Biomarkers · Nutritional

Serum Vitamin C (Ascorbic Acid)

Higher values go with lower risk of death. Not measured in our NHANES panel. The curve is drawn from the published study (source below).

Serum Vitamin C (Ascorbic Acid) and risk of death

Published curve higher than the NHANES fitNHANES fit higher

Risk of death relative to the curve's reference value, drawn from the published study (source below).

Published risk of death0.61×highest vs lowest category of circulating vitamin C (protective form as reported) (95% CI 0.53–0.69) · Meta-analysis of 41 prospective observational studies (total n=507,251; 73,965 deaths) of dietary/circulating antioxidants, general population

Serum Vitamin C (Ascorbic Acid) by age and sex

Each bar runs from the 5th to the 95th percentile, the darker part from the 25th to the 75th, and the tick is the median. Not a reference range or a target.

The percentiles as a table

Each row is one sex and age band: the values below which 5%, 25%, 50%, 75% and 95% of people fall (umol/L), from the survey named in the row. Not a reference range or a target.
Sex	Age	5th	25th	Median	75th	95th	n	Cycle / source
All	20-39	10.0	29.9	49.3	65.3	86.3	1,423	NHANES 2017-2018
All	40-59	9.02	27.6	49.7	65.9	97.7	1,559	NHANES 2017-2018
All	60+	9.31	33.5	56.0	74.9	107	1,906	NHANES 2017-2018
All	all	9.45	30.0	51.7	68.1	97.7	4,888	NHANES 2017-2018
Men	20-39	9.37	23.9	43.9	60.9	78.4	682	NHANES 2017-2018
Men	40-59	8.97	24.2	46.8	61.9	89.7	730	NHANES 2017-2018
Men	60+	8.77	29.1	50.0	65.3	92.6	965	NHANES 2017-2018
Men	all	9.03	26.1	46.5	62.5	86.3	2,377	NHANES 2017-2018
Women	20-39	10.7	34.2	54.0	70.4	90.8	741	NHANES 2017-2018
Women	40-59	9.48	30.5	53.9	71.5	103	829	NHANES 2017-2018
Women	60+	9.74	39.5	63.6	82.5	117	941	NHANES 2017-2018
Women	all	10.1	33.9	55.8	74.2	103	2,511	NHANES 2017-2018

What studies found when this marker was changed

They describe what happened in those study groups, not a recommendation. See all catalogued interventions.

Measured changes in Serum Vitamin C (Ascorbic Acid), study by study

4 effects with a numeric size, each from one study arm: the dot is the reported change, the line its 95% interval where one was given. Green points move the marker the way lower risk of death lies; amber the other way. Study results in the groups studied, not predictions for a person.

Each row is one study: what was changed, the effect it reported on this marker, and the source.
Type	Intervention	Reported effect	Evidence	Source
diet	Monthly grocery voucher for healthy foods (65-85 dollars) for 6 months vs usual access in food-insecure adults with diabetes	Ascorbic acid level changed -0.18 umol/L (95% CI -4.3 to 4.7) vs control at 6 months; no effect; n=390 randomised	RCT	Persaud N, Ul Haq MZ, Buadu A, et al. JAMA Intern Med. 2025;185(12):1434-1441.
supplement	Vitamin C 1 g vs placebo in repeated randomized n-of-1 cycles in healthy young men with vitamin C inadequacy	Plasma vitamin C rose 20.6 umol/L (95% CI 16.8 to 24.5) vs placebo, short-term, duration not stated; eight participants in aggregated n-of-1 trials	RCT	Nastos GG, Lolli L, Atkinson G, et al. Free Radic Biol Med. 2026;250:274-283.
supplement	Vitamin C 500 mg daily for five years in middle-aged Japanese adults with atrophic gastritis (randomized vs 50 mg/day)	Serum vitamin C rose 38.5% (95% CI 27.0 to 49.9) after five years of supplementation with 500 mg/day, vs 13.0% with 50 mg/day; 124 subjects on 500 mg	RCT	Kim MK, Sasazuki S, Sasaki S, et al. J Am Coll Nutr. 2003;22(3):208-216.

Things that worsen it

Each row is one study: what was changed, the effect it reported on this marker, and the source.
Type	Condition or exposure	Reported effect	Evidence	Source
clinical	Surgical procedures (various types): plasma vitamin C during the first postoperative week vs pre-surgery, meta-analysis of prospective studies and control arms	Plasma vitamin C fell -17.99 umol/L (39% depletion; CI -22.81 to -13.17) in the first postoperative week vs pre-surgery; 25 trial arms, n=565	meta-analysis	Travica N, Ried K, Hudson I, et al. Br J Nutr. 2022;127(2):233-247.

Sources

Risk curve: Jayedi 2018 (PMID 30239557): all-cause RR 0.61 (0.53-0.69) highest vs lowest category of circulating vitamin C (protective form as reported). Scaled to US values (NHANES).
Jayedi et al. Dietary Antioxidants, Circulating Antioxidant Concentrations, Total Antioxidant Capacity, and Risk of All-Cause Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Observational Studies. Advances in nutrition (Bethesda, Md.). 2018;9:701-716.

Map Serum Vitamin C (Ascorbic Acid) against another biomarker.

Map Serum Vitamin C (Ascorbic Acid) against another marker