Mind & body, in brief

Almost every mammal makes its own vitamin C. Humans and the other primates cannot, because the gene for the final step is broken. [2]

The broken gene is still in the human genome. It is called GULOP, and it is missing five of the twelve working sections a rodent's version has. [2]

That is what makes vitamin C a vitamin. A vitamin is only a vitamin for a body that cannot build the thing itself. [7][2]

The word came from a guess. Casimir Funk coined vit-amine in 1912 for substances he thought were vital and were amines; he was wrong on the chemistry. [7]

The body cannot store it either. The whole body holds about 1,500 mg, and the kidneys clear the surplus, so the supply has to be near-continuous. [1]

Vitamin C's main job is not to be a building block. It is a helper that keeps two enzymes working while they build collagen. [3]

Collagen is the body's main structural protein. It is a quarter to a third of all the protein a person is made of. [38]

A collagen molecule is three chains wound into a rope. The rope only holds if certain links along each chain are chemically altered first. [3]

Two enzymes do that altering: prolyl hydroxylase and lysyl hydroxylase. Both need vitamin C to keep running. [3][13]

Without it the triple rope forms badly. The collagen wrapped around the smallest blood vessels goes weak, and they leak. [1]

That is scurvy: swollen and bleeding gums, loose teeth, bleeding under the skin, and wounds that will not heal. [48] The giveaway sign is bleeding around each hair follicle. [20]

It is slow. One to three months of almost no vitamin C pass before the first signs show. [1]

It is also fast to reverse. In published cases, the skin and gum signs clear in days to a couple of weeks once vitamin C is given. [1][16]

Ten milligrams a day is enough to prevent it. That number comes from a study done in Sheffield in 1953. [5]

Britain's official recommendation is 40 mg a day, set in 1991 and built on that 1953 figure. [5]

The United States recommends 90 mg a day for men and 75 mg for women - more than twice Britain's number for the same species. [1][5]

A 2026 commentary argues the British figure ignored evidence that already existed, including six trials in people already getting 40 mg or more. [5]

Smokers are told to add 35 mg a day, because burning tobacco raises how fast the body uses it up. [1]

More than about 200 to 400 mg at once does not get in. The gut's carriers saturate, and the extra leaves in urine. [1][6]

Scurvy is not history. A review published in February 2026 counted 280 adult cases in the medical literature since 2000. [4]

Almost none of them were spotted quickly. The typical case is a long hunt for an autoimmune or bleeding disorder that was never there. [4]

The people it reaches now are not sailors. They are people with eating disorders, psychosis, autism, homelessness, or an appetite that a drug has shut down. [11][12][13][14]

The best test of the cold claim is recent and large. A network analysis of 107 trials in 101,751 adults found the things that cut respiratory infections were catechin and probiotics, not vitamin C. [24]

Big doses are not free. In more than 23,000 Swedish men followed for 11 years, reported in 2013, supplement users had twice the rate of kidney stones. [21]

Very high doses also break blood tests. Ascorbate interfered with lactate, lipase, cholesterol, triglyceride and several glucose readings in a 2026 laboratory study. [23]

Why it matters. Watch whether Britain's 40 mg figure gets reopened - the 2026 commentary is the first serious push at a number set in 1991, and nothing has been re-measured since. [5]

A three-year-old had fever, swelling, bone pain and pinpoint skin bleeding for five weeks. Biopsies and autoimmune tests were negative. His diet was mostly rice. [8]

Why it matters. The diagnosis was made by asking what he ate, after everything expensive had been tried.

Two hospitals in Catania diagnosed eight young children between October 2021 and October 2023. The authors also reviewed 126 papers holding 253 further cases. [9]

Why it matters. A disease called extinct in rich countries is being found in clusters wherever someone looks.

A hospital in southern Thailand found 46 children with vitamin C deficiency from 2004 to 2024. Limb pain hit 76%; 52% refused to walk. [10]

Why it matters. The first sign is often a child who stops walking, which sends doctors looking at bones.

A review of 18 reports found 19 adults with both scurvy and a psychotic illness, median age 54. In 26%, the presenting problem was psychiatric. [11]

Why it matters. An illness that changes what a person will eat becomes an illness that changes what their blood contains.

An 18-year-old woman with autism had almost no vitamin C in her blood, and lithium levels that stayed too low however much was given. After treatment, both changed. [12]

Why it matters. It is a single case, and the authors call the drug link a hypothesis, not a finding.

A 60-year-old man with unstable housing came in short of breath. He had bleeding into the roof of his mouth, bruising, and severely low vitamin C and B6. [13]

Why it matters. His diet was processed carbohydrates, which is what food costs money looks like inside a body.

People taking GLP-1 appetite-suppressing drugs are turning up with bleeding gums and easy bruising. The mechanism is not the drug but the collapse in how much and how varied the eating is. [14]

Why it matters. Any intervention that cuts food volume cuts the nutrients that ride in with it.

A woman in her late 50s had high blood pressure in her lung arteries and a weak heart output. She had a long-standing eating disorder and severe vitamin C deficiency. [15]

Why it matters. Pressures and output returned to normal within a week of vitamin supplementation, which is not how most heart disease behaves.

A middle-aged man could not stand up. He had bleeding inside his thigh muscles, corkscrew hairs, and anaemia needing blood. His diet had been badly restricted. [16]

Why it matters. He improved within three days of vitamin C, after being worked up for a bleeding disorder.

A 55-year-old man with obesity and a 45-year-old woman were both worked up for vasculitis, an inflammation of small blood vessels. Both had undetectable vitamin C. [17][18]

Why it matters. Obesity is caloric plenty, and it does not rule out a missing nutrient - the report calls it hidden hunger.

A 26-year-old man with heavy bruising and thickened skin on one leg had normal results on every clotting test, and was heading for a diagnosis of unknown cause. [19]

Why it matters. International guidance already says to consider nutrition in such cases, and the case shows why.

Dermatologists in Nepal set out the dermoscopy signs of scurvy - the pattern of bleeding around each hair follicle and the corkscrew shape the hairs take. [20]

Why it matters. A cheap handheld lens can shorten a hunt that otherwise runs to biopsies.

Vitamin C is taken up efficiently at low doses and saturates above roughly 200 to 400 mg. Beyond that, plasma barely moves and the kidneys clear the rest. [1][6]

Why it matters. It is why sustained-release and split doses show more than a single large tablet does.

Twelve adults took the same 101.7 mg of vitamin C as powder, as raw fruit and vegetables, and as juice. Juice gave the highest blood exposure. [27]

Why it matters. The antioxidant activity measured afterwards did not stay raised in any of the three groups.

Among more than 23,000 Swedish men followed 11 years, about 2% got kidney stones, and vitamin C supplement users were twice as likely to be among them. A standard multivitamin was not. [21]

Why it matters. Reported in 2013, and still the clearest measured cost of routine high-dose use.

In a survey of 26,372 people, eating citrus, melons and berries daily was linked to lower odds of kidney stones, as were tomatoes and milk. [53]

Why it matters. The same nutrient looks protective in fruit and risky in a tablet, and no trial separates them.

In a population sample across Poland, being overweight or obese carried the highest rate of stones and stone-like pain, above any individual dietary item. [52]

Why it matters. It puts the supplement finding in proportion: a real effect, not the main one.

Vitamin C and benzoic acid, a common food preservative, are both cleared by the kidneys. In poor kidney function both build up, and in the lab they react to form benzene. [51]

Why it matters. The evidence is laboratory and animal work, and the authors call the human version a hypothesis.

A review of 74 studies covering 2,801 patients given at least 6 g a day intravenously found no consistent excess harm in blinded trials. It did find five cases of oxalate kidney injury. [22]

Why it matters. Also three cases of red blood cells breaking down in people with a common enzyme deficiency.

Sodium ascorbate added to blood at up to 200 mg/dL interfered with lactate, lipase, cholesterol, triglyceride and several glucose platforms, including a bedside meter. [23]

Why it matters. A person on very high doses can get a wrong reading with nobody in the room knowing why.

A network analysis of 107 trials in 101,751 adults ranked nutritional supplements for preventing respiratory infections. Catechin, one probiotic species and multi-strain probiotics came top. [24]

Why it matters. Vitamin C is not among the winners, and it is the one most people buy for exactly this.

Airborne was created in the 1990s by a schoolteacher, and there is no strong evidence it prevents colds. Orange juice does not shorten one either. [25][26]

Why it matters. A cup of orange juice does carry more than a day's vitamin C, which is not the same as doing anything to a virus.

In 141 children admitted to intensive care in China with suspected sepsis, a quarter were deficient. Each step up in vitamin C level tracked with 52% lower 28-day death. [32]

Why it matters. It measures a level on arrival, so it may be marking how ill a child already was rather than causing anything.

Sixty patients in septic shock got 1 g of vitamin C a day with a statin for five days. Inflammation markers and organ-failure scores fell. Deaths did not differ. [31]

Why it matters. This gap - better numbers, same outcome - is the pattern across the whole vitamin C sepsis literature. [30]

At the concentrations only a drip can reach, vitamin C stops protecting cells and starts damaging them, and researchers are pairing it with drugs designed to exploit that. [33][34]

Why it matters. The same molecule sold as an antioxidant is being tested precisely for being a pro-oxidant.

Vitamin C is a helper for the TET enzymes, which strip chemical marks off DNA and change which genes are read. In cells missing TET2, its effect was blunted. [35]

Why it matters. It is why vitamin C keeps appearing in blood cancer research, where TET2 is often broken.

In 10,118 people surveyed in the United States, higher blood vitamin C went with a lower biological age score. The line flattened above 1.46 mg/dL. [36]

Why it matters. It is a snapshot, not a trial, and the flattening is the informative half.

Thirty patients had vitamin C injections after surgery to repair a cut finger tendon. Movement and function scored better than the control group, but not significantly. [37]

Why it matters. Collagen needs vitamin C, and that is not the same as extra vitamin C building extra collagen.

A review of a decade of sports nutrition found high-dose vitamin C and E can blunt the body's adaptation to exercise, including the building of new mitochondria. [46]

Why it matters. The stress that a workout causes is part of the message the workout sends.

Researchers identified a ratio - three glycine to one proline to one hydroxyproline - that extended life in worms and improved grip strength in old mice. In people, biological age fell 1.4 years in six months. [39]

Why it matters. The human part was an observational trial, and a review of over 60 collagen studies still calls the evidence inconsistent. [59]

In human skin cells, genes for assembling collagen peaked in the day and genes for making and breaking it peaked at night. A 30-woman trial timed two skin treatments to match. [40]

Why it matters. It suggests when a skin ingredient is applied may matter as much as which one.

Fibrosis is collagen overproduction, and attempts to block the signals that drive it have failed. Researchers are now targeting the chemistry that supplies the raw material instead. [41]

Why it matters. The same protein whose shortage causes scurvy causes organ scarring in excess.

Fruit flies under heat stress or kept awake selectively ate antioxidants, including vitamin C. Pre-feeding it removed the craving, and the preference did not run through known taste receptors. [44]

Why it matters. Something inside the animal is reading its own chemistry and steering what it eats.

Goji berries contain the only stable natural derivative of vitamin C, which survives heat and light and is broken back down to the active form inside the body. [45]

Why it matters. Ordinary vitamin C degrades with air, heat and light, which is half the problem with fortifying food.

Twenty Korean adults took liposomal and ordinary multinutrients in a crossover trial. Vitamin C levels were significantly higher from one to eight hours with the liposomal version. [47]

Why it matters. It is a small study on a claim that is usually made with none at all.

Iron from plants is absorbed poorly. Vitamin C improves how much of it gets in, while the tannins in tea reduce it. [29] In 96 adults with iron-deficiency anaemia, plant iron plus 90 mg of vitamin C did better than the same iron alone. [28]

Why it matters. The vitamin that builds collagen is also the one letting iron in, which is why a shortage rarely stays a shortage of one thing.

Anaemia is usually blamed on iron, folate or B12. A review sets out the rarer causes - vitamin C, copper, zinc, selenium, vitamins A and E - which resist all three treatments. [49]

Why it matters. A treatment that fails is sometimes evidence about the diagnosis, not the dose.

Micronutrient shortages persist across low- and middle-income countries, driven by poverty, thin diets and weak health services, and show up as stunted growth and poor cognitive development. [50]

Why it matters. Scurvy in a rich country is a case report; the same class of problem elsewhere is a population statistic.

A meta-analysis of eight trials found a specific bacterium, Lactococcus lactis strain Plasma, activated a class of antiviral immune cell and reduced cold-like symptoms in healthy adults. [56]

Why it matters. Zinc shows a preventive effect in children too, while echinacea's trials carry real bias concerns. [55][54]

Intravenous vitamin drips deliver high doses straight into the blood, bypassing the gut limit entirely, and the practice is growing. Cleveland Clinic ran a whole episode weighing whether it is worth it. [57]

Why it matters. The gut's ceiling is the only honest selling point these clinics have, and it is a real one.

A review of vitamins and minerals in cancer notes that patients are often deficient because of the disease and its treatment, and that correcting shortages is a different question from dosing. [58]

Why it matters. The evidence for fixing a deficiency is not evidence for a megadose.

Oral lichen planus is a long-running immune inflammation of the lining of the mouth. A review sets out why vitamin C is biologically plausible as an add-on and how thin the trial evidence is. [42]

Why it matters. Plausible and unproven is the honest label on most of vitamin C's proposed extra jobs.

A review across multiple sclerosis, rheumatoid arthritis, type 1 diabetes and others found low vitamin C is common in these conditions, with few large randomised trials of correcting it. [43]

Why it matters. A nutrient can be low because of an illness, not the reason for it, and this literature cannot yet tell them apart.

Vitamin E was discovered in 1922 and is still being reclassified, with its link to chlorophyll breakdown identified only recently and production now moving to engineered microbes. [60]

Why it matters. A century after a vitamin is found, the basic question of what it does can still be open.