Why is vitamin D important?

Should I be concerned about taking daily vitamin D and, if so, how much should I take and what kind?

Vitamin D regulates calcium metabolism. It also seems to support the body’s immune system and, when deficient, serves as a risk factor for heart disease. About 35 percent of people tested are deficient and, over the last 30 years, the trend is toward more deficiency.

The best explanation is that we spend less time outside. Sunlight contains ultraviolet light that converts the vitamin D we consume into a form the body needs, vitamin D3. Next, this form must also be modified in the liver and kidneys before it assumes its active form. You can also buy vitamin D2 in the store, but D3 is a better supplement because it stays in the body longer so it can be converted to its active form. If deficient, you can develop decreased bone density and muscle weakness.

Vitamin D supplementation is good for everyone. Two thousand IU/day is an adequate yet safe daily dose. Take it with food that contains some fat to achieve better absorption. And with adequate supplementation, you’re taking over where the sun left off.

Ralph Robertson M.D.

About the author

Ralph Robertson, M.D.