These Vitamin D-Rich Foods May Reduce Risk of Prostate Cancer
Women, tell your men to improve their intestinal absorption of calcium, iron, magnesium, phosphate and zinc because this new study has found that vitamin D deficiency in men may be linked to more aggressive and advanced cases of prostate cancer.
The study, published May 1 in the journal Clinical Cancer Research, also found that black men with low vitamin D levels were more likely than those with normal levels to test positive for cancer after a prostate biopsy.
For the study, researchers checked the vitamin D levels of 667 Chicago men between the ages of 40 and 79 who were having biopsies because they had recently had an abnormal prostate specific antigen test (PSA), or because their doctor felt changes to the prostate during an exam.
Nearly 44 percent of the men who tested positive for prostate cancer and 38 percent of those who tested negative had low vitamin D levels. The black men in the study with the lowest levels of vitamin D were 4.89 times more likely to develop an aggressive form of prostate cancer.
While the study did not prove a cause-and-effect relationship between vitamin D deficiency and prostate cancer, it did suggest that the "sunshine vitamin" plays an important role in how it starts and spread.
"It seems to regulate normal differentiation of cells as they change from stem cells to adult cells. And it regulates the growth rate of normal cells and cancer cells," said study author Dr. Adam Murphy, an assistant professor of urology at Northwestern University's Feinberg School of Medicine.
In a 2012 study, researchers found that vitamin D supplements lower levels of a key protein called Ki67 that indicates prostate cancer is spreading. The study also found that vitamin D supplements increase the levels of a cancer growth-inhibitory microRNAs to slow the rate of prostate cancer growth.
Vitamin D levels between 20 nanograms/milliliter to 50 ng/mL are considered normal, while a a level less than 12 ng/mL indicates a deficiency.
Vitamin D is produced naturally in the body when skin is exposed to sunlight, but the amount produced varies based on the time of day, where you live in the world, and skin color. Fair-skinned people only need a few minutes of sun exposure without sunscreen to absorb the UV-B rays that enable the body to manufacture vitamin D. People with darker skin may need up to six times as much exposure.
Vitamin D can also be found in certain foods. The Institute of Medicine recommends 600 international units (IUs) daily for people between the ages of 1 and 70, with 800 IUs recommended for people 70 and older.
Fatty fish such as salmon, tuna, trout and mackerel are good sources of vitamin D. According to the Institute of Medicine, a 3-ounce sockeye salmon fillet contains about 447 IUs of vitamin D. A 3-ounce swordfish has about 566 IUs, while a drained 3-ounce can of tuna has 154 IUs.
Most milk in the United States is fortified with vitamin D. An 8-ounce cup of nonfat, reduced fat, or whole milk contains 115 to 124 IUs of vitamin D.
Like milk, orange juice may be fortified with vitamin D. A typical 8-ounce glass has about 137 IUs, although the amount may vary by brand.
A large egg yolk contains 41 IUs of vitamin D.
Cod liver oil
According to the Institute of Medicine, a tablespoon of cod liver contains 1,360 IUs of vitamin D.