Healing & Recovery

One aspect of natural and alternative medicine that has changed dramatically in the last 10 years is the focus on validation of vitamin supplements, antioxidants and other related products.

This has been driven by regulatory bodies, health professionals, consumers, and by complementary medicine companies seeking to gain a competitive edge. It is a critical undertaking, one finding agreement even within the medical and scientific-academic community as evidenced by the increasing number of publications on natural medicine and improving immunity.

What was shown in previously published large-scale clinical trials?
Five large-scale clinical trials published in the 1990s reached differing conclusions about the effect of antioxidants on cancer. The studies examined the effect of beta-carotene and other antioxidants on cancer in different patient groups. However, beta-carotene appeared to have different effects depending upon the patient population. The conclusions of each study are summarised below.

• The first large randomised trial on antioxidants and cancer risk was the Chinese Cancer Prevention Study, published in 1993. This trial investigated the effect of a combination of beta-carotene, Vitamin E, and Selenium on cancer in healthy Chinese men and women at high risk for gastric cancer. The study showed a combination of beta-carotene, vitamin E, and Selenium significantly reduced incidence of both gastric cancer and cancer overall.

• A 1994 cancer prevention study entitled the Alpha-Tocopherol (Vitamin E)/Beta-Carotene Cancer Prevention Study (ATBC) demonstrated that lung cancer rates of Finnish male smokers increased significantly with beta-carotene and were not affected by vitamin E.

• Another 1994 study, the Beta-Carotene and Retinol (vitamin A) Efficacy Trial (CARET), also demonstrated a possible increase in lung cancer associated with antioxidants.

• The 1996 Physicians' Health Study 1 (PHS) found no change in cancer rates associated with beta-carotene and aspirin taken by U.S. male physicians.

• The 1999 Women's Health Study (WHS) tested effects of Vitamin E and beta-carotene in the prevention of cancer and cardiovascular disease among women age 45 years of older. Among apparently healthy women, there was no benefit or harm from beta-carotene supplementation. Investigation of the effect of vitamin E is ongoing.

Are antioxidants under investigation in current large-scale clinical trials?
Two large-scale clinical trials continue to investigate the effect of antioxidants on cancer. The objective of each of these studies is described below.

• The Selenium and Vitamin E Cancer Prevention Trial (SELECT) is taking place in the United States, Puerto Rico and Canada. SELECT is trying to find out if taking Selenium and/or vitamin E supplements can prevent prostate cancer in men age 50 or older. The SELECT trial stopped recruiting patients in June 2004 and results are yet to be published
  
• The Physicians' Health Study II (PHS II) is a follow up to the earlier clinical trial by the same name. The study is investigating the effects of vitamins E, C, and multivitamins on prostate cancer and total cancer incidence. The PHS II concluded in December 2007 and findings are yet to be published

OTHER HISTORICAL STUDIES

• Among the most widely publicised research trials on antioxidants was a five year study published in 1993, in the journal of the National Cancer Institute, involving approximately 30,000 residents of north-central China, participants were given either a placebo or a dietary supplement containing several vitamin-mineral combinations. Within a short period of the trial those persons who received a daily dose of beta carotene, vitamin E and Selenium had a reduced cancer rate of 13%
  
• Dr Richard Donaldson, assistant chief of surgery at the St Louis Veterans Hospital - 140 patients enrolled in his study, all of whom were certified as being terminally ill. Some patients who were admitted with only weeks to live, were alive and well after four years with no signs or symptoms of cancer. Not all patients were cured, but all had reduction in tumour size and pain. It is unfortunate they did not receive Selenium and vitamin E until they were pronounced incurable. Differing levels of Selenium were used with all patients if insufficient Selenium was not ingested between 200-2000 mgm per day.
  
• Another recent study reported at the Heart Institute (AHA) Scientific Sessions, women who consumed high amounts of antioxidant containing foods had a 33% lower risk of heart attack and a 71% lower risk of stroke, than women who ate few antioxidants containing foods. The study involved 1,795 females.
  
• Considering Selenium blood levels alone those persons having blood Selenium levels have twice the incidence of cancer as those in the highest fifth (Willet, 1983).
  
• Total cancer mortality is three times higher in persons having blood Selenium levels below a certain value than the incidence of cancer in those above this value (Yu, 1985).
  
• Considering Selenium blood levels along, those persons in the lowest tenth of all blood Selenium levels have six times the incidence of cancer as those in the highest tenth (Clark, 1984).
  
• Both Selenium and Vitamin E are needed together to prevent cancer (Horvath, 1983).
  
• When considering both Selenium and vitamin E blood levels, those persons in the lowest third of blood vitamin E level and also having a low blood Selenium level had a more than 11 times the incidence of cancer as those in the upper two-thirds of blood vitamin E and Selenium levels (Salonen, 1985).
  
• Selenium should be considered not only as a preventative but also a therapeutic agent in cancer treatment and may act additively or synergistically with drugs and X-ray treatments (Milner, 1984).
  
• University of Kentucky - PREADVISE study linking the supplementation of Selenium and vitamin E to aid and prevent Alzheimer's.
  
• National Cancer Institute in US - Selenium and vitamin E supplementation on prevention of prostate cancer.
  
• A study undertaken at the University of Tampere, Finland provided further evidence. Blood samples taken from over 20,000 men were frozen and compared 11 years later with the men's medical records. The researchers found that the men who developed lung cancer had had low levels of Selenium in their blood and overall, it was found that men with the lowest levels of Selenium were more than three times likely to develop lung cancer than those with high levels of Selenium. The researchers concluded that "poor Selenium nutrition is a higher significant factor for lung cancer.
  
• Kneckt P et al. ‘Selenium Deficiency and Increased Risk of Lung Cancer' Abstract of paper read at the Fourth International Symposium on Selenium in Biology and Medicine, Tubingen. (West Germany, July 1988).
  
• United States Department of Agriculture - Results of studies with animal tumour models and human clinical trials suggest that Selenium can prevent tumours if consumed at levels greater than nutritional requirements. Current trials in the United States and Europe are evaluating the anti-carcinogenic potential of long-term supplementation of 200 micrograms of Selenium per day.