Blood Pressure

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what supplements affect blood pressure

Grade	Level of Evidence [show legend]
	Robust research conducted with repeated double-blind clinical trials
	Multiple studies where at least two are double-blind and placebo controlled
	Single double-blind study or multiple cohort studies
	Uncontrolled or observational studies only

Level of Evidence ? The amount of high quality evidence. The more evidence, the more we can trust the results.	Outcome	Magnitude of effect ? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.	Consistency of research results ? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.	Notes
	Cocoa Extract	Minor	- See all 23 studies	While not affecting everybody, there appears to be a decrease in blood pressure when assessing mildly hypertensive people; the increase in blood flow seen in healthy people is not accompanied by a decrease in blood pressure, while the xanthine (caffeine) content of chocolate products may cause a mild and transient increase in blood pressure in some subjects.
	Fish Oil	Minor	Very High See all 8 studies	May decrease blood pressure in persons with high blood pressure, but does not appear to have efficacy in persons with normal blood pressure
	Garlic	Notable	High See all 12 studies	Garlic supplementation appears to reduce blood pressure, and the magnitude is quite respectable in persons with hypertension (around 10 points systolic or 8-10%) whereas there is a smaller but present reduction in persons with normal blood pressure.
	Hibiscus sabdariffa
	Magnesium
	Nitrate
	Olive leaf extract
	Arginine
	Caffeine
	Coenzyme Q10
	Curcumin
	Ephedrine
	Grape Seed Extract
	Inositol
	Marijuana
	Melatonin
	Modafinil
	Nigella sativa
	Pycnogenol
	Stevia
	Vitamin D
	Vitamin E
	Alpha-Lipoic Acid
	Chromium
	Creatine
	Ginkgo biloba
	L-Tyrosine
	Nicotine
	Panax ginseng
	Psyllium
	Quercetin
	Red Clover Extract
	1,3-Dimethylamylamine
	Chlorogenic Acid
	Green Coffee Extract
	Hoodia gordonii
	Spirulina
	Ashwagandha
	Blueberry
	CDP-choline
	Chlorella
	Citrulline
	Ecklonia cava
	Fucoxanthin
	Green Tea Catechins
	Hesperidin
	Irvingia gabonensis
	L-Carnitine
	Lavender
	Microlactin
	Nattokinase
	Policosanol
	Pterostilbene
	Pyruvate
	Resveratrol
	Rose Essential Oil
	Rose Hip
	Saffron
	Salvia sclarea
	Sesamin
	Tribulus terrestris
	Vitamin B2
	Vitamin C
	Yohimbine
	7-Keto DHEA
	Alanylglutamine
	Anatabine
	Anethum graveolens
	Astaxanthin
	Bacopa monnieri
	Benfotiamine
	Capsaicin
	Centella asiatica
	Citrullus colocynthis
	Coleus forskohlii
	Conjugated Linoleic Acid
	ECA
	Echinacea
	Eucommia ulmoides
	Ganoderma lucidum
	Lactobacillus casei
	Lactobacillus reuteri
	Ornithine
	Phosphatidylserine
	Rhodiola Rosea
	Rooibos
	Royal Jelly
	Salvia hispanica
	Sceletium tortuosum
	Shilajit
	Sodium Bicarbonate
	Synephrine
	Taurine
	Trimethylglycine
	Vitamin B3 (Niacin)
	Whey Protein
	Yerba mate
	Zinc
	Eclipta alba
	Licorice
	Berberine
	Kava
	Tetradecyl Thioacetic Acid
	Vitamin B1
	Black Cohosh
	Calcium
	Cissus quadrangularis
	Mangifera indica
	Vanadium

All comparative evidence is now gathered in our ​A-to-Z Supplement Reference.

The evidence for each separate supplement is still freely available ​here.

1. Verster JC, Koenig J. Caffeine intake and its sources: A review of national representative studies. Crit Rev Food Sci Nutr. (2018)
2. Guessous I, Eap CB, Bochud M. Blood pressure in relation to coffee and caffeine consumption. Curr Hypertens Rep. (2014)
3. Nurminen ML, et al. Coffee, caffeine and blood pressure: a critical review. Eur J Clin Nutr. (1999)
4. Noordzij M, et al. Blood pressure response to chronic intake of coffee and caffeine: a meta-analysis of randomized controlled trials. J Hypertens. (2005)
5. Greenberg JA, Chow G, Ziegelstein RC. Caffeinated coffee consumption, cardiovascular disease, and heart valve disease in the elderly (from the Framingham Study). Am J Cardiol. (2008)
6. Li M, et al. The effect of caffeine on intraocular pressure: a systematic review and meta-analysis. Graefes Arch Clin Exp Ophthalmol. (2011)
7. Chandrasekaran S, Rochtchina E, Mitchell P. Effects of caffeine on intraocular pressure: the Blue Mountains Eye Study. J Glaucoma. (2005)
8. Lohsiriwat S, Puengna N, Leelakusolvong S. Effect of caffeine on lower esophageal sphincter pressure in Thai healthy volunteers. Dis Esophagus. (2006)