Effects of Taking Vitamin C and D Together on Your Body

Medically reviewed by Alex Yampolsky, PharmD

• Taking vitamin C and vitamin D together is generally safe, provided you adhere to the recommended dosages.

• These supplements may enhance your immune system and support bone strength.

• Exceeding recommended doses of vitamin C or D can lead to side effects such as nausea or diarrhea.

You can safely combine vitamin C and D without worrying about adverse interactions. Here’s how taking both can benefit your health.

1. Enhance Immunity

Obtaining sufficient levels of vitamins C and D is crucial for a well-functioning immune system. Vitamin C supplements can improve immune function and help ward off infections, including those caused by viruses.

Vitamin D has also been shown to enhance the body’s defenses against infections by reducing inflammation and modulating immune responses.

Given their proven immune-boosting properties, combining vitamin C and D can strengthen immune defense, particularly in illness prevention.

2. Combat Viral Infections

Research indicates that vitamin C may possess antiviral properties. Regular consumption of vitamin C can also help shorten the duration of colds.

Similarly, vitamin D contributes to a decreased likelihood of viral infections by strengthening the body’s physical barriers, such as skin and mucous membranes, which defend against invasion by viruses.

This vitamin is also beneficial in reducing the incidence of respiratory infections in both children and adults.

3. Accelerate Wound Healing

Studies reveal that vitamin D promotes skin cell regrowth, thereby aiding the repair process while reducing scarring.

Vitamin C plays a vital role in wound healing. Research suggests that this vitamin boosts the expression of factors essential for healing. The combined intake of vitamins C and D may enhance the speed of recovery from wounds.

4. Strengthen Bone Health

A deficiency in both vitamins C and D can result in reduced bone mineral density, increasing the risk of osteoporosis. Such deficiencies are particularly prevalent among the elderly.

Research indicates that combining vitamin C and D supplements can help mitigate bone loss and foster healthier bones.

This combination may also enhance protection against osteoporosis and related fractures.

5. Mitigate Chemotherapy Complications

Supplementing with vitamin C and D may improve outcomes for individuals undergoing chemotherapy.

In a specific study, these vitamins were linked to fewer complications in patients with leukemia receiving chemotherapy. However, further research is necessary to substantiate these findings.

What Are the Recommended Doses?

The advised daily vitamin D intake varies by age and pregnancy status:

• Age 14 and younger: 10-15 micrograms (mcg), equivalent to approximately 400-600 international units (IU)

• Ages 14 to 70: 15 mcg (600 IU)

• Age 70 and older: 20 mcg (800 IU)

• During pregnancy: 15 mcg (600 IU)

The recommended daily amount of vitamin C also varies based on age and pregnancy:

• 0 to 6 months: 40 milligrams (mg)

• 14 to 18 years: 65–75 mg

Smokers generally require about 35 mg more vitamin C than non-smokers.

Excessive vitamin C intake can lead to issues such as diarrhea, nausea, and stomach cramps, though doses of 2-3 grams daily are often tolerated well.

Individuals with hemochromatosis should approach vitamin C with caution, as it enhances iron absorption and may lead to dangerously high levels of iron in the body.

Consuming extremely high doses of vitamin D—100 micrograms (4,000 IU)—can cause muscle weakness, appetite loss, nausea, confusion, dehydration, excessive thirst and urination, and kidney stones.

Vitamin D may also interact with medications such as diuretics, orlistat, statins, and steroids. It’s crucial to consult a healthcare provider regarding medication interactions.

Are There Any Side Effects?