The myth about vitamins

This unit was adapted from an article in Scientific American February 2013 The Myth of Antioxidants by Melinda Wenner Moyer P56
Vitamins have always been linked to a healthier life style and a longer life expectancy. Vitamin supplements are popular and advertised to be effective against the common cold and to providing extra energy throughout the working day. Although this may be the case in third world countries where the diet is poor it is certainly not the case in Australia where a healthy diet often provides all the nutrients needed.
Vitamin advertisements have always been carefully targeted to members of the population who are likely to be more receptive, specially parents of young children.

Some websites refer to a link between red wine and an antioxidant ( resveratrol) and its health effects of preventing cancer and the common cold. The French have long be associated with the benefits of red wine drinking.

A study, reported by the BBC in 2002, Tuesday, 14 May, 2002, 10:18 GMT 11:18 UK in the Health section

Red wine 'protects from colds'

supposedly linked red wine to the prevention of the common cold. The article stated that

"Experts at five universities found that people who drank more than two glasses of red wine a day had 44% fewer colds than teetotallers."

But this study did not take into account that the type of people who were likely to drink a red wine were unlikely to drink at pubs where the flu is easily transmitted but rather drink at home. The same study found no link between drinking beer and prevention of the common cold.

Antioxidants and the ability to repair oxidative damage due to formation of free radicals has long been associated with living longer by slowing the aging process. Free radical accumulation has long been associated with aging and in 1969 researchers at Duke University discovered the enzyme superoxide dismutase, a natural antioxidant that mops up free radicals in the body.

Recent investigations, however, have failed to show a relationship, between free radical accumulation along with subsequent damage and living longer. What is more, in certain amounts and situations, free radicals are not dangerous but necessary in stimulating defence mechanisms that keep the body healthy.

These studies not only have serious implications for antiaging treatments but also raise serious questions about the common practice of popping antioxidant tablets.

 

For example a 1996 study of some 18,000 men and women found that 28% more lung cancers and 17% more deaths in a group that was given beta-carotene and retinol compared with people who did not receive the antioxidants. The results are shown on the left.

What do the results suggest?

What is a placebo?

In 2010 a paper written by Siegfried Hekimi, a biologist at McGill University, reported that worms, engineered to have high levels of free radicals, survived, on average, 32% longer than normal worms, the results are shown on the right.

In a follow up study Hekimi exposed normal worms to a herbicide known to be a potent free radical producer. He reported the amazing finding that the worms bathed in the toxin lived 58% longer than untreated worms.

 
Scientists now believe that the effect of free radicals in organisms may not be as simple as once thought. They may be beneficial in some context and dangerous in others. There is no doubt that high doses of free radicals causing extensive oxidative damage causes cancer and heart disease.
 
Now here is a twist. Researchers at the University of Washington have engineered a mouse that produces high levels of an antioxidant called amylase. This mouse lives longer than its normal relatives.
 
According to Hekimi it looks like free radicals are part of the defence mechanism of cells. They may be produced as a response to cellular damage and serve to signal the cells repair mechanism. In this case free radicals accumulate as a result of aging not cause it. Scientists believe that minor insults might help the body prepare or withstand bigger ones so exposure to low levels of free radicals in some way prepare the body.

1) What does this advert suggest about the diet of Americans in the 60s and 70s?

2) Is there a need for vitamins when diets are so poor? When are vitamin supplements beneficial?

3) The Flinstone vitamin advert above is aimed at what people in our community? Explain.

4) Studies have shown that people who drink red wine are less likely to catch a cold. Discuss how these studies may be flawed

5) What are free radicals?

6) How are free radicals linked with aging?

67 How do antioxidants react with free radicals?

8) Give an example of a natural antioxidant and a food source that contains the antioxidant?

9) What do recent studies suggest about the link between free radical build up and aging?

10) What is one theory of how free radicals act in our body?