Vitamin Information Center

Long-term supplementation with vitamin E and vitamin C may not prevent cancer, according to data from the Physician’s Health Study II that was presented at the American Association for Cancer Research’s Seventh Annual International Conference in Washington, D.C. on November 16, 2008.[1]

The role of diet in cancer incidence remains a major focus among researchers, as it is becoming more evident that diet may reduce the risk of developing certain types of cancers. For example, vitamin D appears to have a protective effect against pancreatic cancer and also colorectal adenomas.[2][3] In addition, several studies have linked vitamin E, selenium, and lycopene with a reduction in prostate cancer. However, it has also been discovered that supplementation with specific vitamins and minerals often does not have the same protective role as obtaining the nutrients from foods. In other words, there is still much to be learned about the role of nutrients in the prevention of cancer.

The Physician’s Health Study II is a large-scale, long-term, randomized clinical trial involving over 14,000 physicians over the age of 50. The physicians were given either a) 400 IU of vitamin E every other day or placebo or b) 500 mg of vitamin C daily or placebo and were then followed for up to 10 years. The primary endpoint of the vitamin C group was the development of cancer. The primary endpoint of the vitamin E group was the development of prostate cancer, with a secondary endpoint being the development of any type of cancer.

After nearly 10 years of supplementation, there was no evidence that vitamin E or vitamin C played a protective role against cancer. Thus far, there have been 1,929 cancer cases in the group, including 1,013 cases of prostate cancer. The researchers concluded that neither vitamin E nor vitamin C offers any beneficial effect against cancer.

Research in this field is ongoing; however, the results from this study indicate that vitamin supplements may not provide the same benefits as vitamins included as part of a healthy, balanced diet.

References:

[1] Buring JE, Sesso HD, Gaziano JM, et al. A randomized factorial trial of vitamins E and C in the prevention of cancer in men: the Physicians’ Health Study II. Proceedings from American Association for Cancer Research Annual Meeting. Abstract #PR-1.

[2] Skinner HG, Michaud DS, Giovannucci E, Willett WC, Colditz GA, Fuchs CS. Vitamin D Intake and the Risk for Pancreatic Cancer in Two Cohort Studies. Cancer Epidemiology, Biomarkers, and Prevention. 2006;15:1688-95.

[3] Wei MY, Garland CF, Gorham ED. Vitamin D and prevention of colorectal adenoma: A meta-analysis. Cancer Epidemiology, Biomarkers and Prevention. 2008;17(11):2958-2969.

ATLANTA, April 14 (UPI) — U.S. researchers say they are learning how vitamins and minerals can stimulate or prevent the development of colon cancer.

Emory University researchers in Atlanta find in a study of 92 patients that supplementing a diet with calcium and vitamin D appears to increase the levels of a protein call Bax — which controls programmed cell death — that may push pre-cancerous cells to self-destruct.

In another, 200-patient, case-control study, led by Dr. Robert Bostick of Emory University, high levels of calcium and vitamin D together are associated with increased levels of E-cadherin, which moderates colon cells’ movement and proliferation.

A third study on the same 200-patients shows high levels of iron in the diet are linked to low levels of APC, a protein whose absence in colon cancer cells leads to their runaway growth.

All three studies — scheduled to be presented at the American Association for Cancer Research meeting in San Diego — use colorectal biopsy samples and are part of a larger effort to identify a portfolio of measurements which taken together could predict the risk of colon cancer.

“We want to have the equivalent of measuring cholesterol or high blood pressure, but for colon cancer instead of heart disease,” Bostick says in a statement.

ATLANTA, April 14 (UPI) — U.S. researchers say they are learning how vitamins and minerals can stimulate or prevent the development of colon cancer.Emory University researchers in Atlanta find in a study of 92 patients that supplementing a diet with calcium and vitamin D appears to increase the levels of a protein call Bax — which controls programmed cell death — that may push pre-cancerous cells to self-destruct.

In another, 200-patient, case-control study, led by Dr. Robert Bostick of Emory University, high levels of calcium and vitamin D together are associated with increased levels of E-cadherin, which moderates colon cells’ movement and proliferation.

A third study on the same 200-patients shows high levels of iron in the diet are linked to low levels of APC, a protein whose absence in colon cancer cells leads to their runaway growth.

All three studies — scheduled to be presented at the American Association for Cancer Research meeting in San Diego — use colorectal biopsy samples and are part of a larger effort to identify a portfolio of measurements which taken together could predict the risk of colon cancer.

“We want to have the equivalent of measuring cholesterol or high blood pressure, but for colon cancer instead of heart disease,” Bostick says in a statement.

A study by researchers at the Institute for Cancer Research in Oslo, Norway has given further credence to the claim that the benefits of modest sun exposure outweigh the risk of skin cancer for most people. Johan Moan, the researcher who led the study said, “Modest sun exposure gives enormous vitamin D benefits.”

He estimated that doubling the amount of sun exposure for residents of Norway would double the number of deaths due to skin cancer to 300. However, the great benefit to this would be a decrease of 3,000 people who die from other cancers [1].

The human skin synthesizes vitamin D when exposed to the ultraviolet type B (UVB) radiation in sunlight. Solar radiation is the main source of vitamin D for most people. Modest sun exposure causes a significant amount of vitamin D to accumulate in the body and protect from some internal cancers and other illnesses such as diabetes and rickets. Vitamin D promotes bone mineralization and calcium absorption thus protecting against osteomalacia and osteoporosis. The vitamin also helps the body’s immune system function properly [2]. When deficient, the human body is at great risk of acquiring these conditions and deficiency is linked to heart attacks and mental depression. Most people could experience the benefits by increasing their sun exposure, but not too much as to cause any burning.

Vitamin D deficiency has been measured to be as high as 21 to 58 percent in adolescents and adults in the United States [3].

Several factors reduce individuals’ exposure to sunlight and UVB light rays: the amount of time spent in the sun is the most obvious. Also, more polar latitudes, the time of day such as dusk compared to noon, high cloud cover, smog, and sunscreen use lower the amount of UVB radiation that reaches people.

Geographic latitude plays a significant role. Generally, the farther an individual is from the equator, the more difficult it is to synthesize enough vitamin D. For example, in Boston, MA, from November through February, the average amount of sunlight is inadequate for an individual to synthesize enough vitamin D [4]. Additionally, the researchers at the Institute for Cancer Research in Oslo determined that, given the same amount of sunlight, inhabitants of Australia just below the equator produced 3.4 more times the vitamin D than people in Britain and 4.8 times that of Scandinavians [1].

It’s essential to learn the optimal amount of sun exposure that is healthy for you without causing sunburn. Moan recommended that a person’s daily sun exposure should be about half the time that it would take to burn. Lighter skinned people are more sensitive to sunburn and skin damage, but they are more proficient at creating vitamin D with less sun exposure than a darker skinned person (Please see [5] below for a related, generally accepted theory for skin color variance). Light skinned peoples in Southern United States can synthesize enough vitamin D by exposing their face and arms to the sun without sunscreen for about 15 minutes a few times a week. Dark skinned people need about 5 to 10 times more exposure [2].

A consensus has not been made for how much vitamin D is a healthy level for most people, but it’s generally agreed that for people up to the age of 50, 200 IUs (international unit) is the Adequate Intake (AI). For 51 to 70 year olds, 400 IUs is the AI and for individuals over 70, 600 IUs is recommended. The ability to synthesize vitamin D decreases with age. However, recent studies have shown amounts of vitamin D of 2,000 IUs and higher to be more effective and still safe [6]. If a person works outside under the summer sun for hours in a tank-top and shorts, his skin will have made thousands of IUs. Of course, a baseline tan to prevent burning would be a good idea. Normal body levels of vitamin D can’t reach the level that a large vitamin D pill would produce. The body self-regulates; reducing vitamin D synthesis when levels are getting high from sun exposure.

Is there a difference between taking say, 1,000 IUs in pill form and synthesizing it via UVB radiation? Is putting a 1,000 IU pill in your body versus forming it all over your skin comparable to drinking 8 glass of water at once versus spreading it throughout the day? This, I am unsure of.

Within UVB light are a range of wavelengths. Some are more optimal for vitamin D synthesis than others. A person at sea level will receive these wavelengths when the sun is 45 degrees above the horizon or the UV index for the day is above 3. When the sun is at or above this elevation in the sky, sufficient amounts of vitamin D can be made by the skin in about 15 minutes a few times a week. The area of the planet within the tropics provides this solar elevation daily, but it occurs daily only in the spring and summer seasons of temperate regions, and nearly never in the arctic circles [7]. Seasonal supplementation seems to be appropriate.

Sunscreen with a sun protection factor (SPF) of 8 prevents more than 95% of vitamin D production [11]. So when you lather up with this sunscreen, it will take 20 times longer than usual to make enough vitamin D. This effect was observed during a campaign in Australia to increase sunscreen use to prevent skin cancer. The result was an increase in Australians with vitamin D deficiency [8].

If the minimum level of sun exposure can not be obtained, people should look to their diet for vitamin D. Since few foods contain enough vitamin D, some foods are fortified with vitamin D and supplements can be taken to attain an adequate level.

To complicate matters further, there are 5 forms of vitamin D. The two major forms are vitamin D2 (ergocalciferol) and D3 (cholecalciferol). Both forms are present in human nutritional supplements. When our skin comes into contact with UVB radiation, it synthesizes only vitamin D3. Both of these forms are prohormones, precursors to the vitamin D hormone that goes on to perform all of the beneficial processes that have been mentioned. However, the vitamin D3 form is about 3 times more effective at creating the vitamin D hormone and its duration of action is longer that the D2 form. Supplementing with vitamin D3 would be the wiser choice [9].

UVA and UVB radiation exposure is a double edged sword. Excessive exposure will cause damage to the skin and more importantly, to the DNA inside the cells. With more DNA damage comes a greater chance of developing skin cancer. However, only a small percentage of skin cancers are the type that will metastasize (to spread throughout the body from the origin of formation). The wavelengths of UVA light are longer and penetrate farther into the skin. UVA radiation is a more potent cause of skin cancer than the shorter UVB light.

Skin cancers are among the fastest growing types of cancer in the United States and make up about 1 out of 3 new cancers.

With the rise in popularity of sun bathing, something must be said about tanning beds. Although the time spent in a tanning bed is typically much less than say, an afternoon at the beach, the radiation levels are more intense than from sunlight and the UVA to UVB radiation ratio is much higher than from the sun. The amount of UVA radiation in the light of tanning beds is typically between 3 to 8 times greater than in sunlight [10]. Recall that UVA radiation, and UVB less so, put individuals at risk for DNA damage and skin cancer, but only exposure to UVB radiation will produce vitamin D, which protects against many illnesses. Therefore, it is this author’s humble opinion that, while tanning beds may be more convenient, it is safer to get your healthy glow from the sun and good nutrition.

References:

[1]“Addressing the health benefits and risks, involving vitamin D or skin cancer, of increased sun exposure”((http://www.pnas.org/cgi/content/abstrac…)

[2]((http://www.medicinenet.com/script/main/…)

[3]“Vitamin D Deficiency-The Once and Present Epidemic” (http://www.aafp.org/afp/20050115/editorials.html)

[4](http://healthlink.mcw.edu/article/982088787.html)

[5]“Skin Color Adaptation” (http://anthro.palomar.edu/adapt/adapt_4.htm)

[6](http://www.vitamindcouncil.com/treatment.shtml)

[7]((http://upload.wikimedia.org/wikipedia/c…)

[8]Nowson C, Margerison C (2002). “Vitamin D intake and vitamin D status of Australians”. Med J Aust 177 (3): 149-52. PMID 12149085.

[9]“Vitamin D2 Is Much Less Effective than Vitamin D3 in Humans” ((http://jcem.endojournals.org/cgi/conten…)

[10]Woollons, A., Clingen, P.H., Price, M.L., Arlett, C.F., Green, M.H.L. (1997). Induction of mutagenic DNA damage in human fibroblasts after exposure to artificial tanning lamps. British Journal of Dermatology 1997; 137: 687-692.

[11]((www.motherearthnews.com/Natural-Health/…)