← Breastcancer.org

The Importance of Vitamin D

By on August 24th, 2011 Categories: Uncategorized

Vitamin D helps our bodies absorb calcium, which is necessary for good bone health. Vitamin D also helps our immune, muscle, and nervous systems work properly. Plus, vitamin D may have an important role in maintaining normal breast cell growth, given emerging research results suggesting an association between a higher risk of breast cancer and low levels of vitamin D.

Vitamin D has been in the news lately because most doctors and dietitians agree that the current recommended intake levels are too low. Current recommended levels are:

  • 600 IU (international units) for people age 1 to 70
  • 800 IU for people age 71 and older
  • 600 IU for pregnant and breastfeeding women

But how much vitamin D is enough isn’t clear yet.

Most of the vitamin D in our bodies is made when skin is exposed to sunlight. An inactive form of vitamin D in the skin is activated by sunshine. But as more of us spend our time inside, out of the sun, or wear sunscreen when we do go out, the amount of vitamin D we get from the sun is decreasing. We get smaller amounts of vitamin D from fortified milk and other foods, fatty fish, and eggs.

Take it outside: The easiest way to up your vitamin D level is to get more direct sunlight exposure. Just 15 minutes in the sun, 3 times a week can give you more than the current recommended amount of vitamin D. And while it’s impossible to overdose on vitamin D from the sun, sun exposure does have risks. Too much sun exposure increases your risk of skin cancer, including melanoma, the most dangerous type.

Most experts recommend you continue using protection when ultraviolet (UV) radiation levels are moderate or high. UV rays are invisible, so you can’t tell if you’re exposed or not. The U.S. Environmental Protection Agency and the National Weather Service developed the UV Index, which indicates the strength of UV rays on a scale from 1 to 11+ based on your zip code. Check that before you go outside.

Still, the darker your skin and the farther away from the equator you live, the less vitamin D you’ll produce. So many people may have a hard time getting enough vitamin D from only sun exposure.

Is a supplement right for you? Before you take any vitamin D supplements, it’s important to know what you vitamin D serum level is. You can find out with a simple blood test that your doctor can order for you when you’re in for a routine physical. Vitamin D researchers recommend a serum level of 40-60 ng/ml (nanograms/milliliter). It’s also important to talk to your doctor about what a good vitamin D serum level is for you and the risks and benefits of any supplement. My own level was low, just 16. To get back into the normal range, first my doctor prescribed high-dose vitamin D (requires a prescription) over 6 weeks, then a daily maintenance dose to stay in the normal range. About 6 months later, my level was re-checked to make sure I was taking the right dose. For me, 2,000 IU of vitamin D3 is the correct daily dose (and I prefer the gelcaps to the tablets). Some doctors may recommend less, between 400-2,000 IU. Less often doctors might recommend more than 2,000 IU/day. Taking too much vitamin D occasionally can cause you to have too much calcium in your blood. If you’re going to take a vitamin D supplement, most experts recommend taking the D3 form of the vitamin, not the D2 form.

Dietary solutions: Many fish, including:

  • salmon
  • herring
  • catfish
  • oysters
  • mackerel
  • sardines
  • steelhead trout

are rich in vitamin D. Make sure you choose your fish carefully to avoid any species that may have high levels of mercury. For more information, visit the Exposure to Chemicals in Food page in our Lower Your Risk section.

Taking 1 to 3 teaspoons of cod liver oil per day as a supplement can also help meet your vitamin D requirements. (Be sure to buy mercury-free fish oil supplements.) Still, if you’re like me, you probably think cod live oil looks, smells and tastes DISGUSTING. So try these other fortified foods, though they have lower levels of vitamin D:

  • milk
  • some yogurt (read the label to see if it says “fortified with vitamin D”)
  • some orange juice (read the label to see if it says “fortified with vitamin D”)
  • some soy milk (read the label to see if it says “fortified with vitamin D”)

Marisa Weiss, M.D. is the founder, president, and chief medical officer of Breastcancer.org, the world's most trafficked online resource for medically reviewed breast health and breast cancer information, reaching over 14 million visitors per year. A breast cancer oncologist with over twenty years of active practice in the Philadelphia region, Dr. Weiss is regarded as a visionary advocate for her innovative and steadfast approach to informing, empowering, and treating patients with breast cancer.


  1. Caroline Durham

Leave a Comment

To keep our Community safe, you must register to start a topic, post a reply, or use the Chat Rooms. If you are an existing member of our Discussion Boards, you can log in to access your account. Please review our Privacy Statement before registering.

Register now or log in to your account.

Back to top

Breastcancer.org is a non-profit organization dedicated to providing information and community to those touched by this disease. Learn more about our commitment to providing complete, accurate, and private breast cancer information.

Breastcancer.org 120 East Lancaster Avenue, Suite 201 Ardmore, PA 19003

© 2022 Breastcancer.org - All rights reserved.