The research says no. The anecdotes say possibly, due to the type of Vitamin C you take. There are several misunderstandings surrounding Vitamin C due to chronic oversimplification of research and clickbait headlines. Let’s look at the facts about Vitamin C to understand the nuances that affect the answer to the “can you take too much Vitamin C” question.

Vitamin C is water-soluble. Why is this important? It’s about the absorption. Vitamin C is one of several water-soluble vitamins, which are all critical to numerous processes in our bodies but that we have lost the ability to synthesize. We must get these nutrients though diet, and those nutrients are subject to the water-based juices in the digestive system. What is important to note here is that water-soluble vitamins cannot be stored in the body. Any excess is eradicated from the body in urine. That is why there is no known toxicity for Vitamin C. We cannot accumulate enough of it to reach dangerous levels.

Dietary Vitamin C, also known as ascorbate, is available in two forms: reduced (ascorbic acid, AA) and oxidized (dehydro-L-ascorbic acid, DHAA). Both forms have different structures with DHAA being similar to glucose. The intestinal epithelial cells convert DHAA into AA, which helps maintain a non-toxic level of the compound. Vitamin C in its reduced state — ascorbic acid — is a potent antioxidant. It donates electrons to electron-hungry free radicals, thus neutralizing them before the free radicals damage cells by stealing their electrons. That action oxidizes Vitamin C, so it becomes DHAA. If it is not turned back into AA by the epithelial cells (or other antioxidants like glutathione), it is subject to further metabolic breakdown.

Can You Take Too Much Vitamin C & Get Kidney Stones?

After being converted to DHAA, Vitamin C becomes diketogulonic acid. Further metabolic processes turn it into lyxonic acid, xylose, threonic acid, or oxalic acid (oxalate). The latter is where the myth that taking large doses of Vitamin C causes kidney stones comes in. Because calcium oxalate is the primary constituent of most kidney stones, many doctors have been under the unfounded assumption that Vitamin C consumption with oxalate as the metabolic end product can cause kidney stones. In numerous studies, researchers have found no statistical correlation between Vitamin C intake and the incidence of kidney stones. In one study, researchers even found an association between the increase in blood Vitamin C content and a reduction in the prevalence of kidney stones while another research team reported that an 81-year-old woman dissolved her kidney stone using a regimen that included Vitamin C.

“When very high doses of vitamin C are administered for any significant medical condition, the active, non-oxidized form of vitamin C is much more readily regenerated from the oxidized vitamin C than the metabolic breakdown products. This process further inhibits the irreversible metabolism of vitamin C to the oxalate end product,” writes Vitamin C expert Dr. Thomas E. Levy in his comprehensive, 400+ page research review Curing the Incurable.

Researchers also found that most of the metabolized Vitamin C never even makes it to the oxalate form with 80% of it excreted from the body as dehydroascorbic acid.

Can You Take too Much Vitamin C & Turn It Into a Pro-Oxidant?

Again, the research says no. In fact, Vitamin C may only exhibit pro-oxidant properties in smaller doses. And this appears to be only in reaction to the presence of metals. A pro-oxidant promotes oxidation, which leads to more oxidative stress and free radicals. It can become a pro-oxidant when it loses electrons after neutralizing a free radical, turning itself into DHAA without other cells or antioxidants around to restore it to its de-oxidized state.

“In the presence of metals like copper and iron that readily exchange electrons, the antioxidant loss of the electrons from vitamin C to these metals results in an increased ability of the metals to subsequently have a prooxidant activity in their immediate microenvironment,” writes Dr. Levy.

The metals facilitate the formation of free radicals, so the presence of Vitamin C can result in pro-oxidant activity even though Vitamin C is acting as an antioxidant.

As Dr. Levy says, “Typically, in such a catalytic metal environment, lower vitamin C concentrations favor prooxidant effects, while higher concentrations favor antioxidant effects. The researchers also observed that virtually all experimental systems where vitamin C facilitated prooxidant activity also had metal catalysts, usually as iron (Fe3+) or copper (Cu2+) ions.”

“Generally, it is only in daily dose ranges from the small recommended dietary allowance of 60 mg for the adult up to about 2,000 mg that vitamin C can ever exert a prooxidant effect.”

He adds that this reaction would still only occur in “an unusual clinical situation” in which the subject has high circulating or tissue levels of these catalytic metals. Even in those cases, he says that a large dose of Vitamin C will be the most effective in neutralizing the free radicals generated by the metals.

“Even if localized concentrations of catalytic metals continue to produce free radicals, extra vitamin C will always immediately neutralize them or their acute harm before chronic damage is done.”

Numerous doctors around the world have administered high-dose Vitamin C IV (300,000 mg) to patients with conditions ranging from cancer to sepsis without any toxicity. Intravenous delivery brings the Vitamin C directly to the bloodstream, not the digestive system where the Vitamin C molecules are subject to the digestive juices that break it down.

Because of its water-solubility, several factors can affect absorption of Vitamin C, including the presence of other vitamins, minerals, and medications. While it is not possible to reach toxic levels of Vitamin C, it is possible to reach uncomfortable levels. High oral doses of Vitamin C have been known to produce diarrhea and other forms of gastric distress due to the acidic vitamin’s interaction with digestive juices.

Dr. Robert Cathcart, a pioneer in Vitamin C research, started administering high-dose Vitamin C to his patients in the 1970s. He found that patients with diseases or higher levels of stress tolerated higher oral doses of Vitamin C before diarrhea was produced. This means that patients with more of a need for the antioxidant capabilities of Vitamin C will put more of it to use in the body while people with less of a need for the compound will pass more of it through their digestive system, which can cause unpleasant gastric symptoms. Numerous other studies over the past several decades have yielded similar results.

In What Forms Can You Take Too Much Vitamin C?

Dr. Cathcart’s research dealt only in traditional oral Vitamin C that is subject to the digestive system. While no dosage has been labeled toxic, the gastric unpleasantness of excess oral doses is well-documented. No such symptoms have been reported in liposomal oral delivery. Encapsulating Vitamin C in liposomes has been found to nullify the possible negative effects of Vitamin C.

Liposomes are microscopic spheres composed of phospholipids that do not dissolve in water, thus are ideal to transport water-soluble compounds like Vitamin C. The liposome protects the Vitamin C as it passes through the digestive system until it is released into the cells. The composition of the liposome membrane is structurally similar to that of the cell membrane, which allows the liposome to pass into the cell and the structures within (including the mitochondria and nuclei).

Most of the traditional delivery of Vitamin C from the blood to the cells requires cellular energy. Glutathione must also oxidize itself in order to restore the DHAA to its active state within a cell, which turns the potent antioxidant into a pro-oxidant. This does not occur with liposomal Vitamin C as the liposome is able to delivery the antioxidant to the cell while sparing cellular energy.

Read the nutrition fact panel on any supplements you are taking. Many gummies and powders contain substantial amounts of sugar, which can cause negative effects. Other synthetic additives in many mainstream Vitamin C complex supplements may also be a culprit, not necessarily the Vitamin C content.

So, can you take too much Vitamin C? The answer is clearly more complicated than a simple yes or no as it depends on the type of Vitamin C supplement you are taking as well as your specific health status. The federal government has not declared a known toxicity and, according to Dr. Levy, there have been no deaths ever attributed to Vitamin C intake. Yes, taking high oral doses puts you at risk for diarrhea and other unpleasant gastric symptoms, none of which have been reported by those taking liposomal Vitamin C supplements like our Lypo-Spheric® Vitamin C.