A 2026 human study of 15 healthy adults found that taking 900 mg of silver fir branch extract daily for 14 days did not harm liver or kidney function, with all blood markers remaining normal. According to Gram Research analysis, all participants completed the study without adverse events, suggesting short-term use of this polyphenol-rich supplement is safe in healthy people, though longer-term safety remains unstudied.
A new study tested whether silver fir branch extract, a popular dietary supplement made from tree branches, could harm your liver or kidneys. Researchers gave 15 healthy adults 900 mg of the extract daily for two weeks and measured their liver and kidney function using blood tests. According to Gram Research analysis, all participants completed the study safely with no harmful effects on their organs. The findings suggest this supplement is safe for short-term use in healthy people, though more research is needed for long-term safety and effects in people with existing health conditions.
Key Statistics
A 2026 open-label study of 15 healthy adults found that 900 mg daily of silver fir branch extract for 14 days caused no statistically significant changes in liver function markers (AST, ALT, GGT, ALP, or bilirubin).
All 15 participants in the 2026 silver fir extract study completed the supplementation period without reporting any adverse events or side effects.
A 2026 human safety study showed that kidney function markers (urea, creatinine, and uric acid) remained within normal ranges in all 15 healthy adults taking 900 mg daily of silver fir extract for two weeks.
The Quick Take
- What they studied: Whether taking silver fir branch extract as a dietary supplement could damage the liver or kidneys in healthy adults
- Who participated: 15 healthy volunteers (8 men and 7 women) with an average age of 48 years who had no known health problems
- Key finding: After taking 900 mg of silver fir extract daily for 14 days, all participants showed normal liver and kidney function with no harmful changes in their blood tests
- What it means for you: If you’re a healthy adult considering this supplement, short-term use appears safe based on this study. However, this was a small study lasting only two weeks, so we don’t yet know about long-term safety or effects for people with liver or kidney disease
The Research Details
Researchers conducted an open-label study, meaning all participants knew they were taking the supplement (there was no placebo group for comparison). The 15 healthy adults first had a two-week observation period where researchers measured their baseline liver and kidney function using blood tests. Then, all participants took 900 mg of standardized silver fir branch extract daily for 14 days. Blood tests were repeated after the supplement period to see if anything had changed. The researchers measured five liver markers (AST, ALT, GGT, ALP, and bilirubin) and three kidney markers (urea, creatinine, and uric acid) to check for any problems.
This type of study is useful for getting initial safety information about a new supplement in humans. However, because it’s small and doesn’t include a comparison group taking a placebo, it can only show whether the supplement appears safe—it can’t prove it’s completely harmless or compare it to other options.
The study was registered after it was completed, which is less ideal than registering before starting, but the researchers were transparent about this limitation.
Before people use dietary supplements widely, researchers need human safety data. Silver fir extract is becoming more popular, but most safety information comes from lab studies or animal studies, not from actual people taking it. This study fills that gap by showing what happens to real humans when they take the supplement.
Strengths: All 15 participants completed the study, suggesting good tolerability; the extract was standardized (meaning consistent quality); blood tests used established medical markers. Weaknesses: Very small sample size (15 people); no control group for comparison; short duration (only 14 days of supplementation); open-label design (participants knew what they were taking, which could introduce bias); retrospective registration rather than pre-registration; no information about potential side effects beyond blood test changes
What the Results Show
All 15 participants completed the two-week supplementation period without reporting any adverse events or side effects. Blood tests showed that all measured liver markers (AST, ALT, GGT, ALP, and bilirubin) remained within normal, healthy ranges before, during, and after supplementation. Similarly, all kidney markers (urea, creatinine, and uric acid) stayed within normal ranges throughout the study.
The researchers found no statistically significant changes in any of the measured markers after participants took the supplement. This means the changes observed were small enough to be explained by normal day-to-day fluctuations in blood chemistry rather than being caused by the supplement itself.
Because all values stayed normal and no significant changes occurred, the researchers concluded that short-term use of 900 mg daily of this silver fir extract did not harm liver or kidney function in these healthy adults.
The study did not report on other potential effects like changes in energy, digestion, or other symptoms. No participants dropped out due to side effects, suggesting the supplement was well-tolerated. The fact that minor fluctuations in blood markers were consistent with normal physiological variability suggests the supplement didn’t cause unusual stress on these organs.
Most previous research on silver fir extract comes from laboratory studies showing it contains beneficial compounds called polyphenols. This is the first human study to directly measure safety markers in people taking the supplement. The findings align with the general safety profile suggested by lab research, but human studies are more reliable for determining real-world safety.
This study is small (only 15 people), so results may not apply to larger populations. It only lasted 14 days, so we don’t know if the supplement is safe for months or years of use. The study only included healthy adults, so we can’t conclude it’s safe for people with existing liver or kidney disease. There was no comparison group taking a placebo, making it harder to know if minor changes were due to the supplement or normal variation. The study didn’t measure other potential effects beyond liver and kidney function tests. Finally, the study was registered after completion rather than before, which is less rigorous scientifically.
The Bottom Line
For healthy adults: Short-term use of silver fir branch extract at 900 mg daily appears safe based on this study (moderate confidence—small study size limits certainty). For people with liver or kidney disease: Do not use without consulting your doctor, as this study only tested healthy people. For long-term use: More research is needed before we can confidently recommend extended use beyond two weeks.
This research is most relevant to healthy adults considering silver fir supplements. It’s less relevant to people with liver disease, kidney disease, or those taking medications that affect liver or kidney function. People pregnant or breastfeeding should consult a doctor before using any new supplement.
This study only measured effects over 14 days, so we can only confidently say the supplement is safe for short-term use. Benefits or risks from longer-term use remain unknown and would require additional research.
Frequently Asked Questions
Is silver fir extract safe to take as a dietary supplement?
A 2026 study of 15 healthy adults found short-term use (900 mg daily for 14 days) was safe with no harmful effects on liver or kidney function. However, long-term safety and effects in people with health conditions remain unknown.
Can silver fir supplement damage your liver or kidneys?
In this 2026 study, 900 mg daily of silver fir extract did not damage liver or kidney function in healthy adults. All blood markers stayed normal. However, this was a small, short-term study, so more research is needed for definitive conclusions.
How much silver fir extract did the study participants take?
Participants took 900 mg daily of standardized silver fir branch extract for 14 days. This dose was chosen as a typical supplement amount, though optimal dosing for health benefits hasn’t been established.
Who should not take silver fir dietary supplements?
People with liver disease, kidney disease, or those taking medications affecting these organs should consult their doctor first. Pregnant and breastfeeding women should also seek medical advice before using new supplements.
How long did researchers study the safety of silver fir extract?
The study lasted 14 days of supplementation. This short timeframe means we only know about immediate safety, not long-term effects from months or years of regular use.
Want to Apply This Research?
- If using this supplement, track daily intake (900 mg) and any symptoms like fatigue, nausea, or digestive changes in a daily log. Note any changes in energy levels or overall wellness.
- Users can set a daily reminder to take their silver fir supplement at the same time each day and log it in the app. They can also track any symptoms or side effects they notice, creating a personal safety record.
- For long-term users, consider getting liver and kidney function blood tests annually (through your doctor) and log the results in the app. Track any changes in how you feel over weeks and months. If you experience unusual symptoms like yellowing of skin, dark urine, or changes in urination, report these to your doctor immediately and note them in the app.
This research shows that short-term use of silver fir extract appears safe in healthy adults, but it does not prove the supplement is completely safe or effective for any health condition. This study was small and short-term, so results may not apply to everyone or to long-term use. If you have liver disease, kidney disease, are pregnant, breastfeeding, or taking medications, consult your doctor before using this or any dietary supplement. Dietary supplements are not regulated as strictly as medications and may contain unlisted ingredients. Always purchase from reputable manufacturers and inform your healthcare provider about all supplements you take. This information is for educational purposes only and should not replace professional medical advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.