6 things to know about vitamin D

Vitamin D is important for overall health at all stages of life – particularly as a woman ages.

Unfortunately, misinformation abounds. That’s why Dr. Jody Lai at Hoag Women’s Health Institute, frequently shares essential information about this important component of health with her patients.

“People have heard about vitamin D deficiency, but I have found that many people don’t really understand its impact on health or how best to combat it,” Dr. Lai said. “There is a lot to know about vitamin D, and your primary care physician or OB-GYN can help.”

Here are six important things to know about vitamin D:

Vitamin D isn’t actually a vitamin.

It turns out that vitamin D is actually a hormone. More accurately, it is a prohormone. A prohormone is a substance that the body can convert into a hormone. It’s like a "precursor" to a hormone, meaning it needs to undergo a change or transformation inside the body before it becomes fully active.

Vitamin D helps promote healthy aging.

Because vitamin D helps the body absorb calcium, it has long been associated with preventing osteoporosis. It turns out that the nutrient also helps lower the risk of dementia, cancer fatalities, diabetes and the loss of muscle strength as we age.

“New studies about vitamin D’s role in healthy aging have put vitamin D deficiency squarely in the spotlight,” Dr. Lai said. “It is clearly important to get enough vitamin D, but people should talk with their doctor to get a better sense of how much is right for them.”

Your body makes vitamin D – just maybe not enough.

Ultraviolet B (UVB) rays from the sun trigger your skin to convert cholesterol to vitamin D3. This then gets stored in the body’s fat cells, where it waits until the body turns it into calcitriol, which helps regulate calcium levels in the body. 

“Only five to 30 minutes of sun exposure twice a week is enough to get the vitamin D that most people need, but indoor living and other factors make it difficult to know who is getting enough vitamin D,” Dr. Lai said. “Factors like skin tone and age can reduce the amount of vitamin D intake from the sun, which is why coming up with a plan with your doctor will help determine whether a supplement may be right for you.”

Wear sunscreen – but now it blocks vitamin D.

Because it blocks UV rays, sunscreen can limit the production of vitamin D. But that’s not a reason not to wear it. More than 1,000 people are diagnosed with skin cancer in Orange County every year. Meanwhile, rates of vitamin D deficiency below the 37th parallel (which cuts through Washington state) are significantly lower than those in this nation’s more northern reaches.

“The risk of skin cancer far outweighs the health risks of vitamin D deficiency for most people in Orange County,” Dr. Lai said. “Most of us don’t wear enough sunscreen or don’t wear it properly. Skin protection is important year-round.”

Many foods contain vitamin D.

Worried about not getting enough vitamin D from the UV light? Great news: Many foods are fortified with vitamin D, and many others contain the nutrient naturally.

Foods that contain vitamin D include egg yolks, cheese, cod liver oil, beef liver and fatty fish. Fortified foods include milk, cereal and certain yogurts, and orange juices. Though, Dr. Lai cautions that levels of vitamin D may not be enough in food to make up the difference for a person who has a deficiency.

Supplements help – but they can also harm.

Most people get 80 percent of their vitamin D from the sun and 20 percent from their diet. As we’ve just seen, neither of these methods is 100 percent effective, so many people turn to supplements. But that’s not a perfect solution, either.

In fact, the U.S. Preventive Services Task Force is considering a recommendation against vitamin D supplements for fracture prevention in older adults due, in part, to the supplement increasing the risk of kidney stones.

“Supplements can be helpful in boosting vitamin D in people who may be facing a deficiency, but you should work with your physician to determine how much – and whether – you need to consider a supplement,” Dr. Lai said. “It is important to tailor your approach to your own needs, health and wellness goals.”