Once upon a time, you could get an abundance of vitamin D just by sitting or working out in the sun for a moderate amount of time each day. Adequate vitamin D intake is important because it can help strengthen bones… normalize blood pressure… boost heart function… enhance memory power… soothe aching joints… balance blood sugar levels… promote healthy skin… and lift your mood.

Nowadays most people are deficient in the “sunshine vitamin.” Here’s why:

• If you’re over 50—your body can’t properly absorb vitamin D from natural sunlight. Plus, your kidneys are less able to convert vitamin D to its active hormone form. By age 60 it’s nearly impossible to process enough vitamin D to protect your health. So even if you’re out in the sun—you’re not getting optimum levels of vitamin D.
• Sunscreen—for years, you’ve been told to lather on the sunscreen and wear a hat before going outside in the daylight, right? Well, the fact is that sunscreen blocks the critical absorption of vitamin D by a whopping 99.9%.
• Indoor living—most Americans spend the daytime indoors. No steady sun exposure means you don’t produce optimum levels of vitamin D.
• Darker skin—the melanin that darkens your skin also makes it more difficult for the sun to penetrate your skin. That means olive- and dark-skinned people are more prone to a vitamin D deficiency. And low levels of vitamin D can also trigger unhealthy blood pressure.
• Eating processed foods—most processed foods contain very little, if any, vitamin D. If your diet isn’t rich in vitamin D foods such as egg yolks, liver, mackerel, sardines and cod liver oil—you may have a high risk for a vitamin D deficiency.
• Seasonal changes—winter months mean less sunlight, no matter where you live. And that could be a serious problem if you’re relying on the sun for vitamin D. You just won’t get enough of this essential nutrient to protect your health.
• Cultural background—women who are required to cover their entire bodies in heavy clothing block out the sun. This significantly reduces vitamin D production.
• Fat restrictions—vitamin D is a fat-soluble vitamin. That means it requires some dietary fat for proper absorption. Folks with liver problems, digestive problems, pancreatic enzyme deficiency or who have undergone gastric bypass surgery or removal of part of the intestines are especially at risk for a vitamin D deficiency. Even strict vegetarians may be vitamin D deficient.

Supplementation may be necessary to increase your levels of vitamin D during the winter months, and possibly all year-round. You can have a physician measure your vitamin D levels so you can base your intake of this nutrient on your individual needs. According to The Vitamin D Council, vitamin D3, or cholecalciferol, is the most effective form of the nutrient.