The Truth About Ascorbic Acid: Healthy or Dangerous?

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In some health and fitness circles, where ascorbic acid is considered a “synthetic form of vitamin C,” influencers and some nutritionists warn their followers of the dangers of ascorbic acid. But is it really as bad as they claim, or like many things in nutrition, are they misinformed?

I’ll try to set the record straight, covering many of the reasons some people warn against using ascorbic acid, and also covering its benefits and why I use and recommend it.

If you have thoughts or questions I don’t cover, share them in the comments area.

What is Ascorbic Acid?

You may have heard the term “ascorbic acid,” but what exactly is it? Ascorbic acid is a water-soluble vitamin, commonly known as vitamin C. Chemically speaking, it is an organic compound with the molecular formula C₆H₈O₆.

This essential nutrient plays a crucial role in the functioning of our bodies. It acts as an antioxidant, protecting cells from harmful free radicals, which are unstable molecules that can cause damage. Ascorbic acid also plays a vital role in collagen synthesis, a protein that supports the structure and health of our skin, bones, and connective tissues.

One study published in the Journal of the American College of Nutrition found that adequate vitamin C intake is associated with a reduced risk of chronic diseases, such as cardiovascular disease and certain types of cancer.¹ Another study published in Nutrients emphasized the role of ascorbic acid in enhancing immune function and supporting the body’s defense against pathogens.²

What is the difference between ascorbic acid and vitamin C?

The terms “ascorbic acid” and “vitamin C” are often used interchangeably, but they’re not the same. All ascorbic acid is vitamin C, but not all vitamin C is ascorbic acid.

Ascorbic acid is a specific form of vitamin C. Chemically, ascorbic acid is the purest form of vitamin C, with the molecular formula C₆H₈O₆ I mentioned above. It is the active and most well-known component of vitamin C.

However, vitamin C is a broader term that encompasses not only ascorbic acid but also other related compounds with vitamin C activity. These compounds include dehydroascorbic acid, ascorbyl palmitate, and various mineral ascorbates, which are salts of ascorbic acid.

While ascorbic acid is the most common and readily available form of vitamin C, “vitamin C” describes the presence and activity of all the compounds. They contribute to the overall vitamin C activity and have similar functions and benefits as ascorbic acid itself.

Different forms of vitamin C can be found in a variety of food sources. For example:

Ascorbic Acid: This is the purest form of vitamin C and is commonly found in fruits and vegetables such as citrus fruits (oranges, lemons), berries (strawberries, blueberries), kiwi, bell peppers, and leafy greens (spinach, kale).³
Dehydroascorbic Acid: This is an oxidized form of vitamin C that can be converted back to ascorbic acid within the body. Foods like broccoli, Brussels sprouts, and cauliflower contain dehydroascorbic acid, which can be utilized by the body to provide vitamin C activity.
Ascorbyl Palmitate: This is a fat-soluble form of vitamin C that can be found in some processed foods, supplements, and skincare products. It is commonly used as a vitamin C supplement due to its stability and potential benefits in certain formulations.⁴
Mineral Ascorbates: These are mineral salts of ascorbic acid, such as calcium ascorbate, magnesium ascorbate, or sodium ascorbate. These compounds are often used in dietary supplements and are beneficial for individuals who may require additional minerals along with their vitamin C intake.⁵

When you see a supplement or food label listing “ascorbic acid” or “vitamin C,” it generally refers to ascorbic acid. These terms are used interchangeably in most contexts.

Ascorbic Acid Health Benefits

Ascorbic acid offers a wide array of health benefits when consumed through dietary sources or as a supplement:

Immune System Support: Several studies have shown that supplementation with ascorbic acid can enhance immune function. A randomized controlled trial found that regular vitamin C supplementation reduced adults’ duration and severity of common cold symptoms.⁶ Another study showed that ascorbic acid supplementation improved immune function in people under intense physical stress.⁷
Collagen Synthesis and Wound Healing: Supplementing with ascorbic acid promotes collagen synthesis, which is essential for wound healing, maintaining healthy skin, and tissue repair.⁸
Antioxidant Protection: Ascorbic acid is a potent antioxidant, neutralizing free radicals and reducing oxidative stress. A study published in the Journal of Nutritional Science and Vitaminology showed that ascorbic acid supplementation increased antioxidant capacity in healthy young adults.⁹ I recommend supplementing with antioxidants outside your workout window, though, as I explained in Antioxidants And Exercise: Avoid them around your workouts.
Cardiovascular Health: Research suggests that ascorbic acid supplementation may positively affect cardiovascular health, improving endothelial function, blood pressure, and other cardiovascular risk factors.¹⁰
Cognitive Function: Preliminary evidence suggests that ascorbic acid supplementation may have beneficial effects on cognitive function. A study published in the Journal of Nutrition, Health & Aging found that vitamin C supplementation was associated with improved cognitive performance in older adults.¹¹
Iron Absorption: Ascorbic acid enhances the absorption of non-heme iron from plant-based foods, contributing to the prevention and treatment of iron deficiency anemia.¹² This would be most important for women of childbearing age. Pairing foods rich in iron with a source of ascorbic acid can optimize iron absorption.
Eye Health: Ascorbic acid, along with other antioxidants, plays a role in maintaining eye health and reducing the risk of age-related macular degeneration (AMD) and cataracts.¹³ These conditions are associated with oxidative stress and cellular damage, which can be mitigated by adequate antioxidant intake.

Is Ascorbic Acid Dangerous?

Despite its established safety, a few specific concerns have led to the misconception that ascorbic acid may be bad for you. I’ll address these concerns and shed light on the truth.

Acidic Nature: Ascorbic acid is often associated with acidity, leading some to worry about its potential harm to the digestive system. While it is true that ascorbic acid is acidic in nature, when consumed in normal amounts, it does not have a significant negative impact on the body’s pH balance. The body has efficient mechanisms to maintain the acid-base balance, and the acidity of ascorbic acid is easily buffered. In reality, many people suffer from stomachs that are too alkaline rather than acidic.
Kidney Stones: Another concern is the belief that ascorbic acid increases the risk of developing kidney stones. However, current scientific evidence does not support this claim.¹⁴ Of course, if you have a history of kidney stones or kidney disease, consult with a healthcare professional regarding your vitamin C intake.
Oxalate Formation: Some argue that ascorbic acid can contribute to the formation of oxalate crystals, possibly leading to kidney stone formation. However, this would require you to take extremely high levels of ascorbic acid for a very long time. When taken within the recommended dosage guidelines, ascorbic acid has not been found to increase oxalates significantly.¹⁵

Understanding and addressing these concerns helps dispel the notion that ascorbic acid is bad for you. It is crucial to note that ascorbic acid is safe and beneficial when consumed appropriately.

Ascorbic Acid Dosages

Researchers have found that daily dosages well in excess of the Recommended Daily Allowance (RDA) provide health benefits. That is not surprising since the RDA is the amount necessary to avoid deficiency, not the amount that supports optimal health.

The RDA for ascorbic acid varies depending on age, sex, and life stage. For most adults, the RDA ranges from 75 to 90 milligrams per day.¹⁶ This amount is sufficient to prevent deficiency and support overall health.

Research has explored the effects of higher doses of ascorbic acid, with intakes as high as three grams per day.

Antioxidant Support (Up to 2 grams per day): Doses of 2 grams per day increased antioxidant capacity in healthy young adults.¹⁷
Cold and Flu Prevention (600 mg – 3 grams per day): A meta-analysis published in the Nutrients examined the effects of regular oral vitamin C supplementation on preventing and treating respiratory infections. The study found that daily supplementation with vitamin C (ranging from 0.2 to 2 grams) reduced the duration of colds in adults by 8% and in children by 14%. A randomized controlled trial published in the Journal of Manipulative and Physiological Therapeutics investigated the preventive effects of oral vitamin C supplementation on the incidence and severity of colds in a marathon race population. The study found that participants who took 600 milligrams of vitamin C per day experienced a 50% reduction in cold occurrence compared to the placebo group.¹⁸ A randomized controlled trial published in Nutrients found that a daily intake of 2 grams of vitamin C reduced the severity and duration of common cold symptoms in adults.¹⁹ A meta-analysis published in the Cochrane Database of Systematic Reviews indicated that regular supplementation with vitamin C (doses ranging from 200 to 2,000 milligrams per day) slightly reduced the duration and severity of the common cold.²⁰ Another study found that a daily dose of 1-2 grams of vitamin C reduced the incidence and duration of the common cold in physically active individuals.²¹
COVID-19 (1-8 grams per day): A retrospective study examined the association between vitamin C supplementation and COVID-19 outcomes. The study analyzed data from hospitalized COVID-19 patients who were supplemented with vitamin C (ranging from 1 to 8 grams per day). The findings indicated that vitamin C supplementation was associated with a reduced risk of severe illness, ICU admission, and mortality.²² Another study found that patients who received high-dose oral vitamin C (1 gram per day) had a significantly shorter duration of symptoms compared to those who did not receive vitamin C supplementation.²³
Exercise-Induced Stress: In individuals undergoing physical stress, such as marathon runners, higher doses of ascorbic acid (up to 3 grams per day) have been shown to enhance immune parameters and attenuate the increases in stress hormones.

Practical Summary

Incorporating ascorbic acid, also known as vitamin C, into your daily routine offers numerous health benefits. Ascorbic acid supports immune function, aids in collagen synthesis, acts as a powerful antioxidant, enhances iron absorption, and contributes to eye health. It even helps you combat the effects of intense physical stress.

Being the purest form of vitamin C, ascorbic acid is not only safe but very effective in supporting your health, regardless of what some alarmists may say online.

Of course, the answer isn’t to get your vitamin C only through supplementation but through a combination of supplements and healthy food.

Photo by Diana Polekhina on Unsplash

1 thought on “The Truth About Ascorbic Acid: Healthy or Dangerous?”

Marta Merrick

June 10, 2023 at 10:44 am

Great article! I love taking my YL vitamin C daily and will often take an extra capsule when I’m feeling off. I have also found that it helps reduce bruising in my elderly mom!