Vitamin E in Diet Protects Against Many Cancers

Researchers find form commonly used in supplements has no such benefit. 

Vitamin E in vegetable oils and nuts prevents cancer, according to research done at Rutgers University and the Cancer Institute of New Jersey.

Next time you need to choose between vegetable oil and margarine in that favorite recipe, think about your health and reach for the oil.

While the question of whether vitamin E prevents or promotes cancer has been widely debated in scientific journals and in the news media, scientists at the Center for Cancer Prevention Research, at Rutgers Mario School of Pharmacy, and the Cancer Institute of New Jersey, believe that two forms of vitamin E – gamma and delta-tocopherols – found in soybean, canola and corn oils as well as nuts do prevent colon, lung, breast and prostate cancers.

“There are studies suggesting that vitamin E actually increases the risk of cancer and decreases bone density,” says Chung S. Yang, director of the center. “Our message is that the vitamin E form of gamma-tocopherols, the most abundant form of vitamin E in the American diet, and delta-tocopherols, also found in vegetable oils, are beneficial in preventing cancers while the form of vitamin E, alpha- tocopherol, the most commonly used in vitamin E supplements, has no such benefit.”

Director of the Center for Cancer Prevention Research at Rutgers Ernest Mario School of Pharmacy

Yang and colleagues, Nanjoo Suh and Ah-Ng Tony Kong, summarized their findings recently in Cancer Prevention Research, a journal of the American Association for Cancer Research. In a Commentary, Does Vitamin E Prevent or Promote Cancer? the Rutgers scientists discuss animal studies done at Rutgers as well as human epidemiological studies that have examined the connection between vitamin E and cancer.

Yang says Rutgers scientists conducting animal studies for colon, lung, breast and prostate cancer found that the forms of vitamin E in vegetable oils, gamma and delta-tocopherols, prevent cancer formation and growth in animal models.

“When animals are exposed to cancer-causing substances, the group that was fed these tocopherols in their diet had fewer and smaller tumors,” Yang says. “When cancer cells were injected into mice these tocopherols also slowed down the development of tumors.”

In researching colon cancer, Yang pointed to another recently published paper in Cancer Prevention Research indicating that the delta-tocopherol form of vitamin E was more effective than other forms of vitamin E in suppressing the development of colon cancer in rats.

This is good news for cancer research. Recently, in one of the largest prostate cancer clinical trials in the United States and Canada, scientists found that the most commonly used form of vitamin E supplements, alpha-tocopherol, not only did not prevent prostate cancer, but its use significantly increased the risk of this disease among healthy men.

This is why, Yang says, it is important to distinguish between the different forms of vitamin E and conduct more research on its cancer preventive and other biological effects.

“For people who think that they need to take vitamin E supplements,” Yang says, “taking a mixture of vitamin E that resembles what is in our diet would be the most prudent supplement to take.”

 

Reference

Yang CS, Suh N, Kong AN. Does Vitamin E Prevent or Promote Cancer? Cancer Prev Res (Phila). 2012 Apr 16. [Epub ahead of print]

 

Fruits and vegetables reduce risks of specific types of colorectal cancers

According to new study published in the Journal of the American Dietetic Association

The effects of fruit and vegetable consumption on colorectal cancer (CRC) appear to differ by site of origin, according to a new study published in the October issue of the Journal of the American Dietetic Association. Researchers found that within the proximal and distal colon, brassica vegetables (Brussels sprouts, cabbage, cauliflower and broccoli) were associated with decreased risk of these cancers. A lower risk of distal colon cancer was associated with eating more apples, however an increased risk for rectal cancer was found with increasing consumption of fruit juice.

“Fruits and vegetables have been examined extensively in nutritional research in relation to CRC, however, their protective effect has been subject to debate, possibly because of different effects on different subsites of the large bowel,” commented lead investigator Professor Lin Fritschi, PhD, head of the Epidemiology Group at the Western Australian Institute for Medical Research, Perth, Western Australia. “It may be that some of the confusion about the relationship between diet and cancer risk is due to the fact that previous studies did not take site of the CRC into account. The replication of these findings in large prospective studies may help determine whether a higher intake of vegetables is a means for reducing the risk of distal CRC.”

Researchers from the Western Australian Institute for Medical Research, University of Western Australia and Deakin University investigated the link between fruit and vegetables and three cancers in different parts of the bowel: proximal colon cancer, distal colon cancer, and rectal cancer. The case-control study included 918 participants with a confirmed CRC diagnosis and 1021 control participants with no history of CRC. The subjects completed extensive medical and nutritional questionnaires and were assigned a socioeconomic status based on their home address.

Consumption of brassica vegetables (e.g., broccoli, cabbage) was associated with reduced incidence of proximal colon cancer. For distal colon cancer, both total fruit and vegetable intake and total vegetable intake appeared to decrease risk. Distal colon cancer risk was significantly decreased in association with intake of dark yellow vegetables and apples, although there was an increased risk for rectal cancer with consumption of fruit juice. Risk of proximal colon cancer and rectal cancer was not associated with intakes of total fruit and vegetable, total vegetable or total fruit.

Previous studies on CRC have often failed to distinguish between the different sites of origin of cancers in the large bowel, even though it is now well established that tumors in the proximal colon develop along different pathways to those of the distal colon and rectum and that risk of cancer varies by subsite within the colorectum. The mechanisms for different effects of dietary components on different sites of the large bowel have not yet been determined.

The authors conclude that “from a public health point of view it is easier to translate food-based analyses into dietary recommendations, rather than using the intake of single nutrient.”

A video featuring commentary by Professor Fritschi and colleagues

 

Reference

Annema N, Heyworth JS, McNaughton SA, Iacopetta B, Fritschi L. Fruit and vegetable consumption and the risk of proximal colon, distal colon and rectal cancers in a case-control study in Western Australia. Journal of the American Dietetic Association 2011; 111 (10): 1479-1490.

 

Confirmation That Vitamin D Acts As A Protective Agent Against The Advance Of Colon Cancer

A study conducted by VHIO researchers confirms that a lack of vitamin D increases the aggressiveness of colon cancer.

Héctor G. Palmer. Photo: Katherin Wermke.

The indication that vitamin D and its derivatives have a protective effect against various types of cancer is not new. In the field of colon cancer, numerous experimental and epidemiological studies show that vitamin D3 (or cholecalciferol) and some of its derivatives inhibit the growth of cancerous cells.

Researchers at the Vall d’Hebron Institute of Oncology (VHIO), in collaboration with the Alberto Sols Institute of Biomedical Research (CSIC-UAB), have confirmed the pivotal role of vitamin D, specifically its receptor (VDR), in slowing down the action of a key protein in the carcinogenic transformation process of colon cancer cells. These results have been in the journal PLoS One.

This protein, known as beta-catenin, which is normally found in intestinal epithelial cells where it facilitates their cohesion, builds up in large quantities in other areas of the cells when the tumour transformation begins. As a result of these changes, the protein is retained in the cell nucleus, where it facilitate the carcinogenic process, and this is the point at which vitamin D intervenes, or rather, the vitamin D receptor (VDR).

“Our study has confirmed the pivotal role of the VDR in controlling the anomalous signal that sparks off the growth and uncontrolled proliferation of colon cells which, in the final instance, ends up causing a tumour to emerge”, says Héctor Palmer, the coordinator of this study and head of the VHIO’s Stem Cells and Cancer laboratory. He continues, “The stimulation of this receptor suppresses the action of the beta-catenin protein, intercepting the series of events that change the intestinal cell into a malignant tumour cell”.

The study was conducted on mice and human colon cancer cells. The mice were used as a model to replicate the initial phases of colon cancer. “These findings show that mice of this kind, which also lack the VDR and hence do not respond to vitamin D, present larger and more aggressive tumours than mice with the VDR”, explains Dr. Palmer, and concludes: ”The number of tumours is not influenced by the absence of VDR, which would indicate that this factor does not protect against the appearance of the tumour but does intervene in its growth phase, reducing its aggressiveness”.

The researchers then analysed the effect of the VDR on human colon cancer cell cultures and observed that the concentration of the altered protein, beta-catenin, increased in cells without the VDR. These findings were repeated in the three types of colon cancer cells studied, and confirmed the results observed in the mice.

In two-thirds of advanced colon cancer tumours there was a lack of VDR in the cancer cells, and this circumstance leads us to believe that this loss may contribute to speeding up the growth of the tumour. The findings of this study confirm this supposition.


Vitamin D: essential in the initial phases of colon cancer

In light of these findings, chronic vitamin D deficiency represents a risk factor in the development of more aggressive colon tumours. Patients in the initial stages of colon cancer, the time when the VDR still has a substantial presence in the cells, could benefit from being treated with vitamin D3. However, this would not be useful in the advanced stages of the disease when the presence of the VDR is very much reduced.

The study data support the development of anti-tumour medicines based on the structure of vitamin D, although their use in patients will require further research in the next few years.

The body not only obtains vitamin D from food, especially milk and fish oils, but also manufactures it from exposure to sunlight. Prolonged exposure is not necessary; just 10 minutes in the sun every day when it is not at its peak is sufficient to stimulate its production. During the summer, when we are more likely to sunbathe, it is important to use the appropriate protective measures against sunburn to avoid future sun damage. Use high-factor solar protection products and do not expose the skin to the sun in the middle of the day to protect against skin cancers.