Vitamin D and Hypertension

Hypertension

Hypertension, also known as high blood pressure, is a medical condition in which the blood pressure in the arteries is elevated. High blood pressure causes your arteries to stretch beyond normal. There are risk factors that can increase your chances of developing hypertension. Some of these risk factors are based on your lifestyle and can be controlled, like your diet. Other risk factors can’t be controlled, such as age or gender. Research shows that there is a link between vitamin D and hypertension. People with higher vitamin D levels tend to have lower blood pressure and are less likely to develop hypertension. Some studies show that taking a vitamin D supplement may help people lower their blood pressure. However, the research has been inconsistent, meaning that we can’t say for sure whether or not taking vitamin D supplements would reduce your chances of developing hypertension or reduce your blood pressure. If you have hypertension or you are trying to prevent hypertension and want to take vitamin D, it is unlikely to make your hypertension worse or cause you any harm, as long as you take less than 10,000 IU per day. However, we also can’t say for sure if it will help to prevent or treat hypertension. If you have hypertension, you shouldn’t take vitamin D in place of your treatment medications. Talk to your doctor for more advice about taking supplements.

What is hypertension?

Hypertension is a chronic medical condition in which the blood pressure in the arteries is elevated. High blood pressure causes your arteries to stretch too much. Stretched arteries can form scars, which catch debris such as cholesterol, calcium or blood cells. A build-up of this debris can block your arteries, so less blood is able to travel throughout your body. This can put extra stress on your heart because it will have to work harder to get blood to different parts of your body¹, which can increase your chance of other complications, like a stroke.

What are the symptoms of hypertension?

Hypertension often has no symptoms but can cause other complications. Some complications that hypertension can cause include:

• Heart and artery damage
• Stroke
• Vision loss
• Memory loss
• Kidney damage
• Peripheral artery disease

In rare cases of extremely high blood pressure, hypertension can give rise to symptoms. This is known as a hypertensive crisis and occurs in about 1% to 5% of people with hypertension². Symptoms of hypertensive crisis include¹:

• Severe headaches
• Nosebleeds
• Trouble breathing
• Severe anxiety

How common is hypertension?

Worldwide, about 4 out of 10 people have hypertension. In the United States,  1 out of every 3 adults has hypertension. There are some risk factors that increase your risk of developing hypertension¹:

• Gender. Hypertension is more common among men.
• Family history. If a close family member has or had hypertension, then you have an increased risk.
• Age. As you get older, your blood vessels lose the ability to expand, which can contribute to high blood pressure.
• Race. African-Americans are at a greater risk of having high blood pressure.
• Diet. A diet high in cholesterol, salt, and fat can increase your chance of developing high blood pressure.
• Being overweight or obese
• Smoking
• Diabetes
• Lack of exercise

What causes hypertension?

It is difficult to determine the cause of hypertension once it has been diagnosed. Hypertension may be caused by⁴:

• Arteries becoming narrower
• A faster or more forceful heartbeat
• More blood in your vessels

Hypertension is diagnosed based on your blood pressure. Blood pressure is measured as your systolic blood pressure over your diastolic blood pressure. Systolic blood pressure is the pressure put on your arteries when your heart beats and pumps blood. Diastolic blood pressure is the pressure put on your arteries between heartbeats, when your heart is resting. High blood pressure is when your systolic blood pressure is higher than 140 millimeters of mercury (mmHg) and/or diastolic blood pressure is higher than 90 mmHg¹.

What is the link between vitamin D and hypertension?

Studies have shown that there is a link between vitamin D and hypertension. People who have higher vitamin D intake tend to have lower blood pressure. Sometimes, your body can produce too many cells in the muscle that lines your blood vessels. A build-up of these cells can lead to plaque, which makes it harder for blood to travel throughout your body. Researchers have found vitamin D receptors on these cells, and vitamin D can bind to these receptors. This may help to reduce the risk of cells building up in your blood vessels. Also, vitamin D may help in reducing the activity of the system that controls your blood pressure. This system is called the renin-angiotensin system. When this system is overactive, blood pressure can increase. However, researchers still aren’t sure what causes the blood pressure system to become overactive and don’t know yet for sure how vitamin D can help to control its activity.

What does the research say in general about vitamin D and hypertension?

Research has looked at the role of vitamin D in helping to lower blood pressure in people who don’t have hypertension. One large study found that people with higher levels of vitamin D had lower blood pressures and a lower risk of developing hypertension⁵. Some experiments have looked at the effect of vitamin D on blood pressure in people who have hypertension. One review of many experiments found that taking a vitamin D supplement lowered systolic blood pressure but not diastolic blood pressure⁶. However, not all studies have found that vitamin D lowers blood pressure, so we can’t say for sure whether or not vitamin D helps lower blood pressure and reduce the risk of hypertension.

What does recent research say?

A review in 2013⁷ looked at many studies involving people with hypertension. They found that:

• For each 10 ng/ml increase in someone’s vitamin D levels, they had a 12% lower risk of developing hypertension.
• The people with the highest vitamin D levels had a 30% lower risk of developing hypertension compared to the people with the lowest levels.

This study was very large and looked at many people. However, all of the studies were done in the United States meaning that we can’t know for sure if the results would be the same in other populations. An experiment in 2013⁸ looked at the effects of taking a vitamin D supplement on risk of hypertension in African Americans who had normal blood pressure. The researchers assigned 250 people to receive either 1,000 IU per day, 2,000 IU per day, 4,000 IU per day, or a placebo for 3 months. Here is what the researchers found:

• For every increase in vitamin D supplementation and vitamin D levels in the body, systolic blood pressure decreased.
• Diastolic blood pressure didn’t change in any group.

Some of the people in the study were taking medication that lowers blood pressure, so we can’t know for sure if vitamin D was responsible for the results. An experiment in 2008⁹ used data from a large experiment that assigned women to either receive 1,000 mg per day of calcium plus 400 IU per day of vitamin D or a placebo pill. For this study, the researchers took those results and looked at how it changed their blood pressure and risk of getting hypertension. The results showed:

• There was no difference in blood pressure changes between the groups.

The study used only a small dose of vitamin D and also included calcium, which makes it hard to say whether or not vitamin D on its own would have had an effect. An experiment in 2012 in Denmark¹⁰ looked at the effects of vitamin D supplements on lowering blood pressure in people with hypertension. For 20 weeks, people either took 3,000 IU per day of vitamin D or a placebo pill. The researchers measured a few different types of blood pressure and found that:

• The people in the vitamin D group lowered their blood pressure more than the people getting the dummy pill.
• People in the vitamin D group who had low levels of vitamin D at the beginning of the study had a bigger reduction in their blood pressures.

Vitamin D may be more effective in lowering blood pressure in people who have low levels of vitamin D. However, all of the patients in the study were taking medication for their hypertension, so we can’t say for sure whether the results are from vitamin D or from the medication. An experiment in 2013 in Italy¹¹ looked at the role of vitamin D supplementation on regulating the blood pressure system in the body. A small group of people with hypertension was given 25,000 IU per week of vitamin D for a total of 8 weeks. The researchers found:

• Vitamin D levels increased throughout the study.
• The blood pressure system was greatly reduced.

Since an overactive blood pressure system can lead to higher blood pressure, vitamin D may help to reduce risk of hypertension.

Key points from the research

• Research has shown that people with higher vitamin D levels are more likely to have lower blood pressure and are less likely to develop hypertension.
• Studies have shown that taking a vitamin D supplement can reduce blood pressure in people with hypertension.
• Some research has shown that taking a vitamin D supplement helps regulate the blood pressure system in the body.
• However, not all trials show reduced blood pressure after taking vitamin D. This means that we can’t say for sure if vitamin D is a main factor in preventing hypertension or in lowering blood pressure.

More experiments are needed to say for sure whether or not vitamin D may help to lower blood pressure and reduce risk of hypertension.

What does this mean for me?

Research shows that there is a link between vitamin D, hypertension and blood pressure. People with high vitamin D levels have lower blood pressure and are less likely to develop hypertension. Studies have shown that supplementing with vitamin D may help lower blood pressure and may help regulate the blood pressure system in people with hypertension. However, most experiments have used a small sample size, so more experiments are needed. If you have hypertension or you are trying to prevent hypertension and want to take vitamin D, it is unlikely to make your hypertension worse or cause you any harm, as long as you take less than 10,000 IU per day. However, it’s not proven that it will help your hypertension. It’s also not proven if taking vitamin D will help you prevent hypertension. Research shows that there is a link between vitamin D, hypertension and blood pressure. People with high vitamin D levels have lower blood pressure and are less likely to develop hypertension. Studies have shown that supplementing with vitamin D may help lower blood pressure and may help regulate the blood pressure system in people with hypertension. However, most experiments have been small, so more experiments are needed. If you have hypertension or you are trying to prevent hypertension and want to take vitamin D, it is unlikely to make your hypertension worse or cause you any harm, as long as you take less than 10,000 IU per day. However, it’s not proven that it will help your hypertension. It’s also not proven if taking vitamin D will help you prevent hypertension. If you have hypertension, you shouldn’t take vitamin D in place of your treatment medications. Talk to your doctor for more advice about taking supplements.

Sun exposure and blood pressure

Other aspects of sunlight may help to regulate blood pressure in your body. Researchers are interested in the ability of ultraviolet-A wavelengths to help release stores of nitric oxide in your skin and help them move throughout your body. Nitric oxide helps to regulate and lower blood pressure!

References

1. High Blood Pressure. American Heart Association, 2012. Web. 21 February 2014. https://www.heart.org/en/health-topics/high-blood-pressure.
2. Yeo, T. P. & Burrell, S. A. Hypertensive Crisis in an Era of Escalating Health Care Changes. Journal of Nurse Practitioners 2010;6;338-346.
3. Raised blood pressure. World Health Organization, 2014. Web. 21 February 2014. https://www.who.int/gho/ncd/risk_factors/blood_pressure_prevalence_text/en/.
4. Your Guide to Lowering High Blood Pressure. National Heart, Lung, and Blood Institute, 2014. Web. 25 February 2014. https://www.nhlbi.nih.gov/health/high-blood-pressure
5. Ullah, M. et al. Does Vitamin D Deficiency Cause Hypertension? Current Evidence from Clinical Studies and Potential Mechanisms. International Journal of Endocrinology 2010;579640;1-11.
6. Witham, M. et al. Effect of vitamin D on blood pressure: a systematic review and meta-analysis. Journal of Hypertension 2009;27;1948-1954.
7. Kunutsor, S. K. et al. Vitamin D and risk of future hypertension: meta-analysis of 283,537 participants. European Journal of Epidemiology 2013;28;205-221.
8. Forman, J. et al. Effect of vitamin D supplementation on blood pressure in blacks. Hypertension 2013;61;779-785.
9. Margolis, K. L. et al. Effect of calcium and vitamin D supplementation on blood pressure: the Women’s Health Initiative Randomized Trial. Hypertension 2008;52;847-855.
10. Larsen, T. et al. Effect of Cholecalciferol Supplementation During Winter Months in Patients with Hypertension: A Randomized, Placebo-Controlled Trial. American Journal of Hypertension 2012;25;1215-1222.
11. Carrara, D. et al. Cholecalciferol administration blunts the systemic renin-angiotensin system in essential hypertensives with hypovitaminosis D. Journal of the renin-angiotensin-aldosterone-system 2013;15;82-87.