You’ve likely heard of the power of vitamin D, also known as the sunshine vitamin. You can either get vitamin D through the sun’s rays, which signal your body to make vitamin D, or through certain foods or supplements.
Vitamin D is a fat-soluble, rather than water-soluble, vitamin — so when you get it through your diet, you’ll best absorb it alongside a fat-containing food, such as almonds, peanut butter, or avocado. The vitamin is important for your health: Research suggests that it may help with everything from athletic performance to heart disease, and may even help protect against type 2 diabetes.
What Does Vitamin D Do for Our Bodies and Our Health?
Vitamin D plays many important roles in the body, and helps you maintain healthy bones, joints, and teeth, as well as a well-functioning immune system. “Vitamin D aids in the absorption of calcium in the body to promote bone growth,” notes Erin Palinski-Wade, RD, CDE, author of The 2-Day Diabetes Diet: Just 2 Days a Week and Dodge Type 2 Diabetes, who is in private practice in Franklin, New Jersey. “Some observational studies suggest vitamin D may also play a role in the prevention of certain diseases and disorders, such as diabetes.”
The sunshine vitamin may also help keep your ticker healthy: A review published in January 2014 in the journal Circulation Research suggested that vitamin D deficiency is detrimental for heart health. This is important to note because people with type 2 diabetes are at a greater risk for heart problems. In fact, the Centers for Disease Control and Prevention (CDC) notes people with diabetes are two times more likely to die from heart disease than people without diabetes.
How Are Vitamin D and Diabetes Connected?
A growing number of studies suggest a link between vitamin D and type 2 diabetes. “Research has found that people who are deficient in vitamin D may be more likely to develop diabetes,” says Vandana R. Sheth, RDN, CDE, a spokesperson for the Academy of Nutrition and Dietetics, who is in private practice in Rancho Palos Verdes, California.
It’s also been noted that people newly diagnosed with type 2 diabetes tend to have lower vitamin D levels than people without the disease. “In type 2 diabetes, sometimes the cells of the pancreas do not work properly and struggle to produce sufficient insulin to help control blood sugar levels,” explains Shahzadi Devje, RD, CDE, of Toronto, Canada. “Specific receptors in the pancreas may only switch on when sufficient vitamin D is available. The thinking is that vitamin D may support the function of the pancreas.”
Also, higher vitamin D intake may reduce the risk of developing type 2 diabetes, according to a review published in the European Journal of Clinical Nutrition.
What We Don’t Yet Know About the Benefits of Vitamin D for Diabetes
More research is still needed in this area, as the American Diabetes Association notes that there’s insufficient evidence to recommend the routine use of vitamin D to improve blood sugar control in those with diabetes. “What’s critical is to maintain a sufficient vitamin D status, which is greater than 20 to 30 nanograms per milliliter,” says Devje.
Getting enough vitamin D may also help reduce insulin resistance, which is the hallmark of type 2 diabetes, found a review published in July 2015 in the World Journal of Diabetes. This may help prevent the onset of type 2 diabetes in the first place.
Still, “It’s important to review the scientific evidence with a critical lens,” says Devje. “Much of the research has focused on observational and epidemiological studies, which illustrate an association between vitamin D and diabetes, and do not prove causality.”
What Factors Can Lead to a Vitamin D Deficiency?
Regardless, experts agree getting enough vitamin D is important for overall health, so you should make sure you’re getting your fix.
Although the optimal source of vitamin D is sunlight, it can be challenging to get your daily dose this way, especially during the winter months in northern climates. You’d need to be outside during peak daytime hours — typically 10 a.m. to 3 p.m. standard time or 11 a.m. to 4 p.m. daylight saving time — and soak in the rays for 10 to 20 minutes, then stop and apply sunscreen. The app Dminder tracks the sun to help you get optimal vitamin D.
“You may struggle to get enough vitamin D if you don’t get sufficient sunlight, because many of us spend a significant portion of our day indoors,” says Devje. “People who cover their skin all the time with sunscreen or clothes may also struggle to get enough vitamin D from sunlight.” According to the Harvard T.H. Chan School of Public Health, people with darker skin are at a greater risk for insufficiency because the skin acts as a natural sunscreen, slowing production of vitamin D, while people who are overweight or obese also tend to have lower levels of vitamin D.
What Foods Are High in Vitamin D Yet Also Diabetes-Friendly?
Besides sunlight, another great way to take in more vitamin D is from food. Food sources of vitamin D include fatty fish (such as salmon, herring, and tuna), fortified foods (milk, yogurt, orange juice, and some cereals and breads), and eggs, as well as smaller amounts from some cheeses and some kinds of mushrooms.
If your blood levels of vitamin D are too low, your doctor may recommend a supplement. To determine if you need one, speak with your doctor about getting your levels tested. “I always recommend my clients with diabetes be screened for a vitamin D deficiency so the appropriate vitamin D supplementation level can be recommended,” says Palinski-Wade.
How Much Vitamin D Should People With or at Risk for Diabetes Take?
The daily vitamin D intake goal for most adults is 600 international units (IU), and adults over age 70 need a little more — 800 IU — according to the National Institutes of Health (NIH). People with diabetes are no exception.
But which form of vitamin D is best? “I suggest opting for drops, emulsions, powders, or capsules to increase chances of absorption,” says Devje. “I’d recommend choosing D3 because it’s absorbed and utilized better in the body than D2.” The difference between vitamin D2 and vitamin D3 supplements is that vitamin D2 has to go through an additional conversion step to be used by the body, which means that your body absorbs less of it.
Vitamin D2 is also suitable for vegans, while vitamin D3 is typically manufactured from an animal source. At high doses, vitamin D3 may be more effective, according to the NIH.
Make sure to choose a supplement that’s been tested by a third party so you know it contains what it says it does on the label.
Can You Take Too Much Vitamin D, and How Do You Know if You Have?
Be careful about taking too high of a supplement dose, as research suggests there’s such a thing as taking too much vitamin D.
Consider an article published in June 2017 in the journal JAMA that looked at observational data of more than 39,000 survey participants from the National Health and Nutrition Examination Survey (NHANES). During 2013–2014, 18 percent of the population took in more than 1,000 IU vitamin D daily, and 3 percent took in more than the tolerable upper limit of 4,000 IU daily. Getting too much vitamin D may be linked with heightened risk of fractures and falls in the elderly, and a higher risk of kidney stones when the higher vitamin D intake is alongside calcium.
If you’re unsure about whether you’re getting enough or too much vitamin D, consult your healthcare provider, who can give you blood tests to test for vitamin D deficiency or excess.