For all the years we have been hiding under beach umbrellas, slathering on sunscreen, and wearing every ultraviolet-blocking piece of clothing we can find to protect ourselves from skin cancer, we are just now realizing the importance that sunlight has in our lives. One of the main health benefits of sunshine is to get your daily dose of vitamin D, often called the “sunshine vitamin.”
When UVB rays from the sun hit your skin, 7-dehydrocholesterol in your body is converted to vitamin D. From there, vitamin D takes on many critical roles. For one, it is essential for calcium absorption, which is why most dairy products are fortified with vitamin D.
But vitamin D does much more than that, as researchers are learning. It can also reduce your risk of many diseases, including cardiovascular disease, tuberculosis, type 2 diabetes, respiratory infections and multiple sclerosis. Just as importantly, studies show vitamin D improves your mental and emotional health by warding off depression and improving your mood overall.
And more and more studies are confirming that vitamin D reduces the risk of certain cancers, such as breast and colon, and has a protective effect in lung cancer. Researchers have also found that deficiencies in vitamin D may be associated with more aggressive forms of prostate cancer.
For years, evidence on vitamin D’s defensive powers against breast cancer has been mounting. One study that followed almost 1,900 women found that vitamin D from either sun exposure or from taking vitamin D supplements was associated with a significantly reduced risk of breast cancer tumors.
Another study evaluated the vitamin D intake of almost 3,500 patients with breast cancer from 1980 to 1996. Researchers found that premenopausal women who consumed more than 500 IU daily of vitamin D had a 30 percent lower risk of breast cancer, compared to those women who consumed less than 150 IU per day.
In one recent meta-analysis of 18 studies involving 1 million participants, researchers concluded, “Vitamin D intake and blood levels of 25-hydroxyvitamin D were inversely associated with the risk of colorectal cancer.”
While vitamin D has not been found to prevent lung cancer from occurring in the first place, it does seem to prevent recurrence and aid in survival in patients with non-small cell lung cancer.
Researchers followed 447 patients with early-stage non-small cell lung cancer over a period of 72 months. Of those 447 patients, 161 had recurrences and 234 died. Of the survivors, the researchers determined, “Vitamin D may be associated with improved survival of patients with early-stage NSCLC, particularly among stage IB-IIB patients.”
The relationship between vitamin D and prostate cancer prevention is still unclear, although research has shown that low concentrations of vitamin D in the blood are associated with more aggressive and more advanced cancers. In fact, men deficient in vitamin D had a two-fold increased risk of advanced versus localized prostate cancer.
The ABCs of Getting Vitamin D
There are three ways to get your daily dose of vitamin D:
The easiest way to get the vitamin D you need is to spend approximately 20–30 minutes in the sun daily — without sunscreen.
If it is not feasible for you to get out in the sun for this amount of time, if you live in an area that doesn’t get much sun, or if you have been advised to avoid going outside without sunscreen, then you can get your vitamin D other ways.
Salmon and cod liver oil are the most abundant naturally occurring food sources of vitamin D, providing anywhere from 600–1,000 IU of the nutrient. In contrast, fortified dairy products like milk and yogurt provide about 200 IU.
3. Vitamin D Supplements
In addition, you should consider taking a vitamin D supplement. This inexpensive nutrient is widely available in most pharmacies, retail stores and online. Just be sure to choose a supplement that contains vitamin D3 in the form of cholecalciferol. This form of vitamin D is best absorbed and utilized by the body. (If you’re looking for a high-quality vitamin D supplement, you can simply click here.)
The recommended daily dosage for people under the age of 70 is 600 IU per day, and 800 IU daily for people over 70. However, you can safely take up to 2,000 IU a day, according to the National Academy of Sciences.
Of course, if you are concerned for any reason that you might have a vitamin D deficiency, ask your doctor to test your levels.
 Mitchell D. The relationship between vitamin D and cancer. Clin J Oncol Nurs. 2011 Oct;15:5, 557–60.
 Blackmore KM et al. Vitamin D from dietary intake and sunlight exposure and the risk of hormone-receptor-defined breast cancer. Am J Epidemiol. 2008 Oct 15;168, 915.
 Shin MH et al. Intake of dairy products, calcium, and vitamin D and risk of breast cancer. JNCI J Natl Cancer Inst. 2002;94:17, 1301-1310.
 Ma Y et al. Association between vitamin D and risk of colorectal cancer: A systemic review of prospective studies. J Clin Oncol. 2011 Oct 1;29:28, 3775–82.
 Zhou W et al. Circulating 25-hydroxyvitamin D levels predict survival in early-stage non-small-cell lung cancer patients. J Clin Oncol. 2007 Feb 10;25:5, 479–85.
 Gilbert R et al. Associations of circulating 25-hydroxyvitamin D with prostate cancer diagnosis, stage and grade. Int J Cancer. 2011 Oct 27. doi:10.1002/ijc.27327.
 Mitchell D.