Along with fulvic acid, humic acid is the other major humic fraction in shilajit.
Heavier , insoluble at acid pH and soluble in basic pH , it mainly plays a role
structural and chelating . This guide provides a complete and sourced summary:
definition, proposed mechanisms (chelation, adsorption, microbiota, immunomodulation), level of evidence ,
EU safety/regulations, quality criteria (COA, heavy metals) and informed usage advice.
1) What is humic acid?
1.1 Definition & Origin. Humic substances – humic acids, fulvic acids and humins – come from
from the slow decomposition (humification) of plant and microbial matter. They form naturally in
soils, peats, composts, sediments and organic deposits (e.g.: leonardite ), but also in certain matrices
mineral-organic compounds at the origin of shilajit .
1.2 A “whole”, not a single molecule. Humic acid corresponds to a heterogeneous mixture
of macromolecules/supramolecules (aromatic nuclei, aliphatic chains, carboxyl / phenolic groups).
Its composition depends on the source (soil, compost, vermicompost, shilajit), the extraction process (pH, solvents,
filtration) and purification .
1.3 Solubility, pH and size. By convention, humic acid is insoluble in acidic media (pH < 2)
and soluble in neutral/basic medium . Its high molecular weight and its organization in associations
supramolecular structures distinguish it from fulvic acid (smaller, soluble at all pH ).
Note: talking about "humic acid" is like talking about a family . Two preparations can have different profiles.
distinct physicochemical and biological. Hence the importance of traceability and batch analyses (COA) .
1.4 In shilajit. Humic fractions (humic + fulvic) coexist with minerals and organic compounds.
Humic acid plays a rather structural/adsorbent role; fulvic acid is often described as a carrier
(transport of trace elements). For an example of a raw material, see the
quality shilajit .
2) Key properties
2.1 High molecular weight & local action
Due to its size and supramolecular associations , humic acid diffuses poorly across membranes.
Its role is mainly local : interactions in the intestinal lumen and at the level of the epithelial barrier .
2.2 pH-dependent solubility
Insoluble at acid pH (stomach) but soluble in neutral/basic (small intestine): this gradient conditions
surface interactions (complex formation, adsorption).
2.3 Chelation, complexation and adsorption
Carboxyl / phenolic groups bind various cations (Pb, Cd, Cu, Fe, etc.) and interact with toxins
(e.g. aflatoxin B1 ). This results in stable complexes and surface adsorption that can
reduce the bioavailability of these substances.
2.4 Buffer capacity & colloids
Humic preparations exhibit amphoteric behavior, antioxidant properties (aromatic nuclei) and a
tendency to form colloidal aggregates influencing turbidity and the mucosal interface.
2.5 Analytical indicators (quality)
-
Humic/fulvic content : IHSS/ISO methods according to matrix.
-
Trace element profile : ICP-MS for heavy metals (Pb, Cd, Hg, As).
-
Organic pollutants : GC-MS/HPLC for PAHs (e.g. benzo[a]pyrene), residual solvents.
-
Microbial load : total germs, yeasts/molds, specific pathogens.
3) Potential biological roles
3.1 Reduction of heavy metal absorption
By chelation/complexation , humic acid can bind Pb, Cd, Hg, As (depending on chemical forms) and
reduce their bioavailability at the intestinal level. Solid data in vitro /animal and in the literature
environmental.
3.2 Adsorption of toxins
Several preclinical studies show adsorption of mycotoxins (notably AFB1 ) and preservation of
the integrity of the intestinal barrier . Mechanism consistent with the aromatic/colloidal nature of humics.
3.3 Intestinal microbiota & mucosa
Small human trials report an increase in some colonic microbial concentrations without loss of diversity,
suggesting a local environmental effect .
3.4 Immunomodulation (caution)
Cellular/animal models describe cytokine modulations (TNF-α, IL-6/IL-10, etc.) and antiviral pathways.
Limited clinical extrapolation : no hard endpoints established at this stage.
Important: These roles are potential and come mainly from preclinical data. In Europe, they do not constitute
not authorized health claims .
4) Scientific data: what we know (and what we don't know)
4.1 Quick overview. The literature includes in vitro studies (complexation, adsorption),
animal (intestinal barrier, liver parameters) and some pilot human trials
(tolerance, microbiota).
4.2 Examples of (popularized) studies.
-
Microbiota (45 days, healthy volunteers). A standardized humic preparation increased colonic bacterial concentrations
without altering diversity. Favorable tolerance. Limited number → results to be confirmed.
-
Aflatoxin B1. Humic acids adsorb AFB1 and attenuate injury markers; effect related to
barrier protection and microbiota adjustments (models).
-
Toxicology 90 days (rat). A purified humic/fulvic preparation has a high NOAEL at the doses tested,
without major signal on target organs.
Study in brief #1: 45-day humic supplementation → increase in pre-existing colonic microbial concentrations ,
preserved diversity (healthy volunteers).
Study in Brief #2: Under controlled conditions, humic preparations adsorb AFB1 and reduce translocation
of intestinal permeability markers in animals. Human transposition to be confirmed.
4.3 “Level of evidence” table.
| Domain |
Results set |
Level of proof |
| Chelation of heavy metals |
Pb, Cd, Cu complexation; decreased bioavailability in models; solid environmental basis. |
Robust in vitro /animal; limited human data . |
| Adsorption of toxins (AFB1, etc.) |
Measurable adsorption; barrier protection and liver parameters in animals. |
Convincing preclinical; little clinical . |
| Microbiota & barrier |
↑ of certain bacterial concentrations; indicators of mucosal integrity preserved. |
Some pilot human studies; to be reproduced . |
| Immunomodulation/antiviral |
Cytokine modulations; interactions with certain viral envelopes in models. |
Review/preclinical; no claims . |
4.4 Methodological limitations.
Variability of preparations (source, extraction), small numbers, short duration, absence of blinding/placebo in certain studies,
difficulty in isolating the effect of humics among other components (e.g. in shilajit).
5) Safety & Regulation (EU)
5.1 Regulatory framework. In Europe, health claims must be authorized and listed in the EU Register.
To date, there is no specific claim for humic acid.
5.2 Contaminants and compliance. Priority to purity . Expected controls:
heavy metals (Pb, Cd, Hg, As), PAHs (e.g. benzo[a]pyrene), mycotoxins (AFB1, OTA, DON depending on matrix),
residual solvents , microbial load . Reference: maximum levels of current regulations.
Require a recent COA (ideally by batch) detailing methods and detection limits.
5.3 Interactions & at-risk populations. As a precaution, space 2–3 hours with medications
or sensitive minerals (risk of binding/adsorption). Avoid in pregnant/breastfeeding women and in case of
renal failure , except on medical advice.
Caution: Informational content, does not replace medical advice. Follow the manufacturer's dosage instructions .
Discontinue and consult a doctor if any adverse reaction occurs.
6) Choosing a good product: practical guidelines
6.1 Origin & traceability
Specify the source (soils/compost/vermicompost/leonardite/shilajit), the extraction process (pH, solvents, filtration),
purification (removal of impurities) and standardization (batch-to-batch consistency).
6.2 Batch Analysis (COA)
-
Heavy metals : ICP-MS (Pb, Cd, Hg, As).
-
PAH : GC-MS/HPLC (including benzo[a]pyrene).
-
Mycotoxins : AFB1, OTA, DON (depending on matrix).
-
Residual solvents : compliance with applicable thresholds.
-
Microbiology : total germs, yeasts/molds, pathogens.
6.3 Transparency
Favor brands that publish COAs per batch, a clear batch number , a QR code and a factual usage guide .
Feedback is available on the customer reviews page.
6.4 Formulation
Humic alone ( binding/adsorption orientation) or humic + fulvic complex (complementarity with fulvic acid).
Avoid unnecessary additions if unwanted.
7) Usage tips (general)
7.1 Forms & textures. Capsules, powder, liquid or integration into a complex (e.g. shilajit).
The choice depends on the comfort of use and the announced standardization .
7.2 Time of intake. Often with a large glass of water; many people prefer during a meal (tolerance).
Avoid simultaneous association with sensitive medications / minerals .
7.3 Graduality & observation. Start low (follow the product label ), observe tolerance (digestive, transit),
adjust only within the manufacturer's recommendations .
Example (non-prescriptive): A study in healthy adults used a standardized humic preparation for ~45 days
with good tolerance reported. This is not a dosage : refer to your product label.
8) Humic acid vs. fulvic acid
| Criteria |
Humic acid |
Fulvic acid |
| Size/structure |
Supramolecular associations, high weight
|
Low molecular weight, smaller structures |
| Solubility |
Insoluble at acid pH , soluble in neutral/basic |
Soluble at all pH
|
| Main role |
Adsorption/chelation , local action
|
Possible vector of trace elements |
| Bioavailability |
Rather weak/situation-dependent |
Higher (reduced size) |
| Typical uses |
Digestive comfort via local connection (be careful with language) |
Mineral synergy, “delivery” supplements |
| Position in shilajit |
“Structural” fraction |
Fraction “vector” |
For a detailed overview of the light fraction (mechanisms, safety, uses), read:
Fulvic acid: benefits, mechanisms and safety .
9) FAQ
Humic acid is a group of macromolecules that are insoluble in acid , generally
local in the intestine and adsorbent/chelating . Fulvic acid is more
small , soluble at all pHs and often described as a carrier of trace elements.
They are complementary in shilajit.
We are talking more about chelation/adsorption : humic acid can bind certain heavy metals and toxins
in the intestinal environment, which could reduce their absorption . Human data remain limited ;
in the EU, these are not health claims .
No. Its large size and pH-dependent solubility limit its cellular passage;
Its action is mainly local . Fulvic circulates more easily.
Preclinical models show cytokine modulations . At this stage, no strong clinical evidence
allowing a claim in the EU. To be considered as a scientific lead .
The purified preparations tested show good tolerance in the available evaluations.
The key point remains quality (recent COAs, heavy metals, PAHs, mycotoxins, solvents).
Testimonials and feedback can be read on the customer reviews page.
