Antioxidant properties of hemp proteins and their health effects
What it found
Hemp proteins and the peptides made from them act as antioxidants in lab tests and in animals, and early animal and cell studies suggest possible benefits for high blood pressure, inflammation and cancer.
Human trials are still lacking.
What they found
Studies in people
Allergy and safety
Hemp is a mild allergen for some people and can cause hives, itching and severe symptoms. A case report described a 30-year-old man who worked in hemp harvesting and got contact urticaria. Two major hemp allergens, thaumatin-like protein and lipid transfer protein, have been found and can be removed by food processing.
Animal and lab studies
Antioxidant power in lab tests
Hemp protein broken down with alcalase for 1 hour showed DPPH radical scavenging ability of 3.75 mg/mL, superoxide radical scavenging of 3.5 mg/mL, hydroxyl radical scavenging of 7.25 mg/mL, and FRAP ability of 0.21 mg/mL. Hemp seed extracts showed high ORAC activity at 127 µmol TE/g and DPPH radical scavenging of 40%.
Metal ion chelating
Hemp protein hydrolysate made with alcalase had strong metal ion chelating ability at 72%. Another hemp protein hydrolysate made with neutrase had metal ion chelating ability of 1.7 to 1.8 mg/mL and DPPH radical scavenging of 2.3 to 2.4 mg/mL.
Blood pressure in rats
In 36 rats with high blood pressure, those treated with hemp protein hydrolysate had lower systolic blood pressure, lower plasma ACE activity and lower renin levels than the control group. Another study with 32 rats found that those fed hemp hydrolysate at 1.0% or 0.5% had higher plasma SOD and CAT activities than controls.
Inflammation in cells
In mouse microglial cells, hemp protein hydrolysates increased the gene expression of IL-10 and suppressed the mRNA levels of IL-1β, TNF-α and IL-6. Hemp seed compounds also suppressed TNF-α and IL-6 mRNA levels and increased SIRT1 and HO-1 expression while reducing ROS.
Cancer cells in lab
In liver cancer cells, low molecular weight hemp protein hydrolysate reduced cell viability, proliferation, migration, Bcl-2 levels and Akt phosphorylation, while increasing Bax, caspase 3, and phosphorylation of GSK-3β and β-catenin. Normal liver cells showed no statistical differences. In another study, hemp antioxidant peptides reduced hydrogen peroxide-induced toxicity in PC 12 cells.
Studies in people and animals
Antioxidant enzymes in animals
In rats with high blood pressure, those fed a hemp diet had significantly higher plasma SOD and CAT activities than the control group. In cell culture, hemp seed extracts increased the gene expression of SOD, CAT and GPx in liver cells.
Other findings
Breaking down hemp protein
Hemp protein can be broken into smaller peptides using pH-shift or enzymes. In one study, pancreatin gave the highest degree of hydrolysis at 47.5%, followed by trypsin at 46.6%, a mix of enzymes at 34%, and pepsin at 19.7%.
What the authors conclude
“Taken together, the antioxidant potential of hemp proteins may provide both functional food benefits and phytotherapy efficacy to human health.”
Also in their conclusions
- They say the structure-activity relationship of antioxidant peptides is impacted by molecular size, the compositions of amino acids and the sequences of amino acids.
- They note that many scholars have offered a broad spectrum of potential pharmacology for diseases such as hypertension, inflammatory diseases and cancer, based on positive pre-clinical properties of hemp protein.
- They call for more high-quality experiments such as proteomic analysis, genomics analysis, and clinical trials of large sample size for more scientific evidence.
How it was done
Excessive oxidation is one of the primary causes of mitochondrial damage, DNA damage, cell death, cancer and chronic diseases. The safety of some synthetic antioxidants has been questioned, so natural antioxidants like hemp protein have attracted more attention.
The authors reviewed studies on how hemp proteins are broken down into smaller peptides, how their antioxidant power is measured in lab tests, and what animal and cell studies show about their effects on blood pressure, inflammation and cancer. They also ran a small pilot experiment comparing hemp protein hydrolysate with soybean protein hydrolysate.
What it can’t tell you
- Most of the studies in this review were done in cells or animals, so they cannot show what happens in people.
- There are no large human trials of hemp protein for antioxidant effects, blood pressure, inflammation or cancer.
- The review does not show whether eating hemp protein prevents or treats any disease in people.
Who paid
- Funding
- Funded by Global Food Systems Initiative, Kansas State University (from the PubMed record).
- Conflicts
- The authors declare no conflict of interest.
- Authors work at
- Kansas State University, USA
The paper
- Title
- Antioxidant Properties of Hemp Proteins: From Functional Food to Phytotherapy and Beyond
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Zhang J, Griffin J, Li Y, Wang D, Wang W (2022). Antioxidant Properties of Hemp Proteins: From Functional Food to Phytotherapy and Beyond. Molecules (Basel, Switzerland). doi:10.3390/molecules27227924Free full textPubMed 36432024DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error