The sunshine vitamin can be good for your blood pressure, bone strength, mood, and a whole lot more. Unfortunately, the majority of people don’t get enough of this nutrient. One reason is there are few foods that are rich in vitamin D and the ones that are excellent sources tend not to make the top ten lists of favorite foods for most people. (For example, that list includes fatty fish such as salmon and tuna, and beef liver. Fair sources are fortified orange juice, fortified cereals, and egg yolks.) An- other reason is that few people get adequate, healthy exposure to the sun, which the body needs to manufacture vitamin D.
Vitamin D is unlike other vitamins because the body makes this nutrient when you expose your skin to sunlight regularly. When the skin is exposed to sunlight, it makes large amounts of vitamin D, (cholecalciferol) and sends it to the liver, where the organ transforms it into a substance called 25-hydroxyvitamin D, or 25(OH) D. This substance travels throughout the body, and some of it ends up in the kidneys, where 25(OH) D is changed into activated vitamin D, which is the form that performs its many functions, such as supporting bone health, enhancing the immune system, participating in calcium metabolism, and promoting heart health.
How Vitamin D Affects Blood Pressure
Although experts do not fully understand the relationship between vitamin D and hypertension, there are some things they do know. For example, vitamin D may help lower blood pressure in three ways:
- It can modify the activity of an enzyme called renin, which is involved in constricting blood vessels and thus raising blood pressure.
- It can increase insulin sensitivity. This is important because resistance to insulin is a risk factor for high blood pressure.
- It can reduce hardening of the arteries. Vitamin D has a role in regulating the absorption and metabolism of calcium. Calcification that develops in the arteries can contribute to high blood pressure. However, if the body has an adequate amount of vitamin D, it can help ensure the calcium is sent to the bones and teeth rather than to the arteries.
Why is vitamin D important for high blood pressure?
Investigators have made some observations. One is that people with lower vitamin D levels are at a greater risk of high blood pressure. For example, a review of the association between vitamin D intake and hypertension conducted at Massachusetts General Hospital and reported in 2012 noted that low levels of 25-hydroxy vitamin D was associated with higher systolic blood pressure levels as well as a higher incidence of high blood pressure. The 25(OH) D form of vitamin D is the one that is measured in the blood to determine your vitamin D levels and whether you are vitamin D deficient. A Harvard study of women found that those with vitamin D levels of 17 nanograms per milliliter (am/mL) (42 nanomoles per liter, nmol/L) had a 67 percent increased risk of developing high blood pressure.
The Vitamin D Council, a nonprofit dedicated to educating the public about vitamin D, reports that the ideal level of vitamin D is 50ng/mL. To learn what your vitamin D is, you will need to have a simple blood test. If you have high blood pressure and low levels of vitamin D, then taking vitamin D supplements may be beneficial.
Another group of researchers observed the risk of developing systolic hypertension among premenopausal women over a fifteen-year period. At the beginning of the study in 1992 and annually thereafter, the 559 white women (ages 24—44) had their blood pressure checked. Vitamin D levels were measured in 1993 and in 2007. The investigators found that women who had vitamin D deficiency in 1993 had three times the risk of developing systolic hypertension fourteen years later than did women who had normal vitamin D levels.
If you are black, you should be especially mindful of your vitamin D intake. That’s because research shows not only that African-American men and women tend to have lower levels of vitamin D than whites but also that lower vitamin D levels are associated with an increased risk of hypertension. The good news 1s that taking vitamin D supplements seems to help, as demonstrated in a 2013 study from Brigham and Women’s Hospital researchers. They found that taking 4,000 International Units (IUs) of vitamin D daily resulted in a 4.0mmHg decline in systolic blood pressure compared with an increase of 1.7 mmHg among study participants who took a placebo. A dose of 2,000 IUs daily resulted in a 3.4mmHg decline in systolic blood pressure.
Testing for Vitamin D Levels
Testing for your vitamin D level is relatively simple and nearly painless. A simple blood test, called a 25(OH) D blood test, is all you need. There are three ways you can have this test done:
- See your doctor. He or she can take a blood sample and send it to a lab. You should check with your insurance company to see if it covers this test.
- Self-test. There are in-home tests you can order online. These tests are accurate and easy to use: just prick your finger, place the sample on the material sent to you, and then mail it to the appropriate lab for testing.
- Have laboratory testing done. Several Web sites offer the ability to skip going to your doctor and allow you to go straight to a testing laboratory. If you don’t want to do an in-home test, you can purchase a test from healthcheckusa .com, mymedlab.com, or privatedmdlabs.com and then have the test done at a Lab Corp location near you.
Taking Vitamin D
The best way to “take” your vitamin D is through regular exposure to sunlight and those all-important ultraviolet B (UVB) rays. You can get all the vitamin D for one day from just about fifteen minutes of exposure to the sun (without sunscreen) if you are fair skinned, but you will need more time in the sun if your skin is medium to dark. A general rule to follow, according to the Vitamin D Council, is to expose your skin to the sun for half the time it takes your skin to turn pink. Therefore, if you know your skin begins to turn pink after being in the sun for thirty minutes you have had your daily vitamin D “fix” from the sun after fifteen minutes.
Your body can produce 10,000 to 25,000 [Us of vitamin D in less time than it takes for your skin to turn pink. The more skin you expose to the sun, the more vitamin D your body can make. Naturally, you should be sure to put on sunscreen after the time you spend making vitamin D to protect your skin against cancer and aging.
Many people don’t get enough sun exposure, especially during the winter months. Therefore, supplements are often necessary to boost vitamin D levels. However, before you take vitamin D supplements you should have your 25(OH) D levels checked. If you are significantly deficient in vitamin D, you may need to take higher doses of vitamin D supplements for a while, then taper back as your blood levels of vitamin D improve.
The recommended daily dose of vitamin D differs among experts. The U.S. government’s Food and Nutrition Board recommends adults take 600 to 800 IUs, while the Endocrine Society more than doubles that amount to 1,500 to 2,000 1Us daily. The Vitamin D Society recommends adults take 5,000 IUs per day. More and more clinicians and researchers are finding that the 600-to-800-IU dose seems to be too low and are recommending their patients take higher amounts, depending on their blood vitamin D levels and amount of sun exposure.
Vitamin D is fat soluble, which means your body’s fat cells hold on to the vitamin for a while. Therefore, you don’t want to take too much vitamin D. The safe upper limit of vitamin D ranges from 4,000 to 10,000 {Us daily, depending on which experts you believe. However, unless you take more than the upper limit of vitamin D every day for several months you are unlikely to experience any side effects. Indications of an overdose of vitamin D include headache, weakness, fatigue, and loss of appetite, dry mouth, nausea, vomiting, and a metallic taste.
When you are choosing a vitamin D supplement, experts recommend you take D, rather than D, because vitamin D is the form of the nutrient your body makes. However, vitamin D, is typically made from lambs’ wool, so if you are a vegetarian or vegan and have ethical reasons for not wanting to take vitamin D, you may choose vitamin D,, which is made from plants (fungi). However, you should be aware that vitamin D; is not metabolized by the body in the same way as vitamin D, and also produces some substances that the body may have difficulty eliminating.
Vitamin D supplements are available as tablets, capsules, and liquid and can be taken with or without food. You often see supplements that contain both calcium and vitamin D because these two nutrients benefit bone health. Be sure the vitamin D in these supplements is D, and check the amount of vitamin D delivered per dose to be sure you are getting the recommended amount per day.
