Product Reviews
Vitamin C Supplements Review

Initial Posting: 3/10/17  Last Update: 4/3/20Vitamin C Supplements Tested by

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  • Does it help? If you get sufficient vitamin C from your diet (which you can get from a cup of tomato or orange juice), taking more from a supplement will generally not be helpful. Nevertheless, taking high-dose vitamin C daily from a supplement during cold season can slightly reduce the risk of getting a cold, particularly if you are deficient in vitamin C — although it won't help once you're sick. Vitamin C supplementation may also slightly reduce blood pressure, although it has not been shown to reduce rates of cardiovascular disease. Taking vitamin C has also been associated with reducing the risk of gout. (See What It Does)
    • COVID-19 UPDATE: Due to vitamin C's role in maintaining immune system health, vitamin C supplements are being promoted by some to help prevent coronavirus (COVID-19), the infection caused by the SARS-CoV-2 virus. This effect has not been proven, although it is generally advisable that one's intake of vitamin C meets the daily requirements. Prior to the emergence of SARS-CoV-2, small studies showed that that very high doses of vitamin C given to people on ventilators reduced the time on ventilators. This is being tried in patients with severe COVID-19. See the COVID-19 section for more details regarding vitamin C.
  • How much should I take? If you want to be sure you're getting the daily requirement, a supplement providing roughly 50 mg to 100 mg of vitamin C is sufficient for most adults and is quite safe (see What to Consider When Using).
    When higher doses are taken in hopes of reducing the risk of a cold or gout, or to slightly reduce blood pressure, a typical dose is 500 mg taken twice daily or up to 2,000 mg per day. Be aware, however, that taking more than 500 mg of vitamin C per day on a regular basis (which will saturate your blood with vitamin C) may increase your risk of developing cataracts, and taking more than 1,000 mg per day may also increase your risk of kidney stones. Diarrhea can result from a single dose of more than 2,000 mg for an adult and lower amounts for children (see Concerns and Cautions). In short, there is a risk/benefit trade-off with taking high-dose vitamin C.
  • Which form is best? There are many forms of vitamin C available (ascorbic acid, sodium ascorbate, calcium ascorbate, liposomal vitamin C, etc.) but there is no compelling evidence that one is much better than another. The ascorbate forms may be easier on your stomach, but you will still run a risk of developing loose stools at a very high dose. Whole foods will provide additional bioflavonoid compounds, which may be of some benefit, but are not necessary to meet your nutritional needs, and natural vitamin C, such as from rose hips, is in the exact chemical form as in most synthetic vitamin C supplements -- L-ascorbic acid. (See Forms of Vitamin C).
  • Which product is best? Among the products which contained the amounts of vitamin C listed and were "Approved" by, five were chosen as CL's Top Picks. Unfortunately, we also discovered three products which contained roughly 50% more vitamin C than listed. Depending on the dose you take, this could increase your risk of adverse effects from vitamin C.
What It Is:
Vitamin C (ascorbic acid or dehydroascorbic acid) is an essential water-soluble vitamin that the human body can't manufacture. It must, therefore, come from foods or supplements. Fruits and vegetables are the richest food sources of vitamin C. Dietary supplements are typically sold as ascorbic acid, calcium ascorbate (Ester-C®), sodium ascorbate, ascorbyl palmitate, or a combination of these forms. Supplements also commonly contain natural sources of vitamin C such as rose hips (the pear-shaped fruit of the rose, without the flower's petals) and/or acerola (a cherry-like fruit). (See ConsumerTips™: What to Consider When Buying for more information about types of vitamin C).

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