Prostate Cancer

Does Natural Vitamin E Protect Against Prostate Cancer?

Vitamins and minerals are nutrients found in nature. As you probably know, the only way to obtain most vitamins is through the diet. Some of them can be synthesized in the body.

For example, vitamin K is produced by the gut microflora and vitamin D by sunlight exposure. But vitamin E does not have an alternative source. We should consume dietary sources or supplements.

As you will see throughout this article, vitamin E is beneficial for the organism. It has potent antioxidant activity and may reduce the incidence of cancer. But, can you have protection against prostate cancer with vitamin E? What sources and types of vitamin E are recommended?

What is vitamin E

Vitamin E is a fat-soluble vitamin involved in the function of the immune system and cell signaling. This vitamin is also essential for gene expression and other activities in the cell. It inhibits enzymes that contribute to cell proliferation in cancer. It inhibits platelet aggregation and has a vital role in cardiovascular health, too.

Some vitamins only act as cofactors, activating enzymes. Others have an innate ability to protect the body regardless of enzymes.

Vitamin E belongs to the latter group. Similar to vitamin C and beta carotene, vitamin E has antioxidant potential. It scavenges free radicals, reducing oxidative stress. In other words, vitamin E inactivates these unstable molecules and protects the body.

These unstable molecules contain an unpaired electron. They react with other molecules and oxygen, creating reactive oxygen species (ROS). These ROS travel throughout the body and damage tissues and structures of the body. What vitamin E does is stabilizing these molecules and stopping the production of ROS.

Actually, vitamin E is one of the most popular antioxidants people look for. It is often consumed along with selenium supplements, an important mineral for the innate antioxidant activity of the human body (1).

Vitamin E use is encouraged in current smokers and to fight the effects of aging in the skin. Another use recently adopted is to prevent prostate cancer, as we will discuss in this article.

What are the types of vitamin E?

In nature, vitamin E comes in eight different variants. They are subdivided into two main groups, tocopherols, and tocotrienols. There are four types of tocopherols and four types of tocotrienol—each one of them as a different degree of biological activity in the human body.

Out of the 8 variants, alpha and gamma-tocopherol are perhaps the most useful for humans (2).

Vitamin E supplements are usually in the form of alpha-tocopherol. However, other variants have similar effects on cardiovascular disease and other health parameters.

Alpha-tocopherol

Dietary intake of alpha-tocopherol is extremely important for the organism. Actually, it is the form of vitamin E that frequently circulates in the body. Alpha-tocopherol is absorbed in the gut and goes directly into the liver. The liver gives preference to alpha-tocopherol and secretes this molecule.

It uses an enzyme called alpha-tocopherol to transfer protein and metabolizes other forms of vitamin E. This enzyme protects alpha-tocopherol from quick metabolization and elimination.

As a result, the concentration of vitamin E in the blood and tissues is almost exclusively alpha-tocopherol. There are other variants of vitamin E in the body but in a lower concentration. Thus, scientific research is usually focused on figuring out alpha-tocopherol (3).

For many years, alpha-tocopherol was the only type of vitamin E in use. Scientists believed it was the only one important. Now, other isoforms of tocopherol are considered necessary as well.

The absorption of tocopherol and tocotrienol follows the exact same path. It requires dietary fat to be absorbed, and the molecule reaches the skin, adipose tissue, and other structures of the body.

Recent studies have also detected significant concentrations of other types of vitamin E in the plasma. That’s why science has recently started to give more importance to gamma-tocopherol and tocotrienols (4).

Gamma tocopherol

Vitamin supplements with gamma-tocopherol are metabolized very rapidly by the liver. The liver breaks down this molecule pretty fast. However, it does have a potent biological function, especially as an anti-inflammatory.

Despite having a reduced proportion in the blood, gamma-tocopherol can be found in the plasma. It is actually the most important form of vitamin E in the modern diet.

Gamma tocopherol has similar functions to those detected in alpha-tocopherol. But others are slightly different. For example, gamma-tocopherol inhibits a type of free radical more rapidly.

It has an important anti-inflammatory activity by inhibiting an enzyme called cyclooxygenase. It also contributes to the secretion of sodium by the kidneys, reducing blood pressure. Many studies suggest that gamma-tocopherol can significantly reduce cardiovascular risk. It is also a very promising weapon against prostate cancer (5).

Does vitamin E protect against prostate cancer?

The anticancer effect of vitamin E is given by different mechanisms. In this section, we are covering the main reasons why vitamin E protects against cancer. So, vitamin E can be used for cancer prevention, making use of these mechanisms (6):

  • Antioxidant effects: As mentioned above, vitamin E scavenge free radicals. This vitamin prevents lipid peroxidation and reduces oxidative stress. As a result, the biological membranes are protected, as well as DNA integrity. Additionally, gamma-tocopherol stimulates the expression of glutathione peroxidase. This is one of the most potent antioxidants produced by the human body. Tocotrienols will also do their part, inducing another antioxidant enzyme called superoxide dismutase.

  • Anti-inflammatory effect: This effect is more pronounced in gamma-tocopherol and tocotrienols. They inhibit the enzyme cyclooxygenase, which creates prostaglandins. Some variants of vitamin E also inhibit another enzyme called lipoxygenase. By doing so, they suppress inflammation, which is vital for tumor growth. Cancer feeds off inflammation, using this function to obtain more nutrients and grow. By reducing inflammation, vitamin E may inhibit the progression of the cell cycle in cancer cells. It may even induce apoptosis or programmed cell death.

  • Anti-proliferative effect: Normal cells trigger healthy self-destruction when they detect abnormalities. Not having these mechanisms leads to an increased risk of cancer. But vitamin E arrests the cell cycle in cancer cells and promotes self-destruction. Once again, gamma-tocopherol is more potent than alpha-tocopherol in this particular function. They may trigger programmed cell death, contributing to the prevention of cancer.

  • Anti-angiogenic effect: Angiogenesis is new blood vessel creation to obtain new nutrients. It has an important role in tumor growth and metastasis. Vitamin E inhibits new blood vessel creation by cancer. This is especially the case when we use tocotrienols. They inhibit cell signaling used by cancer cells to promote endothelial cell migration and proliferation, which is the first step for new blood vessel formation.

  • Anti-platelet effect: Alpha-tocopherol inhibits platelet aggregation. It may also potentiate the anti-platelet effects of aspirin. Platelets form blood clots around circulating tumor cells. This way, cancer cells are protected in the blood and undergo metastasis. They are not recognized by white blood cells that may eliminate them. By reducing platelet aggregation, vitamin E may inhibit this protective effect and lead to a decreased risk of metastasis in advanced prostate cancer and lung cancer.

  • Inhibition of HMG CoA Reductase: HMG CoA Reductase is dysregulated in some malignant cells. This dysregulation contributes to cancer proliferation. The anti-tumor effect by inhibiting this enzyme is found mainly in the tocotrienols. This field of study is yet under research and warrants further studies.

All of these effects contribute to reducing the prevalence of different types of cancer. Thus, vitamin E and prostate cancer is a highly debated topic since the 1980s.

Where are we now in this particular field of investigation? Is vitamin E considered a useful way to reduce cancer risk? Can we reduce prostate cancer incidence by taking vitamin E supplements? What about prostate cancer prevention?

What does the research say?

Vitamin E supplements were, for many years, proposed as a potential way to reduce cancer incidence. In theory, they should work. But in practice, many clinical trials show inconsistent results. Sometimes they do find a protective effect, but in other cases, no difference is found.

One of the most important clinical trials is the ATBC study. This study was performed in healthy men. It evaluated the incidence of lung cancer and the effect of vitamin E and carotenes. The researchers did not find any correlation with lung cancer at first. But then, they realized there was a relationship between prostate cancer and vitamin E. Higher alpha-tocopherol levels were associated with a lower incidence of prostate cancer (78).

Later on, in an 18-year follow-up of the ATBC study, the results were almost the same. The preventive effect of vitamin E and beta-carotene resulted in lower prostate cancer mortality (9).

The SELECT trial was another study, performed between 2001 and 2004 in three countries. This was a randomized controlled trial that was meant to be a cancer prevention trial. But the vitamin E group did not have a lower incidence of prostate cancer compared to placebo. Instead, the incidence was a bit higher though not statistically different (10).

The studies continued to be conflicting and inconsistent for many years. Recently, more attention was given to other isoforms of vitamin E. For example, gamma-tocopherol, and tocotrienols. The investigators discovered that a mixture of different isoforms of vitamin E is more efficient. It protects healthy cells from becoming prostate cancer cells.

Moreover, alpha-tocopherol alone was found to inhibit the anticancer activity of other isoforms of vitamin E. This finding explained the results of the SELECT trial and paved the way to ongoing research (11, 12).#

As noted above, old epidemiological data was not taking into account different isoforms of vitamin E. When the studies were formulated, only alpha-tocopherol was considered important. We now know the potential anticancer activity of gamma-tocopherol and tocotrienols.

More specifically, research showed gamma-tocopherol, especially in combination with other forms of vitamin E such as delta-tocopherol, prompted cell death in prostate cancer cells. Alpha-tocopherol alone did not have this impact. More recent studies have provided evidence that gamma tocotrienols may be effective in targeting prostate cancer stem cells.

Gamma-tocopherol and Prostate Cancer

Some forms of vitamin E offer better anticancer benefits than others. This is true when it comes to alpha-tocopherol and gamma-tocopherol.

In a John Hopkins study, a total of 10,456 men participated in the trial, in which researchers compared alpha-tocopherol, gamma-tocopherol, and selenium.

They found that men who had the highest blood levels of gamma-tocopherol were five times less likely to get prostate cancer.

Another important finding was that alpha-tocopherol and selenium protected against prostate cancer only when gamma-tocopherol intake was high. That means the alpha- and gamma-tocopherols have a synergistic effect when it comes to prostate cancer.

Then there was a review published in “Carcinogenesis” in 2010 in which the authors explained how many large-scale studies with alpha-tocopherol had not shown anticancer benefits.

The authors suggested this lack of effect was caused by high doses of alpha-tocopherol, which reduced the body’s levels of delta-tocopherols. They also noted that gamma-tocopherol had “strong anti-inflammatory” properties and that it “may be the more effective form of vitamin E in cancer prevention.

They concluded by saying, “we propose that a gamma-tocopherol-rich mixture of tocopherols is a very promising cancer-preventive agent and warrants extensive future research.”

Yet another study indicated that gamma-tocopherol can help protect against development of prostate cancer.

From a total of approximately 20,000 men who donated blood samples for analysis of micronutrients and prostate cancer risk, the investigators found “potential chemopreventive effects of gamma-tocopherol on prostate cancer” and a weak association between alpha-tocopherol and risk of prostate cancer.

Alpha- and gamma-tocopherols work together

The alpha form inhibits the production of cell-damaging free radicals, while the gamma form captures and neutralizes them. If the level of alpha-tocopherol gets too high in the body, it tries to eliminate gamma-tocopherol in the cells. Therefore, both forms of vitamin E have to be kept in relative balance.

Men taking selenium and Vitamin E together did see a small increase in prostate cancer risk. However that increase in risk was so small that it fell well below the threshold for statistical significance.

There are a multitude of studies showing the prostate health benefits of both Vitamin E and Selenium and so we still recommend them as vital health supplements. Also it is important to note that the study used dl-alpha tocopheryl and we recommend mixed tocopheryls, which are very different.

The select trial is a single piece of research and we view it in the context of all of the other research into this nutrients. Overall we remain convinced by the scientific consensus that there are general and prostate specific health benefits to taking Selenium and Vitamin E.

So before you begin vitamin E supplementation, always check the label. Generally, vitamin E is a blanket term that covers a whole range of different nutrients, both synthetic and natural and so you can be easily mislead.

Vitamin E supplements

Intake of vitamin E should follow the Dietary Reference Intakes for healthy people. These references take into consideration gender and age.

In adults, it is generally recommended to receive 15 mg of alpha-tocopherol every day. In lactating women, this number goes slightly up, reaching 19 mg a day. Children’s intake is lower, ranging from 5 mg at one year and 11 mg at 9 to 13 years (13).

Food sources of vitamin E include:

  • nuts and seeds

  • some vegetable oils

  • fortified cereals

  • green leafy vegetables

However, the majority of Americans obtain vitamin E from:

  • soybean

  • corn

  • canola oil

This is not alpha-tocopherol but gamma-tocopherol instead.

People often use vitamin E supplementation due to dietary restrictions and to prevent prostate cancer and other diseases. These dietary supplements sometimes come as a blend of tocopherols and tocotrienols. Each one of them has a distinct biological activity.

However, it is important to note that vitamin E supplements can be synthetic. It makes a lot of difference if you’re consuming synthetic or natural vitamin E. Synthetic vitamin E is half as active as the same amount of natural vitamin E. Therefore, you need to find a supplement that is either natural or has a double concentration of synthetic alpha-tocopherol (14).

Prostate cancer cases could be prevented by including in the diet sufficient vitamin E. But not only alpha-tocopherol. According to the current line of investigation, vitamin E supplements that only contain alpha-tocopherol are not enough.

What we need is a blend of vitamin E isoforms combined with selenium and other nutrients. Together they can potentially reduce the incidence of cancer.

That is why Total Health Vegicaps include different isoforms of vitamin E, not only one. It is an attempt to move forward and offer a top-notch dietary supplement according to the latest evidence.

Conclusion

Reducing prostate cancer risk is nowadays challenging because there are many risk factors. Vitamin E has many potential pathways to reduce the incidence of cancer. It is a powerful antioxidant and reduces oxidative stress.

It has anti-inflammatory properties that cut the resources of cancer. It is anti-proliferative and triggers apoptosis in prostate cancer cells. It has anti-angiogenic activity, inhibiting the creation of new blood vessels in tumors. It also inhibits platelet aggregation, which is useful in cases of aggressive prostate cancer.

However, the clinical trials so far are outdated and do not take into consideration what we now know about vitamin E isoforms. They only evaluate the role of alpha-tocopherol and do not take into consideration tocotrienols and gamma-tocopherol.

Prostate cancer screening will always be important for a reduced risk of prostate cancer mortality. But nutraceuticals and natural products are now on the vanguard. In the case of vitamin E supplements, we should look for a blend of vitamin E isoforms instead of only alpha-tocopherol. That way, we will get the complete array of benefits that make vitamin E a potential anticancer agent

Sources

  1. Hoekstra, W. G. (1975, October). Biochemical function of selenium and its relation to vitamin E. In Federation proceedings (Vol. 34, No. 11, pp. 2083-2089).
  2. Katherine, L., & Ziegler, T. R. (2012). Modern nutrition in health and disease.
  3. Traber, M. G. (2007). Vitamin E regulatory mechanisms. Rev. Nutr., 27, 347-362.
  4. Meganathan, P., & Fu, J. Y. (2016). Biological properties of tocotrienols: evidence in human studies. International journal of molecular sciences, 17(11), 1682.
  5. Jiang, Q., Christen, S., Shigenaga, M. K., & Ames, B. N. (2001). γ-Tocopherol, the major form of vitamin E in the US diet, deserves more attention. The American journal of clinical nutrition, 74(6), 714-722.
  6. Abraham, A., Kattoor, A. J., Saldeen, T., & Mehta, J. L. (2019). Vitamin E and its anticancer effects. Critical reviews in food science and nutrition, 59(17), 2831-2838.
  7. Cardenas, E., & Ghosh, R. (2013). Vitamin E: a dark horse at the crossroad of cancer management. Biochemical pharmacology, 86(7), 845-852.
  8. Heinonen, O. P., Huttunen, J. K., Albanes, D., Haapakoski, J., Palmgren, J., Pietinen, P., … & Greenwald, P. (1994). Effect of vitamin-E and beta-carotene on the incidence of lung-cancer and other cancers in male smokers. New England Journal of Medicine, 330(15), 1029-1035.
  9. Virtamo, J., Taylor, P. R., Kontto, J., Männistö, S., Utriainen, M., Weinstein, S. J., … & Albanes, D. (2014). Effects of α‐tocopherol and β‐carotene supplementation on cancer incidence and mortality: 18‐Year postintervention follow‐up of the Alpha‐Tocopherol, Beta‐Carotene Cancer Prevention Study. International Journal of Cancer, 135(1), 178-185.
  10. Lippman, S. M., Klein, E. A., Goodman, P. J., Lucia, M. S., Thompson, I. M., Ford, L. G., … & Parsons, J. K. (2009). Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). Jama, 301(1), 39-51.
  11. Das Gupta, S., & Suh, N. (2016). Tocopherols in cancer: An update. Molecular nutrition & food research, 60(6), 1354-1363.
  12. Huang, P. H., Chuang, H. C., Chou, C. C., Wang, H., Lee, S. L., Yang, H. C., … & Chen, C. S. (2013). Vitamin E facilitates the inactivation of the kinase Akt by the phosphatase PHLPP1. Science signaling, 6(267), ra19-ra19.
  13. Institute of Medicine. 2000. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: The National Academies Press.
  14. Flory, S., Birringer, M., & Frank, J. (2019). Bioavailability and metabolism of vitamin E. In Vitamin E in Human Health (pp. 31-41). Humana Press, Cham.

 

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