Antioxidants and Cancer

General | March 3, 2017 | Author: Naturopath

cancer

Antioxidants and Cancer

What are antioxidants?

Antioxidants are substances that protect your cells against the damage done from free radicals, which are the molecules produced by our body when breaking down food, or from external sources such as to tobacco smoke, air pollutants, industrial chemicals, and exposure to X-rays.

A balance between free radicals and antioxidants is necessary for proper cell function. An imbalance may lead to our antioxidant defence system not being able to protect us from free radical generation.This may lead to a condition known as oxidative stress, which  is associated with many chronic health problems including the initiation, promotion, and progression of cancer.

There are many substances that act as antioxidants. The principal vitamin antioxidants and probably the most familiar are:

  • Vitamin E
  • Beta-carotene
  • Vitamin C

Other antioxidants include (but not limited to):

  • Selenium - a trace mineral found naturally in the soil and in some foods
  • Glutathione - a molecule made of three simple amino acids - produced naturally in the body
  • Melatonin - a naturally occurring hormone
  • Coenzyme Q10 and lipoic acid, both vitamin-like substances produced in the body.
  • Spices – turmeric, cumin, ginger, garlic, saffron, black pepper, and chilli.

Antioxidant Supplements in Australia

In Australia, antioxidants are available as an individual supplement or as part of a multi-vitamin preparation, and according to the Australian Bureau of Statistics, 16% of the population consume multi-vitamin and/or multi-mineral supplements, many of which contain antioxidants.

Can Antioxidants prevent cancer?

The research related to the role of food, nutrition and physical activity in cancer prevention is growing faster than ever, and a mounting body of evidence has consistently shown that people who eat more vegetables and fruits have lower incidence of cancer, cardiovascular diseases, and other chronic diseases.

Regarding antioxidant supplements, thus far, research has not shown that they reduce the risk of developing cancer.

Should I take antioxidant supplements following my cancer diagnosis?

Many cancer patients choose to use complementary and alternative medicine while undergoing chemotherapy and/or radiotherapy; however, the use of antioxidant supplements remains controversial and highlights the need for further research.

A review of 49 studies in which antioxidant supplements were used as an adjuvant therapy for cancer patients during chemotherapy or radiotherapy concluded that:

The good:

  • Certain antioxidant supplements, in combination or alone, may increase tumour regression and survival rate, and alleviate the adverse effects of chemotherapy and radiotherapy.
  • Lower-dose antioxidant supplementation may protect normal cells and reduce the toxicity of radiation and chemotherapy.

The bad:

  • At high doses, antioxidant supplementation may reduce therapeutic effects of radiotherapy or chemotherapy by protecting not only normal cells but also cancer cells.
  • Smokers who took beta-carotene supplementation during radiotherapy for head and neck cancers had significantly increased cancer recurrence and mortality, suggesting that a combination of smoking and consumption of a high dose antioxidant during radiotherapy may result in lower survival rates.

The case for specific antioxidants

  • Vitamin C. Laboratory studies have shown that high-dose vitamin C can decrease cancer spread. These results were supported by trials in cancer patients that reported that vitamin C, administered in high doses by intravenous infusions, improved quality of life and decreased side effects. Vitamin C can help mop up free radicals produced after cancer treatment and aid in tissue repair.
     
  • Selenium. A recent small study in men at high risk for prostate cancer or diagnosed with prostate cancer showed that taking selenium supplements for only five weeks had a preventive effect on prostate cancer progression.
     
  • Green tea. Many laboratory and animal studies have shown the anti-cancer properties of a natural antioxidant compound in green tea called EGCG.
    The exact dosage for cancer prevention is unknown, but a Japanese study found that people who drank 10 cups of green tea per day, equivalent to 2.5 g green tea extract, experienced a significant delay of cancer onset. Another study showed that green tea significantly prevented recurrence of colorectal cancer in Japanese patients.
     
  • Turmeric. Curcumin, the major component of the spice turmeric, is a potent antioxidant and anti-inflammatory. Extensive research demonstrates that curcumin exhibits anti-cancer properties.


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Which foods are rich in antioxidants?

Plant-based foods are the best sources of antioxidants.

  • Berries: Blueberries, blackberries, raspberries, strawberries and cranberries
  • Beans: Small red beans and kidney, pinto and black beans
  • Fruits: Pomegranate, many apple varieties (with peels), avocados, cherries, green and red pears, fresh or dried plums, pineapple, oranges, and kiwi
  • Vegetables: Artichokes, spinach, red cabbage, red and white potatoes (with peels), sweet potatoes and broccoli
  • Beverages: Green tea, coffee, red wine and many fruit juices
  • Nuts: Walnuts, pistachios, pecans, hazelnuts and almonds
  • Herbs: Ground cloves, cinnamon or ginger, dried oregano leaf and turmeric powder
  • Grains: Oat-based products
  • Dessert: Dark chocolate

The Bottom Line

No single food can protect you against cancer by itself. But there is overwhelming evidence that a diet filled with a variety of plant foods such as vegetables, fruits, whole grains and beans can lower the risk of cancer.

A plant-base diet is loaded with potent antioxidants and contains other substances that are necessary for good health like fibre, vitamins and minerals with clear evidence for their health benefits.

Many people can derive health benefits from using antioxidant supplementation; however, If you already have cancer, never take a supplement without talking to your doctor first.

 

References

Albanes, D., Heinonen, O. P., Taylor, P. R., et al. (1996). Alpha-Tocopherol and beta-carotene supplements and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: effects of base-line characteristics and study compliance. Journal of the National Cancer Institute, 88(21), 1560–70.

Australian Bureau of Statistics 2014, Australian Health Survey: Nutrition First Results - Foods and Nutrients, 2011-12 - Supplements, ABS, retrieved February 23, 2017,

Cancer Council 2009, Position Statement- Beta carotene and cancer risk, Cancer council retrieved February 23, 2017,

Hercberg, S., Ezzedine, K., Guinot, C., et al., (2007). Antioxidant supplementation increases the risk of skin cancers in women but not in men. The Journal of Nutrition, 137(9), 2098–105.

Kok, D. E. G., Kiemeney, L. A. L. M., Verhaegh, G. W., et al (2017). A short-term intervention with selenium affects expression of genes implicated in the epithelial-to-mesenchymal transition in the prostate. Oncotarget, 8(6), 10565–10579.

Lobo, V., Patil, A., Phatak, A., & Chandra, N. (2010). Free radicals, antioxidants and functional foods: Impact on human health. Pharmacognosy Reviews, 4(8), 118–26.

Mayo Clinic 2007, Antioxidants: Preventing Diseases, Naturally, ScienceDaily, retrieved February 23, 2017

National Cancer Institute 2014, Antioxidants and Cancer Prevention, NIH, retrieved February 23, 2017,

National Center for Complementary and Integrative health 2013, Antioxidants: In Depth,  NIH, retrieved February 23, 2017,

PDQ Integrative, Alternative, and Complementary Therapies Editorial Board, A. and C. T. E. B. (2013). High-Dose Vitamin C (PDQ®): Health Professional Version. PDQ Cancer Information Summaries. National Cancer Institute (US).

Suganuma, M., Takahashi, A., Watanabe, T., et al. (2016). Biophysical Approach to Mechanisms of Cancer Prevention and Treatment with Green Tea Catechins. Molecules, 21(11), 1566.

The Nutrition Source Harvard T.H. Chan School of Public Health 2017, Antioxidants: Beyond the Hype, Harvard School of Public health, retrieved February 23, 2017,

Yasueda, A., Urushima, H., & Ito, T. (2016). Efficacy and Interaction of Antioxidant Supplements as Adjuvant Therapy in Cancer Treatment: A Systematic Review. Integrative Cancer Therapies, 15(1), 17–39.

Zheng, J., Zhou, Y., Li, Y., et al. (2016). Spices for Prevention and Treatment of Cancers. Nutrients, 8(8).

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