Helvy
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Hormones
In the UK, the standard clinical (NHS) reference range for IGF-1 (Insulin-like Growth Factor 1) is 10–36 nmol/L (age-dependent — declines ~14% per decade after 30), with 18–28 nmol/L (mid-range, balancing anabolic benefit and longevity risk) considered the performance-optimised range. A result within these ranges suggests typical status; only a qualified clinician can interpret an individual reading.
Insulin-like Growth Factor 1 is a peptide hormone produced primarily by the liver in response to growth hormone (GH) stimulation. Unlike GH, which is released in pulsatile bursts, IGF-1 circulates at relatively stable levels throughout the day — making it a far more reliable marker of GH axis activity. IGF-1 mediates most of the anabolic effects attributed to growth hormone: muscle protein synthesis, bone density maintenance, tissue repair, and cellular regeneration.
Optimal range · UK
18–28 nmol/L (mid-range, balancing anabolic benefit and longevity risk)
Performance-optimised band · clinical (NHS) range 10–36 nmol/L (age-dependent — declines ~14% per decade after 30)
Reference ranges for IGF-1, not a personal result. Any individual reading should be interpreted by a qualified clinician.
Optimal ranges
| Range | Value |
|---|---|
| Clinical (NHS) reference range | 10–36 nmol/L (age-dependent — declines ~14% per decade after 30) |
| Performance-optimised range | 18–28 nmol/L (mid-range, balancing anabolic benefit and longevity risk) |
The clinical range defines what is considered medically “normal” — broad enough to cover 95% of the population. The performance range reflects where research and clinical experience suggest most people feel and function at their best. A result in either range suggests typical status and is not a diagnosis; any individual reading should be interpreted by a qualified clinician.
Why it matters
IGF-1 sits at the intersection of performance and longevity — and the optimal range is a deliberate trade-off. Higher IGF-1 (within range) supports muscle growth, recovery, bone density, and cognitive function. But persistently elevated IGF-1 above the reference range is associated with increased cancer risk in epidemiological studies, because the same growth-promoting signals that repair tissue also accelerate tumour cell proliferation. For active adults, the goal is a healthy mid-range IGF-1: high enough to support recovery and lean mass, low enough to avoid excess proliferative signalling. Low IGF-1 in younger adults often signals poor protein intake, chronic caloric restriction, liver dysfunction, or growth hormone deficiency — all of which impair recovery and accelerate sarcopenia.
Symptoms
Low / Deficiency
High / Excess
Dietary sources
Supplementation
IGF-1 is not directly supplemented over the counter. It is modulated through lifestyle: adequate protein intake (1.6–2.2 g/kg/day), sufficient calories to avoid chronic energy deficit, quality sleep (7–9 hours — growth hormone is released primarily during slow-wave sleep), and resistance training (heavy compound movements transiently increase GH secretion). Zinc deficiency directly suppresses IGF-1 — supplement 15–30 mg/day if serum zinc is low. Vitamin D deficiency is also associated with lower IGF-1 levels. Intermittent fasting transiently suppresses IGF-1 (this is part of the proposed longevity mechanism of fasting, but may be counterproductive for muscle preservation). If IGF-1 is persistently below range despite adequate nutrition, a GP referral for GH stimulation testing is warranted — adult growth hormone deficiency is underdiagnosed and treatable. Conversely, if IGF-1 is persistently above range, investigation for acromegaly is essential. Retest at 90 days after any lifestyle change, fasted morning draw preferred.
Testing
IGF-1 is measured from a blood sample. With Helvy, that means a finger-prick kit taken at home and posted to a UKAS-accredited UK laboratory, with results in around 5 days, reviewed by a qualified clinician. Your result is reported against both the clinical range (10–36 nmol/L (age-dependent — declines ~14% per decade after 30)) and the performance-optimal range (18–28 nmol/L (mid-range, balancing anabolic benefit and longevity risk)), so you can see not just whether you are “normal” but whether you are optimal. If you make a change, retest after 8-12 weeks to confirm it worked.
Research
Serum insulin-like growth factor I and risk of cancer: results from the EPIC study
Rinaldi S, Cleveland R, Norat T, et al.
International Journal of Cancer (2010)
DOI: 10.1002/ijc.25007Related biomarkers
Related guides
This content is for educational purposes only and does not constitute medical advice. Your data suggests areas for optimisation, but any concerns should be discussed with a qualified healthcare professional. If your results flag values outside safe ranges, we recommend consulting your GP.
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