Supplement Health Claims: Fact or Fiction

An evidence-based resource on more than 150 health claims related to vitamins, plants and other health supplements


Vitamins, herbal supplements, omega oils are often associated with health. Daily multivitamin supplements to improve energy and performance; plants that foster weight loss, roots that boost concentration...but how many of these claims are actually proven by science?

Luckily, researchers Stephanie Smith and Miriam Quick gathered data on the scientific evidence behind the most popular health claims associated to supplements. We took their spreadsheet and adapted it to visualize it in this Silk. 

Of course, we give Stephanie Smith and Miriam Quick full credit for the data and research, which you can refer back to, to understand the methodology. The research  has been lastly updated on September 11th, 2015).

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Most popular Google searches for claims with little evidence: Black Tea for Cancer and Coffee for Alzheimer's and Dementia

Research shows that one of the most googled health claims is that regarding Green Tea for Cholesterol. In case you were wondering: the scientific evidence to back it up is conflicting, so don't believe everything you'll find when googling this.

Other two popular claims are Iron for child development and Coconut Oil for obesity. In both these cases the evidence is also promising.

Other top googled health claims are supported by much less evidence, despite their popularity. Caffeine might help slow down Alzheimer's and dementia, but there's still no certain conclusion. And there's no proof that Black Tea reduces ovarian and breast cancer, even if this is the 4th most googled claim in our dataset.

You might also beware of some health claims that are actually harmful. For example, Aloe Vera for digestion is the 6th most popular health claim on Google, but ingestion of the plant is actually "associated with diarrhea, electrolyte imbalance and kidney dysfunction".

Fewer people search for it on Google, but there is strong evidence that coffee helps lower the risk of heart disease (but don't drink too much of it!) and that St. John's Wort is just as effective as conventional medications in treating depression.

Evidence and Popularity (Google Hits) of Claims

Page Title
Evidence
Popularity (Google Hits)
Abatacept - Osteoarthritis4 (Promising)0.13
Aloe Vera - Burns, Cuts1 (No Evidence)88.5
Aloe Vera - Diabetes2 (Slight)88.5
Aloe Vera - Digestive Aid0 (Harmful)88.5
Andrographis - Respiratory Tract Infections1 (No Evidence)0.25
Anti-oxidants - Infertility In Men3 (Conflicting)30.2
Anti-oxidants - Mortality0 (Harmful)30.2
Astaxanthin - Oxidative Stress1 (No Evidence)3.4
Astragalus - Chronic Kidney Disease3 (Conflicting)3
Astragalus - DNA Damage, Immune System2 (Slight)3
B Vitamins - Alzheimer's Disease2 (Slight)8.2
Bee Pollen - Cancer1 (No Evidence)23
Benfotiamine - Ageing, Diabetes3 (Conflicting)2
Beta-glucans - Cancer1 (No Evidence)0.36
Beta-glucans - Colds, Immune System4 (Promising)0.36
Bitter Melon - Diabetes1 (No Evidence)3.7
Black Cohosh - Menopause2 (Slight)0.91
Black Tea - Cancer1 (No Evidence)196
Borage Seed Oil - Rheumatism4 (Promising)1.2
Bromelain - Arthritis3 (Conflicting)0.97
Butterbur - Migraine2 (Slight)0.66
Caffeine - Memory5 (Good)29.8
Caffeine - Skin Cancer2 (Slight)29.8
Calcium + Vitamin D - Breast Cancer In Premenopausal Women, Cancer3 (Conflicting)2.4
Calcium - Blood Pressure4 (Promising)36.9
Calcium - Colorectal Cancer4 (Promising)37.3
Calcium - Osteoporosis2 (Slight)37.3
Capsaicin - Non-Allergic Rhinitis1 (No Evidence)5.4
Carnosine - Ageing1 (No Evidence)0.6
Cat's Claw - Cancer1 (No Evidence)4.8
Chamomile - Bowel Disorders1 (No Evidence)5.6
Chocolate (Dark) - Blood Pressure3 (Conflicting)39.7
Chromium - Diabetes2 (Slight)7.1
Cinnamon - Diabetes1 (No Evidence)48
Coconut Oil - Obesity4 (Promising)205
Coffee - Alzheimer's Disease, Dementia2 (Slight)193
Coffee - Heart Health6 (Strong)29.8
Colostrinin - Alzheimer's Disease1 (No Evidence)0.001
Coq10 - Blood Pressure3 (Conflicting)12.6
Coq10 - Diabetes3 (Conflicting)12.6
Coq10 - Migraine1 (No Evidence)12.6
Cranberry - Urinary Tract Infections1 (No Evidence)19.1
Creatine + Coq10 - Cognitive Performance3 (Conflicting)13.9
Dandelion - Tonsilitis3 (Conflicting)8.8
Devil's Claw - Arthritis4 (Promising)1.1
DHEA - Ageing1 (No Evidence)3.7
DHEA - Memory3 (Conflicting)3.7
Dong Quai - Menopause In Breast Cancer Patients0 (Harmful)0.6
Echinacea - Colds3 (Conflicting)3.8
Egg Shell Membrane - Joints, Arthritis5 (Good)0.53
Elderberry - Flu1 (No Evidence)5.4
Elderberry - Lipid And Antioxidant Status2 (Slight)5.4
Evening Primrose Oil - PMS1 (No Evidence)10.9
Feverfew - Migraine5 (Good)0.4
Flax Seeds - Breast Cancer1 (No Evidence)10
Folic Acid - Birth Defects5 (Good)25
Folic Acid - Cancer0 (Harmful)9.3
Gaba - Stress, Anxiety1 (No Evidence)1.3
Garlic - Blood Pressure1 (No Evidence)86.4
Garlic - Cancer3 (Conflicting)86.4
Garlic - Colds1 (No Evidence)86.4
Ginger - Nausea And Vomiting4 (Promising)96.5
Gingko Biloba - Dementia1 (No Evidence)8.3
Ginseng - Cognitive Performance1 (No Evidence)44.1
Glucosamine - Arthritis, Joints3 (Conflicting)9
Glutamine - Gastrointestinal Disease In Infants1 (No Evidence)3.8
Glutamine - Morbidity And Mortality In Preterm Infants1 (No Evidence)3.8
Goji Berry - Eye Health1 (No Evidence)34
Grape Seed Extract - Wound Healing, Swelling1 (No Evidence)4
Green Tea - Cancer3 (Conflicting)349
Green Tea - Cholesterol3 (Conflicting)349
Horse Chestnut Seed Extract - Chronic Venous Insufficiency4 (Promising)0.24
Hyaluronic Acid - Arthritis3 (Conflicting)5
Iron + Folic Acid - Maternal And Infant Health4 (Promising)9.29
Iron - Child Development (when Not Anaemic)4 (Promising)256
Kava - Anxiety2 (Slight)1.24
Krill Oil - Arthritis1 (No Evidence)16
Krill Oil - PMS1 (No Evidence)16
L-Arginine - Exercise Performance1 (No Evidence)4.4
L-Carnitine - Diabetes3 (Conflicting)5.3
L-Carnitine - Impotence1 (No Evidence)5.3
L-Lysine - Herpes1 (No Evidence)2.4
Lavender - Depression4 (Promising)69.6
Lavender - Sleep, Relaxation1 (No Evidence)69.6
Leucine - Protein Synthesis1 (No Evidence)2.4
Lingzhi + San Miao San - Arthritis2 (Slight)1.9
Lutein - Eye Health1 (No Evidence)3.8
Lycopene - Prostate Cancer2 (Slight)4.1
Magnesium + Vitamin B6 - Child ADHD3 (Conflicting)0.004
Magnesium - Blood Pressure3 (Conflicting)26.5
Marijuana - Chronic Pain4 (Promising)61.6
Marijuana - Glaucoma1 (No Evidence)61.6
Marijuana - Nausea And Vomiting Due To Chemotherapy3 (Conflicting)61.6
Marijuana - Spasticity3 (Conflicting)61.6
Melatonin - Sleep2 (Slight)5.9
Milk Thistle - Hepatitis, Diabetes3 (Conflicting)8.2
MSM - Arthritis2 (Slight)12.5
N-acetyl Cysteine (NAC) - OCD, Addiction1 (No Evidence)1.5
Nettles - Prostate-Related Urinary Problems1 (No Evidence)1.08
Olive Leaf Extract - Blood Pressure, Cholesterol1 (No Evidence)2
Omega 3 - Alzheimer's Disease, Dementia1 (No Evidence)80
Omega 3 - Asthma1 (No Evidence)80
Omega 3 - Cancer Symptoms2 (Slight)80
Omega 3 - Cardiovascular Disease3 (Conflicting)80
Omega 3 - Child ADHD1 (No Evidence)63.1
Omega 3 - Child Intelligence2 (Slight)80
Omega 3 - Colorectal Cancer4 (Promising)80
Omega 3 - Crohn's Disease1 (No Evidence)80
Omega 3 - Depression, Mental Illness3 (Conflicting)80
Omega 3 - Diabetes1 (No Evidence)80
Omega 3 - Heart Health1 (No Evidence)0.21
Omega 3 - Low Sperm Count3 (Conflicting)79.7
Omega 3 - Prostate Cancer0 (Harmful)80
Omega 3 - Psychosis2 (Slight)80
Omega 6 - Cancer1 (No Evidence)2.34
Omega 6 - Heart Health1 (No Evidence)2.34
Pau D’Arco - Decongestant0 (Harmful)0.6
Peppermint Oil - IBS5 (Good)25.8
Piracetam - Memory, Dementia3 (Conflicting)2.7
Potassium - Blood Pressure1 (No Evidence)12.3
Probiotics + IBS (b. Infantis 35624 And B. Coagulans Gbi-30,6086)3 (Conflicting)28.2
Probiotics - Cholesterol, Blood Pressure3 (Conflicting)28.2
Probiotics - Diarrhoea Related To Antibiotic Use5 (Good)28.2
Quercetin - Athletic Performance1 (No Evidence)0.84
Resveratrol - Cancer1 (No Evidence)27.2
Resveratrol - Diabetes1 (No Evidence)27.2
Resveratrol - Heart Health3 (Conflicting)27.2
Rhodiola Rosea L. - Fatigue3 (Conflicting)0.8
SAM-e - Depression4 (Promising)2.9
SAM-e - Liver Disease1 (No Evidence)2.9
Saw Palmetto - Prostate-Related Urinary Problems1 (No Evidence)4.23
Selenium - Cancer1 (No Evidence)7.8
Silicic Acid - Alzheimer's Disease1 (No Evidence)0.022
Slippery Elm - Sore Throat1 (No Evidence)0.35
Spirulina - Blood Pressure, Cholesterol1 (No Evidence)50.6
St John's Wort - Depression6 (Strong)20.5
St John's Wort - PMS1 (No Evidence)1.5
Taurine - Weight Loss, Cholesterol1 (No Evidence)2.9
TMG - Metabolism1 (No Evidence)0.38
Tryptophan + 5-HTP - Depression3 (Conflicting)1.9
Turmeric (Curcumin) - Cancer2 (Slight)60.8
Turmeric (Curcumin) - Peptic Ulcer, Ulcerative Colitis4 (Promising)60.8
Tyrosine - Alertness, Memory4 (Promising)0.36
Tyrosine - Depression3 (Conflicting)0.36
Ubiquinol - Heart Health3 (Conflicting)6.6
Valerian - Anxiety1 (No Evidence)3.63
Valerian - Insomnia0 (Harmful)3.63
Vitamin A: Beta-carotene - Cancer1 (No Evidence)2.13
Vitamin A: Retinol - Birth Defects0 (Harmful)0.74
Vitamin B12 - Cankersores3 (Conflicting)15.6
Vitamin B2 - Migraine2 (Slight)0.64
Vitamin B3 - Heart Health0 (Harmful)3.8
Vitamin B8 - Depression3 (Conflicting)0.38
Vitamin B8 - OCD, Panic Disorder3 (Conflicting)0.38
Vitamin C - Colds4 (Promising)46.1
Vitamin D - All-cause Mortality5 (Good)43.8
Vitamin D - Bone Health4 (Promising)43.8
Vitamin D - Cancer2 (Slight)43.8
Vitamin D - Depression, Mood Disorders2 (Slight)43.8
Vitamin D - Diabetes3 (Conflicting)43.8
Vitamin D - Flu4 (Promising)43.8
Vitamin D - Heart Health3 (Conflicting)43.8
Vitamin E - Alzheimer's Disease3 (Conflicting)42.4
Vitamin E - Mortality0 (Harmful)42.4
Vitamin K2 - Heart Health3 (Conflicting)1.13
Vitamin K2 - Osteoporosis4 (Promising)1.13
Vitamin K2 - Prostate Cancer4 (Promising)1.13
Xylitol - Teeth1 (No Evidence)2.65
Zinc - Colds4 (Promising)16.5


There was no evidence, or only slight evidence, in 50% of the 169 claims researched

Evidence of Claims


Other than the claims with scarce scientific evidence, there are also ten cases in which science proved that the supplements were actually harmful for the health conditions they claimed to improve.

Harmful Claims grouped by Supplement


Scientific community's interest and Googlers' interest don't always match

Google hits and number of Google scholar citations don't go hand in hand for all health claims researched. Iron for child development is the most cited claim on Google Scholar, and the second with most hits on Google. Yet, in most other cases, the claims most searched on Google aren't among the top interests of the scientific community. 

While people are searching for Green Tea, Black Tea, Coffee, and Coconut Oil, Google Scholar reports most citations for Calcium, Potassium, Zinc and Vitamin D.

Scientific Community Interest and Popularity (Google Hits) of Claims

Scientific Community Interest = Number of citations on Google Scholar (2000-2012) - supplement name + health

Most claims in this dataset are for Cancer, Diabetes and Blood Pressure

What Healt Condition Are Most Claims about


Omega 3 and Vitamin D are the supplements with most claims (in this dataset)

Number of Claims per Suppelment


Browse through all health claims and supplements

All Claims


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