Vitamin C

Does vitamin C lower blood pressure?

Updated 3 Nov 2026

Short answer

Short trials found a small fall. A 2012 review of 29 trials found that systolic pressure fell by 3.84 mmHg, with a median of 500 mg a day for 8 weeks.[1] A 2023 review of 20 trials found a fall of 3.0 mmHg, larger in people with high blood pressure or diabetes.[2] Two large trials of 500 mg a day for 8 and 9.4 years found no fewer heart attacks or strokes.[3][4]

What the reviews found

In observational studies, people who had more vitamin C in their diet or blood had lower blood pressure, but single trials gave mixed results.[1] Three meta-analyses of randomized trials found a small fall in blood pressure. Systolic pressure is the upper number, and diastolic pressure the lower one.[1][2][5]

  • 2012, 29 trials. The trials gave oral vitamin C for at least 2 weeks, with 10 to 120 people each. The median dose was 500 mg a day for 8 weeks. Systolic pressure fell by 3.84 mmHg and diastolic pressure by 1.48 mmHg. With 9 more trials whose results had to be estimated, the fall was smaller but still significant.[1]
  • People with high blood pressure, same review. Systolic pressure fell by 4.85 mmHg. The fall in diastolic pressure, 1.67 mmHg, could have been chance.[1]
  • 2020, 8 trials in 614 people with high blood pressure. Systolic pressure fell by 4.09 mmHg and diastolic pressure by 2.30 mmHg. With 500 mg a day or more, systolic pressure fell by 5.01 mmHg.[5]
  • 2023, 20 trials in 890 adults. The median dose was 757.5 mg a day for 6 weeks. Systolic pressure fell by 3.0 mmHg, by 3.2 mmHg in people with high blood pressure and by 4.6 mmHg in people with diabetes.[2]

Blood vessel function

The endothelium is the inner lining of blood vessels. Through it, the vessels widen.[6] A 2014 meta-analysis of 44 trials found that vitamin C improved endothelial function.[7] The trials gave vitamin C in more than one way, and the effect did not depend on the route.[7] It improved in people with atherosclerosis, diabetes or heart failure, and the effect was stronger in people at higher risk of heart disease and with higher doses.[7]

Heart attacks and strokes

Large trials have not found fewer heart events:[3][4]

  • In 14,641 US male doctors aged 50 or older, 500 mg a day for a mean of 8 years did not lower heart attacks, strokes or deaths from heart disease.[3]
  • In 8,171 women at high risk of heart disease, 500 mg a day for a mean of 9.4 years had no effect on heart events.[4]
  • A 2022 review of 884 trials of 27 micronutrients found that vitamin C did not change the risk of heart disease or type 2 diabetes.[8]

Why it may work

Studies have found that vitamin C helps the lining of blood vessels make nitric oxide and widen the vessels.[6]

What is still unknown

Most trials lasted only weeks. The authors of the 2012 review called for long trials that also count heart attacks and strokes.[1] The authors of the 2023 review called for long trials in people with poor heart and metabolic health.[2] People who take a statin for cholesterol should talk to a doctor or pharmacist before adding vitamin C, because their blood fats should be checked.[6]

Sources (8)

  1. Effects of vitamin C supplementation on blood pressure: a meta-analysis of randomized controlled trials. Juraschek SP, Guallar E, Appel LJ, Miller ER 3rd Am J Clin Nutr, 2012. PMID 22492364
  2. Vitamin C supplementation showed greater effects on systolic blood pressure in hypertensive and diabetic patients: an updated systematic review and meta-analysis of randomised clinical trials. Lbban E, Kwon K, Ashor A, Stephan B, Idris I, Tsintzas K, et al. Int J Food Sci Nutr, 2023. PMID 37791386
  3. Vitamins E and C in the prevention of cardiovascular disease in men: the Physicians' Health Study II randomized controlled trial. Sesso HD, Buring JE, Christen WG, Kurth T, Belanger C, MacFadyen J, et al. JAMA, 2008. PMID 18997197
  4. A randomized factorial trial of vitamins C and E and beta carotene in the secondary prevention of cardiovascular events in women: results from the Women's Antioxidant Cardiovascular Study. Cook NR, Albert CM, Gaziano JM, Zaharris E, MacFadyen J, Danielson E, et al. Arch Intern Med, 2007. PMID 17698683
  5. Effects of vitamin C supplementation on essential hypertension: A systematic review and meta-analysis. Guan Y, Dai P, Wang H Medicine (Baltimore), 2020. PMID 32080138
  6. Vitamin C: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
  7. Effect of vitamin C on endothelial function in health and disease: a systematic review and meta-analysis of randomised controlled trials. Ashor AW, Lara J, Mathers JC, Siervo M Atherosclerosis, 2014. PMID 24792921
  8. Micronutrient Supplementation to Reduce Cardiovascular Risk. An P, Wan S, Luo Y, Luo J, Zhang X, Zhou S, et al. J Am Coll Cardiol, 2022. PMID 36480969

More about vitamin c

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For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.