More than 122 million American adults — nearly half — have high blood pressure (hypertension).1 Left untreated, hypertension dramatically increases your risk of stroke, heart failure, kidney failure, and sudden death, so it’s not an exaggeration to say that high blood pressure is one of the most dangerous and most overlooked conditions you can face. Early signs include headaches, dizziness, shortness of breath, or no symptoms at all — which is why it's often called the "silent killer."
Once diagnosed, most people are put on a lifetime prescription of medications, with little to no discussion of underlying causes or lifestyle-based solutions. However, new research has shown that optimizing your vitamin D level offers hope, even if you haven’t changed other contributing factors, such as your diet. This revelation offers immediate relief for people looking to address their blood pressure without suffering from the side effects of blood pressure medications.
Vitamin D Supplementation Slashes Blood Pressure
A meta-analysis published in Cureus analyzed how vitamin D supplementation impacts blood pressure in adults across a wide range of clinical settings and populations.2 The researchers selected 12 studies from all around the world, spanning countries such as the United States, China, Iran, Denmark, and Australia.
For the analysis, the team looked at changes in both systolic and diastolic blood pressure after vitamin D supplementation. Most of the participants were adults dealing with either high blood pressure or borderline hypertension — not already on medication for more serious conditions, but at enough risk to warrant intervention. Some were vitamin D deficient at baseline, while others had suboptimal but not deficient levels.
• High-dose vitamin D creates rapid results in a short span — In one of the reviewed studies, subjects took 50,000 IU of vitamin D per week for just eight weeks. The results were remarkable — systolic blood pressure dropped by 28.44 mmHg, and diastolic pressure fell by 7.38 mmHg.
“This finding suggests that high-dose supplementation over a short duration may yield greater blood pressure reductions, potentially due to the rapid correction of vitamin D deficiency,” the researchers said.
• Other studies saw more modest improvements, depending on the dose and duration — For example, one study wherein participants were given 1,200 IU per day for eight weeks still saw a drop in systolic pressure by 4.5 mmHg.
In another study, using only 200 IU daily for 16 weeks, researchers reported a 3.4 mmHg drop in systolic pressure and a 2.6 mmHg drop in diastolic pressure. Although smaller, these changes are still profound, especially in those with early-stage hypertension. According to the researchers, some of these shifts occurred even without changes to diet or exercise, showing the direct role vitamin D plays in blood pressure regulation.
• High weekly doses worked faster and produced greater results than lower daily doses spread over months — For instance, the study that administered 50,000 IU per week not only produced the biggest reductions, but did so in just two months.
In contrast, trials that stretched out over 24 to 48 weeks and used smaller doses (like 2,000 to 4,000 IU/day) resulted in blood pressure reductions closer to 1 to 4 mmHg. The results weren’t uniform, but the pattern was clear.
• Results vary, but deficient participants benefited the most — In these individuals, correcting vitamin D deficiency triggered rapid, noticeable improvements in both systolic and diastolic pressure. This reinforces the importance of testing your vitamin D level.
Researchers also pointed out the wide range in outcomes, noting that studies with similar doses produced very different effects depending on the starting health status of the participants. For example, one study gave 4,000 IU/day for 48 weeks and saw almost no change, while another used the same dose over 24 weeks and saw a clear 4 mmHg drop in systolic pressure.
What Happens to Your Body When You Take a Vitamin D Supplement?
One key mechanism has to do with how vitamin D affects the renin-angiotensin-aldosterone system (RAAS). This system controls how much fluid your kidneys retain and how tightly your blood vessels constrict.
When vitamin D is low, RAAS tends to be overactive, leading to more fluid retention, higher vascular resistance, and elevated blood pressure. The review found evidence that vitamin D helps suppress renin, which then lowers the activity of angiotensin II, a hormone that causes blood vessels to tighten up.
• Vitamin D supports blood pressure by improving endothelial function — The endothelium is the lining of your blood vessels. When it’s healthy, your vessels expand and contract easily. When it’s damaged, they stiffen, and that raises blood pressure.
Vitamin D also increases the production of nitric oxide, a molecule that helps blood vessels relax as well as reduces oxidative stress. Over time, this prevents stiffening of the arteries and supports better blood flow.
• Chronic inflammation is regulated — Many of the participants in the reviewed studies had markers of inflammation, either due to obesity, hypertension, or metabolic syndrome. In the context of the study, the researchers noted that vitamin D reduces levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), two cytokines known to worsen vascular inflammation.
Taken altogether, the study provides insight into the importance of maintaining proper vitamin D levels, and what can happen to your health if you don’t have enough of it. While the researchers looked into supplementation, you actually don’t have to spend a single cent to optimize your vitamin D levels — sunlight exposure may be enough, provided you live in a sunny enough locale.
How to Optimize Your Vitamin D Level
If you notice your blood pressure creeping up, or if you're already on medication and wondering why it's not fully working, take a look at your vitamin D level. Here are my recommendations to get your health on the right path again:
1. Sensible sunlight exposure is the best way to optimize your vitamin D — The ideal way to optimize your vitamin D levels is via safe sun exposure. Harnessing the sun's power for vitamin D production offers benefits far exceeding simple vitamin synthesis. However, if your diet includes significant amounts of seed oils, extra caution is warranted.
These oils, rich in linoleic acid (LA), an omega-6 fatty acid, readily oxidize under UV light. This interaction on your skin initiates a cascade of breakdown products, leading to inflammation and DNA damage.
Ideally, reduce consumption of these oils for four to six months before increasing sun exposure. During this time, limiting time in the sun to early morning or late afternoon is recommended. Avoid direct sunlight during peak hours (10 a.m. to 4 p.m.) until your body has cleared the seed oils. Individual factors like skin pigmentation and body composition also influence safe sun exposure.
Those with darker skin tones require longer exposure to generate the same amount of vitamin D as those with lighter skin. Since body fat stores LA, individuals with higher body fat percentages should also exercise additional caution, as those stored oils prolong the risk period even after dietary changes.
To determine safe sun exposure, use the "sunburn test." Monitor your skin for any redness. Staying below the threshold of even slight pinkness indicates you're within safe limits. Avoid sunburn at all costs.
2. Take high-quality vitamin D3 if necessary — For individuals living in northern climates or those with limited sun exposure, supplementing with high-quality vitamin D3 is often necessary to achieve and maintain optimal vitamin D levels. Vitamin D3 is synthesized naturally in your skin when it's exposed to sunlight, specifically ultraviolet B (UVB) rays.
On the other hand, vitamin D2 is typically derived from plant sources, including yeast and mushrooms exposed to UV light. While both forms are available as supplements, research has uncovered distinct differences in their effectiveness. Vitamin D3 is significantly more effective than D2 at raising blood vitamin D levels.3
3. Take your vitamin D with magnesium and vitamin K2 — If you take supplemental vitamin D3, you also need to be mindful of taking extra vitamin K2 and magnesium. It’s important to increase your vitamin K2 intake when taking high-dose supplemental vitamin D to avoid complications associated with excessive arterial calcification.
You need 146% more vitamin D to achieve a blood level of 40 ng/mL (100 nmol/L) if you do not take supplemental magnesium, compared to taking your vitamin D with at least 400 mg of magnesium per day.
Vitamin D improves magnesium absorption, but taking large doses of vitamin D can deplete magnesium, as magnesium is required in the conversion of vitamin D into its active form. Combined intake of both supplemental magnesium and vitamin K2 has a greater effect on vitamin D levels than either individually. You need 244% more oral vitamin D if you’re not concomitantly taking magnesium and vitamin K2.
4. Take your supplements with a bit of healthy — Both vitamin D and K2 are fat-soluble nutrients, which means they require fat to get into your system effectively. However, the type of fat matters.
If you’re still eating food high in vegetable oils — like soybean, canola, or even too much olive oil — you’re flooding your cells with linoleic acid (LA), which damages how your mitochondria process light and nutrients. Switch to grass fed butter, tallow, or ghee instead. I recommend reducing your LA intake to less than 5 grams per day, but don’t go overboard with healthy fat, either. Carbohydrates are still your body’s preferred fuel — not fat.
Additional Guidelines for Safe Sun Exposure
When you begin getting regular sun exposure, use this simple safety test — watch your skin for the first sign of pinkness, which is an early warning of sunburn. Stop sun exposure before your skin turns pink to prevent damage. This pinkness threshold helps you determine your safe exposure time.
Now, what if you need to spend time under the sun but haven't completely removed LA from your body yet? Here are some protective strategies I recommend:
• Take 12 milligrams of astaxanthin daily to enhance your skin's UV resistance.
• Apply topical niacinamide (vitamin B3) cream before sun exposure to protect against UV-induced DNA damage.
• Take a baby aspirin 30 to 60 minutes before sun exposure to help prevent LA conversion to harmful oxidized linoleic acid metabolites (OXLAMs).
• Use molecular hydrogen supplements to combat oxidative stress.
Check Your Vitamin D Levels Regularly
For optimal health, you’ll want to aim for a vitamin D level between 60 ng/mL and 80 ng/mL. The minimum cut off for sufficiency is 40 ng/mL to 60 ng/mL.
I've published a comprehensive vitamin D report in which I detail vitamin D's mechanisms of action and how to ensure optimal levels. I recommend downloading and sharing that report with everyone you know. A quick summary of the key steps is as follows:
1. First, establish your baseline — Once you know what your current blood level is, you can assess the dose needed to maintain or raise it. If you cannot get enough vitamin D from the sun (you can use the DMinder app4 to see how much vitamin D your body can make depending on your location and other individual factors), then you'll need an oral supplement.
2. Assess your individualized vitamin D dosage — To do that, you can either use the chart below, or use GrassrootsHealth's Vitamin D*calculator. To convert ng/mL into the European measurement (nmol/L), simply multiply the ng/mL measurement by 2.5. To calculate how much vitamin D you may be getting from regular sun exposure in addition to your supplemental intake, use the DMinder app.
3. Retest in three to six months — Lastly, have your vitamin D level retested in three to six months, to evaluate how your sun exposure and/or supplement dose is working for you.
Frequently Asked Questions About Vitamin D and Its Impact on Blood Pressure
Q: Why is high blood pressure often called the silent killer?
A: High blood pressure (hypertension) affects around half of U.S. adults. It often shows no symptoms for years, quietly damaging vital organs like the heart, kidneys, brain, and eyes. If left untreated, it leads to stroke, heart failure, kidney failure, and even sudden death, making it one of the most dangerous and overlooked health conditions.
Q: Can vitamin D supplementation help lower blood pressure?
A: Yes. Research revealed that high-dose vitamin D supplementation reduces blood pressure within weeks. Even smaller daily doses showed modest but significant drops. The benefit was most noticeable in people who were vitamin D deficient to begin with.
Q: How does vitamin D influence blood pressure levels?
A: Vitamin D helps regulate the renin-angiotensin-aldosterone system (RAAS), which controls blood vessel constriction and fluid retention. It also enhances nitric oxide production, helping vessels relax. Moreover, it reduces oxidative stress and vascular inflammation and lowers levels of inflammatory markers like IL-6 and TNF-alpha.
Q: What’s the best way to optimize my vitamin D levels naturally and safely?
A: Start with smart sun exposure — aim for 15 to 30 minutes of midday sunlight on bare skin without sunscreen, but only if you’ve purged your body of vegetable oils for at least six months. If you’re just working to removing these oils, avoid peak sunlight hours to protect your skin.
Q: How should I monitor and adjust my vitamin D levels?
A: Regular testing is key. Aim for blood levels between 60 ng/mL and 80 ng/mL for optimal health. The steps below summarize the process:
1. Test your vitamin D level.
2. Use GrassrootsHealth's Vitamin D*calculator to determine your proper dose.
3. Retest every three to six months to track and fine-tune your approach. Apps like DMinder can help estimate vitamin D synthesis from sun exposure based on your location and lifestyle.