- Health and wellness
- 3 views
- How much vitamin C to take per day
- How long to take vitamin C
- Supplementing with 1,000 mg per day
- The risks and symptoms of excessive vitamin C intake
- Frequently asked questions
How much vitamin C to take per day
Vitamin C, or ascorbic acid, is a water-soluble nutrient that the body cannot produce on its own. It must therefore be obtained daily through the diet and, when there is a specific need, can be supplemented with dedicated products.
The amount required varies according to age, sex and stage of life. For most adults, daily requirements can be met through a varied diet that regularly includes fruit and vegetables. Supplements may provide support when dietary intake is insufficient or requirements increase, but high doses are not necessary to automatically obtain greater benefits.
The choice should be based on the amount already obtained from food and individual needs, always checking the dose per serving.
The daily dose for adults
According to the LARN reference values reported by ISSalute, the recommended daily vitamin C intake for adults is:
- Men: 105 mg per day;
- Women: 85 mg per day;
- Pregnancy: 100 mg per day;
- Breastfeeding: 130 mg per day.
Smokers may have higher requirements: nutritional guidelines consider an additional intake of approximately 35 mg per day compared with the reference values. These amounts represent nutritional targets to be achieved through the diet and are not mandatory supplement dosages.
Vitamin C is found in many foods, particularly plant-based foods. Some of the most interesting sources include:
- Peppers: especially red and yellow peppers, which can provide high amounts of vitamin C;
- Kiwi fruit: a convenient source to include at breakfast or as a snack;
- Citrus fruits: oranges, lemons, mandarins and grapefruits contribute to daily intake;
- Strawberries and blackcurrants: fruits that naturally contain vitamin C;
- Broccoli and cabbage: several vegetables belonging to these families can make a significant contribution to daily requirements;
- Tomatoes and potatoes: provide varying amounts of vitamin C depending on the variety and preparation method.
Vitamin C is sensitive to heat, light and prolonged storage. To limit losses during preparation, it may be useful to alternate raw and cooked foods and favour short cooking methods, such as steaming. However, dietary variety remains more important than focusing on a single particularly rich food.
How long to take vitamin C
There is no fixed duration for taking vitamin C supplements. The period of use depends on the reason for supplementation, the amount obtained through the diet and any recommendations from a healthcare professional.
If the aim is to correct insufficient dietary intake, the duration should be assessed according to eating habits and individual circumstances. If supplementation has been recommended for a specific condition or a documented deficiency, it is advisable to follow the doctor's instructions, as they can determine the appropriate amounts and duration.
Vitamin C is water-soluble, and the body regulates its levels through absorption and urinary excretion. This does not mean that it needs to be taken continuously as a supplement: daily requirements can be met through food without necessarily resorting to concentrated products.
Several aspects should be considered:
- Purpose of supplementation: clarify whether the aim is to correct insufficient intake or address a specific need;
- Usual diet: assess how much vitamin C is already obtained from fruit and vegetables;
- Daily dose: consider the total amount from food, drinks and other supplements;
- Individual circumstances: in the presence of medical conditions or medication use, seek advice from a doctor or pharmacist;
- Duration: avoid extending supplementation or increasing the dose without a specific reason.
If fatigue or other symptoms persist, they should not automatically be attributed to vitamin C deficiency. They may depend on numerous factors and require a medical assessment. Supplements should not be used to delay investigations or replace prescribed treatment.
Supplementing with 1,000 mg per day
A dose of 1,000 mg of vitamin C per day is much higher than the nutritional requirements of an adult, which according to LARN are 85 mg for women and 105 mg for men. This does not mean that a single 1,000 mg dose will necessarily cause harm, but it also does not mean that this amount is necessary for everyone.
High doses are sometimes used in supplements intended to support general wellbeing or during particularly demanding periods. However, taking a larger amount does not automatically lead to a proportionate increase in benefits. Intestinal absorption of vitamin C decreases when intake is very high, and some of the excess absorbed amount is eliminated through urine.
When evaluating a 1,000 mg product, it is therefore important to consider the overall context. If the diet already provides adequate amounts of vitamin C, such a high level of supplementation may not offer any significant additional benefit. It is also important to check whether the same vitamin is present in multivitamins, sports products or other formulations taken throughout the day.
A 1,000 mg dose may be tolerated by many healthy adults, but some people may experience gastrointestinal discomfort even at lower amounts. Anyone with a history of kidney stones, iron metabolism disorders or medical conditions requiring specific precautions should seek medical advice before taking high doses.
The maximum tolerable daily intake
The maximum tolerable daily intake, also known as the UL (Tolerable Upper Intake Level), is the highest level of habitual intake that, according to scientific assessments, is unlikely to cause adverse effects in most of the population.
For vitamin C, it is important to distinguish between the reference values adopted by different authorities. EFSA has not established a European tolerable upper intake level because the available data were not considered sufficient to define one. In the United States, however, the Food and Nutrition Board has set an UL of 2,000 mg per day for adults, taking into account total intake from food, drinks and supplements.
Furthermore, occasionally exceeding a limit does not necessarily mean that adverse effects will occur, but consistently high intake may increase the risk of problems.
To interpret these values correctly, it is useful to remember that:
- 85-105 mg per day: the LARN reference values for adult women and men;
- 1,000 mg per day: a high amount compared with daily requirements, which may cause gastrointestinal discomfort in some people;
- 2,000 mg per day: the maximum tolerable limit established in the United States for adults, not a recommended dose.
Anyone wishing to take high amounts of vitamin C should assess whether this is actually necessary with a healthcare professional, particularly in the presence of kidney disease, a predisposition to kidney stones or conditions affecting iron metabolism.
The risks and symptoms of excessive vitamin C intake
Vitamin C generally has low toxicity, but this does not mean that high amounts are always free of consequences. When intake exceeds the body's ability to absorb and process it, adverse effects may occur, particularly in the gastrointestinal tract.
The most common problems associated with high vitamin C intake include:
- Diarrhoea: some unabsorbed vitamin C may draw water into the intestines and lead to more frequent bowel movements;
- Nausea: this may occur particularly after taking high doses or on an empty stomach in sensitive individuals;
- Abdominal cramps and pain: these may accompany digestive discomfort;
- Flatulence: some people may experience increased intestinal gas and abdominal discomfort;
- Heartburn: some ascorbic acid formulations may not be well tolerated by the stomach.
There are also situations in which excessive vitamin C intake requires particular attention. Vitamin C promotes the absorption of non-haem iron, which is mainly found in plant-based foods. In people with hereditary haemochromatosis, a condition that causes excessive iron accumulation, high doses of vitamin C may worsen iron overload and contribute to tissue damage.
Another potential concern involves kidney stones. Some vitamin C is metabolised into oxalate, which is eliminated through urine. In predisposed individuals, particularly those with hyperoxaluria or a history of calcium oxalate stones, high supplemental intake could increase the risk. Evidence does not indicate that this effect necessarily occurs in all healthy adults, but it is an important precaution for anyone with existing risk factors.
The effects of an overdose on the liver
The liver is involved in numerous metabolic processes, but there is no evidence that normal amounts of vitamin C or moderate supplementation cause liver damage. Vitamin C is not considered a common cause of hepatitis or liver failure and, at usual amounts, is not generally associated with clinically significant changes in liver function.
Available information indicates that even high doses are not normally associated with clinically evident liver damage. In certain circumstances, extremely high amounts may be associated with temporary changes in some liver enzymes, such as transaminases, but these findings do not demonstrate that vitamin C necessarily causes liver injury.
It is therefore important to distinguish gastrointestinal effects, which are relatively more common with high doses, from possible liver effects, for which evidence of direct clinical damage is very limited. It is not correct to claim that taking 1,000 mg of vitamin C per day automatically causes liver overload or damage in a healthy person.
The overall safety of a supplement nevertheless depends on the dose, duration, individual circumstances and the presence of other substances in the formulation. Anyone with liver disease or taking medication should seek medical advice before using high doses or combination products.
Frequently asked questions
Can taking vitamin C help reduce anxiety?
Vitamin C contributes to the normal functioning of the nervous system and protects cells from oxidative stress. Some studies have investigated the possible relationship between vitamin C intake and the perception of stress or anxiety, but the evidence is insufficient to consider it a treatment for anxiety disorders.
A controlled study conducted on a small group of students observed a reduction in anxiety scores after two weeks of supplementation with 500 mg of vitamin C per day. However, this was a limited study in terms of size and population, and its findings cannot be generalised to everyone or used to establish a therapeutic dose.
Vitamin C therefore does not replace psychotherapy, prescribed treatments or professional assessment. In the presence of persistent anxiety, it is important to identify possible causes and consider the most appropriate support. To explore the different options available, you can consult our guide to supplements for anxiety, remembering that no supplement can guarantee symptom reduction on its own.
What are the benefits of liposomal vitamin C?
Liposomal vitamin C is a formulation in which ascorbic acid is enclosed in small structures made of phospholipids, known as liposomes. This technology was developed to protect the nutrient during gastrointestinal transit and promote its absorption.
Some clinical studies have observed greater bioavailability of liposomal vitamin C compared with conventional ascorbic acid, with increases in measured plasma concentrations and, in some studies, in leukocytes. A review published in 2025 found favourable results in most of the studies analysed, but also highlighted significant differences between formulations and the need for further research into biological and clinical effects.
Greater bioavailability does not automatically demonstrate superior health benefits. Available studies have mainly assessed absorption and blood concentration parameters, while evidence demonstrating better clinical outcomes compared with traditional formulations remains limited.
In this case too, the choice should be based on composition, amounts per dose and individual needs, without assuming that one formulation is necessary for everyone.
How long can you take 500 mg of vitamin C?
There is no fixed duration for taking 500 mg of vitamin C per day. The period of use depends on the reason for supplementation, dietary intake and individual circumstances. A 500 mg dose is higher than the daily requirement for an adult, but this does not automatically mean that it causes adverse effects in everyone.
If supplementation has been recommended for a specific need, it is advisable to follow the healthcare professional's instructions and periodically reassess whether it is still useful. If your diet already provides adequate amounts of vitamin C, taking 500 mg every day for extended periods is not necessarily beneficial.
Anyone with a history of kidney stones, kidney problems, haemochromatosis or other conditions requiring precautions should seek medical advice before using high-dose supplements. It is also important to consider any vitamin C contained in multivitamins or other products taken throughout the day.
The daily vitamin C requirement for adults is generally much lower than the amounts found in many high-dose supplements. A varied diet rich in fruit and vegetables is the starting point for meeting nutritional needs, while supplementation can be considered when there is a specific reason. Taking 1,000 mg per day is not necessary for everyone and may cause gastrointestinal discomfort, particularly in sensitive or predisposed individuals.
