Medically Reviewed

Is It Possible to Take Too Much Vitamin C When You're Getting Over the Sniffles?

Vitamin C is more than just a delicious glass of orange juice. It’s plentiful in most healthy diets. But if you’re not getting enough, does a supplement help?

Vitamin C is probably one of the most well-known and oft-used supplements available today. People reach for vitamin C supplements for their quick dose of immune support. But does it help?

Vitamin C is a strong antioxidant that helps protect the body from harmful free radicals, supports seasonal lung and sinus issues, and even helps heal wounds. It’s also essential for the production of collagen, a protein found in connective tissue throughout many systems in the body.

Because vitamin C is water-soluble, excess amounts that are not being used are simply excreted through urine, rather than stored in the body. This means that your body requires a consistent daily intake, ideally through diet but, if not there, then through supplementation.

How much Vitamin C should you take per day?

The recommended daily allowance (RDA) for vitamin C varies based on age, sex, and health status. Here are the current RDA values:

  • 1-3 years: 15 mg
  • 4-8 years: 25 mg
  • 9-13 years: 45 mg
  • Males 14-18 years: 75 mg
  • Females 14-18 years: 65 mg
  • Adult men (19 years and older): 90 mg
  • Adult female (19 years and older): 75 mg
  • Pregnant female: 85 mg
  • Breastfeeding female: 120 mg

Under certain circumstances individuals may require additional vitamin C beyond these guidelines, such as in the case of deficiencies or a limited diet. (More on that later).

Is it possible to take too much vitamin C?

The recommended maximum daily intake or tolerable upper limit (TUL) of vitamin C for adults is 2,000 mg. Higher doses above the 2000 mg may increase the risk for potential digestive discomfort. Since vitamin C is water-soluble, any excess that the body does not need or use will not be absorbed. Instead, it will be easily expelled in urine and is unlikely to cause any significant problems.

People with excess iron in their system should be cautious with higher doses, and those with kidney issues should, according to this source, keep their dosage below 500 mg. It is important to discuss any supplementation with your physician.

Symptoms of taking too much vitamin C

Although too much vitamin C in healthy adults is unlikely to be harmful, as you will likely expel excess in your urine, it could result in digestive symptoms such as diarrhea, vomiting, stomach cramps, and indigestion.

Can vitamin C help boost immunity?

A number of studies have found that adequate intake of vitamin C will support the human immune system while managing reactive oxidative species, thanks to its antioxidant properties. One study of ultramarathoners demonstrated that 600 mg of vitamin C daily reduced the incidence of post-race lung and sinus issues and may do the same in the more sedentary population. While other studies have found results to be amixed bag, nobody debates the need for a healthy diet rich in vitamin C.

How does vitamin C play a role with your immune system?

The immune system is a complex network of tissues, organs, cells, proteins, and chemicals that are designed to protect the body and keep it healthy. There is a close relationship between nutritional health and optimal immune function, and adequate amounts of vitamin C are necessary for a healthy immune system.

In conjunction with vitamin D and zinc, vitamin C supports both the innate and adaptive immune systems, the epithelial barrier function, phagocyte cells, natural killer (NK) cell functions, and lymphocyte proliferation and differentiation. The trio of vitamin C, vitamin D, and zinc are actively used by cells of the immune system, promoting a healthy immune response to harmful free radicals. Many factors can contribute to free radicals and oxidative stress, such as stress, diet, pollution, and other environmental factors.

Sources of vitamin C

You can get the vitamin C you need through food sources or supplementation. It’s uncommon to have a deficiency in vitamin C since it can be found in a plethora of foods. However there are factors that can increase the risk for deficiency such as alcohol intake, tobacco use, and socioeconomic status. Because some populations do have occasional vitamin C deficits, supplementing is a good option to keep in mind.

Vitamin C Supplements

If you don’t already have a preferred brand of supplements, ask your physician, close family members, and friends for recommendations. As always, do your homework. There are a multitude of vitamin C supplements available in liquid, powder, chewable tablet, and pill form.

You should always use a high-quality, high-potency supplement, checking for dosage, percentage of recommended dietary allowance (RDA), and ingredients. It is important to look for supplements that are free of artificial ingredients or preservatives, and, if necessary or desired, sugar or added sweeteners.

Know the recommended dosage – 90 mg for healthy men, and 75 mg for healthy women – and shop according to your needs. If you’re looking for something in pill form, Care/of’s Vitamin C supplement is a high-quality, easily digested formula that provides maximum absorption.

Natural sources of vitamin C

The best way to obtain vitamin C is through a balanced and nutritious diet. Most people will be able to get the amounts they need that way, since vitamin C is in such a wide variety of foods. Fruits and vegetables are typically the best sources.

Among the most potent sources is the Acerola cherry. It is bursting with flavor and contains a plethora of phytonutrients, like carotenoids, phenolics, anthocyanins, and flavonoids. With a whopping 1500-4500 mg of vitamin C per 100 g, it surpasses the orange or lemon by a staggering 50-100 times!

Other good sources of vitamin C include: (per 100 grams of vitamin C):

Vitamin C dosage considerations for certain groups of people

People who do not have a varied diet might be at risk for vitamin C deficiency, as well as smokers and those exposed to pollution or secondhand smoke. Age, overall health status, and stress level are also possible factors in determining your need to supplement vitamin C.

Vitamin C for smokers and those with diets limited in fruits and veggies

People who smoke have an increased need for vitamin C. This is because smoking creates oxidative stress in the body, requiring additional vitamin C to counteract those effects. It’s recommended that those who smoke consume an additional 35 mg of vitamin C per day. Anyone who smokes, then, may want to consider a vitamin C supplement, to ensure they’re getting adequate amounts.

In addition, individuals whose diets are limited in fruits and veggies should consider supplementing with vitamin C to bridge any nutrient gaps. It can be difficult to obtain proper amounts of vitamin C from meals alone without meeting the recommended serving of fruits and veggies.

Vitamin C for older adults

Older adults may require additional supplementation of vitamin C. According to this study, older adults living in institutions tend to have lower C levels. This could be due to various factors. For one, the diets of older adults may lack the necessary abundance of fresh fruits and vegetables, leading to decreased vitamin C levels. Also, the aging process brings changes to our body's nutrient absorption and metabolism, emphasizing the need to be aware of our vitamin C intake.

Vitamin C and prenatal health

Vitamin C is especially important among pregnant people. During pregnancy, we need vitamin C for collagen formation, which ensures proper growth and development for the baby. It is also critical for immune health, helping both the parent and fetus maintain optimal health. Another aspect of vitamin C's role in prenatal health is its ability to enhance the absorption of non-heme, or plant-based, iron.

Vitamin C can be found in most prenatal vitamins.

The Bottom Line

Vitamin C is essential to many critical functions in the human body. The good news is that most people can get adequate amounts from a healthy diet, especially when consuming fresh food at peak ripeness. If you need more, supplementation is fairly simple and straightforward. While there is widespread agreement among medical professionals as to the critical functions of vitamin C, always, check with your physician or healthcare provider when exploring appropriate supplementation.

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