Limited evidenceHeart & metabolic

D-Pinitol

A methylated inositol found in carob and soy, proposed to act as an insulin second messenger. Small human trials give mixed results: some show a lower glucose response, one found no change in glucose tolerance at all.

Evidence last reviewed: August 2026

What the science says

Acute post-meal glucose Limited evidence
A randomized trial found a single acute dose of pinitol from a natural food ingredient lowered post-load glucose and insulin in healthy subjects. It was an acute, single-dose study in a small group.
Insulin sensitivity with continued use Limited evidence
A randomized controlled trial of chronic consumption of an inositol-enriched carob extract reported improved postprandial glycaemia and insulin sensitivity in healthy subjects over several weeks. The sample was small and the participants were not diabetic.
Glucose tolerance in older adults Limited evidence
A randomized study of acute pinitol supplementation in older humans raised plasma pinitol but did not improve whole-body glucose tolerance or skeletal muscle insulin receptor activation. This negative result tempers the positive trials.

Dosage & safety

Studied doseHuman studies used roughly 0.6–4 g per day, often as a single acute dose of about 1–2 g before a carbohydrate load. Supplement labels typically suggest 500–1000 mg daily.

SafetyShort-term studies report no notable adverse effects; digestive upset is possible at higher doses. Long-term safety is unstudied. People on insulin or sulfonylureas should monitor glucose because of the theoretical additive effect. Soy-derived products may matter for soy allergy.

Scientific references

A single acute dose of pinitol from a naturally-occurring food ingredient decreases hyperglycaemia and circulating insulin levels in healthy subjects
Hernández-Mijares A, Bañuls C, Peris JE — Food Chem, 2013
Chronic consumption of an inositol-enriched carob extract improves postprandial glycaemia and insulin sensitivity in healthy subjects: A randomized controlled trial
Bañuls C, Rovira-Llopis S, Falcón R — Clin Nutr, 2016
Effects of acute pinitol supplementation on plasma pinitol concentration, whole body glucose tolerance, and activation of the skeletal muscle insulin receptor in older humans
Stull AJ, Wood KV, Thyfault JP — Horm Metab Res, 2009

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