Supplement
Gamma oryzanol is a group of plant compounds found in rice bran oil, where they act as antioxidants that protect the oil, and it is sold as a supplement. People mostly look at it for cholesterol, but the research is thin: one small trial of 30 men with mildly high cholesterol found no clear difference in LDL or HDL. Evidence is very limited, and a separate study of 22 people also found no clear change in the stress hormone cortisol.
Sources: PMID 15309429
- Updated
- How we grade
- 2 studies cited
- Best evidence
- Grade D
- Conditions studied
- 4
- Outcomes
- 33
- Graded outcomes
- 0005
Evidence by condition
- Strong
- Moderate
- Limited
- Very limited
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| High-density lipoprotein (HDL) No effect | NoneNo effect | 1 study | 30 people | |||
Studies that measured high-density lipoprotein (hdl) | ||||||
| Low-density lipoprotein (LDL) No effect | NoneNo effect | 30 people | ||||
| Total cholesterol | Improves (the measure goes down) | 30 people | ||||
Muscle Size Strength
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Cortisol No effect | NoneNo effect | 22 people | ||||
| High-density lipoprotein (HDL) | Improves (the measure goes up) | 1 study | 22 people | |||
Studies that measured high-density lipoprotein (hdl) | ||||||
| Power Output | Improves (the measure goes up) | 1 study | 22 people | |||
Studies that measured power output | ||||||
| Estrogen | Changes; see studies | 22 people | ||||
| Growth Hormone | Improves (the measure goes up) | 22 people | ||||
| Insulin | Changes; see studies | 22 people | ||||
| Plasma Endorphins | Improves (the measure goes up) | 22 people | ||||
| Testosterone | Improves (the measure goes up) | 22 people | ||||
| Total cholesterol | Improves (the measure goes down) | 22 people | ||||
| Triglycerides | Improves (the measure goes down) | 22 people | ||||
General Athletic Performance
- Cortisol
- High-density lipoprotein (HDL): improves
- Power Output: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Cortisol No effect | NoneNo effect | 22 people | ||||
| High-density lipoprotein (HDL) | Improves (the measure goes up) | 1 study | 22 people | |||
Studies that measured high-density lipoprotein (hdl) | ||||||
| Power Output | Improves (the measure goes up) | 1 study | 22 people | |||
Studies that measured power output | ||||||
| Estrogen | Changes; see studies | 22 people | ||||
| Growth Hormone | Improves (the measure goes up) | 22 people | ||||
| Insulin | Changes; see studies | 22 people | ||||
| Plasma Endorphins | Improves (the measure goes up) | 22 people | ||||
| Testosterone | Improves (the measure goes up) | 22 people | ||||
| Total cholesterol | Improves (the measure goes down) | 22 people | ||||
| Triglycerides | Improves (the measure goes down) | 22 people | ||||
Muscle Size & Strength
- Cortisol
- High-density lipoprotein (HDL): improves
- Power Output: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Cortisol No effect | NoneNo effect | 22 people | ||||
| High-density lipoprotein (HDL) | Improves (the measure goes up) | 1 study | 22 people | |||
Studies that measured high-density lipoprotein (hdl) | ||||||
| Power Output | Improves (the measure goes up) | 1 study | 22 people | |||
Studies that measured power output | ||||||
| Estrogen | Changes; see studies | 22 people | ||||
| Growth Hormone | Improves (the measure goes up) | 22 people | ||||
| Insulin | Changes; see studies | 22 people | ||||
| Plasma Endorphins | Improves (the measure goes up) | 22 people | ||||
| Testosterone | Improves (the measure goes up) | 22 people | ||||
| Total cholesterol | Changes; see studies | 22 people | ||||
| Triglycerides | Changes; see studies | 22 people | ||||
Key findings
- High-density lipoprotein (HDL)
- Low-density lipoprotein (LDL)
- Cortisol
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- Grade D
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Studies cited
2 studies from PubMed