Biomarkers · Vitamins & Endocrine

Insulin-like Growth Factor 1 (IGF-1)

Both low and high values go with higher risk of death. Not measured in our NHANES panel. The curve is drawn from the published study (source below).

IGF-1 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 death1.33×low vs middle IGF-1 category (high vs middle HR 1.23, 1.06-1.44; high vs low HR 0.84… (95% CI 1.14–1.57) · Meta-analysis of 19 prospective cohort studies of adults, 30,876 participants

IGF-1 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 (ng/mL), 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	40-59	76.0	109	138	170	211	349	MIDUS 3 Biomarker Proj…
All	60+	65.0	99.0	126	154	207	388	MIDUS 3 Biomarker Proj…
All	all	67.0	104	132	162	208	737	MIDUS 3 Biomarker Proj…
Men	40-59	84.6	118	150	176	213	133	MIDUS 3 Biomarker Proj…
Men	60+	74.6	108	135	162	220	193	MIDUS 3 Biomarker Proj…
Men	all	77.2	112	139	172	217	326	MIDUS 3 Biomarker Proj…
Women	40-59	63.5	105	134	165	207	216	MIDUS 3 Biomarker Proj…
Women	60+	60.7	93.0	116	146	184	195	MIDUS 3 Biomarker Proj…
Women	all	61.5	99.0	125	155	196	411	MIDUS 3 Biomarker Proj…

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 IGF-1, 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. 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	Ad libitum ketogenic diets (>55% energy from fat, ketosis confirmed) for 1-20 weeks in adults of any health status	Serum IGF-1 -24.9 ng/mL (95% CI -31.7 to -18.1) pre vs post diet, about a 20% reduction	meta-analysis	Rajakumar G, et al. Ageing Res Rev. 2024. Effect of ketogenic diets on…
diet	Low-fat diet vs control diet in adults (meta-analysis of 6 RCTs)	IGF-1 changed 1.63 ng/mL (95% CI -1.34 to 4.59) vs control, not significant; 6 trials, n=1029; duration not stated	meta-analysis	Sangsefidi ZS, et al. J Health Popul Nutr. 2024;43(1):201.
supplement	Whey protein to 1.5 g/kg/day vs placebo for 24 weeks in healthy adults aged 65 and over (2x2 factorial RCT)	IGF-1 was 14.2 ng/mL (95% CI 7.5 to 21.0) higher with whey protein than placebo at 24 weeks; n=128	RCT	Ceglia L, et al. Am J Clin Nutr. 2026;123(5):101257.
supplement	Protein-based multinutrient supplementation vs control for 12-48 weeks in older adults with sarcopenia (meta-analysis of 10 RCTs)	IGF-1 rose 0.49 ng/mL (95% CI 0.33 to 0.65) vs control; duration not stated for this outcome (trials ran 12 to 48 weeks)	meta-analysis	Xie M, et al. Aging Clin Exp Res. 2025;37(1):306.

What else moves this marker

They describe those study groups, not an individual, and an association is not a cause.

Diseases and conditions

Each row is one study: what it compared and the change it reported in this marker.
What	Effect on the marker	Comparison · population	Source
↑ Multiple sclerosis · MS patients vs healthy controls, blood IGF-1	SMD +0.2 (95% CI -0.2 to 0.59)	multiple sclerosis patients vs healthy controls · 692 individuals in 8 studies of blood IGF-1 (total review: 531 MS patients, 536 controls)	meta analysis · PMID 38630771
↑ Polycystic ovary syndrome · PCOS patients vs normal controls	SMD +0.89 (95% CI 0.34 to 1.45)	women with PCOS vs controls · 362 women with PCOS and 295 controls in 20 studies	meta analysis · PMID 36516939
↓ Rheumatoid arthritis · RA patients vs controls, serum IGF-1	SMD -0.65 (95% CI -1.184 to -0.115)	rheumatoid arthritis patients vs controls · 27 study arms from 19 publications comparing RA patients with controls	meta analysis · PMID 31430609

Sources

Risk curve: Rahmani J 2022 (PMID 35048526): all-cause HR 1.33 (1.14-1.57) low vs middle IGF-1 category (high vs middle HR 1.23, 1.06-1.44; high vs low HR 0.84, 0.68-1.05). Scaled to US values (NHANES).
Rahmani J, Montesanto A, Giovannucci E, et al. Association between IGF-1 levels ranges and all-cause mortality: A meta-analysis. Aging Cell. 2022;21(2):e13540.

Map Insulin-like Growth Factor 1 (IGF-1) against another biomarker.

Map IGF-1 against another marker