Vitamin D, the "sunshine vitamin," is made in the body when the rays of the sun are absorbed by the skin. Health care professionals and nutrition research scientists have known for years that it's needed for the regulation of calcium and phosphorus to help build and maintain strong bones. But recent research indicates vitamin D may do much more than that.

In fact, in honor of American Heart Month, it's important to know that adequate intake of vitamin D may actually reduce the risk of heart disease.

That's good news given the fact that heart disease remains the leading cause of death in the United States. The most common form of heart disease in the United States is coronary heart disease, which often presents itself as a heart attack. In 2008, an estimated 770,000 Americans suffered a heart attack for the first time, and about 430,000 had a recurrent attack. About every 26 seconds, someone living in the United States will suffer a heart attack, and about one person every minute will die from one.

So what's the connection between vitamin D and heart health? Well, for one, studies indicate that vitamin D deficiency is associated with increased cardiovascular risk, above and beyond established cardiovascular risk factors such as blood cholesterol and blood pressure. In a study of 1,739 Framingham Heart Study participants (whose average age was 59), researchers found that those with blood levels of vitamin D below 15 nanograms per milliliter (ng/mL) had twice the risk of suffering a cardiovascular event such as a heart attack, heart failure, or stroke in the next five years compared with those who showed higher levels of vitamin D.

When researchers adjusted for traditional cardiovascular risk factors such as high cholesterol, diabetes, and high blood pressure, the risk remained significant, with a 62% increased risk of a cardiovascular event in study subjects with low levels of vitamin D compared with those showing higher levels. Study participants had no prior cardiovascular disease and were tested for vitamin D status and then followed for an average of 5.4 years. Overall, 28% of individuals had levels of vitamin D below 15 ng/mL, and 9% had levels below 10 ng/mL. Although levels above 30 ng/mL are considered appropriate for bone metabolism, only 10% of the study subjects had levels in this range.

In a 10-year follow-up study in 18,225 men over the age of 40, those with a low vitamin D level not only had more than double the risk of a heart attack, they appeared more likely to die from the attack. Research studies such as these suggest that vitamin D is important for blood vessel health and controlling blood pressure.

The current daily recommended dietary intake of vitamin D is 200 IU for everyone up to age 50, then 400 IU up to age 70, and 600 IU for those 70 and older. However, according to nutrition experts, that may not be enough. Although how much is enough is still being debated, we may actually need three to four times more than what we get. Especially if you get very little sun exposure, use sunscreen when you are exposed to the sun, are elderly, or have a dark skin complexion. While 10–15 minutes a day of sun exposure can boost vitamin D levels in the body, very few foods in nature contain vitamin D. Fish (such as salmon, tuna, and mackerel) and cod liver oil are among the best sources (3 ounces provide about 200 IU). Small amounts of vitamin D also are found in beef liver, cheese, and egg yolks, but these foods also are high in fat and cholesterol. Fortified foods provide most of the vitamin D in the American diet. For example, almost all of the U.S. milk supply is fortified with 100 IU per cup. To play it safe, supplement your dietary intake with a daily multivitamin/multimineral supplement with plenty of vitamin D. Look for a comprehensive formula with at least 400 IU to 800 IU of vitamin D per serving.

And remember, a healthy lifestyle that includes and promotes modest weight loss, healthful food choices and regular physical activity are your best weapons for fighting off heart disease:

• If overweight, a weight loss of 5–10% of your body weight can lead to significant improvements in cardiovascular disease risk factors such as high blood cholesterol, high blood pressure, and high blood sugar.
• Choose lean meats and poultry without skin and prepare them without added saturated and trans fats.
• Select fat-free, 1% fat, or low-fat dairy products.
• Limit your consumption of foods containing partially hydrogenated vegetable oils to reduce trans fats in your diet.
• Cut back on foods high in dietary cholesterol. Aim to eat less than 300 mg of cholesterol each day.
• Reduce your intake of beverages and foods with added sugars.
• Choose and prepare foods with little or no salt. Aim to eat less than 2,300 mg of sodium per day (or less than 1,500 mg if you are in a higher risk group for high blood pressure).
• If you drink alcohol, do so in moderation. That means no more than one drink per day if you're a woman and two drinks per day if you're a man.
• Engage in at least 30 minutes of moderate-type activity (e.g. brisk walking) on most days of the week.

         Vitamin D is essential to your diet.