Many people feel that supplementing vitamin C can help them fight illness or prevent disease. But what if your vitamin C supplements are expired? Vitamin C is an unstable and easily degradable vitamin. Is it still safe to use them? Here's what the science says.
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Expired vitamin C is most likely not unsafe, but the potency could be greatly reduced.
Is Expired Vitamin C Safe?
According to an April 2018 study published in the Brazilian Journal of Pharmaceutical Sciences, 92 percent of vitamin C supplements have significant losses in concentration amounts after 12 months of storage.
An October 2016 study published in International Journal of Applied Pharmaceutics found that under refrigeration, vitamin C has a lower rate of degradation compared to room temperature. Temperatures, Ph levels, and sunlight exposure can all impact the degradation of vitamin C.
According to a February 2017 article published in the American Journal of Clinical Nutrition, many manufacturers of vitamins add ingredients in amounts that are far above the quantity stated on the labels to compensate for losses during storage over time. The researchers say that this measure could cause overexposure when combined with the average intakes ingested through food sources.
Why Take Vitamin C
Vitamin C is a water-soluble vitamin found in many foods. Humans are unique from other animals in that they are not able to synthesize vitamin C, so it is vital that is obtained through diet, according to the U.S. Department of Health and Human Services (DHHS). Vitamin C contributes to the following:
- Wound healing
- Protein metabolism
- Collagen synthesis
- Neurotransmitter synthesis
- Antioxidant regeneration
It is quite easy to get enough vitamin C through your diet, especially if you like citrus fruits. If you ingest doses above 1 gram per day, your absorption rate falls below 50 percent, and anything not absorbed is excreted through your urine. So, consuming vitamin C supplements is generally not necessary and any excess will be excreted if you already get enough through your diet.
The DHHS says that adult males need 90 milligrams per day while females need 75 milligrams per day unless they are pregnant or lactating, in which case they would need 85 milligrams and 120 milligrams per day, respectively. It is also important to note that if you smoke, you will require an extra 35 milligrams per day compared with nonsmokers. Foods that are high in vitamin C include:
- Citrus fruits
- Tomatoes and tomato juice
- Red peppers
- Kiwi fruit
- Brussel sprouts
Uses For Expired Vitamin C Tablets
If you are concerned about the level of vitamin C in expired tablets, then you may wish to look into other uses for expired vitamin C tablets. It is possible to dissolve vitamin C tablets to use on your face in lotions and masks.
Since vitamin C is an antioxidant and anti-inflammatory, as well as a stimulator for producing collagen, using it for your skin could be beneficial, according to the Linus Pauling Institute. The topical use of vitamin C may also help prevent and treat ultraviolet-induced photodamage.
Dissolving 20 500-milligram tablets in 100 milliliters of distilled water will create a 10 percent concentration of vitamin C. The Linus Pauling Institute recommends a maximum of 20 percent vitamin C solution for use on the skin. A 10 percent vitamin C solution does not cause any adverse effects, they say.
You can use your homemade vitamin C solution by dipping a cotton ball into your mixture and dabbing it on your face and neck. This product does not need to be rinsed off and will absorb into your skin.
- Brazilian Journal of Pharmaceutical Sciences: "Stability of Antioxidant Vitamins in Commercial Vitamin Supplements"
- American Journal of Clinical Nutrition: "Analytical Ingredient Content and Variability of Adult Multivitamin/Mineral Products: National Estimates for the Dietary Supplement Ingredient Database"
- U.S. Department of Health and Human Services: "Vitamin C"
- Linus Pauling Institute: "Vitamin C and Skin Health"
- International Journal of Applied Pharmaceutics: "Effect of Storage Conditions on the Stability of Ascorbic Acid in Some Formulations"