Vitamin C and Immune Function: A Review
Nutrients • Nov 2017
Quality: 5/5
DOI: 10.3390/nu9111211
Scientific Studies
Browse our curated collection of scientific research on natural compounds. Each study includes a plain-language summary and quality rating.
Filter studies by:
By compound
By condition
By body system
Rhodiola rosea for Mental and Physical Fatigue: A Systematic Review
BMC Complementary and Alternative Medicine • May 2012
n=714Quality: 4/5
DOI: 10.1186/1472-6882-12-70
NAC for Psychiatric Disorders: A Systematic Review
Neuroscience & Biobehavioral Reviews • Jan 2015
n=2,000Quality: 4/5
DOI: 10.1016/j.neubiorev.2014.10.023
CoQ10 for Statin-Induced Myopathy: A Meta-Analysis
Mayo Clinic Proceedings • Sep 2015
n=575Quality: 4/5
DOI: 10.1016/j.mayocp.2015.05.002
CoQ10 for Heart Failure: The Q-SYMBIO Study
JACC Heart Failure • Dec 2014
n=420Quality: 5/5
DOI: 10.1016/j.jacc.2014.08.016
Melatonin for Primary Sleep Disorders: A Meta-Analysis
PLoS ONE • May 2013
n=1,683Quality: 5/5
DOI: 10.1371/journal.pone.0063773
Berberine for Type 2 Diabetes: A Systematic Review and Meta-Analysis
Phytomedicine • Mar 2021
n=2,569Quality: 4/5
DOI: 10.1016/j.phymed.2020.153433
Zinc Lozenges and Common Cold Duration: A Meta-Analysis
Open Forum Infectious Diseases • Apr 2017
n=575Quality: 4/5
DOI: 10.1093/ofid/ofx059
Probiotics and Anxiety/Depression: A Systematic Review
Journal of Affective Disorders • Jan 2019
n=1,901Quality: 4/5
DOI: 10.1016/j.jad.2018.09.049
Probiotics for IBS: A Systematic Review and Network Meta-Analysis
The Lancet Gastroenterology & Hepatology • Oct 2018
n=11,500Quality: 5/5
DOI: 10.1016/S2468-1253(18)30223-2
Curcumin for Depression: A Meta-Analysis of Randomized Controlled Trials
Journal of Affective Disorders • Oct 2017
n=531Quality: 4/5
DOI: 10.1016/j.jad.2017.06.001
Curcumin for Osteoarthritis: A Systematic Review and Meta-Analysis
BMC Musculoskeletal Disorders • Jul 2021
n=1,621Quality: 4/5
DOI: 10.1186/s12891-021-04525-2
Magnesium and Sleep Quality: A Systematic Review
BMC Complementary Medicine and Therapies • Sep 2022
n=7,582Quality: 4/5
DOI: 10.1186/s12906-022-03706-z
Magnesium Supplementation for Blood Pressure: A Meta-Analysis
Hypertension • Aug 2016
n=2,028Quality: 5/5
DOI: 10.1161/HYPERTENSIONAHA.116.07664
Ashwagandha Effects on Testosterone and Male Reproductive Health
American Journal of Mens Health • Dec 2015
n=46Quality: 4/5
DOI: 10.1177/1557988315598713
Omega-3 Fatty Acids for Major Depressive Disorder: A Meta-Analysis
Translational Psychiatry • Aug 2019
n=2,160Quality: 4/5
DOI: 10.1038/s41398-019-0515-5
REDUCE-IT: Cardiovascular Risk Reduction with Icosapent Ethyl
New England Journal of Medicine • Jan 2019
n=8,179Quality: 5/5
DOI: 10.1056/NEJMoa1812792
Vitamin D and Depression: A Systematic Review and Meta-Analysis
Critical Reviews in Food Science and Nutrition • Feb 2022
n=53,235Quality: 4/5
DOI: 10.1080/10408398.2022.2036099
Vitamin D Supplementation and COVID-19 Outcomes
Scientific Reports • Apr 2022
n=76,428Quality: 4/5
DOI: 10.1038/s41598-022-10515-2
Vitamin D and Calcium Supplementation Reduces Cancer Risk
JAMA Network Open • Sep 2019
n=30,970Quality: 5/5
DOI: 10.1001/jamanetworkopen.2019.11941
Lion’s Mane and Cognitive Function in Older Adults
Phytotherapy Research • Mar 2009
n=30Quality: 3/5
DOI: 10.1002/ptr.2634
Omega-3 and Cardiovascular Disease: Meta-Analysis
JAMA Cardiology • Oct 2019
n=127,477Quality: 5/5
DOI: 10.1001/jamacardio.2019.3780
Effect of Magnesium Supplementation on Sleep Quality
Journal of Nutritional Science • Oct 2022
n=46Quality: 4/5
DOI: 10.1017/jns.2022.21
Ashwagandha Root Extract for Stress and Anxiety: A Systematic Review
Journal of Ayurveda and Integrative Medicine • Jan 2021
n=1,542Quality: 4/5
DOI: 10.1016/j.jaim.2019.01.004
Understanding Our Study Ratings
Each study is rated on methodology quality (1-5 stars). Higher ratings indicate more rigorous research design, larger sample sizes, and more reliable conclusions. Meta-analyses and randomized controlled trials typically receive higher ratings than observational or in-vitro studies.