Vitamin D has long been recognized as an essential nutrient for calcium absorption and for building strong bones.
More recently, research has spotlighted the importance of vitamin D in immune function. Deficiencies have been linked with increased susceptibility to viral respiratory infections as well as cancer, autoimmune disorders, and chronic infections. Multiple studies have shown that supplemental vitamin D boosts the immune system and protects against acute respiratory tract infections. It is also being explored as a supportive treatment for severe viral infections.
Our focus here, however, is on vitamin D and the heart. Although this gets less attention than bone and immune health, a low vitamin D blood level is associated with an increased risk of hypertension, coronary artery disease, heart failure, and other cardiovascular disorders. Unfortunately, low vitamin D status is not uncommon. Let’s look at the role this vitamin plays in cardiovascular health and what you can do to optimize your level.
How Does Vitamin D Help Your Heart?
Many of vitamin D’s cardiovascular benefits stem from its effects on the endothelium, the thin layer of cells lining the inner walls of the blood vessels. Damage to these cells leads to endothelial dysfunction, which is an early step in atherosclerosis (the buildup of plaque and the hardening and narrowing of the arteries), coronary artery disease, stroke, and hypertension. Vitamin D supports endothelial health in the following ways:
- Boosts nitric oxide production and lowers blood pressure: Vitamin D helps trigger the production of nitric oxide, a signaling molecule produced in the endothelium that relaxes and dilates the arteries, thus improving blood flow and blood pressure.
- Helps repair endothelial damage: A 2018 study published in the International Journal of Nanomedicine reveals that vitamin D helps repair damage to the endothelial lining of the blood vessels.
- Curbs inflammation: Chronic inflammation is a significant cardiovascular risk factor, and vitamin D helps reduce inflammation.
- Modulates the renin-angiotensin-aldosterone system (RAAS): Vitamin D has a modulating effect on the RAAS, which is a complex system of hormones involved in the regulation of blood pressure and cardiovascular function.
- Lowers diabetes risk: A low vitamin D blood level is associated with an increased likelihood of developing diabetes, a condition that significantly raises cardiovascular risk.
Vitamin D receptors are also present in cells throughout the heart, including the myocardium (the heart muscle). Research suggests that vitamin D enhances the heart’s pumping ability and protects against enlargement and other structural changes that are characteristic of heart failure.
Low Vitamin D Status Linked with Heart Disease
Not surprisingly, numerous studies have demonstrated that individuals with a low blood level of 25(OH)D, the most accurate test for vitamin D status, are more likely to have heart disease, high blood pressure, heart attack, strokes, heart failure, and premature death from cardiovascular disease (CVD).
Researchers at the University of Copenhagen reviewed data from studies involving more than 10,000 Danes and compared those with the lowest levels of vitamin D (less than 15 ng/mL or 37 nmol/L) to those with the highest levels (more than 50 ng/mL or 125 nmol/L). They discovered that individuals with the lowest levels of vitamin D were 64% more likely to have a heart attack. Plus, they had a 40% higher risk of ischemic heart disease, a 57% increased risk of early death, and an 81% higher risk of dying from heart disease.
The adverse cardiovascular effects of low vitamin D status were further bolstered by a study published in December 2021 in the EuropeaHeart Journal. Using a complex analytical method (non-linear Mendelian randomization), researchers analyzed data on 267,980 men and women, ages 37–73 years. Data included health, lifestyle, and genetic information as well as 25(OH)D measurements.
This study found that individuals with the lowest vitamin D levels (under 25 nmol/l) had the highest risk of hypertension and cardiovascular disease. Risk gradually, but significantly, decreased as the 25(OH)D level reached 50 nmol/l, which was the average level. Above that, it pretty much leveled out, although having a vitamin D level of 75 nmol/l conferred some additional protection.
The researchers concluded, “While improving vitamin D status among people with the lowest concentrations is likely to have the strongest effects, a population-wide approach to eradicate vitamin D deficiency could reduce the burden of CVDs.”
How to Raise Your Vitamin D Level
Vitamin D is produced in the body via a biochemical reaction triggered by sunlight striking the skin. How much of this vitamin you make depends not only on how much time you spend in the sun but also on geographic location, time of year, skin color, use of sunscreen, genetics, and age. You can also get a little vitamin D in your diet, primarily from fatty fish, egg yolks, and fortified milk and juice.
Many people assume they’re getting enough vitamin D from sun exposure or diet, yet vitamin D deficiency is still a widespread problem, affecting 30%–50% of the population.
That’s why supplements are important.
How Much Vitamin D Should You Take?
There are two types of supplemental vitamin D: D2 and D3. Always opt for D3. It’s the form that is produced in the skin, plus D3 raises blood levels more efficiently than D2.
Most multivitamins contain vitamin D, but it’s usually the paltry RDA of 600–800 IU (15–20 mcg). Considerably higher doses are often required to achieve a healthy vitamin D level. My general recommendation is 4,000 IU (100 mcg) of vitamin D3 per day. This may seem like a lot, but vitamin D is well tolerated, and even larger doses have been used in long-term clinical trials with no adverse effects.
The only way to know for sure what dose is right for you is to have your 25(OH)D blood level tested. If it’s in the optimal range of 50–75 nmol/L, you’re good. If not, adjust your dose and retest again in about three months.