How much vitamin C do you need in a day? Here's what you need to know

Brenda Braslow, MS, RDN, LDN, CDCES - Registered Dietitian Nutritionist and Certified Diabetes Care and Education Specialist (CDCES)

An essential nutrient, vitamin C is not produced or stored by the body, so how much vitamin C do you need in a day? Controversy exists about vitamin C's role with the common cold. Some researchers think that mild vitamin C deficiency may be more prevalent than you think. Like most nutrients, it is best to get enough instead of excessive amounts.

How much vitamin C do you need in a day?

Since the human body does not produce or store vitamin C, we must consume it regularly through fruits and veggies. It supports a large number of body processes related to growth and repair. Vitamin C works with protein to make skin, tendons, and blood vessels. It helps heal wounds and repair cartilage, bones, and teeth. Adequate amounts also result in less bruising, faster healing, and healthier gums and teeth. Vitamin C helps increase iron absorption from plant-based foods. An important antioxidant, vitamin C also plays a role in immune function. So, yes, it is vital to our health, but megadosing is not the answer.

So, how much vitamin C is enough? The RDA primarily depends on age and sex. For example,

Adult men, 19 and older: 90 mg/day
Adult women, 19 and older: 75 mg/day
Adult pregnant women: 85 mg/day
Adult breastfeeding women: 120 mg/day
Adult smokers need an additional 35 mg/day because of smoke's oxidative effects.

The tolerable upper limit (UL) for vitamin C is 2,000 mg /day. Megadosing on vitamin C supplements above the UL may cause diarrhea, nausea, vomiting, heartburn, abdominal bloating and cramping, headache, insomnia, and kidney stones. Also, prolonged use of large doses of vitamin C may increase the nutrients's metabolism, causing losses. Once vitamin C decreases, you could develop rebound scurvy. As is the case with most nutrients, it is best to get enough vitamin C, but not in excessive amounts.

Common cold and vitamin C, fact or futility?

Controversy exists about vitamin C's role with the common cold. Some research shows that vitamin C levels in the body decrease at the start of a cold and that increasing vitamin C intake might be beneficial. Other evidence shows that the body holds onto vitamin C due to increased demand and that extra vitamin C intake does not help combat a cold. Cold prevention using high-dose vitamin C supplements lacks evidence. With its weak antihistamine effects, vitamin C might make cold symptoms milder and shorten its duration.

Some researchers think that mild vitamin C deficiency may be more widespread than you think. Vitamin C deficiency can result in fatigue, anemia, bleeding gums, decreased ability to fight infection, increased bruising, nosebleeds, swollen and painful joints, and dry, splitting hair. After three to five months, sustained vitamin C deficiency can cause scurvy with symptoms of bleeding gums and loose teeth.

Practical tips to get vitamin C

Most nutrition experts agree that a diet high in fruits and vegetables provides adequate vitamin C.
All fruits and vegetables contain some vitamin C, so include at least five servings per day.
Vitamin C is highest in raw fruits and veggies. Cooking vitamin C-rich foods reduces the vitamin C content. Microwaving and steaming reduces nutrient losses.
Vitamin C content decreases after harvest, so eat fresh produce within a week. Frozen produce retains more nutrients because it's flash-frozen shortly after harvest.
Drink orange juice within one week of opening. Purchase it three to four weeks before expiration date.
A standard multivitamin usually contains vitamin C.
Add vitamin C to your MyNetDiary Dashboard to track your daily intake.

High sources of vitamin C

guava (126 mg/1 fruit)

papaya (93 mg per 1/2 medium)

orange juice (93 mg per 6 oz)

orange (70 mg per medium

green bell pepper 60 mg per 1/2 cup)

red bell pepper (59 mg/1/2 cup)

broccoli (51 mg per 1/2 cup)

kohlrabi (42 mg per 1/2 cup)

grapefruit (39 mg per 1/2 medium)