Can You Take Vitamin C With Vitamin D?

Quick answer

Neither NIH fact sheet describes any effect of one on the other. Vitamin C dissolves in water and the excess leaves in urine; vitamin D is fat soluble and is absorbed best with a meal containing fat. The adult limits are 2,000 mg of vitamin C and 100 mcg (4,000 IU) of vitamin D a day.^1,2,3

Key facts

About 70% to 90% of vitamin C is absorbed at intakes of 30 to 180 mg a day, and less than half above 1 g.¹
In a trial of 50 older adults, a breakfast with fat gave a 32% higher peak in blood vitamin D3 than a fat-free breakfast.⁴
Both limits count food as well as supplements: 2,000 mg a day for vitamin C and 100 mcg (4,000 IU) for vitamin D.^2,3
The body holds only about 300 mg to 2 g of vitamin C, while the form of vitamin D measured in blood has a half-life of about 15 days.^1,5

Two vitamins handled in opposite ways

Vitamin C and vitamin D sit at opposite ends of how vitamins are handled. Vitamin C dissolves in water: the body absorbs a moderate dose well, keeps blood levels in a narrow range and passes the excess in urine. Vitamin D dissolves in fat: it is absorbed along with dietary fat, converted in the liver and then the kidneys, and held in body fat.^1,5

White blood cells are saturated at about 100 mg of vitamin C a day, and above about 200 mg a day blood levels rise only a little.^1,6

25-hydroxyvitamin D, the form measured in blood tests, has a half-life of about 15 days in the blood, so levels change over weeks rather than days.⁵

In practice, a large single dose of vitamin C is partly lost, while vitamin D levels build up and fall back over weeks. Neither NIH fact sheet describes either vitamin changing how the other is absorbed, and we found no trial that tested the pair on that question.^1,5,6

Where their roles overlap

NIH lists vitamins C and D, with vitamins A and E, selenium and zinc, among the nutrients the immune system needs in adequate amounts. Their graded statements are quoted below. Both are about getting enough, not about taking extra.⁷

Contributes to the normal function of the immune system*^1,6,7,8

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 normal immune function*^5,9,10

Moderate evidence

NIH lists immune function among vitamin D's roles, and 'contributes to the normal function of the immune system' is a permitted nutrient-function statement in the EU. Whether supplements help people get through the year with fewer respiratory illnesses is unsettled: the latest pooled analysis, covering 40 trials and 61,589 people, found a small effect that was not statistically significant.

Amount studied: The recommended daily intake from food, sun and supplements

NIH also points out that no single, simple measure of immune function exists, which is one reason supplement trials in this area are hard to read.⁷

Taking them at the same time

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.⁶

NIH gives no advice on the time of day for vitamin C. Vitamin D is best absorbed with a meal or snack that includes some fat, so a meal with some fat, at any hour, suits both.^1,3

If you take a large amount of vitamin C, splitting it across the day gives a larger share absorbed than one big dose. That holds for vitamin C whether or not vitamin D is in the same capsule.⁶

Adding up the amounts

Vitamin C and vitamin D for adults, per day^1,2,3
Per day, adults	Vitamin C	Vitamin D
Recommended amount	90 mg for men, 75 mg for women	15 mcg (600 IU), or 20 mcg (800 IU) from age 71
Extra for people who smoke	35 mg more	None set
Upper limit	2,000 mg	100 mcg (4,000 IU)
What the limit counts	Food and supplements	Food, drinks and supplements

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

Vitamin D3: Vitamin D-3, 50 mcg (2,000 IU) per serving, from the label
Men's Multi: Vitamin D, 10 mcg per serving, from the label
Ashwagandha Complex: Vitamin D3, 20 mcg per serving, from the label
Immune Support: Vitamin D3, 40 mcg per serving, from the label

One of our products carries both vitamins. Taken on the same day as our Vitamin D3, it brings the vitamin D total close to the adult limit before any food is counted:

Our Vitamin D3 with our Immune Support

Vitamin D3 and Immune Support together provide 90 mcg of vitamin D a day. That is close to the 100 mcg upper limit for adults, which counts food as well. Most people do not need both.

Kidney stones, medicines and who should ask first

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.^1,6

Taking calcium with vitamin D can raise the chance of kidney stones. In the Women's Health Initiative, 36,282 women after menopause given 1,000 mg of calcium and 400 IU of vitamin D a day had 17% more kidney stones over 7 years than those on placebo.⁵

The two reach the same caution by different routes: high vitamin C adds oxalate to urine, and vitamin D taken with calcium adds calcium. Anyone who has had kidney stones should ask before taking large amounts of either.^1,5

Your doctor may want to check on you

In one study, vitamin C taken with other antioxidants such as vitamin E, selenium and beta-carotene blunted the rise in HDL cholesterol from simvastatin taken with niacin. It is not known whether this happens with other cholesterol medicines, and NIH says doctors should check cholesterol levels in people taking both.^1,2

Reported in studies

Ask your pharmacist or doctor first

High intakes of vitamin D, especially from supplements, might make atorvastatin, lovastatin and simvastatin less potent, because they appear to compete for the same enzyme that breaks them down. Statins may also reduce the body's own production of vitamin D.^3,5

Reported in studies

Ask first if you have hemochromatosis or another cause of iron overload, because vitamin C raises iron absorption.¹
Ask first if you take an amphetamine medicine or levothyroxine, which vitamin C can affect, or a thiazide water pill, steroid tablets, orlistat or a bile acid sequestrant, which affect vitamin D.^3,7,11
Ask first if you use a blood glucose meter, since high vitamin C intakes can cause false readings on some meters.⁷
Ask first if you have high blood calcium or kidney disease, or are pregnant or nursing.

Questions people ask

Can you take vitamin D3 with vitamin C?

D3 is the form the skin makes and the form used in the largest vitamin D trials, and neither NIH fact sheet describes vitamin C changing how it is absorbed. Take it with a meal that has some fat.^3,5,12

Is it better to take vitamin C and vitamin D at different times?

Our sources give no reason to separate them. Timing matters more for each one on its own: fat in the meal for vitamin D, and smaller doses for vitamin C, since single doses of 500 mg or more are absorbed less completely.^3,6

See what we make

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See the Full Measure line Immune Support Men's Multi Ashwagandha Complex

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.