Defense Against Disease

Get your share of Vitamin D’s protective power

By Teller Stalfort, UVA Health System registered dietitian

With daylight savings beckoning warmer weather and longer days, we have more reason, and opportunity, to get outside -- a great way to boost vitamin D levels. Low levels have been linked to multiple diseases and conditions, including heart disease -- the number one killer of American women.

Diet alone not enough

It is difficult to meet vitamin D needs from diet alone. Good sources include fortified milk, juices and cereals and fish such as herring and sardines. Not all fish, though, are good sources of D and focusing just on good sources will only get you so far. 

The good news is that supplements exist as well as our skin’s own natural ability to make vitamin D by reacting with the sun’s rays. Several factors interfere with this process, such as sunscreen use, skin color, age, latitude, clothing and season. SPF 15 sunscreen can block up to 98% of vitamin D production, but you don’t have to risk skin cancer in order to get enough vitamin D.   

• For light-skinned people, spending just 10 - 15 minutes in the sun at peak exposure (without sunscreen) meets your daily quota. 
• Darker-skinned people have to spend several hours in the sun to make enough vitamin D so it is more practical to rely on supplements -- an excellent source of vitamin D for all populations.   

What’s the right level?

Most supplements have traditionally contained 200-400 international units (IUs) of vitamin D, levels now thought to be insufficient. Winter months and northern climates make it difficult to rely on a small daily dose of sunshine year-round, so supplements are a safe way for everyone to ensure adequate daily intake. 

As we age, our skin cannot make as much vitamin D, prompting daily intake recommendations to increase with age. Here’s the current recommended daily amount depending on your age: 

• If you’re 19 to 50, you need 200 IU
• If you’re 51 to 70, you need 400 IU
• If you’re 71 and older, you need 600 IU. 
• Children need 400 IU (recently increased from 200) 

More may be better

Many physicians now recommend at least 1,000 IU daily for all adults -- and supplements are following suit. It is now possible to find 1,000 IU supplements, and in some cases, physicians will prescribe a pharmacologic dose of 50,000 IU taken once a week for 8-12 weeks if a documented deficiency is found. 

Ask your doctor if you are at risk for vitamin D deficiency and if you should get your levels checked. Doing so might just reduce your heart disease risk!