Antioxidants speed up lung cancer- The Scientist, 29th January 2014
What is an antioxidant?
An antioxidant is a chemical compound that seeks out potentially harmful compounds in the body, known as free radicals, and reacts with them to make them harmless.
Free radicals are highly reactive molecules that are produced as part of normal cellular function. However, in excess free radicals can damage important biological molecules and are often involved in disease such as cancer and rheumatoid arthritis. They are also thought to be responsible for the natural ageing process whereby cumulative damage over the years leads to mistakes in DNA replication. Free radicals are often oxygen containing molecules which is how antioxidants came by their name; they were thought to prevent the consumption of oxygen. It is now known that free radicals do not have to contain oxygen, but many of them do, and that antioxidants actually react with the free radicals to make new harmless chemicals.
Two very well known antioxidants are vitamin E and vitamin C but they cannot be synthesised by the human body, instead they must be absorbed through the food we eat. Other antioxidants can be made in the body and supplement those taken in through diet.
Do we need Vitamin E or antioxidant supplements?
The blog ‘information is beautiful’ has compiled a beautiful and very interesting ‘info-graphic’ about health supplements. It very clearly shows the results of trials into a huge variety of health supplements, shockingly few have strong evidence to suggest that they are worth taking. Interestingly the relatively little research done into vitamin E shows very little convincing evidence that it is beneficial, however the evidence that antioxidants help prevent heart disease is fairly strong. This is the problem with taking vitamin supplements, while it may be helpful for certain conditions, for example heart disease, it may actually be harmful if you are a healthy adult.
A new study has shown that when mice with cancer were given an overdose of vitamin E (5 or 50 times required dose), the cancer actually grew faster. A dose 50 times greater than the daily recommended amount may sound like a lot but some supplements provide 20 times the recommended daily amount for humans. This does not mean we should stop eating antioxidant rich foods, as explained above, we need antioxidants to track down rogue free radicals and some of them can only come from our diet. However, a healthy body knows what it needs and will get all the antioxidants it requires from food as long as a healthy diet is followed. Additionally, if you are deficient in vitamin E it may not be due to a dietary deficiency, there may be a problem absorbing the vitamin E from the intestine which may not be solved by increasing vitamin E intake.
The vitamin E study was carried out in mice so the same effects may not be seen in humans but the results cannot be ignored. Many recent articles have reported on the fallacy of taking vitamin supplements, it seems as more research is carried out the results become more inconclusive. This may seem unhelpful but in reality it reflects the complexity of human heath, research must become more specific so that we may say antioxidants are good at preventing heart disease but not helpful if you have cancer. It is also important to remember that the mice in this study were pre-disposed to grow tumours, which means vitamin E may only promote growth of tumours once they appear and not actually cause them.
This blog has written about vitamin supplements several times but the conclusion never changes, a healthy adult who has a good diet should have no need for vitamin supplements unless there is a physiological deficiency. This new research only goes to show that we still have much to learn about disease and that, as ever, in excess even cures can become poisons.