Reviewed by Dietitian Annie Nguyen, M.A., RD
Photographer: Carson Downing; Food Stylist: Holly Dreesman; Prop Stylist: Gabriel Greco. EatingWell design.
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A new study found a link between vitamin D and heart disease.
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Vitamin D deficiency and insufficiency are both common.
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Vitamin D is found in few foods, but it is produced with sunlight skin exposure.
While we often refer to heart disease as one condition, it’s actually a term that comprises many conditions related to the heart and blood vessels. Under the umbrella of cardiovascular disease (CVD), there are specific categories like atherosclerotic cardiovascular disease (ASCVD). Athersclerotic heart diseases are related to plaques that accumulate in the arteries.
Those plaques narrow the blood vessels—sometimes completely—or narrow them so much that blood clots can’t get through, sealing off the blood vessel. This can result in a heart attack or stroke. The plaques also make the blood vessels less elastic and stiffer, which can raise blood pressure, a risk factor for cardiovascular disease and stroke.
Cardiovascular disease remains the number one cause of premature death in the U.S. and worldwide. And while women’s rates of heart disease tend to be lower than men’s earlier in life, women’s risk of heart disease rises to match men’s after menopause.
There is evidence that suggests a connection between vitamin D blood levels and cardiovascular disease, the atherosclerotic variety in particular. Researchers from Germany took a closer look at this relationship and recently published their findings in the journal Clinical Nutrition. Let’s break down what they found.
Related: What Happens to Your Body When You Take Vitamin D Every Day
How Was This Study Conducted?
More than 500,000 participants have health data in the UK Biobank, and these researchers drew data for almost 410,000 of them who met the study criteria. On average, participants were 57 years old when the study began, and about 55% were female. The average follow-up time was 16 years.
Researchers pulled information including medical records and death certificates, vitamin D blood levels at baseline and whether or not the participants took a vitamin D supplement.
The types of atherosclerotic cardiovascular disease researchers were examining were:
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ischemic heart disease, which happens when clogged blood vessels limit oxygen to the heart
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peripheral artery disease, which happens when clogged arteries in the extremities, like the legs, limit blood to your limbs
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cerebrovascular disease, which happens when arteries to the brain are clogged, preventing the brain from getting the oxygen it needs
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atherosclerotic disease, or a buildup of plaque in arteries that can lead to ischemic heart disease.
Researchers adjusted for lifestyle factors like BMI, smoking status and alcohol intake. The team considered vitamin D deficiency as having vitamin D levels less than 30 nmol/L, and vitamin D insufficiency at a range between 30 and <50 nmol/L. Sufficient vitamin D levels were defined as 50 to <100 nmol/L, and high vitamin D levels were over 100 mmol/L.
More than half the participants were either vitamin D deficient (almost 21%) or insufficient (over 34%). Very few were over the recommended vitamin D blood levels (1.5%). Of the entire study population, 4.3% reported supplementing specifically with vitamin D, and another 21% took a multivitamin that included vitamin D—those multivitamins typically offer much less vitamin D than a pure vitamin D supplement.
What Did This Study Find?
Overall, the researchers found that vitamin D deficiency was associated with a 10% increased risk of atherosclerotic cardiovascular disease. And after breaking atherosclerotic cardiovascular disease down into specific conditions, vitamin D deficiency was associated with increased risks of ischemic heart disease (10%), cerebrovascular disease (7%), atherosclerotic disease (17%) and peripheral artery disease (13%).
For those who were only vitamin D insufficient—not deficient—insufficiency was associated with a 5% increased risk of total atherosclerotic heart disease and a 4% increased risk of ischemic heart disease.
Those with vitamin D deficiency showed a 35% increased risk of dying from atherosclerotic heart disease compared to an 8% increase in non-fatal ASCVD.
For those who took vitamin D supplements, they experienced a 6% reduced risk of atherosclerotic heart disease and a 10% reduced risk of ischemic heart disease. Supplementing with a multivitamin containing vitamin D was associated with a reduced risk of total atherosclerotic heart disease (7%), ischemic heart disease (8%) and peripheral artery disease (8%).
Like all studies, this one has its limitations. Many of the covariates—lifestyle factors that researchers adjust for—were self-reported, which may lead to bias and misreporting. There was also missing information regarding the dosage, frequency and ingredients of the vitamin D supplements, so researchers can’t be sure how much they were taking.
Plus, the data used was drawn from the start of the study, which doesn’t take into account others who may have started supplementing at a later date or those who stopped. Lastly, the UK Biobank is composed mostly of white men and women, so it is unknown if these results apply to other ethnicities.
Related: 5 Supplements to Avoid If You Have High Blood Pressure, According to Experts
How Does This Apply to Real Life?
Researchers recommend that you get your levels tested before supplementing with vitamin D. If your vitamin D levels are below 60 nmol/L, they suggest that you may benefit from supplementation to help reduce the risk of atherosclerotic heart disease.
There is evidence that about 25% of Americans are vitamin D deficient, and 41% have insufficient levels of vitamin D. This means that a whopping two-thirds of Americans may be at an increased risk of heart disease due to a lack of vitamin D. Thankfully, this can be remedied.
Getting outdoors more often to get sun exposure may be the best way to get your vitamin D, because being in nature offers other benefits, too, including improved mood and blood pressure. But since that’s not always possible, make sure you’re including foods that contain vitamin D, like fortified milk (cow’s or plant-based), whole eggs (the vitamin D is in the yolk), trout, salmon, sardines and mushrooms grown with UV light. And yes, this is pretty much an exhaustive list of foods with vitamin D, which is another reason it’s so easy to have insufficient levels of it.
Regarding heart disease prevention, vitamin D is a tiny piece of the puzzle. Other nutrients, like omega-3s, fiber, antioxidants, vitamins and minerals also play a role. Then there’s physical activity, managing stress and getting enough quality sleep.
The good news is that these health habits are connected. For example, when you get enough physical activity, you may also help reduce stress and sleep better. And you’ll likely want nutritious foods to fuel your efforts. So don’t let the list stress you out—just take things one step at a time.
Related: 8 Conditions When You Might Need a Vitamin D Supplement, According to Health Experts
The Bottom Line
This study suggests that due to deficient or insufficient levels of vitamin D, many people may benefit from supplementing with vitamin D, which in turn may reduce the risk of heart disease. Regularly getting outdoors and including foods that contain vitamin D is a good way to ensure your levels are sufficient. It can also be helpful to work with a registered dietitian, who can help you incorporate these foods into your diet.
It’s interesting to note that this recommendation is contrary to what the Endocrine Society recommends regarding vitamin D. But if you know you don’t spend enough time outdoors, aren’t eating foods with vitamin D, live in a climate with temperatures that don’t allow enough skin exposure to sunlight, or you have any symptoms of vitamin D deficiency—including depression, weak bones and high blood pressure—you may want to get your levels checked. And ultimately, other than the prick of the needle, it can’t hurt to just have the blood test done so you know your levels.
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