← All supplements
Limited evidenceGut health

Humic Acid

A soil- and peat-derived mixture of organic acids sold for gut and immune support. Almost all of the research is agricultural; there is essentially one small human study, and it measured bacteria, not health.

Where to buy

View on iHerb

Ships to 180+ countries · welcome discount for new customers

Referral link — this site may earn a commission on purchases.

What the science says

  • Colonic microbiota Limited evidence

    An open-label study followed 14 healthy volunteers taking an oral humic acid preparation for 45 days and found total colonic bacterial concentrations rose while individual microbial profiles and diversity stayed unchanged. There was no control group and no clinical outcome was measured.

  • Immune support Limited evidence

    Claims about immunity rest on livestock and laboratory work; no controlled human trial has tested humic or fulvic acid supplements against infection rates or any immune endpoint.

  • Detoxification and heavy metals Limited evidence

    Humic substances bind metals in soil and water, which is the source of the marketing claim, but no human trial shows that oral supplementation removes heavy metals from the body, and the raw material can itself carry contaminants.

Dosage & safety

Studied doseThe single human study used 3 × 800 mg/day for 10 days followed by 3 × 400 mg/day for 35 days. Label doses vary widely and are not based on dose-finding work.
SafetyNo serious adverse events were reported in the one small study, but safety data in humans are minimal. Because humic and fulvic products are extracted from soil, peat or shale, heavy metal contamination is a genuine concern; choose third-party tested products. Avoid in pregnancy, breastfeeding and children given the absence of data.

How to take it

TimingTiming does not matter; the single study split it into three doses a day.
With food?Either way.
Worth knowingBuy only products with a current third-party heavy metal certificate, since these are extracts of soil, peat or shale.

Frequently asked questions

Does humic acid improve gut health?

Humic acid has only limited evidence for gut health: the one human study, an uncontrolled trial in 14 healthy volunteers, found total colonic bacteria rose after 45 days but diversity did not change, and no health outcome was measured. That is not enough to say humic acid does anything useful for your gut.

Does humic acid detox heavy metals from the body?

No human trial shows that oral humic acid removes heavy metals from the body; the claim comes from the fact that humic substances bind metals in soil and water. Humic acid products can themselves carry heavy metal contaminants, so the evidence for detox is limited and the risk runs the other way.

Is humic acid safe to take?

Human safety data on humic acid are minimal: the single small study reported no serious adverse events, but it is extracted from soil, peat or shale, so heavy metal contamination is a genuine concern. If you take humic acid, choose a product with a current third-party heavy metal certificate, and avoid it in pregnancy, breastfeeding and children.

How much humic acid should I take per day?

There is no established dose of humic acid; the only human study used 3 × 800 mg/day for 10 days, then 3 × 400 mg/day for 35 days. Label doses vary widely and are not based on dose-finding work.

Scientific references

Related in Gut health