Vitamin D

Should Those In The North Begin Taking Supplements To Prevent Cancer?

We hear about many people being having a Vitamin D deficiency, especially those who live in areas where the intensity of the sun's ultraviolet rays decreases. People who live above latitude 37º North and below 37º South are at more of a risk of being Vitamin D deficient.
latitude-vitaminD.jpgThere has also been some evidence that Vitamin D can help prevent some cancers. With the known fact that you can get Vitamin D from the sun, people who live in the area above latitude 37º, have started to take supplements. However, too much of anything is not good. Overconsumption of Vitamin D can mess with the calcium levels in your blood, which can damage the kidneys, lungs, blood vessels, and heart. So the question is: should people who live in the north take Vitamin D supplements to prevent cancer?
As health professionals this is an important question because many of us will be living in this region that is above Washington DC, and our clientele may want to know if there is something they can due to help prevent cancer.

What is Vitamin D?
Vitamin D (calciferol) is called the sunshine vitamin because the sun can synthesize up to 100% of the Vitamin D that the body needs. It is a fat soluble vitamin so the vitamins are stored in the body's fatty tissue. It's been said that if a person has been exposed to sunlight in the past six days (without sunscreen or such, that it is an equivalent to about forty-nine days having not being exposed to any sun at all. Because of its function, Vitamin D is considered a prohormone that is activated once it is inside the body.
2 Forms:
Vitamin D3 (Cholecalciferol) - produced in the skin and found in animal foods
Vitamin D2 (Ergocalciferol) - found in plants and dietary supplements

Bone growth - Calciferol acts as a hormone to stimulate the absorption of calcium and and phosphorus in the intestinal tract. As the calcium levels rise, more calcium is stored in the bone. So it helps build and maintain bone growth and mass and increase the bone mineralization. A Vitamin D deficiency can lead to osteoporosis and rickets.

Blood Pressure- Vitamin D acts on the system that regulates blood pressure. It appears to reduce the activity of the system so blood pressure is decreased. People with mild hypertension may be able to lower their BP by being out in the sun.

Regulate Immune System- The active form (calciferol) may reduce the risk of developing certain autoimmune disorders. It has been suggested that Vitamin D inhibits the progress of autoimmunity and affect the function of the immune system.

May Prevent Diabetes and Some Cancers- Research studies have shown that people who live in "sun poor" regions of the world, have more prevalence of breast, colon, and prostate cancers than those living in sunny regions. Researchers think that Vitamin D deficiency can reduce the healthy cells and allow cancer cells to develop. Individuals with type 2 diabetes often have low levels of Vitamin D. Insulin resistance was more profound in people with low levels of Vitamin D.



How to get Vitamin D
Sun's UV rays
Foods: fish, cheese, fortified milk, yogurt, fortified cereals

Daily Needs
Both teenagers and adult males and females should be getting 600 IU (15 mcg) a day.
0-12 months need 400 IU (10 mcg)
Male and females over 70 years need 800 IU (20 mcg)

Vitamin D Absorption

Causes of Deficiency
Lifestyle- If you spend less time outdoors, cover up with clothes when outside, or just get less exposure to they sun, you don't make as much Vitamin D
Sunscreen- If applied correctly, sunscreen blocks the UV rays that cause skin cancer, but it also blocks the ability to make the vitamin
Geographic Location- People who live above and below the latitude 37º are more likely to be deficient in Vitamin D
Skin Tone- People with darker skin have more melanin, which acts as a natural sunscreen. This slows the skin production of Vitamin D.
Age- The ability make Vitamin D in the skin drops as age increases.
Body Weight- Since Vitamin D is extracted from the blood by fat cells, being obese can affect its release into the blood.

*Vitamin D can also be used to treat skin conditions, such as vitiligo and actinic keratosis.*

Vitiligo is a condition where the skin loses its melanin. When the cells that create melanin die or just stop making melanin, those areas of the skin begin to appear as enlarged, irregular patches. In relation to Vitamin D, a person can take vitamin D supplements as well as other topical ointments and creams to help restore those cells, while also either staying out of the sun or using SPF 30+ sunscreen (if they must be exposed to the sun).

Actinic Keratosis is a type of skin condition where lesions of skin that usually appear as warts are found on parts of the skin (face, scalp, if bald, hands) that have been exposed to the sun and damaged by UV rays. If this goes untreated and progressively worsens, it can lead to squamous cell carcinoma 9the second most common skin cancer). In relation to Vitamin D, Vitamin D cannot be used as a cure, but only as an alternative source (supplements) of getting the some amounts of vitamin D without having to endure this condition from being in the sun.

Too Much Vitamin D
The upper limit has been set at 2000 IU. Excess Vitamin D can cause hypervitaminosis D, which causes calcium to be over absorbed from the intestines and calcium loss from bones. If his happens, blood calcium levels can become dangerously high. Hypercalcemia is a chronically high amount of calcium in the blood. It can cause calcium deposits, which can damage the kidneys, lungs, blood vessels, and heart. Hypervitaminosis D can't occur from eating foods (exception is cod liver) or from the sun. It can come from the overuse of Vitamin D supplements (1). Also, one can experience weakness (lack of energy, fatigue, sleepiness, headache, loss of appetite, dry mouth, nausea, and vomiting.

The Evidence thiet-ke-website.png.jpeg

According to research that was based out of Columbia University, the researchers claimed that there is still insufficient data from clinical trials to say that people should take Vitamin D supplements for breast cancer prevention or treatment. Future studies will need to gain a better understanding of the biological effects of Vitamin D in breast tissue. However, observational studies have shown that patients with breast cancer and deficient in Vitamin D have been associated with worse clinical outcomes and increased rates of mortality (2).

According to scientists and researchers of McGill University, taking vitamin D is not the ultimate cure for preventing cancer, but it does have some control in slowing the process down. In cancerous cells, Vitamin D can control the function, rate, and production of cMYC (a cancerous gene), while also increasing the production of MXD1 (a natural antagonist of cMYC). In the American Cancer Society's Cancer Prevention Study, about 120,000 men and women who were diagnosed with colorectal cancer were tested. It was said that of those men who had the highest intakes of Vitamin D in their diets and through supplements (13 micrograms/525 IU per day), had a slightly lower risk of their colorectal cancer, even though those results were not that much siginificant.

A PubMed study was used to see the correlation between Vitamin D and prostate cancer. People who lived in sunny areas and who had a history of exposure to high levels of sunlight, had a lower risk of prostate cancer. In a study of 19,000 men, those with Vitamin D levels below 16 ng/mL had a 70% high incidence rate of prostate cancer than those with levels above 16 ng/mL. Prostate cancer was 3.5 times higher for younger men with levels below 16 ng/mL than the same age group with levels of 16 ng/mL or above. However, PubMed has not found any other studies with these associations.
PubMed also did a study with breast cancer. They found that breast cancer death rates tended to be higher in areas with low sunlight levels. Women who were regularly exposed to sun and individuals who consumed above-average amounts of Vitamin D, had significantly lower incidence rates of breast cancer. Women with the lowest levels of the vitamin had a 5 times higher risk of the cancer than those with the highest levels. The low levels were associated with metastatic breast cancer that progressed quickly. Mortality rates of premenopausal ovarian cancers were lower in sunny regions as well. A study was done on rates and mice that resulted in a reduced incidence of mammary cancer in the mice and rates that had a high intake of Vitamin D and calcium. The incidence was only one quarter as high in rates that received high levels of Vitamin D and calcium.
These groups of observational studies found a positive relationship between a high intake of Vitamin D and a lower risk of cancer. The evidence from these studies suggest that with Vitamin D supplementation, the incidence of cancer could reduce, with few or no adverse effects (4).

Dr. Jacques Rossouw of the of the National Heart, Lung, and Blood Institute of the National Institutes of Health showed data from the Women's Health Initiative from a large observational study that included clinical trials on postmenopausal hormone therapy, low-fat dietary pattern, ad calcium and Vitamin D supplements. It looked at 68,000 women aged 50 to 79 who were relatively healthy and had no serious illness or prior cancer within 10 years of starting the study. The calcium and Vitamin D portion of the study was based off of 36,000 women to determine whether a 1,000 mg calcium and 400 IU of vitamin D one-a-day supplement reduced hip fractures. It also assessed the association between the Vitamin D levels and breast and colorectal cancer risk. The mean follow up was seven years. The supplementation showed no benefit for cancer prevention, but there was improved bone mineral density and a reduced risk of hip fractures. Dr. Rossouw said "The dose of 400 IU was sufficient to show biological effect. These findings raise serious doubt that Vitamin D in larger doses will prove to be a useful strategy in preventing cancer." He did question if the dose of the vitamin was too low. However he also stated, "I would think that it may be too low, but this was a very large, very long trial, and it worries me that there was absolutely no indication of benefit with regard to breast and colorectal cancer. I do think that the result needs to be taken seriously. Another long-term trial will need to be done with doses of 2,000 IU to determine whether it has value for cancer prevention" (6).


There has been mixed results from the studies examined to say whether a Vitamin D prevents cancer and if a supplement will help reduce the risk. We already know that those living in the North are more likely to be deficient. More research needs to be done to determine whether a supplement or Vitamin D actually does prevent cancer. However, taking a supplement of Vitamin D will not hurt, especially for people who don't get enough sunlight or eat foods with the vitamin in them. The upper limit for Vitamin D is set at 2,000 IU (50 mcg) so over 3 to 10 times the RDA. There has been evidence that shows up to 10,000 IU a day is safe (2). A supplement will help bone density and growth, so anyone could take a supplement of that regardless of where they live. People in the North can take one too. It's important to not over consume Vitamin D as this could cause Hypervitaminosis D. The majority of the population is consuming too little Vitamin D rather than too much. I would say that taking a supplement is not dangerous as long as the amount is being kept track of. Northerners could very much benefit from this. But I would tell people to take it with the intent of reducing the risk of bone mineral loss and for overall health; not for preventing cancer, as more research still needs to be done. Another suggestion would be to use sunscreen only after being exposed to the sun for 5 to 15 minutes, two to three times a week (1,2,3,7).


1. Blake, Joan Salge. Nutrition: From Science to You. San Francisco: Benjamin Cummings, 2010.

2. Crew, Katherine D. “Vitamin D: Are We Ready to Supplement for Breast Cancer Prevention and Treatment?,”

ISRN Oncology, vol. 2013, Article ID 483687, 22 pages, 2013. doi:10.1155/2013/483687

3. Evert, Alison. Vitamin D. 8 January 2011. 31 March 2013 <>.

4. Lowry, Fran. "Without randomized trials, role of vitamin D in cancer prevention remains uncertain." Oncology News International Jan. 2010: 30. General OneFile. Web. 31 Mar. 2013.

5. Harvard Health Publications. Time for more vitamin D. 9 September 2008. 31 March 2013 <>.

6. MF Holick, et al. "Dealing With Innovation And Uncertainty. The Role Of Vitamin D In Cancer Prevention." American Journal Of Public Health 96.2 (2006): 252-261. CINAHL. Web. 31 Mar. 2013.

7. National Institutes of Health. Vitamin D. 24 June 2011. 31 March 2013 <>.

8. The Nutrition Source. Low Vitamin D: What Increases the Risk? 3 June 2012. 31 March 2013 <>.

9. "Find a Vitamin or Supplement: Vitamin D." n. page. Web. 31 Mar. 2013. < D.aspx?activeIngredientId=929&activeIngredientName=VITAMIN D>.

10. "Vitamin D and Cancer Prevention: Strengths and Limits of the Evidence." 17 5 2012: n. page. Print. <10.>.

11. "Vitiligo." n. page. Web. 31 Mar. 2013. <>.

12. "Actinic Keratosis (AK)." n. page. Print. <>.

13. "Vitamin D and Cancer Prevention: Strengths and Limits of the Evidence." n. page. Web. 31 Mar. 2013. <>.

14. "Newly Discovered Effects of Vitamin D on Cancer."Vitamin D slows the progression of cells from premalignant to malignant states, keeping their proliferation in check. 22 11 2012: n. page. Web. 31 Mar. 2013. <>.