C and Zinc: Taking Them Together

Quick answer

Vitamin C and zinc are often sold together, and NIH's fact sheets describe no effect of either on how the body absorbs the other. Both have established roles in normal immune function. The adult limits are 40 mg of zinc and 2,000 mg of vitamin C a day, counting food, and high zinc lowers copper.^1,2,3

Key facts

Both upper limits count food, drinks and supplements together: 40 mg a day for zinc and 2,000 mg for vitamin C in adults.^1,2
Zinc at 50 mg a day or more for weeks can lower copper. Reports that high vitamin C does the same have not been confirmed.^1,2
About 70% to 90% of vitamin C is absorbed at 30 to 180 mg a day, and less than half above 1 g a day.¹
Counting the 13 mg of zinc an average man gets from food, our two products that carry both nutrients bring the day to about 39 mg of zinc, just under the 40 mg limit.²

What the fact sheets say about the pair

NIH's fact sheets on vitamin C and on zinc set out how each is absorbed and what gets in its way, and neither names the other. Vitamin C is known to raise how much iron the gut takes from plant foods. For zinc, the things NIH names are phytate in meals and iron supplements taken at the same time.^1,2,4

Taking a supplement with 25 mg of iron or more at the same time as zinc can reduce zinc absorption. The iron added to fortified foods does not have this effect.^2,4

So the pairing itself has no documented clash. The questions worth asking are about the amounts, the copper that high zinc uses up, and the medicines each one touches.

Their roles in the immune system

Both nutrients have long-established roles in normal immune function, which is why they so often share a label. NIH also notes that when people already get enough of a nutrient, routine supplements probably add little.^3,5

Contributes to the normal function of the immune system*^1,3,6,7

Moderate evidence

A well-established nutrient function. NIH describes roles for vitamin C in both the first-line and the learned parts of the immune system: it helps keep barrier tissues intact and helps white blood cells multiply and do their work, and these cells hold far more vitamin C than blood does. EU regulators permit this wording for foods that are at least a source of vitamin C. It is about getting enough. NIH notes that when people are not short of a nutrient, routine supplements probably add little, and most people in the United States get enough vitamin C from food.

Amount studied: Recommended intake: 75 mg a day for women and 90 mg for men, from food and supplements

Contributes to the normal function of the immune system*^2,5,8

Moderate evidence

A well-established nutrient function. NIH describes zinc as needed for lymphocytes, the immune cells that respond to specific germs, to form, mature and become active, and for the activity of other immune cells. EU regulators permit this wording for foods that are at least a source of zinc. It is about getting enough: NIH notes that when people are not short of a nutrient, routine supplements probably add little.

Amount studied: Recommended intake: 11 mg a day for men and 8 mg for women, from food and supplements

They act at different points. Vitamin C keeps barrier tissues intact and is held at many times the blood level inside white blood cells, while zinc is needed for lymphocytes to form, mature and become active.^1,3,5

Copper is a zinc question, not a vitamin C one

A marker of copper status fell in people taking about 60 mg of zinc a day for up to 10 weeks.⁹

Reports that high intakes lower vitamin B12 and copper, wear tooth enamel or cause allergic reactions have not been confirmed, and some came from errors in lab tests.¹

The 40 mg zinc limit was set to protect copper status. That is why multivitamins that hold zinc often add copper, as our Men's Multi does with 2 mg beside its 15 mg of zinc.²

Absorption and timing

In a controlled study, a single 200 mg dose of vitamin C was fully absorbed, while single doses of 500 mg or more were absorbed less completely and more of them was passed in urine.⁷

Phytates in beans, whole grains and seeds bind zinc in the gut, so less zinc is absorbed from meals rich in them. Zinc is also absorbed less well from mixed meals than from meals of animal foods alone.²

Neither NIH fact sheet gives a time of day for these nutrients. With vitamin C, the absorption data point to dose size: single doses of 500 mg or more are taken up less completely. With zinc, what is in the meal matters more than the clock.^7,10,11

In a crossover study of 15 healthy adults given 10 mg of zinc without food, about 61% was absorbed from zinc citrate and from zinc gluconate, and about 50% from zinc oxide. Three people absorbed little or none of the oxide.^2,12

How the amounts add up

Daily amounts for adults, from NIH, and what our two products give^1,2
	Vitamin C	Zinc
Recommended amount	75 mg for women, 90 mg for men	8 mg for women, 11 mg for men
Upper limit, all sources	2,000 mg	40 mg
Average from food	About 84 mg for women, 105 mg for men	About 9.2 mg for women, 13 mg for men
Our immune formula	180 mg, as ascorbic acid	11 mg, as zinc citrate
Our Men's Multi	150 mg, as ascorbic acid	15 mg, as zinc oxide

Both products together give 330 mg of vitamin C and 26 mg of zinc a day. Add the 13 mg of zinc an average man gets from food and the total is about 39 mg, a hair under the 40 mg limit, so one more product with zinc would take most men past it. Vitamin C stays far below its limit either way.^1,2

What's in ours

What’s in ours

Men's Multi: Vitamin C, 150 mg per serving, from the label
Immune Support: Vitamin C, 180 mg per serving, from the label

What’s in ours

Men's Multi: Zinc, 15 mg per serving, from the label
Immune Support: Zinc, 11 mg per serving, from the label

Side effects, medicines and who should ask first

High doses can cause diarrhea, nausea, stomach cramps and other gut upset, because vitamin C that is not absorbed draws water into the gut.^1,10

Too much zinc upsets the stomach in its own way, with nausea, vomiting, cramps and loss of appetite, and it can leave a metallic taste.^5,11

High intakes raise the oxalate and uric acid passed in urine, which could add to kidney stones, especially in people with kidney problems. Studies conflict, and NIH says the best evidence of a link is in people who already pass too much oxalate.^1,7

Ask your pharmacist how far apart to take them

Quinolone antibiotics such as ciprofloxacin and levofloxacin, and tetracycline antibiotics such as tetracycline, can bind zinc in the gut, so less of both may be absorbed when they are taken close together. NIH advises taking them apart, and the ciprofloxacin, levofloxacin and tetracycline labels list zinc among the products that reduce absorption.^{2,11,13,14,15,16}

On the medicine's label

Ask your pharmacist or doctor first

Prescribing labels for extended-release mixed amphetamine salts name ascorbic acid, which is vitamin C, as an example of an acidifying agent that lowers blood levels of amphetamine and can make it less effective. Tell your prescriber if you take vitamin C.^17,18

On the medicine's label

Some eye formulas for age-related macular degeneration, taken on a doctor's advice, hold 500 mg of vitamin C and 80 mg of zinc with 2 mg of copper. That zinc amount is twice the adult limit, which does not apply to people given zinc as medical treatment under a doctor's care. If you take one, ask before adding another vitamin C and zinc product.^1,2

Ask your doctor first if you have hemochromatosis or another cause of iron overload, because vitamin C raises iron absorption¹
Ask first if you have had kidney stones or have kidney disease¹
Ask first if you take a quinolone or tetracycline antibiotic, penicillamine, a thiazide diuretic, levothyroxine, a statin or an amphetamine medicine^3,10,11
Ask first if you are having chemotherapy or radiation therapy¹
Ask first if you are pregnant or nursing

Questions people ask

What is the best time to take vitamin C with zinc?

No source we read names one. NIH gives no time-of-day advice for either nutrient. Zinc is absorbed less from meals rich in phytate and when taken with an iron supplement of 25 mg or more, and a single 200 mg dose of vitamin C was fully absorbed in a controlled study.^2,7

Does vitamin C help the body absorb zinc?

Not according to the sources we read. Vitamin C raises the absorption of iron from plant foods, and that is the absorption effect NIH describes for it. Neither of NIH's fact sheets says it changes zinc absorption.^1,2

Is it better to take them together or apart?

We found no study that compared the two. Since neither fact sheet describes one changing the other's absorption, the totals for the day matter more than whether they are in one pill.^1,2

See what we make

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Sources

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.