Do zinc or vitamin C actually shorten a cold?

Zinc yes, by somewhere between half a day and three days, if you start it early and can stand the taste. Vitamin C only if you were already taking it every day before the cold arrived, and then by about 8 per cent, which is roughly half a day. Neither of them stops you catching colds, unless you are a soldier in the subarctic or running marathons.

The question everyone gets backwards

These two supplements are sold for the same shelf and behave in opposite ways, and almost every article about them blurs the difference.

Vitamin C works, weakly, as something you take every day before you get sick. Started once your nose is running, it does nothing consistent. Zinc is the reverse: taken every day it does not stop colds, and started within a day of symptoms it shortens the one you have.

Established. Taken daily, vitamin C shortened colds by 8 per cent in adults and 14 per cent in children across 9,745 cold episodes. In children taking 1 to 2 grams a day the reduction was 18 per cent. The same review found no consistent effect in the trials that started vitamin C after symptoms began.

How much cold you actually save

A typical cold in these trials ran about a week. The 2024 Cochrane review of zinc found treatment shortened colds by 2.37 days, on low-certainty evidence with very high variation between trials. An individual patient data analysis of three zinc acetate lozenge trials put it at 2.73 days against a seven-day baseline.

Unsettled. Those numbers look decisive and the certainty rating does not match them. Heterogeneity in the Cochrane pooling was 97 per cent, which means the trials disagree with each other almost completely, and the reviewers graded the result low-certainty for exactly that reason. The honest version is that zinc probably shortens a cold, and that anyone quoting you a precise number is over-reading the evidence.

For vitamin C, 8 per cent of a seven-day cold is about half a day for an adult, and 14 per cent is about a day for a child. A separate meta-analysis of 10 double-blind trials found severity fell by 15 per cent, and that the effect sat on severe symptoms rather than mild ones. Half a day less of the bad part of a cold is a modest but real thing.

What neither of them does

Myth. Neither supplement prevents colds in ordinary life. Vitamin C taken daily by 10,708 people in the community gave a risk ratio of 0.97, which is close enough to nothing that the reviewers said routine supplementation is not justified. Zinc taken to prevent colds gave 0.93, with an interval that crosses one.

There is one striking exception, and it is specific enough to be worth naming. In five trials in 598 marathon runners, skiers and soldiers on subarctic exercises, daily vitamin C halved the chance of catching a cold. Severe physical stress in cold conditions is apparently a different physiological situation from an office in November.

The cost of trying zinc

Not for everyone. Zinc used for cold treatment produced about a third more non-serious side effects than placebo, on moderate-certainty evidence. In practice that means a metallic taste, nausea and stomach upset. Zinc sprayed into the nose is a separate product with a separate problem: pooling three trials found no significant benefit, and the reviewers concluded that unquantified concerns about permanent loss of smell may mean the question is never settled scientifically. The lozenge is the form the trials support.

The other cost is longer term and comes from continuing. The upper limit for zinc is 40 mg a day, and doses of 50 mg or more kept up for weeks interfere with copper absorption, weaken immune function and lower HDL cholesterol. The lozenge trials used 45 to 276 mg a day for up to three weeks, which is well above that ceiling. For a few days that is the point. As a winter-long habit it is the copper problem waiting to happen.

Not for everyone. Food can push you over that ceiling on its own, and oysters are where it happens. Raw oysters carry 39.3 mg of zinc per 100 g, so three of them cover the whole 11 mg daily reference value, and a cup of them, 225 g, carries 88.4 mg. More than twice the 40 mg upper limit, from one serving. A cup of steamed oysters is 67.2 mg. An oyster dinner now and then is not what the limit was written about. Oysters most weeks, on top of a zinc supplement taken through the winter for immunity, is how somebody reaches the copper-blocking dose without ever holding a large tablet.

One assumption is worth checking before any of this applies to you, which is that you are short of zinc to begin with. Against the 11 mg Daily Value on labels, 68.6 per cent of American adults fall below it, and among women 79.4 per cent. Against the requirement that the Daily Value is built out of, it is 39.8 per cent of women aged 19 to 30 and 43.4 per cent of men the same age. Median intake is 8.66 mg a day. Nearly seven in ten against about four in ten, from the same survey and the same dinners. The larger number is the one advertising quotes. The smaller one is the one that means something.

Vitamin C is gentler and not free either. Above about two grams a day the reliable results are diarrhoea, nausea and cramps, and in people who have formed kidney stones, a higher chance of another one.

What zinc does when the question is not a cold

Since the cold evidence is what brings people to zinc, it is worth naming the use with a cleaner result. In seven studies of patients with pressure sores, zinc supplements improved healing by about 44 per cent against usual nutrition care. That is a supervised dose in a hospital setting, and it is the closest thing zinc has to a treatment role.

Two larger results point the same way, and both of them belong to children rather than to you. Across 28 randomised trials in 237,068 children under five, zinc cut deaths from any cause by 16 per cent, a relative risk of 0.84. Those trials were run in places where zinc deficiency is common, and the effect was largest at 10 mg a day or more. It is the strongest thing zinc has ever been shown to do, and none of it carries over to a well-fed adult reaching for a lozenge.

The second result comes with its own price tag attached. In 38 trials of children with acute diarrhoea, zinc shortened the illness by about thirteen hours and made vomiting roughly half again as likely, a risk ratio of 1.46. Lower doses caused less vomiting than higher ones, and the reviewers who did the work for the World Health Organization concluded the dose should come down. That is the same bargain this page keeps running into. Zinc does something real, and your mouth and your stomach are what pays for it.

What to do with this

If you feel a cold starting

Zinc lozenges, started within about a day of the first symptoms, are the intervention with the best trial support. Take them for the duration of the cold and then stop, because the doses used in the trials run from 45 to 276 mg a day, far above the 40 mg ceiling meant for daily use. Leave the nasal sprays alone.

If you are thinking about a daily supplement

Vitamin C every day will not stop you catching colds and will shave a few hours off the ones you get. Whether that is worth a daily habit is a judgement rather than a medical question, and a few hundred milligrams with food does everything a gram does. Five varied servings of fruit and vegetables a day already supply more than 200 mg.

If you do serious endurance training in the cold

You are the one population where daily vitamin C has a large effect on catching colds, and it is worth knowing that the trials that found it were in people doing exactly that.

If you have a child with a cold

The vitamin C effect is larger in children than in adults, and the zinc trials in children are fewer and messier than the adult ones. Neither is a reason to skip the ordinary advice about fluids, rest and time.

What would change this answer

• A large zinc treatment trial with a single formulation and a pre-registered protocol. The 97 per cent heterogeneity in the current pooling comes from trials using different salts, doses and dosing frequencies, and nobody has run the trial that would settle it.
• A therapeutic vitamin C trial at a high dose started within hours rather than days. The Cochrane authors point out that the therapeutic trials are few and that the regular-supplementation effect is consistent, which leaves room for a properly designed treatment trial to find something.
• Trials that report the taste and smell side effects properly. Adverse event reporting in this literature is thin, and the trade-off a reader cares about is days of cold against days of metallic mouth.

How we searched

Sources

1. cold-z1 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomised trials · n = 972 in this analysis, 8,526 across the review
   When zinc is used for cold treatment, there may be a reduction in the mean duration of the cold in days (MD -2.37, 95% CI -4.21 to -0.53; I² = 97%; 8 studies, 972 participants; low-certainty evidence)
   
   Who: adults and children with a cold, 8 treatment trials
   Effect: duration of the cold 2.37 days shorter (95% CI 0.53 to 4.21), heterogeneity 97 per cent
   Certainty: low-certainty evidence, very high heterogeneity
   Nault et al., Cochrane Database of Systematic Reviews, 2024 · checked 2026-09-16 · we read the abstract
2. cold-z2 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis · n = 1,449
   There may be little or no reduction in the risk of developing a cold with zinc compared to placebo (risk ratio (RR) 0.93, 95% CI 0.85 to 1.01; I2 = 20%; 9 studies, 1449 participants; low-certainty evidence)
   
   Who: adults and children, 9 prevention trials
   Effect: risk of developing a cold, risk ratio 0.93 (95% CI 0.85 to 1.01)
   Certainty: low-certainty evidence
   Nault et al., Cochrane Database of Systematic Reviews, 2024 · checked 2026-09-16 · we read the abstract
3. cold-z3 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis · n = 2,084
   There is probably an increase in the risk of non-serious adverse events when zinc is used for cold treatment (RR 1.34, 95% CI 1.15 to 1.55; I2 = 44%; 2084 participants, 16 studies; moderate-certainty evidence)
   
   Who: participants of 16 treatment trials
   Effect: non-serious adverse events risk ratio 1.34 (95% CI 1.15 to 1.55)
   Certainty: moderate-certainty evidence
   Nault et al., Cochrane Database of Systematic Reviews, 2024 · checked 2026-09-16 · we read the abstract
4. cold-z4 · Meta-analysis or systematic review · individual patient data meta-analysis of three randomised placebo-controlled trials · n = 199
   The one stage meta-analysis gave an overall estimate of 2.73 days (95% CI 1.8, 3.3 days) shorter colds by zinc acetate lozenge usage.
   
   Who: adults with a cold, mostly aged 20 to 50
   Effect: 2.73 days shorter (95% CI 1.8 to 3.3) by one-stage analysis and 2.94 days (2.1 to 3.8) by two-stage, against a 7 day average duration
   Certainty: small total sample, effect not modified by allergy, smoking, age, sex or severity
   Hemilä et al., British Journal of Clinical Pharmacology, 2016 · checked 2026-09-16 · we read the abstract
5. cold-z5 · Meta-analysis or systematic review · Cochrane systematic review of randomised trials · n = 17 lozenge studies
   Zinc gluconate was given at doses between 45 and 276 mg/day for between 4.5 and 21 days.
   
   Who: participants of the lozenge trials in the review
   Effect: zinc gluconate given at 45 to 276 mg a day for 4.5 to 21 days
   Certainty: description of the interventions in the included trials
   Nault et al., Cochrane Database of Systematic Reviews, 2024 · checked 2026-09-16 · we read the abstract
6. cold-z6 · Meta-analysis or systematic review · systematic review and meta-analysis of randomised placebo-controlled trials · n = 5 studies found, 3 pooled
   Unquantified concerns about permanent anosmia followingthe use of intranasal zinc may mean that the issues raised will never be scientifically resolved.
   
   Who: adults with a common cold, 3 trials pooled
   Effect: relative risk of benefit at day 3 was 0.62 (95% CI 0.18 to 2.19), not significant; unquantified concerns about permanent anosmia
   Certainty: small number of trials, no studies in children
   Hulisz et al., Journal of Primary Health Care, 2009 · checked 2026-09-16 · we read the abstract
7. cold-c1 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of placebo-controlled trials · n = 10,708 in the community analysis
   In the general community trials involving 10,708 participants, the pooled RR was 0.97 (95% confidence interval (CI) 0.94 to 1.00).
   
   Who: general community participants taking at least 0.2 g a day
   Effect: risk of developing a cold, pooled risk ratio 0.97 (95% CI 0.94 to 1.00)
   Certainty: large body of randomised, double-blind trials
   Hemilä and Chalker, Cochrane Database of Systematic Reviews, 2013 · checked 2026-09-16 · we read the abstract
8. cold-c2 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis · n = 598
   Five trials involving a total of 598 marathon runners, skiers and soldiers on subarctic exercises yielded a pooled RR of 0.48 (95% CI 0.35 to 0.64).
   
   Who: marathon runners, skiers and soldiers on subarctic exercises, 5 trials
   Effect: risk of developing a cold, pooled risk ratio 0.48 (95% CI 0.35 to 0.64)
   Certainty: consistent across five trials in an unusual population
   Hemilä and Chalker, Cochrane Database of Systematic Reviews, 2013 · checked 2026-09-16 · we read the abstract
9. cold-c3 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis · n = 9,745 cold episodes
   In adults the duration of colds was reduced by 8% (3% to 12%) and in children by 14% (7% to 21%). In children, 1 to 2 g/day vitamin C shortened colds by 18%.
   
   Who: adults and children taking vitamin C regularly, 31 comparisons
   Effect: duration 8 per cent shorter in adults (3 to 12 per cent) and 14 per cent in children (7 to 21 per cent); 18 per cent in children at 1 to 2 g a day
   Certainty: consistent across trials, and not reproduced when vitamin C was started after symptoms began
   Hemilä and Chalker, Cochrane Database of Systematic Reviews, 2013 · checked 2026-09-16 · we read the abstract
10. cold-c4 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis · n = 3,249 cold episodes
    Seven comparisons examined the effect of therapeutic vitamin C (3249 episodes). No consistent effect of vitamin C was seen on the duration or severity of colds in the therapeutic trials.
    
    Who: people starting vitamin C at the onset of symptoms, 7 comparisons
    Effect: no consistent effect on duration or severity in the therapeutic trials
    Certainty: the authors still suggest an individual trial of it, on grounds of cost and safety rather than of evidence
    Hemilä and Chalker, Cochrane Database of Systematic Reviews, 2013 · checked 2026-09-16 · we read the abstract
11. cold-c5 · Meta-analysis or systematic review · meta-analysis of placebo-controlled trials · n = 15 comparisons
    Compared to placebo, vitamin C significantly decreased the severity of the common cold by 15% (95% CI 9-21%).
    
    Who: healthy people taking at least 1 g a day, 10 trials
    Effect: severity of the common cold 15 per cent lower (95% CI 9 to 21 per cent); the effect sat on severe symptoms rather than mild ones
    Certainty: fixed-effect pooling of ratio of means, all trials randomised and double-blind
    Hemilä, BMC Public Health, 2023 · checked 2026-09-16 · we read the abstract
12. zn-02 · Position of an expert body
    19+ years: 11 mg [male], 8 mg [female]; Pregnancy: 11 mg; Lactation: 12 mg
    
    Who: adults
    Effect: 11 / 8 / 11 / 12 mg per day
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Zinc · checked 2026-09-15
13. zn-03 · Position of an expert body
    19+ years: 40 mg
    
    Who: adults 19+
    Effect: UL 40 mg/day
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Zinc · checked 2026-09-15
14. zn-05 · Meta-analysis or systematic review
    Supplemental zinc in lozenge or syrup form appears to reduce the duration, but not the severity, of signs and symptoms of the common cold when taken shortly after a person develops a cold.
    
    Who: adults with colds
    Effect: shorter duration, severity unchanged
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Zinc · checked 2026-09-15
15. zn-06 · Meta-analysis or systematic review
    The authors also concluded that it is unclear whether zinc affects the severity of cold symptoms. They noted that all of these conclusions were based on low to very low certainty of evidence.
    
    Who: adults with colds
    Effect: uncertain effect on severity
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Zinc · checked 2026-09-15
16. zn-07 · Position of an expert body
    If used for weeks, doses of 50 mg zinc or more...can interfere with copper absorption (which can cause low copper status), reduce immune function, and lower HDL cholesterol levels.
    
    Who: adults on long-term high-dose zinc
    Effect: copper deficiency, lower HDL
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Zinc · checked 2026-09-15
17. zn-08 · Position of an expert body
    High zinc intakes can cause nausea, dizziness, headaches, gastric distress, vomiting, and loss of appetite.
    
    Who: adults
    Effect: acute side effects
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Zinc · checked 2026-09-15
18. zn-w1 · Meta-analysis or systematic review · systematic review and meta-analysis of randomised and non-randomised trials · n = 7 studies
    The intervention group significantly had improved healing vs that of the control group (relative risk, 1.44; 95% CI, 1.01-2.06; P = 0.043, I2 = 19.3%).
    
    Who: patients with pressure injuries, 7 studies
    Effect: healing rate relative risk 1.44 (95% CI 1.01 to 2.06), heterogeneity 19 per cent; greater reduction in wound area and better PUSH scores
    Certainty: borderline confidence interval, mixed randomised and non-randomised studies
    Song et al., Nutrition in Clinical Practice, 2020 · checked 2026-09-17 · we read the abstract
19. zn-r5-1 · Meta-analysis or systematic review · systematic review and random-effects meta-analysis of randomised clinical trials, graded with GRADE and risk of bias 2.0 · n = 237,068 participants across 28 randomised trials contributing 30 risk ratios
    Combining 30 RRs from 28 RCTs including 237,068 participants revealed that zinc supplementation has significantly reduced the risk of all-causes mortality by 16% in children (SRR: 0.84, 95% CI: 0.74, 0.96)...Zinc supplementation significantly reduced the risk of death from pneumonia (0.70: 0.64, 0.98) and infection (0.54; 0.39, 0.76), also changed the risk of mortality from diarrhea by 15% (0.85; 0.70, 1.03) and sepsis by 57% (0.43; 0.18, 1.02).
    
    Who: children under five years of age in trials of preventive or therapeutic zinc supplementation
    Effect: all-cause mortality summary relative risk 0.84 (95% CI 0.74 to 0.96); death from pneumonia 0.70 (0.64 to 0.98) and from infection 0.54 (0.39 to 0.76), while death from diarrhoea 0.85 (0.70 to 1.03) and from sepsis 0.43 (0.18 to 1.02) did not reach significance
    Certainty: the trials were run where zinc deficiency is common, so the result does not transfer to well-fed populations; the effect was largest at 10 mg a day or more and with under eleven months of supplementation
    Rouhani et al., European Journal of Nutrition, 2022 · checked 2026-09-17 · we read the abstract
20. zn-r5-2 · Meta-analysis or systematic review · systematic review and meta-analysis of randomised controlled trials, commissioned by WHO for its childhood diarrhoea guideline revision, GRADE-rated · n = 38 randomised controlled trials
    Our findings suggest that, in children with acute diarrhoea, zinc supplementation resulted in a greater proportion of children who recovered from diarrhoea at last follow-up (risk ratio (RR) = 1.07; 95% confidence interval (CI) = 1.03, 1.1; moderate certainty of evidence) and a reduction in the duration of diarrhoea (mean difference (MD) = -13.27 hours; 95% CI = -17.66, -8.89; moderate certainty of evidence) when compared to placebo. A significant number of children in the zinc group compared to placebo experienced vomiting (RR = 1.46; 95% CI = 1.22, 1.76; moderate certainty of evidence)
    
    Who: children under ten years of age with acute or persistent watery diarrhoea
    Effect: duration of diarrhoea mean difference -13.27 hours (95% CI -17.66 to -8.89) and recovery risk ratio 1.07 (95% CI 1.03 to 1.1), both moderate certainty; vomiting risk ratio 1.46 (95% CI 1.22 to 1.76), with fewer episodes on low-dose than high-dose zinc, 0.80 (0.72 to 0.89)
    Certainty: moderate certainty for the main outcomes; the persistent-diarrhoea result was low certainty because of high heterogeneity, and the reviewers concluded the dose should be reduced
    Ali et al., Journal of Global Health, 2024 · checked 2026-09-17 · we read the abstract
21. vitc-02 · Position of an expert body
    RDA for adults: 90 mg for males 19+; 75 mg for females 19+
    
    Who: adults 19+
    Effect: 90 mg/day men, 75 mg/day women
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Vitamin C · checked 2026-09-15
22. vitc-03 · Position of an expert body
    UL for adults 19+: 2,000 mg
    
    Who: adults 19+
    Effect: UL 2,000 mg/day
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Vitamin C · checked 2026-09-15
23. vitc-05 · Meta-analysis or systematic review
    Prophylactic use of vitamin C did not significantly reduce the risk of developing a cold in the general population.
    
    Who: general population
    Effect: no significant reduction in risk of developing a cold
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Vitamin C · checked 2026-09-15
24. vitc-06 · Meta-analysis or systematic review
    In the general population, the use of prophylactic vitamin C modestly reduced cold duration by 8% in adults and 14% in children.
    
    Who: adults and children
    Effect: cold duration −8% adults, −14% children
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Vitamin C · checked 2026-09-15
25. vitc-07 · Position of an expert body
    The most common complaints are diarrhea, nausea, abdominal cramps, and other gastrointestinal disturbances.
    
    Who: adults taking high doses
    Effect: diarrhea, nausea, abdominal cramps
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Vitamin C · checked 2026-09-15
26. vitc-08 · Position of an expert body
    high vitamin C intakes also have the potential to increase urinary oxalate and uric acid excretion, which could contribute to the formation of kidney stones.
    
    Who: general
    Effect: potential increase in stone formation
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Vitamin C · checked 2026-09-15
27. vitc-09 · Position of an expert body
    People who smoke and those exposed to secondhand smoke
    
    Who: smokers and passive smokers
    Effect: higher risk of inadequacy
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Vitamin C · checked 2026-09-15
28. vitc-12 · Position of an expert body
    Consuming five varied servings of fruits and vegetables a day can provide more than 200 mg of vitamin C.
    
    Who: general
    Effect: >200 mg/day from five servings
    NIH Office of Dietary Supplements, Health Professional Fact Sheet: Vitamin C · checked 2026-09-16
29. zn-a-08 · Position of an expert body · USDA FNDDS household measures with gram weights, per-portion zinc recalculated from the per-100-g value and compared with the label reference value and the US upper level · n = two FNDDS foods, 3 household measures each
    Oysters, raw · Zinc, Zn 39.3 MG на 100 г [fdc_id 2706351] · 1 oyster 15 г 5.9 MG · 1 cup 225 г 88.4 MG || Oysters, steamed · Zinc, Zn 49.75 MG на 100 г [fdc_id 2706353] · 1 oyster 15 г 7.5 MG · 1 cup 135 г 67.2 MG
    
    Who: oysters, raw and steamed
    Effect: raw oysters (fdc_id 2706351) 39.3 mg per 100 g: 1 oyster = 15 g = 5.9 mg, 1 cup = 225 g = 88.4 mg. Steamed oysters (2706353) 49.75 mg per 100 g: 1 oyster = 15 g = 7.5 mg, 1 cup = 135 g = 67.2 mg. The Daily Value is 11 mg and the US Tolerable Upper Intake Level is 40 mg/day
    Certainty: per-portion figures are a RECALCULATION from the per-100-g table, and the per-100-g figure for oysters is itself unusually uncertain (card zn-a-07) — a cup of British oysters would compute higher still. The upper level is set for chronic daily intake, so a single large oyster meal is not the hazard it looks like arithmetically; the point for a page is that this is the one common food where an ordinary restaurant portion passes the upper limit at all, which is not true of any supplement dose people take casually. Steamed oysters read higher per 100 g than raw because steaming removes water, not because steaming adds zinc.
    USDA FNDDS 2021-2023 and 21 CFR 101.9(c)(8)(iv) · checked 2026-09-21 · we read the dataset
30. zn-a-09 · Position of an expert body · NHANES 2021-2023 day-one dietary recall, weighted with WTDRD1, shares computed against both the FDA Daily Value and the Estimated Average Requirement · n = 4,886 adults (2,148 men, 2,738 women)
    zinc_mg · усі 19+ n=4886 median 8.66 mean 9.89 · Daily Value FDA (не EAR) = 11.0 floor: усі 19+ 68.6% · ж 19+ 79.4% · ч 19+ 57.1% · EAR (DRI, National Academies) floor: ж 19-30 (6.8) 39.8% проти DV 76.8% · ч 19-30 (9.4) 43.4% проти DV 56.5% · ж 71+ (6.8) 45.3% проти DV 82.5%
    
    Who: US adults aged 19 and over, by sex and age band
    Effect: median intake 8.66 mg/day for all adults, 10.05 for men, 7.65 for women. Below the Daily Value of 11 mg: 68.6% of adults, 79.4% of women, 57.1% of men. Below the EAR: women 19-30 (EAR 6.8 mg) 39.8% against 76.8% below the Daily Value; men 19-30 (EAR 9.4 mg) 43.4% against 56.5%; women 71+ 45.3% against 82.5%
    Certainty: one day of recall, not habitual intake, and recall under-reports systematically. Only the EAR share may be called inadequacy: for women aged 19-30 the Daily Value figure is nearly double the EAR figure, so quoting 'four in five women do not get enough zinc' would be false by roughly a factor of two. Zinc has the widest gap between the two yardsticks of any nutrient examined in this run. United States only, and none of this accounts for phytate, which changes how much of the measured zinc is usable (cards zn-04, zn-a-03).
    NHANES 2021-2023 (DR1TOT/DEMO), weighted; EAR from DRI, National Academies · checked 2026-09-21 · we read the dataset