Vitamin C
Ascorbic acid, a water-soluble vitamin
A water-soluble vitamin, also called ascorbic acid or ascorbate, found in citrus fruit, peppers and berries and sold in supplements as ascorbic acid, sodium ascorbate and liposomal forms. This page covers only studies in people that measured thinking, memory, mood, stress, sleep, energy, tiredness or quality of life, not all vitamin C research. In those, vitamin C is studied mostly for stress and tiredness, and for mood, by mouth and by hospital drip. Here is every one we could find, sorted from each study's summary.
- Found in: citrus fruit, peppers and berries
- Most tested: 1,000 mg a day
- Mostly by mouth, some by hospital drip
From every paper to the studies that matter
Our search looked only at vitamin C papers on thinking, mood, stress, sleep and energy, not at all vitamin C research. Most of those are lab or animal work, or only measure vitamin C in the blood or diet. A smaller share gives vitamin C to people, and that is what this page is about.
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5,893 papers on vitamin C and thinking, mood, stress, sleep or energy.Every record in PubMed, all years
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295 are about people.The rest: 1,916 lab and animal studies, 697 reviews, 2,985 on chemistry, farming and more
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76 give vitamin C on its own.71 more give vitamin C with vitamin E, other vitamins or minerals, or in a blend
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42 are randomised against a placebo.Randomised controlled trials In a randomised controlled trial, people are put into groups by chance, one taking the treatment and one a placebo or other comparison. Chance spreads differences such as age and health evenly, so a difference between the groups is more likely to be down to the treatment., the strongest kind of study
Bar lengths use a square-root scale so the small numbers stay visible.
How much research there is
- 76 studies giving vitamin C to people, on thinking, mood, stress, sleep and energy
- 42 of them randomised against a placebo A placebo-controlled trial compares a real treatment with a dummy that looks the same, the placebo. People often feel better when they expect to, so comparing against a placebo shows how much of the change comes from the treatment itself.
- 6,852 people taking part, where studies say
- 101 systematic reviews A systematic review searches for every study on a question in a set, written-down way, judges the quality of each and sums up what they show together. Many include a meta-analysis. The Atlas lists these as pooled reviews. pooling the trials
Studies in people, by year published
Vitamin C on its own, by mouth or by drip.
What the studies looked at
Each study can measure several things. Choose a topic to see its studies in the list below.
Studies in people with a diagnosed condition are counted here and listed with their population. We describe what they measured, not what they might treat. Most studies also report safety; see below.
What was tested, and how much
Vitamin C is a single compound, so milligrams compare directly from one study to the next. Most oral studies gave 500 to 3,000 mg a day, far more than the 40 mg a day the NHS says adults need. The dots furthest to the right are mostly high-dose drips given in hospital, which are a different kind of dose from a tablet or drink. Some studies gave a single dose, and others gave it daily for a few weeks.
Daily amount, one dot per study
Studies per extract
Named extracts are the maker's brand. "Not named" means the study didn't say.
All studies in people
Filter the list, then open a study on PubMed. Each row comes from the study's published summary, and about half involve people with a health condition, many given vitamin C by drip alongside usual care.
| Study | Who took part | People | Extract and daily dose | Length |
|---|---|---|---|---|
| Dhivya 2025RCT, active or other control | Post-menopausal women with mild cognitive impairment | 180 | Ascorbic acid, 100 mg | 26 weeks |
| Freeberg 2025Crossover, placebo | Healthy young and older adults | 41 | Ascorbic acid | – |
| Sim 2025RCT, placebo | Healthy young adults with low vitamin C status | 40 | Ascorbic acid, 1,000 mg | 4 weeks |
| Fletcher 2024RCT, placebo | Adults aged 18-35 with low vitamin C status | 155 | Ascorbic acid, 250 mg | 4 weeks |
| Beglaryan 2024RCT, active or other control | Women with stress-related hypercortisolemia | 69 | Ascorbic acid, 1,000 mg | 9 weeks |
| Rocha 2024Crossover, placebo | Overweight and obese men | 14 | Ascorbic acid, 3,000 mg | – |
| Rocha 2023Crossover, placebo | Overweight or obese men under mental stress | 15 | Ascorbic acid, 3,000 mg | – |
| Sim 2022RCT, placebo | Healthy young adults with low vitamin C status | 46 | Ascorbic acid, 1,000 mg | 4 weeks |
| Mansoor 2021RCT, placebo | Breast cancer patients on standard treatment | 350 | Ascorbic acid, 3,571 mg | 4 weeks |
| Thomas 2021RCT, active or other control | Outpatients with SARS-CoV-2 infection | 214 | Ascorbic acid, 8,000 mg | 1 weeks |
| Ali 2021Crossover, placebo | Recreationally active women | 10 | Ascorbic acid, 300 mg | – |
| Hureau 2021Crossover, placebo | Adults with COPD | 8 | Ascorbic acid, 2,000 mg | – |
| Conner 2020RCT, placebo | Young adults with low vitamin C levels | 167 | Ascorbic acid, 250 mg | 4 weeks |
| Margaritelis 2020RCT, active or other control | Volunteers screened for low vitamin C or glutathione | 36 | Ascorbic acid, 1,000 mg | 4 weeks |
| Batista 2020Crossover, placebo | Overweight or obese men under mental stress | 14 | Ascorbic acid, 3,000 mg | – |
| Lux-Battistelli 2019Single-arm or open-label | Patients withdrawing from alcohol, low vitamin C | 47 | Ascorbic acid | 12 weeks |
| Bazzan 2018Observational | Cancer patients receiving IV ascorbic acid | 86 | Ascorbic acid | – |
| Vollbracht 2018Single-arm or open-label | Patients with allergy-related respiratory or skin disease | 71 | Pascorbin | – |
| Moritz 2017RCT, placebo | Healthy graduate students | 142 | Ascorbic acid, 1,000 mg | – |
| Vijayakumar 2017RCT, active or other control | Postmenopausal women with mild cognitive dysfunction | 56 | Ascorbic acid, 500 mg | 12 weeks |
| Choi 2017Other | Korean women | 24 | Ascorbic acid | 4 weeks |
| Plotnick 2017Crossover, placebo | Healthy young men under mental stress | 15 | Ascorbic acid, 1,000 mg | – |
| Jeon 2016RCT, placebo | Patients having laparoscopic colectomy | 100 | Ascorbic acid | – |
| Khajehnasiri 2015RCT, placebo | Depressed male rotating shift workers | 136 | Ascorbic acid, 500 mg | 9 weeks |
| Biniaz 2015RCT, placebo | Hemodialysis patients | 62 | Ascorbic acid, 107 mg | 8 weeks |
| Sahraian 2015RCT, placebo | Adults with major depression on citalopram | 43 | Ascorbic acid | 8 weeks |
| de Oliveira 2015RCT, placebo | High school students | 42 | Ascorbic acid, 500 mg | 2 weeks |
| Hoffer 2015Single-arm or open-label | Advanced cancer patients on chemotherapy | 14 | Ascorbic acid | – |
| Mikirova 2014Observational | Patients with EBV infection and chronic fatigue | 178 | Ascorbic acid | – |
| Khajehnasiri 2013RCT, placebo | Depressed shift workers | 136 | Ascorbic acid, 500 mg | 9 weeks |
| Schmidt 2013RCT, active or other control | Healthy young adults exposed to aircraft noise | 75 | Ascorbic acid | – |
| Mazloom 2013RCT, placebo | Patients with type 2 diabetes | 45 | Ascorbic acid, 1,000 mg | 6 weeks |
| Amr 2013RCT, placebo | Children with major depression on fluoxetine | 24 | Ascorbic acid, 1,000 mg | 26 weeks |
| Huck 2013RCT, placebo | Obese adults on calorie-reduced diet | 20 | Ascorbic acid, 500 mg | 4 weeks |
| Rossman 2013Crossover, placebo | Patients with COPD | 10 | Ascorbic acid, 2,000 mg | – |
| Wang 2013RCT, active or other control | Acutely hospitalised patients | – | Ascorbic acid, 1,000 mg | 1 weeks |
| Suh 2012RCT, placebo | Healthy office workers | 141 | Ascorbic acid, 10,000 mg | – |
| Schencking 2012Single-arm or open-label | Adults with shingles | 67 | Ascorbic acid | 2 weeks |
| Sagheb 2012RCT, placebo | Hemodialysis patients with restless legs | 60 | Ascorbic acid, 200 mg | 8 weeks |
| Pareyson 2011RCT, placebo | Adults with Charcot-Marie-Tooth type 1A | 277 | Ascorbic acid, 1,500 mg | 104 weeks |
| Vollbracht 2011Non-randomised controlled | Breast cancer patients on chemo or radiotherapy | 125 | Ascorbic acid | 4 weeks |
| Singer 2011RCT, placebo | Severe kidney failure or dialysis patients | 99 | Ascorbic acid, 107 mg | 13 weeks |
| Fernandes 2011RCT, placebo | Obese children aged 8-12 | 21 | Ascorbic acid, 500 mg | 6 weeks |
| Zhang 2011RCT, active or other control | Acutely hospitalized patients | – | Ascorbic acid, 1,000 mg | – |
| Evans-Olders 2010Single-arm or open-label | Acutely hospitalized patients with low vitamin C | – | Ascorbic acid | 1 weeks |
| Kang 2009RCT, placebo | Women with cardiovascular disease or risk factors | 2,824 | Ascorbic acid, 500 mg | 281 weeks |
| Nakhostin-Roohi 2008RCT, placebo | Healthy untrained men | 16 | Ascorbic acid, 1,000 mg | – |
| Carrillo 2008RCT, placebo | Healthy exercisers | 12 | Ascorbic acid, 1,500 mg | 2 weeks |
| Rabadi 2007Non-randomised controlled | Ischemic stroke patients in rehabilitation | 46 | Ascorbic acid, 1,000 mg | – |
| Yeom 2007Single-arm or open-label | Terminal cancer patients | 39 | Ascorbic acid, 4,000 mg | 1 weeks |
| Ataka 2007Crossover, placebo | Healthy volunteers | 18 | Ascorbic acid, 1,000 mg | 1 weeks |
| Johnston 2006RCT, placebo | Young adults with marginal vitamin C status | 22 | Ascorbic acid, 500 mg | 8 weeks |
| Davison 2006Crossover, placebo | Endurance-trained men | 9 | Ascorbic acid, 1,000 mg | 2 weeks |
| Davison 2005Crossover, placebo | Moderately trained men | 6 | Ascorbic acid | – |
| Taji 2004Non-randomised controlled | Unselected haemodialysis patients | 61 | Ascorbic acid, 43 mg | 26 weeks |
| Pirbudak 2004RCT, active or other control | Women having gynecologic surgery | 22 | Ascorbic acid | – |
| Brody 2002RCT, placebo | Healthy young adults, stress test | 120 | Ascorbic acid, sustained-release (Cetebe), 3,000 mg | 2 weeks |
| Brody 2002RCT, placebo | Healthy young adults, stress test | 108 | Ascorbic acid, sustained-release (Cetebe), 3,000 mg | 2 weeks |
| Brody 2002RCT, placebo | Healthy young adults | 81 | Ascorbic acid, sustained-release (Cetebe), 3,000 mg | 2 weeks |
| Peters 2001Non-randomised controlled | Ultramarathon runners | 45 | Ascorbic acid, 1,500 mg | 1 weeks |
| Kontush 2001Non-randomised controlled | Alzheimer's disease patients | 20 | Ascorbic acid, 1,000 mg | 4 weeks |
| Peters 2001Non-randomised controlled | Ultramarathon runners | 16 | Ascorbic acid, 1,000 mg | 1 weeks |
| Nieman 2000Non-randomised controlled | Ultramarathon runners | 29 | Ascorbic acid, 1,500 mg | 1 weeks |
| Nieman 1997RCT, placebo | Experienced marathon runners | 12 | Ascorbic acid, 1,000 mg | 1 weeks |
| Kodama 1994Other | One healthy male volunteer | 1 | Ascorbic acid | – |
| Levin 1993RCT, active or other control | Smokers trying to quit | – | Ascorbic acid, 300 mg | 5 weeks |
| Gromova 1990Non-randomised controlled | Surgical lung cancer patients | – | Ascorbic acid, 2,000 mg | 2 weeks |
| Kallner 1983Non-randomised controlled | Healthy volunteers, stress exposure | – | Ascorbic acid, 3,000 mg | – |
| Schorah 1981RCT, placebo | Elderly long-term inpatients with low vitamin C | 94 | Ascorbic acid | 9 weeks |
| Adam 1981Crossover, placebo | Healthy young men | 20 | Ascorbic acid | – |
| Naylor 1981Crossover, placebo | Manic-depressive patients | – | Ascorbic acid, 3,000 mg | – |
| Anderson 1977Other | Adults in large trials | – | Ascorbic acid | – |
| Masek 1977Other | Workers and young volunteers | – | Ascorbic acid, 1,000 mg | 2 weeks |
| Liakakos 1975Non-randomised controlled | Healthy children | 20 | Ascorbic acid, 3,000 mg | 1 weeks |
| Kirchhoff 1969Other | Adults under stress (title only) | – | Ascorbic acid | – |
| Margolis 1968Other | Workers in hazardous occupations (title only) | – | Ascorbic acid | – |
What's known about safety
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In trials
High-dose vitamin C given by drip has generally been well tolerated in clinical trials. Kidney failure has been reported after it in people who already had kidney problems, and one report linked a drip to fluid overload. The NHS says more than 1,000 mg a day by mouth can cause stomach pain, diarrhoea and wind, which should pass once the supplement is stopped.
National Cancer Institute, Intravenous Vitamin C PDQ summary (updated May 2025); NHS vitamin C page, Oct 2026
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In the UK
Vitamin C as L-ascorbic acid, sodium, calcium, potassium, magnesium or zinc ascorbate, or ascorbyl palmitate, can be sold in food supplements. The NHS says adults aged 19 to 64 need 40 mg a day, and that taking less than 1,000 mg a day of supplements is unlikely to cause harm. Drips are given in hospital or clinic settings, not bought as supplements.
Directive 2002/46/EC Annex II as retained in UK law (legislation.gov.uk); NHS vitamin C page, Oct 2026
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Check first
A review of high-dose vitamin C by drip says case reports link it to red blood cell breakdown in people with G6PD deficiency, and that it can falsely raise readings on some finger-prick glucose meters. Animal and lab studies suggest vitamin C may interfere with the cancer drug bortezomib. We found no source on pregnancy or breastfeeding. Speak to a pharmacist or doctor first if any of these applies to you.
National Cancer Institute, Intravenous Vitamin C PDQ summary, adverse effects and drug interactions sections (updated May 2025), Oct 2026
Where these studies come from
We list every published study in people that gave vitamin C and measured thinking, memory, mood, stress, sleep, energy, tiredness or quality of life, as ascorbic acid, sodium ascorbate or liposomal vitamin C, by mouth or by drip, including high-dose intravenous vitamin C. Vitamin C added to a medicine or usual care counts as vitamin C on its own; vitamin C given with vitamin E or other vitamins and minerals counts as a blend. Studies that only measured vitamin C in the blood or diet, or gave it only to the control group, are left out. This first version is built from each study's summary; full-paper checks come next.
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We search
PubMed, the world's main library of medical research, for every paper on L-theanine.
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We keep studies in people
Lab and animal work is counted but left out of the list, because it doesn't tell you what happens in people.
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We note the basics
Who took part, how many, how much and for how long, from each study's published summary. A second check corrects what the first read gets wrong.
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We read them in full
Results appear once we've read the whole paper and checked every number. The date at the top shows when this entry was last updated.
Download the study list
Every study in people as a spreadsheet, 76 rows, free to reuse with a link back.
Versions
Each update to the data gets a new version number, so you can tell what changed and when.
See every version
1.0 · 24 Oct 2026. First release. Every published study giving vitamin C to people that measured thinking, memory, mood, stress, sleep, energy or quality of life is listed from its summary. None is read in full yet.
