Does vitamin D lower blood pressure?

Where the idea comes from

The idea involves vitamin D and the body's blood-pressure hormone system. It comes from lab and animal studies and from observational data.

What trials found

A pooled analysis of 46 randomized trials found no effect on systolic or diastolic pressure. The DAYLIGHT trial, in people who were low in vitamin D and had high blood pressure, found no meaningful difference: about −0.8 vs −1.6 mmHg, not significant.

Safety: more isn't always better

The adult upper limit is 4,000 IU a day. In a 3-year trial, 10,000 IU a day lowered bone density compared with 400 IU. Too much from pills can raise blood calcium, causing kidney stones, kidney damage and heart rhythm problems.

Sunlight can't cause toxicity because skin limits production, but pills have no such limit.

What does lower blood pressure

The 2017/2025 AHA/ACC guidelines describe these lifestyle effects:

• DASH eating: about 11 mmHg in people with high blood pressure.
• Cutting sodium: about 5–6 mmHg.
• Regular aerobic exercise: about 5–8 mmHg.
• Potassium from food: about 4–5 mmHg.
• Weight loss: about 1 mmHg per kg.
• Less alcohol: about 4 mmHg.

In-app “Myth or fact?” cards offer short, sourced answers to common blood pressure claims.

How FourNumbers helps

FourNumbers can't tell you whether a supplement or diet is right for you — that's for you and your doctor. What it can do is show what's actually happening to your numbers: log readings the right way, keep your medicines and supplements in one list, and bring a report to your doctor.

Questions people also ask

Sources

• Beveridge et al., JAMA Internal Medicine 2015
• DAYLIGHT, Hypertension 2015
• Burt et al., JAMA 2019
• NIH ODS: Vitamin D
• 2025 AHA/ACC guideline

Related guides

• Supplements for blood pressure: what the evidence says
• Does magnesium lower blood pressure?
• Is a low-carb diet good for blood pressure?

Last checked: October 2026.