The Cochrane review of 2008 has been updated once more, slamming the work of the antioxidants beta-carotene, vitamin E and vitamin A, but it is important not to throw the baby out with the bath water, and here is why.
What are antioxidants?
Every minute of every day, our body breaks down, absorbs and distributes nutrients around the body; this is the way in which we survive. However this process, albeit natural, also causes some damage; free radical damage and this is how.
Oxidation – what is it?
This aforementioned free radical damage is caused by a process using oxygen, and aptly called oxidation. It is this same process that turns butter rancid and metal to rust. In humans, oxidation is an essential part of normal metabolism but it is also caused by environmental factors too. These include exposure to the sun's rays, pollution, smoking and a poor diet, and all can speed up the process of oxidation and therefore the development of free radical damage if left unchecked (this has been blamed for many conditions including premature ageing).
What has that got to do with antioxidants?
Your body does however have a sophisticated method of keeping this oxidation in check. A group of nutrients called anti-oxidants swoop around the body soaking up and destroying any free radical molecules before they can cause any damage. Thankfully antioxidants can be found in abundance if we eat a nutritious whole-food diet. By this I mean a diet rich and varied in fruit, vegetables and whole grains.
Tell me more about what they are and where I can find them…
Perhaps the most well known antioxidants are vitamins A, C and E but there are also a very important group of nutrients called carotenoids. These are the chemicals that give fruit and vegetables their rich colour; for example the orange and yellow colours found in squashes and carrots are from the carotenoid beta carotene. Beta carotene is converted into an active form of vitamin A, known as retinol when in the body, a potent antioxidant. Lycopene is also a strong antioxidant and gives tomatoes their wonderful red colour. Lycopene has been shown to be especially effective at protecting from and repairing skin damage as well as supporting the prostate. Lutein and zeanthinin are also carotenoids receiving a lot of recent positive research. They demonstrate health promoting benefits for the eyes and for strengthening the immune defences. Their names are derived from their natural hue, with lutein derived from the Latin word luteus meaning golden yellow, zea referring to the corn genus, and xantho derived from the Greek word for yellow. While these carotenoids both have yellow pigments, they are found concentrated in foods of others colors, notably leafy green vegetables (kale, spinach, brocolli) as well as eggs, courgettes, corn and peas.
The eyes are repositories for carotenoids with lutein and zeaxanthin concentrated in the retina and lens. Observational studies have noted that higher dietary intake of lutein and zeaxanthin is related to reduced risk of cataracts and age-related macular degeneration. Research suggests that these carotenoids may promote eye health through their ability to protect the eyes from light-induced oxidative damage and ageing, through both their antioxidant actions and an ability to filter out UV light.
Flavonoids are another important group of antioxidants found in red wine and tea among others. Epidemiologists suggest that the reduced rates of heart disease in France may be due to the regular and moderated intake of red wine. These flavonoids are thought to protect the genetic material, or DNA, from free radical damage. Damage to DNA contributes to degenerative diseases such as Alzheimer's and Advanced Cognitive Decline. Green tea contains the highest amount of flavonoids of all tea varieties and exerts many health benefits including repairing skin damage and reducing the risk of some cancers.
Another less talked about antioxidant is a nutrient called alpha-lipoic acid. It is the only antioxidant that can easily interchange between the blood stream and the brain and has therefore been noted as being important in the prevention of strokes for those at high risk. A similar antioxidant, acteyl l carnitine, can delay the onset of age-related cognitive decline. This is where the cognitive functions of memory, mood and logical thinking decline with age and is the very result of an increase of free radical damage. As our bodies produce less of our own supply of antioxidants, the damage outweighs the repair and physical deterioration occurs. In a study conducted with mild age-related cognitive decline, significant improvements (memory, mood and response to stress) were seen in patients that had been given acetyl L carnitine. The antioxidant co-enzyme Q10 also looks promising for it's protective role in the cardiovascular system that includes the heart and arteries, as well as slowing the progression of Parkinson's or Huntington's disease.
Recent research has shown that antioxidants must work together to prevent free radical damage. For example when vitamin E has been neutralized it then becomes a very weak version of a free radical itself. However if it is taken in combination with vitamin C, the vitamin C will ‘recycle’ it so that vitamin E becomes an active antioxidant once again. Similarly vitamin C must be recycled by an antioxidant called glutathione so the same does not happen to it too. Antioxidants also need other team players in the nutrient group such as zinc, magnesium, copper and manganese to do their job optimally. Researchers have in fact found that a combination of vitamin C, E, betacarotene and zinc slows down the progression of age-related macular degeneration by 25%.